## Why Use Aluminum Fins?

According to the heat exchange application and operation, there are various materials.

The common ones are Aluminum, Alloy, Copper, Brass, Nickel, Titanium, Stainless Steel, Carbon Steel, etc, among which the aluminum and alloy are mostly used.

The basic performance for fin tube heat exchange should be with good solder ability and form ability, higher mechanical strength, good corrosion resistance and thermal conductivity. In spite of these, aluminum and alloy are also featured in extension and higher tensile strength increases under lower temperature. Around all world, especially for low temperature and compact heat exchange, they are widely applied.

Let’s see the feature of aluminum

1. Low Density
By alloying and heat treatment, it can reach the structural of construction steel. Suitable for various transportation, especially for small vehicle, reducing weight and consumption.
2. Good Corrosion Resistance
When under harsh conditions, the materials oxide from aluminum is non-toxic. With aluminum heat exchange, no worries that air or liquid inside will be destructed by oxide after long time.
3. Good Thermal Conductivity
Especially suitable for radiating fin, heat transfer evaporator and condenser.
4. High Yielding and resistance to die cutting.
It is easy for processing and forming.

## Fin Tube Ration Affected by Fin Height, Fin Thickness and Fin Pitch

When the fins are root-grounded on the base bare tube, in the case of heat from inside to outside, the heat will be transferred from fin root along fin height. It is also continuously transmitted to the surrounding fluid by convective heat transfer. As a result, the fin temperature gradually decreases along the altitude. This also illustrates that difference between fin temperature and ambient fluid temperature is reducing gradually and the heat change per unit is shrinking. Therefore, the effect of fin surface area on enhanced heat transfer is decreasing. The higher the fin, the contribution of the increased area to heat exchange is smaller.

Fin Height

Generally speaking, as for the high frequency welded fin tube applied in engineering project, when fin height is 15mm, the fin efficiency is about 0.8; when fin height is 20mm, the fin efficiency is decreased to 0.7. Based on this, 15mm is the best height. If fins height above 20mm, the fin efficiency will be very bad, so generally not adopted. However, for the aluminum fin on air cooler, height at 22-25mm are always adopted due to much better heat conductivity coefficient of aluminum than carbon steel.

How will fin pitch affect fin ratio?

Usually smaller pitch can effectively increase fin ratio. While considering the flow gas property and ash deposit , we should pay attention to following factors.

A. Serious heavy ash deposit

Such as electric furnace and converter in steel works and exhaust of industrial cellar furnace, the ash content is heavy. If fin tubes are used for heat exchange, larger fin pitch will be suggested. For example, if pitch above 10mm, it is necessary to add a air discharge and choose an air blower.

B. Occasion with small ash deposit but should also be cared.

Take exhaust on plant boiler and industrial boiler as example, 8mm fin pitch is suitable, but should be designed with self-blowing ability.

C. Occasion with no dust or light dust.

Such as exhaust on burning natural gas equipment or air cooler, fin pitch at 4-6mm is OK. For aluminum air cooler, 3mm as fin pitch is also chosen.

## Fin and tube heat exchangers

With careful design, aluminum exceeds copper-based systems on most key performance indexes – and it is less expensive. Today, all-aluminum design has established itself as the reference.

# Choosing aluminum alloys

When incorporating aluminum in your product, you need to use the correct alloys for the different components. But choosing a combination of alloys that ensures the highest degree of corrosion performance is challenging. Our competence helps you get the best results possible.

# Aluminum meets all design requirements

An all-aluminum fin and tube system can solve all design challenges, with direct cost benefits compared to the alternative with copper tubing:

• No galvanic corrosion between fin and tube
• No formicary corrosion, as aluminum is inherently immune to it
• Can be used in ammonia systems, copper can not
• Heat exchanger manufacturers save 20-25 percent on material costs
• All-aluminum is always easy to recycle

## Materials Choice In Heat Exchanger Design: Aluminum vs. Copper

From heat recovery to air coils and refrigeration to power plants, choosing the right material for heat exchangers — particularly with reference to thermal qualities, resistance to sag during brazing and corrosion resistance — is key.

Did you know that the best example of heat exchange in the natural world is as obvious as the nose on your face? Well, technically it is the nose on your face, which warms inhaled air and cools exhaled air. But heat exchanger design depends on much more than an intuitive understanding of biology.

It requires careful consideration of the operating environment, application and, crucially, the properties of the materials used.
Fortunately, choosing  materials becomes easier once you have assessed the environment and the application. If the heat exchanger will be operating outdoors, or in a processing plant with corrosive media, then a high corrosion resistance will be a necessity.

## How does a shell & tube heat exchanger work?

Likewise, design engineers must consider what fluid will be carried through the exchanger and specify materials accordingly.

For example, it could be critical that a substance remains pure while being passed through a standard shell and tube heat exchanger in a pharmaceutical processing application. In such an environment, the tubes must be made of an inert material, perhaps even an unconventional one that is non-metallic – such as glass.

Generally, the two most commonly selected materials for heat exchangers are aluminum and copper. Both metals have the optimum thermal properties and corrosion resistance to make them ideal choices, with most of the differences being application-specific.

# Copper for heat exchangers

The typical thermal conductivity of generic pure copper is 386.00 W/(m·K) at 20°C. This makes copper the most thermally conductive common metal, which, along with its relatively low specific heat — of approximately 0.385 J/(g·°C — underpins its popularity in heat exchangers.

These characteristics do bring with them a slightly elevated price. Most design engineers and product designers consider this one of the biggest deciding factors between copper and aluminium for smaller projects.

However, there are a few practical considerations to consider when using copper. The density of the material, for example, might mean that it is unsuitable for certain applications that require a lightweight heat exchanger.

Furthermore, opper has lower flexibility than aluminium, making it more difficult to form into certain shapes. Because of this, design engineers working on a plate fin exchanger, which is a type of heat exchanger that uses plates and finned chambers to transfer heat between fluids, might find that aluminium is a better fit for the fins.

In addition, it’s important that copper tubes are joined using brazing rather than soldering, as the latter has been known to create a build-up of substances at joints. This means that design engineers should also source copper with a good sagging resistance to reduce deforming during brazing.

## SWEP Brazed Plate Heat Exchanger (BPHE) is one of the most efficient ways to transfer heat from one medium to another.

There are some long-term corrosion considerations with copper as well. As the material ages, it can develop verdigris — a thin layer of patina, formed by oxidation over time, that gives the material a green hue.

It’s the same chemical reaction that has made the statue of liberty the iconic green colour it is today. This process typically takes 15 or more years, depending on how the material is maintained and its environment.

Of course, there’s no guarantee that the change in a heat exchanger’s external colour will be as well-received as the statue of liberty’s verdigris, so product designers may choose an alternative to copper to deliver a different aesthetic. In any case, the patina is dielectric and may lead to reduced thermal conductivity as it accumulates.

As a matter of fact, although corrosion resistance is not a natural property of copper, Lebronze Alloys, a leading French manufacturer of high-performance materials, has worked on alloy compositions that provide copper with good oxidation resistance, even when exposed to seawater.

Despite these factors, the thermal conductivity of copper arguably compensates for maintenance considerations with its efficient transference of heat. In some cases, copper’s high comparative thermal conductivity means that a copper tube can conduct heat as effectively as two aluminium pipes.

## Aluminium for heat exchangers

For design engineers that require a lighter, thermally efficient material, or are working to a tighter design budget, aluminum is the prime candidate.

Boasting a thermal conductivity of 237 W/(m·K) for pure aluminium or ~160 W/(m·K) for most alloys, aluminium is the third most thermally conductive material and arguably the most cost-effective. Aluminium also offers a specific heat of 0.44 J/(g·°C), making it very nearly as efficient at diffusing heat as copper.

Aluminium is also far more lightweight and flexible than copper, addressing many of the practical issues engineers might encounter with copper. It is far more malleable, so engineers designing a plate-fin exchanger for a gas furnace will find that it is better suited to the intricacies of the fins.

Metallic plate in a heat exchange machine and pump in the food industrial plant.

However, aluminium does typically have lower sag resistance than copper, making it more prone to deformation during the brazing process and after repeated heat cycles.

Fortunately, this can be counteracted by opting to specify an aluminium alloy that has been specifically formulated to bring the metal’s properties closer to that of copper, without significantly increasing the price.

For example, metal supplier Gränges provides aluminium alloy FA6825 H14SR that is suitable for heat exchangers in energy applications. This alloy is fortified with elements such as zinc and manganese to give the alloy a higher tensile strength after brazing. The metal forms large grains during the process, which improve its sag behaviour.

The characteristics of aluminium and copper are very closely matched in terms of suitability for heat exchangers, with the key deciding factor ultimately being the application’s practical requirements.

While the decision may not be as obvious as the nose on your face, design engineers can make it easier by understanding the properties of their materials.

## The Features of Aluminum Finned Tube

1. Good Corrosion Resistance

Under serious conditions, the oxide materials from aluminum are non-toxic. For heat exchange, no need to worry that air or liquid inside will be destructed by oxide even for a long time.

2. Low Density

By treatment as alloying or heat, it can be used as the structure of construction steel. Feasible for various transportation, especially for small vehicles to reduce weight and consumption.

3. High Yielding and resistance to die-cutting.

It is easy to process and form.

4. Good Thermal Conductivity

Especially compatible for radiating fin, heat transfer condenser and evaporator.

As a professional finned tube manufacturer, one of our leading products is aluminum finned tube. If you are interested in our products, please do not hesitate to contact us.

1. Finned tube has compact structure, easy and economical to install. It reduces the joints compared to bare tube, making installation more quickly and cost-saving, reducing the possibility of water leaking at the connection.
Simple for maintenance, you basically don’t need to maintain finned tubes after installation.
2. High efficiency, the finned tube is in full contact with the fin and aluminum pipe, the heat dissipation area is more than 7-8 times that of the bare tube, the inside is smoother, and the internal water flow resistance is small.
3. Long service life, the high mechanical strength of the combination of fins and pipes. The tensile strength is above 200Mpa.
4. Stable heat transfer performance. It has few temperature fluctuations, reduces the high-temperature corrosion and over-temperature damage of the metal surface.
5. Widely adaptable for heat exchange between air-air, air-liquid, liquid-liquid and various fluids.

# Categories of aluminum finned tube in different process technology and shapes

Applications of Aluminum Finned Tube

• Heat exchanger
• Air conditioner
• Air cooler
• Condenser
• Evaporators
• Food processing
• Refrigeration industries
• Economizer
• Preheater
• Industrial boiler
• Gas turbines
• Refining
• Petrochemical industries

# Why Use Aluminum Finned Tube?

Based on the heat exchange application, there are many kinds of materials, and which are Aluminum, Alloy, Copper, Brass, Stainless Steel, Titanium, Carbon Steel, Nickel, etc, while among them, the prominent one is aluminum, and it’s being commonly used.

The fundamental uses of finned tube heat exchange should be with good solderability and better mechanical strength, formability, good corrosion resistance and thermal conductivity. Aside from these, aluminum and alloy also have good advantages as in extension and higher tensile strength increases under lower temperature. All around the world, especially for places where are always at low temperature and compact heat exchange, aluminum finned tubes are widely applied.

Your best solution in heat exchange!

[email protected]

## Heat Exchanger Finned Tube – 8 types you should know about

Fig 1: Large Seven Fan Finned Coil cooler – copper tubes with bulleted aluminum fins

Finned tube heat exchangers generally use air to cool or heat fluids such as air, water, oil or gas, or they can be used to capture or recover waste heat. These heat exchangers can used in a broad range of industries including oil & gas, power generation, marine and HVAC&R.

Finned tube heat exchangers have a wide range of applications, a few of which are:

• diesel charge air coolers;
• oil coolers;
• hydrogen coolers;
• waste heat recovery;
• driers;
• air conditioning;
• air heaters;
• steam condensers;
• generator coolers

Finned tube heat exchangers are often used in circumstances where air is the preferred medium for the cooling or heating, particularly where there is limited or poor quality water.

In a finned tube heat exchanger, heat is exchanged between a thermally efficient fluid that transports heat efficiently, such as a liquid which has some viscosity, and a fluid that does not, such as air or gas with little density. On the ‘air side’, the tube surface is enhanced by the addition of fins or other elements such as looped wires, designed to increase the surface area of the tube and improve its thermal performance.

Fins can range in height (high-fin to low-fin) and the fins can be either pressure connected to the outer surface of the tube or formed into the tube surface.

Depending on the intended duty and the environment in which they are to operate, finned tubes can be manufactured in numerous designs and incorporate a combination of differing materials for both the tubes and the fins. The types and combinations of tubes and fins is significant, but in this article, we will explore only the more common types.

Fig. 2: Finned Tube Dry Air Cooler

Fin Profile

The profile of the fins has significant effect of the performance of a finned tube heat exchanger.  It is important to ensure each fin has a tight connection on the tube surface to provide maximum thermal conductivity.

The larger the fins and the tighter the fin pitch, the more thermal conductivity is achieved. The trade-off may be an increase in pressure drop which may, in turn, adversely affect performance. A balance between the two opposing functions is vital for effective and optimal thermal performance and equipment function.

Fig. 3: Typical Finned tube schematic with annular fins.
A = fin height; B = fin pitch, C = fin thickness and D = Diameter of

1. Elfin Technology

‘Elfin’ finned tubes are used extensively in hydro power generator coolers and have been chosen by hydro power stations such as Snowy Hydro, Hydro Tasmania and Origin Energy, to provide long lasting and reliable cooling of their important generators.

With the Elfin computer-generated technology, each fin strip is mechanically forced over the outside of tube, producing a tight and thermally efficient bond. This process ensures, not only excellent adhesion of the fin to the tube, but the vital inner tube wall is not compromised in any way.

Unlike Elfin tubes, bulleted tube fins are formed by passing a bullet inside the tube to enlarge and force its wall outward into the fins to form a bond with the fins.

Fig. 4: Elfin Technology – Titanium Fins and Titanium Tubes. Note the spacer lip on the fin ensuring exact pitch.

As can be seen in Fig. 4 the fins have been precision punched to leave an ‘L’ shaped lip that ensures exact fin pitch spacing between fins. The computerized punch process can adjust the tube pitch minutely to 0.01mm tolerance to conform with the exacting computer calculations. Elfin finned tubes are produced in blocks which are custom sized to fit the exact duty requirements and dimensions of the heat exchanger.

Bulleting require tubes that are sufficiently thin and ductile to allow for expansion however Elfin technology allows tubes of any wall thickness and material to be used and ensures the inner surface of the tube is not compromised and the strength of both the tubes and the fins is enhanced.

2. Bulleted Fins

With an external appearance similar to Elfin Finned Tubes, bulleted finned tubes are a common and cost-effective way to attach strip fins to tubes. This is achieved by manually placing the fins over the tubes and pushing or pulling a ‘bullet’ through the tube (“bulleting”) to expand the tube wall out into the fins, locking them in place.

Bulleting is commonly used in Fin Coil units found in applications such as HVAC&R and is a cost effective process which requires tubes that are of a material and thickness and sufficiently ductile to enable the tube to be expanded into the fins.

Helical Fins

Round or Helical Fins come in a number of geometries commonly identified by a letter corresponding to the profile of the base of the fin where it connects with the tube.

3. ‘L’ Finned Tubes

One common type of finned tube is the ‘L’ fin. Receiving its name from the letter it creates from the cross-sectional view, the ‘L’ fin relies on maximum surface contact between fin and tube which is ensured by tension-forming a fin strip helically around the base tube.

This type of connection maximizes the heat transfer capacity and enhances the corrosion protection of the tube. The ‘L’ fin accommodates temperatures between 150 to 170 °C and comes in mainly ductile metals such as aluminum or copper which are capable of withstanding the compression around the base of the fin and allow stretching on the outside during installation.

Fig. 9: Typical Heavy-Duty Dry Air Cooler or Condenser – commonly using copper, aluminium or carbon steel tubes with helical aluminium or galvanized fins.
Note the removable bolts in the header box which allow for inspection and cleaning of the tubes.

4. ‘LL’ Finned Tube

Manufactured in the same way as the ‘L’ finned tube, the ‘LL’ fin has overlapping feet to completely enclose the base tube, resulting in excellent corrosion resistance. The maximum operating temperature is approximately the same as the ‘L’ fin. This type of fin commonly available in aluminum and copper. The Overlapped “L” fin design has interlocking fins that are wound together to prevent movement and separation. The fins protect the entire tube and the designation works well for the applications where corrosion is an issue.

5. ‘KL’ Finned Tube

‘KL’ Fin Tubes are also called knurled finned tubes. The fin is wrapped around the tube and the foot is rolled into the outer surface of the pre knurled tube and secured at each end. The fins are manufactured from a strip of metal which is machined into an accurately controlled L shape foot, similar to the L type fin, then it is rolled into a taper causing it to curl. The tube surface is knurled by a rotating tool, then the foot of the fin is knurled into the base tube providing a tight bond that optimizes thermal transfer.

6. ‘G’ Embedded Finned Tube

The main design feature of Embedded Fin tubes involves the fin being inserted and welded into a helical groove cut into the tubes. G fins can be used in higher temperatures and are very durable. Embedded fins are best suited for use in high thermal cycling or high temperatures and where the fin side will be subjected to regular cleaning. This type of fin comes with a major limitation being the need for a minimum wall thickness of 1.65mm to accommodate the grooves. However, the ‘G’ type fin can withstand temperatures of up to 400°C and can incorporate carbon steel fins for better conductivity.

7. Extruded Finned Tube

This fin type is formed from a bi-metallic tube consisting of an aluminum outer tube and an inner tube of almost any material. The fin is formed by rolling material from the outside of the exterior tube to produce an integral fin with excellent heat transfer properties and longevity. Extruded fin offers excellent corrosion protection of the base tube and excludes virtually all exposure to any outside fluid.

Extruded finned tubes are used in high temperature conditions and corrosive atmospheric conditions such as:

• operating temperatures less than 300°C;
• offshore or other remote applications;
• heat pipes;
• dry air coolers for air, gas or oil;
• air to air heat exchangers for HVAC applications;
• air dehumidification in air treatment plants and
• energy recovery in air exhaust system.

Wire Finned Tube

Wire loop tube is a high efficiency tube consisting of a series of elongated wire loops enhancing the surface of the tube, spirally wound on to the tube wall and held in position with a binding wire at the base of the loops. The loops and binding wire are then soft-soldered to the tube wall to give a metallic bond between the wire loops and the tube.

The wire loop secondary surface gives these enhanced tubes excellent heat transfer characteristics due to its ability to promote turbulence in the fluid passing over it. Temperatures of up to 250 °C can be applied to this type of finned tube.

What next?

There are many variables  to be considered to successfully select and design a finned tube heat exchanger including:

• the duty to be performed;
• type, style and number of tubes required;
• metals best suited for the tubes and the fins;
• type of tube enhancement – fins or wire;
• thickness of the tube walls;
• I/D and O/D of the tubes;
• pitch of the fins;
• type and number of fans to provide air flow;
• the environment in which the heat exchanger is to be used and
• the duty it is required to perform

In a nutshell, an applied fin tube (also known as a Tube-Fin Heat Exchanger) is literally what the name suggests — a tube where the fin is applied as a separate material. This creates an annular fin helically wound around the tube that enables an enhanced surface to optimize cooling efficiency.

Applied fin tubes can come in many variations and multiple styles — even under the same tube manufacturer. Knowing which type of fin tube to use and what materials it should include can be critical to the success of the product. Use this blog as a guide.

An individually finned tube exchanger is characterized by helical serrated, slotted, or wavy fins in circular profiles. Fins are attached to the tubes by a tight mechanical bond through tension winding, soldering, brazing, or welding.

One perk to applied fin tubes is you can join 2 dissimilar materials in order to utilize the advantages of both. Similar metals are also common — say a copper tube with a copper fin. It depends on the application. Each material has its own advantages and considerations, depending on end use and effect on performance and efficiency.

For example, an aluminum fin can be applied to a stainless steel tube to maximize air cooling — a very common approach in the cooling industry.

Copper fin delivers superior heat transfer optimization — but can be susceptible to certain corrosion. On the other hand, stainless steel fin has a much lower heat transfer co-efficient but is highly resistant to corrosion and has superior tensile strength properties.

## Advantages & Factors to Consider in Applied Fin Tubing

The beauty of applied finned tubes is you can use alternative materials to enhance cooling efficiency, corrosion resistance, and control material costs.

Another advantage to applied fin tubes is to have balanced thermal conductance on both sides of the heat exchangers. This allows for a minimum-size heat exchanger.  Applied finned tubes support this by a large range of fins per inch (fpi) and fin heights to match the conductance requirements.

The right coatings can also be essential to the success of a bent applied fin tube — such as our Dura IB Brazed Edge Tension Finned Tube or our Dura IS  Soldered Edge Tension Finned Tube. The manufacturing process metallically bonds the fin to the tube using a metal filler. By solidifying and strengthening the bond of the fin, it can better endure bent formation or provide a surface coating.

That’s why applied fin exchangers are used extensively in heat recovery systems, as condensers and evaporators in transit cooling, generator coolers in electric power plants, oil coolers in propulsive power plants, air cooled heat exchangers in process and power industries, and steam coils in processing plants.

## Material Considerations of Applied Fin Tubes

There are generally 4 fin material types.

• Stainless steel
• Carbon steel
• Copper
• Aluminum

Options for tube materials are nearly unlimited depending on the Durafin® applied fin tube you are considering. There can be limitations depending on the material and function of the end product. It’s best to contact a sales specialist to help choose the right tube and best materials — based on manufacturability and performance needs of the end product.

Aluminum is a very common fin material. It’s affordable, very formable and easy to apply.

To achieve a high heat transfer, copper or aluminum fin material is generally preferred. The tradeoff to copper is it’s more expensive — but its superior rate of heat exchange can be worth the investment.

If the tube will be exposed to acidic tube side conditions and a high heat transfer is needed, then a stainless steel fin with a copper tube is ideal. If both sides are exposed to corrosion, then a stainless fin combined with a stainless tube works best.

For an application that is low cost and corrosion is not an issue, carbon steel is ideal as an affordable option. Carbon steel performs well in rough service applications.

Coatings can also be added to the fin or tube for protection against corrosion and the elements.

## Best Practices in Selecting Applied Fin Tubes

Which type of applied fin tube should you use — what materials should it include? That depends on the end product under the following considerations:

• Its operating environment
• Thermo-physical properties of fluids
• Thermo-physical properties of materials
• Mechanical/structural design
• Amount of heat exchange needed
• Cost
• Maintenance

Before deciding the materials and type of applied fin tube, be aware of the pressure the heat exchanger will operate under — and what working temperature you require.

Pay attention to the environment the tube will operate in. A fin tube with a high count of 15 fins per inch won’t function well in a dirty environment, for example — it will clog in a week and won’t perform well.

The beauty of applied fin tubes is the material wrapped around the tube to create edge tension — this way the tube and the fin expand together. With applied fin tubes, it can be decades before fins start to come loose — lasting 3 or 4 times longer than a metal plated approach.

An applied fin tube combines property advantages of varying materials. It delivers optimal cooling efficiency that stands the test of time.

Your best solution in heat exchange!

[email protected]

## Coil Type Heat Exchanger

The Coil Type Heat Exchanger produced by metal industries are suitable to transfer heat in a wide variety operating conditions and to refuse to accept decay for the longest period time possible under the harshest operating circumstances. Coil type exchangers are more efficient than shell and tube exchangers for low flow rates. Due to their simple construction they are low in price and easy to clean on the shell side. Thermal efficiency approximates that a true countercurrent flow type exchanger. Condensers are used for condensation vapors cooling liquids. Condensers are made by fusing number parallel coils in a glass shell. Coil Type Heat Exchanger are artificial to special requirements as to dimensional tolerances, finish and tempers for use in condensers and heat exchangers. Copper heat exchanger tubes are normally supplied in straight length in annealed half hard temper. Coil Type Heat Exchanger shaped by are metal industries not only have the stiff tolerances the most dependable dimensions throughout the tube length. The tube surface is clean both inside. Coils are made in different diameters using tubes different bores.

Specifications :

• The Coil Type Heat Exchanger properties of copper are exploited in copper wires and devices such as electromagnets.
• Vacuum tubes, cathode ray tubes, and the magnetrons in microwave ovens use copper, as do wave guides for microwave radiation.Copper’s greater conductivity versus other metallic materials enhances the electrical energy efficiency of motors.
• Coil Type Heat Exchange is important because motors and motor-driven systems account for of all global electricity consumption all electricity used by industry.
• Coil Type Heat Exchanger, a new technology designed for motor applications where energy savings are prime design objectives, are enabling general-purpose induction motors to meet and exceed National Electrical Manufacturers Association premium efficiency standards.

Applications :

• The Coil Type Heat Exchanger applications of copper are in electrical wires, roofing and plumbing and industrial machinery. Copper is mostly used as a metal, but when a higher hardness is required it is combined with other elements to make an alloy such as brass and bronze.
• Coil Type Heat Exchange of copper supply is used in production of compounds for nutritional supplements and fungicides in agriculture.
• Machining of copper is possible, although it is usually necessary to use an alloy for intricate parts to get good machinability characteristics.

• Coil Type Heat Exchanger circuits and printed circuit boards increasingly feature copper in place of aluminum because of its superior electrical conductivity see Copper interconnect for main article heat sinks and heat exchangers use copper as a result of its superior heat dissipation capacity to aluminum.
• Coil Type Heat Exchanger the mass and cross section of copper in a coil increases the electrical energy efficiency of the motor.

## Advantages and Disadvantages of Shell and Tube and Plate Type Heat Exchangers

Heat exchanger tubes have now turned into a vital part of every home. They are utilized for brilliant residential water heating and also to heat swimming pools and spas. Nonetheless, heat exchanger tubes have turned out to be extremely popular as a result of their composed structure and higher heat exchange rates.

Plate Type Heat Exchangers

• They are simple and compact in size
• Heat exchange effectiveness is more
• Can be effortlessly cleaned
• Dismantling takes no extra space
• By introducing plates in pairs, capacity can be expanded
• Leaking plates can be expelled in sets without substitution, when required
• Maintenance is straightforward
• Turbulent stream helps to bring down deposits which would otherwise meddle with heat transfer

• Initial cost is high since titanium plates are expensive
• Finding spillage is troublesome since weight test isn’t easy
• Bonding material between plates limits working temperature of the cooler
• Pressure drop caused by plate cooler is higher than the tube cooler
• Dismantling and assembling is very time consuming
• Over fixing of the clipping jolts results in expanded weight drop over the cooler
• Joints may run down because of  the working conditions
• Since titanium is a pure metal, different parts of the cooling system are exposed to erosion

Shell and Tube Heat Exchangers

• Less costly as compared to plate type coolers
• Can be utilized as a part of frameworks with higher working temperatures and weights
• Pressure drop over a tube cooler is less
• Tube leaks are effortlessly found and stopped since pressure test is simple
• Tubular coolers in refrigeration framework can go about as recipient also.
• Using sacrificial anodes secures the entire cooling framework against erosion
• Tube coolers might be favored for greasing up oil cooling as a result of the weight difference

• Heat exchange effectiveness is less as compared to plate type cooler
• Cleaning and maintenance is troublesome since a tube cooler requires enough leeway toward one side to expel the tube nest
• Capacity of tube cooler can’t be expanded.
• Requires more space in contrast with plate coolers

## Heat Transfer in Helical Coil Heat Exchanger Abstract

The research paper tends to review the effectiveness of helical coil in heat exchangers (HCHE). Heat exchanger is a device used in transferring thermal energy between two or more fluids or solid interfaces and a fluid, in solid particulates and a fluid at different temperatures and thermal contact. The author has concisely discussed the helical coil in heat exchanger at different shapes and conditions and compared the HCHE with straight tubes heat exchangers, and the factors affecting the performance and effectiveness of the helical coil heat exchanger such as the curvature ratio, and other heat exchangers. The author demonstrated that the HCHE provided more excellent heat transfer performance and effectiveness than straight tubes and other heat exchangers because of secondary flow development inside the helical tube, and heat transfer coefficient increased with an increase in the curvature ratio of HCHE for the same flow rates. The secondary flow and mass flow rates, advantages and disadvantages have also been reviewed. The authors back their findings with available theories. Suitable fluid should be searched for high efficiency in the helical coil.

Keywords

1. Introduction

A heat exchanger is a device that is used to transfer thermal energy (enthalpy) between two or more fluids, between a solid surface and a fluid, or between solid particulates and a fluid, at different temperatures and in thermal contact [1] [2]. In global industrialization, efforts have been made to increase heat transfer rate, minimize the size of heat exchangers, and to improve the effectiveness of heat exchangers. Helical coil heat exchanger (HCHE) offer distinct advantages, such as improved thermal efficiency, compactness, easy maintenance and lower installed cost [3]. Heat transfer in helical coils has been studied and researched, because of the fluid dynamics inside the pipes of a helical coil heat exchange [4]. Helically coiled tube heat exchangers are the most widely used from the family of coiled heat exchangers [5].

Helical coil configuration is very effective for heat exchangers due to their excellent heat transfer performance and compact size as compared to straight tube heat exchangers [6] [7] [8] [9] [10]. The application of curved tubes in laminar flow heat exchange is highly beneficial than straight tubes [11]. Heat transfer rate of helical tube is significantly higher because of the secondary flow caused by the centrifugal force [12] [13]. The development of secondary flows (Dean vortices) in these helical tubes enhances the radial mixing, while keeping a low axial back-mixing behaviour thus increases heat and mass transfer and leads to narrower residence time distributions [14].

According to [15], the secondary flows constitute two sets of distinct re-circulating vortices along the diameter of tube as shown in Figure 1. This secondary flow has the ability for heat transfer enhancement due to mixing of fluid in the tube [4]. [16] reported that the improvement in heat transfer rate in curve tube tubes was due to the centrifugal force which pushed the fluid particles toward the core region that produced a secondary flow field. The intensity of secondary flow [17] [18] developed in the tube is the function of tube diameter (d) and coil diameter (D). This increase in intensity of secondary flow allows proper mixing of the fluid, which enhances heat transfer coefficient for the same flow rate. [19] reported the increase in tube and coil diameter, reduced the secondary flow developed and in turn reduced heat transfer coefficient.

1.1. Heat Transfer Characteristics in Coiled Tubes

Helically coiled tubes are useful for various industrial processes such as combustion systems, heat exchangers, solar collectors, and distillation processes because of their simple and effective means of enhancement in heat and mass transfer

[21]. According to [22], the heat transfer characteristics in coiled tubes are determined by the peculiarities of the axial velocity distribution and of secondary flow as shown in Figure 1. Secondary flow arises in the form of a pair of symmetrical vortices in the cross-section along the tube axis, the fluid trajectory is in the form of a double coil. Hence, the mean heat transfer coefficient for laminar flow in coiled tubes is given by the Equation (1).

Nu¯¯¯¯¯=0.06Re0.7Pr0.43(PrfPrw)0.25(d/Dcoil)0.18Nu¯=0.06Re0.7Pr0.43(PrfPrw)0.25(d/Dcoil)0.18(1)

where Pr is Prandtl number Prf of fluid and Prw of water, Re is Reynolds number, d is the tube diameter, Dcoil is the coil diameter, Nu = αL/λ is Nusselt number which is the dimensionless parameter characterizing convective heat transfer where α is convective heat transfer coefficient, L is representative dimension (e.g., diameter for pipes), and λ is the thermal conductivity of the fluid. Nusselt number is a measure of the ratio between heat transfer by convection (α) and heat transfer by conduction alone (λ/L). Figure 2 shows the necessary parameters of shell and tube HCHE, where Pc is the coil pitch.

For turbulent flow in coiled tubes, the heat transfer coefficient distribution around the tube perimeter is essentially non-uniform. The non-uniformity is caused by the non-homogeneity of the flow velocity and temperature distributions which can cause heat transfer from the inner to the outer generatrix. [22] showed that the mean Nusselt number for a coiled tube is greater than that of straight tube and the heat transfer coefficient also increased with a decrease in the ratio of coil diameter to tube diameter (Dcoil/d). [24] reported that coiled tubes have better heat transfer coefficient and residence time distributions and were therefore used in compact heat exchangers. Also, the application of flow and helical coils in heat exchangers and reactors are due to higher heat and mass transfer coefficients with narrow residence time distributions and compact structure [25].

1.2. Helical Coil Heat Exchanger Overview

According to researchers, HCHE are broadly used in heating and cooling applications such as heat recovery system, food industries, nuclear power plant, chemical processing, solar water heater, and refrigeration and air-conditioning units [16] [26] – [32]. [33] reported that the HCHE showed increase in the heat transfer rate, effectiveness and overall heat transfer coefficient over the straight tube heat exchanger on all mass flow rates and operating conditions. Heat transfer enhancement is one of the key issues of energy saving and compact designs [34].

[35] reported higher temperature drop for helical coil tube when compared to straight tube heat exchanger due to the curvature effect of the helical coil. [36] reported the use of HCHE in falling film evaporator for energy saving by recycling the heat from vapour due to larger surface area in a small volume and are therefore used for applications with small temperature difference or high volumetric heat rating [24]. [37] reported the use of HCHE in heat recovery from exhaust gases using refrigerant R134a and R245fa and showed that refrigerants are better than water as a thermal fluid. HCHE offers distinct advantages, such as improved thermal efficiency, compactness, easy maintenance and lower installed cost [3].

[16] reported that HCHE had advantages over conditions of low flow rates or laminar flow unlike a typical shell-and-tube exchanger which exhibited low heat-transfer coefficients at low flow rate thus becoming uneconomical especially, when there exists low pressure in one of the fluids, usually from accumulated pressure drops in other process equipment. However, when an application requires equipment suitable for high operating pressure and/or extreme temperature gradients, a helical coil unit should be considered [3]. Cleaning of helical coils for these multiple-phase fluids can prove to be more difficult than shell and tube counterpart; however the helical coil unit would require cleaning less often [38]. Hence, the main disadvantages of HCHE are that they cannot be cleaned easily and are therefore not suitable for crystallization type of applications [24].

2. Mass and Heat Transfer in Helical Coil Heat Exchanger

Heat transfer on HCHE depends largely on the coil size, tube size, mass flow rate, type of thermal fluids and number of turns [39]. Studies involving helical coils and heat exchange have focused on two major boundary conditions, namely 1) constant wall temperature and 2) constant heat ﬂux [32] [40]. [41] considered natural convection boundary condition for HCHE outer surface while modelling the performance of two HCHE placed into the storage tank. They reported that heat transfer rate through the coil depends on 1) inner coil convection process 2) outer coil convection process 3) the conduction through the tube wall and 4) the fouling resistances on the inner and outer HCHE surfaces.

Heat transfers in the HCHE can be analyzed by force convection [42] [43] [44] [45], natural convection [32] and mixed convection [46]. Mixed convection, simply is a combination of forced and free convections. According to [47], mixed convection flow is determined simultaneously by both an outer forcing system (the outer energy supply to the fluid system) and inner volumetric or mass forces (which is the non-uniform density distribution of a fluid medium in a gravity field). [48] analyzed the variation in the temperature drop, heat transfer rate and pressure when the numbers of turns in a double tube helical coil heat exchanger are changed. From the study, they showed that:

1) As the number of turn increases, the temperature drops of hot fluid also increased.

2) The increase in number of turns resulted in higher rate of heat transfer.

3) Temperature at the outlet of hot fluid was found to be more at the location far from the coil axis as compared to nearer location.

4) As the number of turn increases, the absolute pressure inside the coil also increased, and it was maximum at inlet section of outer cold fluid.

5) The pressure at the inlet and outer fluid was maximum at the point far from the coil axis.

According to [48], double tube HCHE offers certain advantages over the straight tubes shell and tube type heat exchanger, in terms of better heat transfer and mass transfer coefficients due to its fluid dynamics inside the pipe of double tube HCHE.

[49] presented a comparative analysis of the different correlations given by the different researchers for HCHE and established the overall effect of these parameters on Nusselt numbers and heat transfer coefficient. The analysis showed that helical coils were efficient in low Reynolds numbers. Also, at constant coil diameter (D), increase in the tube diameter (d) increased the curvature ratio (δ), which led to the increase in the intensity of secondary flow developed in fluid flow. The increase in the intensity of secondary flow developed in fluid flow increased the Nusselt numbers. Hence, it was desirable to have small coil diameter (D) and large tube diameter (d) in helical coil heat exchanger, for large intensities of secondary flow in tube.

[33] reviewed on forced convection through HCHE. In the review, it was found that forced convection fluid motion took place by external force so that the fluid velocity was high and heat transfer coefficient was high. The results showed that HCHE showed increase in the heat transfer rate, effectiveness and overall heat transfer coefficient over the straight tube heat exchanger on all mass flow rates and operating conditions as also confirmed by [50].

The computational fluid dynamics (CFD) simulation was carried out to study the variation of coil diameter of HCHE with mass flow rate of water at inlet temperature of 332 K [51]. In the study, temperature drop, heat transfer rate, heat transfer coefficient and Nusselt number were compared with the geometric variations and variation in mass flow rate. Results showed that the temperature drop decreased for decreased in coil diameter and increased in mass flow rate whereas heat transfer rate increased with increase in coil diameter and mass flow rate.

[52] investigated heat transfer and fluid flow characteristics for both Newtonian and non-Newtonian fluids in tube-in-tube helical coil (TTHC) heat exchangers numerically with and without baffles in both parallel and counter flows. The results showed that the frictional and Nusselt number is higher in the TTHC heat exchanger with baffles in the annulus compared to the TTHC heat exchanger without baffles. Also, the TTHC heat exchanger with baffles had significant influence on heat transfer at low Prandtl number whereas at high Prandtl number, the flow configuration had high significance in heat transfer.

[53] studied helical coiled double pipe heat exchanger for counter flow. Characteristics of the fluid flow were also studied for the constant temperature and constant wall heat flux conditions. From the results, Nusselt number increased with increase in curvature ratio. Also, the value of Nusselt number was found to increase with increase in mass flow rate (i.e. inlet velocity). With increase in the ratio of coil diameter to tube diameter (D/d), (inverse of curvature ratio), the Nusselt number and frictional factor decreased for a particular value of Reynolds number (Re). Nusselt number and frictional factor had maximum value for D/d = 10 and minimum value for D/d = 30.

[54] studied the effect of increase in inner coil flow rate for a constant flow rate in the annulus region for double pipe HCHE and observed that the overall heat transfer coefficient increased with increase in inner coil flow rate for a constant flow rate in the annulus region. Also, different characteristics were observed for different flow rates in the annulus region for a constant flow rates in the inner-coiled tube. Also, three-dimensional analysis was used to study the heat transfer characteristics of a double-tube HCHE using nanofluids under laminar flow conditions by [55]. The results showed that for 2% CuO nanoparticles in water and at the same mass flow rate in inner tube and annulus, the heat transfer rate of the nanofluid was approximately 14% greater than of pure water. The results also showed that the convective heat transfer coefficients of the nanofluids and water increased with increase in the mass flow rate and the Dean number.

[56] analyzed the heat transfer and pressure drop of conical coil heat exchanger with various tube diameters, fluid flow rates and cone angles with hot and cold water of flow rate 10 to 100 liters per minute (Re range 500 to 5000) and 30 to 90 per minute respectively. The temperatures and pressure drop across the heat exchanger were recorded at different mass flow rates of cold and hot fluid. The various parameters (heat transfer coefficient (h), Nusselt number (Nu) effectiveness (ε) and friction factor (f)) were estimated using the temperature, mass flow rate and pressure drop across the heat exchanger. The analysis indicated that, Nu and f is function of flow rate, tube diameter, coil angle, and curvature ratio. Increased in tube side flow rate increased Nu, whereas it reduced with increase in shell side flow rate. Increased in coil angle and tube diameter, reduced Nu.

[29] worked on mixed convection heat transfer in vertical HCHE with various Reynolds numbers and Rayleigh numbers and various tube to coil diameter ratios and different coil pitch. The effect of tube diameter, coil pitch, shell-side and tube-side mass flow rate was assessed over the performance coefficient and modified effectiveness of vertical HCHE in both laminar and turbulent flow inside coil. The result showed effective axial temperature profiles of heat exchanger on the mass flow rate of tube-side to shell-side ratio. Also, the ε—NTU model relation of the mixed convection heat exchangers was the same compared to that of a pure counter-flow heat exchanger.

[57] designed the heat exchanger for maximum values of the flow rates at the tube and shell side respectively. The maximum heat transfer of 41 kW with the pinch point temperature difference was fixed at 10 K. In this study, the hot side inlet temperature of the water was 95˚C, while the cold side was an organic fluid, R-404A refrigerant circulated with an inlet temperature of 27˚C, resulting in a pinch point temperature difference at the outlet of the heat exchanger of 10˚C. The mass flow rates of both fluids were fixed at 2.5 kg/s and 0.25 kg/s at the hot and cold side respectively. The results showed that, at higher mass flow rate of the organic fluid, increase in heat transfer in the HCHE was achieved.

Comparing the results from the measurements with the designed specifications gave an enhanced heat transfer of ~10%. Moreover, from the thermal match analysis, a pinch point temperature difference of only 2˚C was reached at the exit of the heat exchanger, which is lower than the designed value of 10 K. From the arguments mentioned in this work, [57] concluded that a more accurate design of the heat exchanger with appropriate correlations could lead to increase in heat transfer and the cycle efficiency, and hence, a new and more accurate correlation for an optimal design of this heat exchanger needs to be derived.

Effectiveness of Helical Coil Heat Exchanger

The effectiveness of heat exchangers is the ratio actual heat transferred to the heat that could be transferred by heat exchanger of indefinite size, and this can be achieved when the heat transfer power is increased or when the pressure losses generated is reduced. [58] reported that the effectiveness of heat exchangers depends on the convection heat transfer coefficient of the fluid. [59] studied the effectiveness of helical coil and straight tube heat exchangers by varying the inlet temperature of the hot water. From the results, it was found that the HCHE had better effectiveness than straight tube heat exchanger for all the inlet temperatures of water. Also, [59] confirmed that the effectiveness of HCHE is found to be higher for all the inlet hot water temperatures when compared to that of the straight tube heat exchanger.

[60] also vary parameters like number of coils, flow rate and temperature to study the effectiveness of a heat exchanger. The results showed that the heat transfer was higher for both parallel and counter flow in HCHE as compared with the straight tube heat exchanger. However, [61] compared the effectiveness of helical coil and straight tube heat exchanger, using mass flow rate of hot water and cold water in both parallel and counter flow configuration. The study showed that, the effectiveness increased with increase in cold water mass flow rate for constant hot water mass flow rate and vice versa for both helical coil and straight tube heat exchangers with parallel and counter flow configuration. But, HCHE counter flow was more effective in all these conditions than the straight tube parallel flow heat exchanger.

[4] concluded that HCHE was seen to increase the heat transfer coefficient compared to a similarly dimensioned straight tube heat exchanger. The improvement of thermal conductivity of based fluid with addition of nano particles increased the effectiveness of HCHE [62] and maximum effectiveness was obtained for CuO/water nanofluid. The determination of convective heat transfer coefﬁcient in both helical and straight tubular heat exchangers under turbulent ﬂow conditions was experimented by [63] using HCHE with coils of two different curvature ratios (d/D = 0.114 and 0.078), and in straight tubular heat exchangers at various ﬂow rates (1.89 × 10−4 – 6.31 × 10−4 m3/s) and for different end-point temperatures (92˚C – 149˚C). The results showed that the overall heat transfer coefﬁcient (U) in the HCHE is much higher than that in straight tubular heat exchangers. In addition, U was found to be larger in the coil of larger curvature ratio (d/D = 0.114) than in the coil of smaller curvature ratio (d/D = 0.078).

[64] experimentally investigated the condensation heat transfer of R-134a in horizontal straight and helically coiled tube-in-tube heat exchangers. The experiments were carried out at three saturation temperatures (350, 400 and 450˚F) with the refrigerant mass flux varying from 100 kg/m2∙s to 400 kg/m2∙s and the vapour quality ranging from 0.1 to 0.8. The effects of vapour quality and mass flux of R-134a on the condensation heat transfer coefficient were investigated. The results indicate that the condensation heat transfer coefficients of the helical section were 4% – 13.8% higher than that of the straight section.

[65] has applied the efficiency and effectiveness method and has obtained promising results. These results are why the efficiency and effectiveness method is used in a relatively complex and without similar problem or conflicting interest.

## Coil Heat Exchangers: Applications and Advantages

When it comes to heat exchangers, coil heat exchangers specifically are ideal for applications including boiler air preheating, pulp dryers, unit heaters, condensing and cooling as well as high-pressure, air tempering and dryer applications. Depending on the application, there are many types and styles of coil heat exchangers to choose from. Some of these include stainless tube bundles, double-pip heat exchangers, stainless steel tube immersion coil, bare tube immersion cooler, gas to water cooler, tedson coil heat exchangers, copper coil heat exchangers, combination ambient air/chiller water cooler, or coil tube-in-shell design to name a few. Each of these may also come in a variety of sizes and each have specific advantages. However, coil heat exchangers in general can be expected to have many advantages overall as well.

Photo courtesy of HEXECO, Inc.

Some advantages of coil heat exchangers include high efficiency, flexibility, low pressure drop, they require little maintenance, are compact and lightweight, and are also easy and inexpensive to install. Coil heat exchangers tend to have higher efficiency than other types because of the large number of closely aligned tubes. This design aspect enlarges the heat transfer area, which results in a higher heat transfer coeffient overall. This efficiency equates to higher production while using less energy and that means big savings both upfront and in the long run. The coil type heat exchanger is also known for being compact and lightweight due again to the closely packed tubes. The exchangers’ compact, lightweight design as well as their unique vertical orientation also means that they will take up less space and will be easier and less expensive to install. Their lightweight and compactness also lends to the flexibility mentioned earlier.

Another advantage of these heat exchangers is that there are many options when it comes to model types and configurations, which means they can be used with a wide variety of temperatures, flows and pressures. This flexibility equates to greater value overall. In addition to the benefits I just mentioned, coil heat exchangers also have low pressure drop and require little maintenance as the structure of the tubes allows for turbulent fluid flow, which minimizes fouling and scale build up. They can also be easily removed from the piping system to be flushed if that is necessary. Saving time and money both on installation and maintenance can go a long way for your business, and allows for overall smoother operations and less hassle and frustration.

Your best solution for heat exchange!

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## An Introduction to Coil Heat Exchangers

Coil heat exchangers in their simplest form, use one or more tubes that run back and forth a number of times. The tube separates the two fluids. One fluid flows inside the tube and another flows on the outside. Let us have a look at a heating example. Heat is transferred from the hot inner fluid to the tube wall via convection, it then conducts through the pipe wall to the other side and the outer fluid carries this away also through convection.

The Coil Type Heat Exchanger produced by metal industries are suitable to transfer heat in a wide variety of operating conditions and to refuse to accept decay for the longest period of time possible under the harshest operating circumstances. Coil-type exchangers are more efficient than shell and tube exchangers for low flow rates. Due to their simple construction, they are low in price and easy to clean on the shell side. Thermal efficiency approximates that of a true countercurrent flow type exchanger.

Condensers are used for condensation vapors cooling liquids. Condensers are made by fusing a number of parallel coils in a glass shell. Coil Type Heat Exchangers are artificial to special requirements as to dimensional tolerances, finish and tempers for use in condensers and heat exchangers.

Copper heat exchanger tubes are normally supplied in straight length in annealed half-hard temper. Coil Type Heat Exchangers shaped by are metal industries not only have stiff tolerances the most dependable dimensions throughout the tube length. The tube surface is clean both inside. Coils are made in different diameters using tubes different bores.

## The Applications of Coil Heat Exchangers

When it comes to heat exchangers, coil heat exchangers specifically are ideal for applications including boiler air preheating, pulp dryers, unit heaters, condensing and cooling as well as high-pressure, air tempering, and dryer applications. Depending on the application, there are many types and styles of coil heat exchangers to choose from.

Some of these include stainless tube bundles, double-pip heat exchangers, stainless steel tube immersion coil, bare tube immersion cooler, gas to water cooler, copper coil heat exchangers, combination ambient air/chiller water cooler, or coil tube-in-shell design to name a few. Each of these may also come in a variety of sizes and each has specific advantages. However, coil heat exchangers, in general, can be expected to have many advantages overall as well.

## The Advantages of Coil Heat Exchanger?

Some advantages of coil heat exchangers include high efficiency, flexibility, low-pressure drop, they require little maintenance, are compact and lightweight, and are also easy and inexpensive to install. Coil heat exchangers tend to have higher efficiency than other types because of the large number of closely aligned tubes. This design aspect enlarges the heat transfer area, which results in a higher heat transfer co-efficient overall.

This efficiency equates to higher production while using less energy and that means big savings both upfront and in the long run. The coil-type heat exchanger is also known for being compact and lightweight due again to the closely packed tubes. The exchangers’ compact, lightweight design as well as their unique vertical orientation also means that they will take up less space and will be easier and less expensive to install. Their lightweight and compactness also lend to the flexibility mentioned earlier.

Another advantage of these heat exchangers is that there are many options when it comes to model types and configurations, which means they can be used with a wide variety of temperatures, flows, and pressures.

This flexibility equates to greater value overall. In addition to the benefits I just mentioned, coil heat exchangers also have low-pressure drops and require little maintenance as the structure of the tubes allows for turbulent fluid flow, which minimizes fouling and scales build-up. They can also be easily removed from the piping system to be flushed if that is necessary. Saving time and money both on installation and maintenance can go a long way for your business, and allows for overall smoother operations and less hassle and frustration.

## How Hot Water, Boosters and Reheat Coils Work

Hot water coils are a type of heat exchanger often called hydronic coils that use hot water from a boiler to heat or remove moisture from the air. The air moves through the fins of the coil which is hot from water flowing through the tubes. This is a type of heat exchanger mostly used in commercial and industrial air handler units, roof top units as well as ductwork installations downstream.

In parts of the country and world, you may be more familiar with radiant heat or baseboard heat. Those particular units do not have air moving through them but simply radiates the air near the units. Hot water coils on the other hand are used in forced air systems and booster coils or reheat coils are used in ductwork downstream to reheat the air that has cooled off.

## Hot Water Coil Components Explained

Hot water coils are one of the simplest parts to an HVAC unit, but it can be important to know the parts so you know what type of connections and where they need to be located. Similar to chilled water coils, If and when a coil is to leak it usually happens in the copper u-bends. But with hot high pressured water, it will first leak at the weakest place which can be on a return bend or in the middle of the coil. When patching a leak in the middle of the coil it will significantly destroy that area causing the coil to lose a great deal of efficiency.

No matter how simple a hot water coil or reheat coil is, you still have options of what materials you should use.

As I mentioned before, one way to protect coils from corrosion-causing materials is to apply coatings. Selecting the right materials for chilled water coils and hot water coils is also important.

All types of industrial plants require coils – chemical plants, water treatment plants, food processing plants … the list goes on and on. Regardless of the type of plant, corrosive materials (carbon and carbon compounds, chlorides, metal oxides, sulfates and sulfuric acid, etc.) are often found inside. These materials can lead to general corrosion and/or localized corrosion in coils, such as pitting and formicary corrosion.

When ordering chilled water coils and hot water coils for industrial plants, there are different materials to choose from. Selecting materials for water coils that are corrosion-resistant offer the most value, even if the initial investment is higher, because coils won’t need to be replaced as often. For example, stainless steel is best suited for use in oxidizing environments, where corrosion resistance is needed. We use stainless steel for tubes and fins.

## Water Coils

Water is the most abundant medium for heating and cooling applications. Luckily there’s a water coil from SPC for just about any hot or cold water application.

We have over 30 years’ experience in the design and manufacture of coils. There are few, if any, design and specification issues that we have not addressed before. When you specify a coil from SPC, you’re sourcing it from the coil experts.

Efficient transmitters of heat energy

A water coil is a heat exchanger. It transfers heat energy between water and another medium (usually air) as quickly and efficiently as possible. Heating coils transmit energy from hot water to a stream of air, cooling coils extract energy from an air stream and add it to cold water.

The coils themselves consist of a matrix of copper tubes through which the water flows. The tubes run back and forth between two end-plates in an arrangement that lets the air flow perpendicular to the tubes. The tubes pass through – and are attached to – a layered array of thin metal plates known as fins. The fins are also perpendicular to the tubes, which means they lie parallel to the direction of air flow. The air flows between them. Energy either passes from the water via the tubes and fins to the air, or from the air via the fins and tubes to the water.

Economy Coil The efficiency of this arrangement depends on the types and thickness of metal used, the integrity of the bond between tubes and fins, the number and the layout of the tubes and fins, the air flow, and the water flow. Our skill lies in pulling all those elements together to make a coil that’s right for your application.

Types of water coil

Heating coils are characterized by the temperature of the water that passes through them.

Low-grade hot water (LGHW) – typically below 60°C. LGHW is associated with condensing boilers or waste water that has already lost much of its heat.
Low-pressure hot water (LPHW) – typically between 60°C and 110°C. LPHW is the most common medium for coil heat exchangers.
Medium-temperature hot water (MTHW) – typically between 110°C and 130°C. To keep water liquid above 100°C requires additional pressure. 120°C requires a pressure of 200kPa (2 bar).
High-temperature hot water (HTHW) – typically above 130°C. The most demanding condition for coil design. 140°C requires a pressure of 360kPa (3.6 bar).

When discussing heating coils, the terms ‘low-‘, ‘medium-‘, and ‘high-temperature’ are interchangeable with ‘low-‘, ‘medium-‘, and ‘high-pressure’.

Cooling coils are characterized by the amount and type of anti-freeze used.

Pure water is the most common medium. It’s used in applications that do not require the water temperature to fall below 0°C, or where there’s no risk of freezing.

The introduction of anti-freeze adversely affects the heat transferring properties of water. The increased viscosity slows flow rates through the coil. Anti-freeze concentrations above 30% require specialist pump equipment. They are not recommended.

Ethylene glycol solution (EGS) is the more efficient and the most widely-used of the two anti-freeze solutions.
Propylene glycol solution (PGS) is always used in the food industry because it is less toxic.

Cooling coils are supplied with a drain pan when condensation from latent cooling is anticipated. Where physical parameters constrain the surface area of the coil, moisture eliminators can be incorporated to prevent moisture carry-over.

Heat exchangers and electric heaters, of whatever design, serve a common purpose: to change the temperature of liquids or gases. However, there are some differences. The two most significant differences probably are: Electric heaters, as the name suggests, are for heating purposes only. Heat exchangers can be designed both for heating and for cooling.

While in heat exchangers a service fluid heats a process fluid without both having direct contact with each other, in electric heaters only the fluid to be heated is in the process. Here, heating is made by means of tubular heating elements immersed directly in the process fluid. Tubular heating elements consist of a coiled resistance wire centered in a tube and electrically isolated from the tube wall with highly compacted magnesium oxide, ensuring a high dielectric strength and excellent heat transfer from the wire to the tube and from the tube to the fluid being heated.

At first glance, this seems to be very interesting. Instead of heating in some way a service fluid, which then heats the process fluid, the required amount of heat is transferred from electric heating elements directly to the process fluid. Significantly lower heat losses through reduced piping, elimination of double temperature control (for service and process fluids) and maintenance-prone control valves.

At least here, a very appropriate question arises: do electric heaters intend to replace traditional heat exchangers? This question is easy to answer: NO. Each of the two heating systems offers some advantages over the other. But both also have their technical limitations, so they cannot be applied to every heating process. Therefore, it is worthwhile to make a closer comparison between both methods.

Process temperatures

If a heating process requires very high final temperatures, heat exchangers are in disadvantage compared to electric heaters. Regardless of their efficiency, heat exchangers can heat the process liquids to just below the highest temperature of the service fluid. Operating fluids may be, as required, hot water (under pressure up to 150°C), steam (up to 375°C at 221 bar), mineral or synthetic heat transfer oils (up to 400°C). The final temperatures of the process liquids are thus always slightly lower than those of the operating fluid.

Electric heaters, on the other hand, can heat liquids up to 625°C (molten salt storage) and gases up to 750°C at process pressures from a few millibars to a few hundred bars. The process temperatures for air and gas are limited by the highest surface temperature at which the intended alloy of the tubular heater can be operated. For high-performance alloys this is in the range of 900°C, which guarantees good operational safety for air and gas temperatures of up to 750°C.

For liquids, the maximum surface temperature of the heating elements must be lower than that to which the liquid can be exposed without altering its properties. As an example, mention may be made of various liquid petroleum products which decompose at critical temperatures. This requires that not only the process temperature be controlled, but also the surface temperature of the tubular heating elements in direct contact with the fluid being heated.

In electric heating, the surface temperature of the tubular heater is limited by designing the correct watt density (W/ cm²). This is based on the properties of the medium to be heated, the flow rate and the temperatures to be achieved. The surface temperature of the heating elements can be predicted with absolute precision by thermodynamic calculation. This is done at Schniewindt with HeatR, a specially developed and verified software.

## Efficiency

Depending on the design, heat exchangers have an efficiency ranging from 70% to 90%. And we must consider that heat exchangers require a primary heat source, the one that delivers the hot service fluid. This operating fluid is supplied by various sources, often steam boilers or thermal oil heaters, both of which are fueled by fossil fuels. Since the overall efficiency of the heating process depends on the heat exchanger and its heat source, it would go too far at this point to list every possible combination and the associated efficiency. The effective efficiencies are well known by everyone in the business.

It may sound exaggerated to say that electric heaters are 100% efficient and this is often contested by those who are less familiar with electric heating. It is not just a simple statement, but this efficiency corresponds to the facts if one considers only the heating element itself. Einstein and the immersion heater send greetings from physics lessons. No energy is lost. All electric energy is converted into heat. Of course, here too, the entire chain, including the generation of electric energy, must be considered. But if renewable energy can be used, then the subject is very interesting (see Power-to-Heat).

Almost universal application of electric heaters

Electric heaters can be used for almost every application where heating of stationary or flowing fluids is required, as long as it remains within the range of the temperatures already mentioned. For heating liquids such as water, oils of all kinds, acids or alkalis, as well as gaseous media such as air, natural gas, methane or nitrogen, just to name a few, electric heaters can be a very good, compact and usually also cost-effective solution. It is nearly impossible to list all known applications for electric heaters.

Electric heating as a primary source of heat is a clean process that does not generate combustion gases through open flames. Electric heaters can be installed directly into the process line where heat is needed without the need for additional steam or hot oil piping. No specialized staff is needed for the operation of an electric heater and they require almost no maintenance during normal operation. The system is controlled by contactors or thyristors, by means of which the temperature can be controlled very quickly and accurately.

Electric heaters, depending on the fluid to be heated and the final process temperature, can be built in a relatively compact design. If water is to be heated, high watt densities (W/cm²) can be applied to the heating elements. Schniewindt has built a 10 MW flanged immersion heater mounted in a circulation heater with a DN 800 (32”) nominal diameter and a total length of 3.000 mm. Of course, such a compact design can only be applied to a water heater. When liquids with high viscosity or low thermal conductivity must be heated or high temperatures are to be reached, such compact solutions are not always possible. But even in these cases, the dimensions are still comparable to those of conventional heat exchangers.

Electric heaters can also be installed in potentially explosive atmospheres, allowing their use in the chemical and petrochemical industries, as well as in refineries and offshore platforms. Here, the areas of zone 1 & 2 as well as the temperature classes T1 to T6 are covered.

But electric heaters also have their limits as far as the application is concerned. Not that electric heaters could not heat everything up. However, there are some areas for which any responsible manufacturer of electric heating systems will advise against using his products directly in the process.

This means that electric heaters are not always suitable for some particular fluids, as they would have to be designed in a way to ensure a high level of operational safety for the protection of the fluid to be heated, causing the price of this heater being beyond economic rationality.

Electric heaters combined with heat exchangers

Whenever heat exchangers are indispensable for heating processes, electric heaters are a very interesting alternative to provide the required hot service fluid. While oil- or gas-fired heat sources must be installed in separate rooms or areas, electric heaters can be mounted directly next to the heat exchangers. This not only reduces the unnecessary need for long piping with avoidable heat losses during transport of the service liquid but increases the overall efficiency of a heating process by the additional replacement of the less efficient fired heat source.

In summary, electric heaters are a good alternative to heating fluids, but they cannot replace conventional heat exchangers in all processes. However, they are also a serious option for new investments as a replacement for fired heat sources to achieve both higher overall efficiency and compliance with environmental regulations. The topic of CO2 savings (CO2 certificates) through the use of renewable energies should also be or become very interesting for many users and operators.

## Solar Hot Water Heat Exchanger

While there is huge interest in solar water heating thanks to increased awareness of our impact on the environment and the surge in the costs of gas and electricity, there is often one major stumbling block – the hot water tank.

Dual coil hot water tanks are available, but they are expensive (as is the cost of removing the existing tank). It is of course possible to add a second hot water tank to a home for solar water heating, but this can also be expensive, complicated, and takes up space (which may not even be available).

In this article we will introduce an affordable heat exchange coil which can easily be retro-fitted in an existing standard hot water tank to enable indirect solar water heating.

## Immersion Coil Heat Exchanger

The product pictured above is an immersion coil heat exchanger. Unlike a standard immersion heater element which is heated by electricity, heated fluid passes through this immersion coil (without coming into contact with the water in the tank – i.e. indirect heating).

If fluid (typically anti-freeze) heated to say 40 degrees Celcius is pumped through this coil of copper pipe, it will lose heat into a hot water tank filled with water at say 20 degrees Celcius. As the anti-freeze cools on its journey through the coil, the heat it loses is efficiently taken by the water in the tank.

The anti-freeze leaving the heat exchanger could well emerge at 25 degrees (having lost 15 degrees), thereby heating the tank (which contains a much larger volume of water) by a fraction of a degree. If hot anti-freeze is continuously pumped through the coil then the temperature of the water in the tank will continue to increase.

This type of heat exchanger is a commercial version of the type discussed in our article DIY Solar Water Heating Prototype. With this immersion coil heat exchanger, a solar water heating panel, a suitable circulation pump, and a simple pump controller, a very effective solar water heating system can be put together relatively inexpensively without the financial costs, trouble, and inconvenience of replacing the existing hot water tank.

The only disadvantage of the coil as pictured is the depth it can reach into the hot water tank – 800mm. The water at the top of a hot water tank can be very hot when the water at the bottom is still cool. A standard immersion element is always fitted at the bottom of a hot water tank so that it heats all of the water in the tank. Fortunately these heat exchange coils can be ordered in custom lengths as required so it is worth requesting a longer one to maximize heating efficiency..

## Heat Exchangers for Solar Systems

Heat Exchangers for Solar Water Heater Systems
Solar water heater systems use heat exchangers to transfer solar energy absorbed in solar collectors to the liquid or air used to heat water or a space.
Heat exchangers can be made of steel, copper, bronze, stainless steel, aluminum, or cast iron. Solar heating systems usually use copper and, because it is a good thermal conductor and has greater resistance to corrosion.

Types of Heat Exchangers
Solar water heating systems use three types of heat exchangers:

• Liquid-to-liquid
A liquid-to-liquid heat exchanger uses a heat-transfer fluid that circulates through the solar collector, absorbs heat, and then flows through a heat exchanger to transfer its heat to water in a hot water tank. Heat-transfer fluids, such as antifreeze, protect the solar collector from freezing in cold weather. Liquid-to-liquid heat exchangers have either one or two barriers (single wall or double wall) between the heat-transfer fluid and the domestic water supply.
A single-wall heat exchanger is a pipe or tube surrounded by a fluid. Either the fluid passing through the tubing or the fluid surrounding the tubing can be the heat-transfer fluid, while the other fluid is the potable water.
Double-wall heat exchangers have two walls between the two fluids. Two walls are often used when the heat-transfer fluid is toxic, such as ethylene glycol (antifreeze). Double walls are often required as a safety measure in case of leaks, helping ensure that the antifreeze does not mix with the potable water supply. An example of a double-wall, liquid-to-liquid heat exchanger is the “wrap-around heat exchanger,” in which a tube is wrapped around and bonded to the outside of a hot water tank. The tube must be adequately insulated to reduce heat losses.
While double-wall heat exchangers increase safety, they are less efficient because heat must transfer through two surfaces rather than one. To transfer the same amount of heat, a double-wall heat exchanger must be larger than a single-wall exchanger.

• Air-to-liquid
Solar heating systems with air heater collectors usually do not need a heat exchanger between the solar collector and the air distribution system. Those systems with air heater collectors that heat water use air-to-liquid heat exchangers, which are similar to liquid-to-air heat exchangers.

Heat Exchanger Designs
There are many heat exchanger designs. Here are some common ones:

• Coil-in-tank
The heat exchanger is a coil of tubing in the hot water tank. It can be a single tube (single-wall heat exchanger) or the thickness of two tubes (double-wall heat exchanger). A less efficient alternative is to place the coil on the outside of the collector tank with a cover of insulation.

• Shell-and-tube
The heat exchanger is separate from (external to) the hot water tank. It has two separate fluid loops inside a case or shell. The fluids flow in opposite directions to each other through the heat exchanger, maximizing heat transfer. In one loop, the fluid to be heated (such as potable water) circulates through the inner tubes. In the second loop, the heat-transfer fluid flows between the shell and the tubes of water. The tubes and shell should be made of the same material. When the collector or heat-transfer fluid is toxic, double-wall tubes are used, and a non-toxic intermediary transfer fluid is placed between the outer and inner walls of the tubes.

• Tube-in-tube
In this very efficient design, the tubes of water and the heat-transfer fluid are in direct thermal contact with each other. The water and the heat-transfer fluid flow in opposite directions to each other. This type of heat exchanger has two loops similar to those described in the shell-and-tube heat exchanger.

Sizing
A heat exchanger must be sized correctly to be effective. There are many factors to consider for proper sizing, including the following:

• Type of heat exchanger
• Characteristics of the heat-transfer fluid (specific heat, viscosity, and density)
• Flow rate
• Inlet and outlet temperatures for each fluid.

Usually, manufacturers will supply heat transfer ratings for their heat exchangers (in Btu/hour) for various fluid temperatures and flow rates. Also, the size of a heat exchanger’s surface area affects its speed and efficiency: a large surface area transfers heat faster and more efficiently.

Installation
For the best performance, always follow the manufacturer’s installation recommendations for the heat exchanger. Be sure to choose a heat-transfer fluid that is compatible with the type of heat exchanger you will be using. If you want to build your own heat exchanger, be aware that using different metals in heat exchanger construction may cause corrosion. Also, because dissimilar metals have different thermal expansion and contraction characteristics, leaks or cracks may develop. Either of these conditions may reduce the life span of your heat exchanger.

Your Best choice for Heat Exchange!

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## Stainless steel: The ideal material for heat exchanger construction

Stainless steel has proven to be a particularly reliable and durable material here. Heat exchangers made of stainless steel are particularly resistance to corrosion and deposits of limestone and other residues are minimised. Viesel heat exchangers have been made of only stainless steel for over 50 years.

Common tube bundle heat exchangers and special heat exchangers can be realised using stainless steel without problem. If single parts are welded to each other, each welded seam always marks a possible weak spot. Always rely on an experienced manufacturer due to reasons of reliability during operation. We have the necessary expertise and experience to perform welded seams cleanly and reliably according to the WIG and/or MIG procedure. Naturally we are certified according to DIN EN ISO 3834-3:2005.

## 304/ 316 Stainless Steel U Tube And ASTM A213 Finned Tube

Exchanger tubes are very popular in the boiler and heat exchanger industry, water heater industry, air conditioning industry, etc. Stainless steel heat exchanger tubes have many properties such as corrosion resistance, good ductility, lightweight, fatigue resistance, low and high-temperature resistance. The stainless steel tube heat exchanger is suitable for transporting all kinds of gases and liquids with extremely low and high-temperature requirements. They are also known as stainless steel spiral heat exchanger.

Stainless Steel Tube Coil heating exchanger is serpentine grade 316 stainless steel tube heat exchanger or 304 Stainless Steel. This heating exchanger has excellent corrosion resistance to most chemicals, salts, and acids. The main advantage is to circulate liquid, vapor, refrigerant with low pressure, very high-efficiency heat exchange, no leakage and resistance to high pressures. Stainless steel U tube is U-shaped tube heat exchangers are designed for high-temperature applications, especially hot oil or steam condensing systems. These stainless steel Utubes are sold in many industries/markets, due to their overall corrosion resistance and good machinability.

They are used for heat exchanging, in the field of Chemistry and Petrochemicals, Energy production, Recycled energy, Pulp and paper industry, Industrial pipelines, Mechanical work, Pharmaceutical / Petrochemical, Food and Beverage Industry. Corrugated stainless steel tubing heat exchanger are Stainless steel corrugated pipes, they are shaped like spiral grooved stainless steel pipes and are obtained from the smooth pipe by cold forming. It can be used for the connection of soft and flexible stainless steel pipes and has features such as good protective displacement and low vibration and noise.

High and low-temperature high pressure Resistant to a variety of delivery media, the hose can operate at high-pressure hydrothermal water, high-temperature steam, high-pressure hydrothermal compression distribution temperature gases, oils, organic solvents, corrosive liquids gas. On other hand, media widely used Stainless steel heat exchangers are particularly advantageous because they do not require the use of system inhibitors and are, in fact, compatible with clean running water. This means that little maintenance is needed to keep the stainless steel heat exchanger in good condition. Stainless steel U-bending pipes and tubes are used to prevent emissions due to applications.

In refinery applications, these carbon steel U-bend pipes and tubes also prevent the mixing of gases with other harmful gases and from escaping to the exterior surface through the drainage system. Stainless steel Finned tubes are a range of tubes used in applications involving the transfer of heat from a hot liquid to a cold liquid through the pipe wall. In other words, finned tubes use their “fins” to increase the area that the external fluid is exposed to. The tube then exchanges heat between the fluid inside the tube and the fluid outside the tube.

# A More Efficient Exchange

## Benefits for Using Murphy Technology to Produce Shell and Tube Heat Exchangers

Murphy finned tubes is selling tubing and offering license opportunities for their new, patented Martensitic Stainless Steel (MS3) tubing for heat exchanger applications. Benefits include: increased performance, increased thermal conductivity and heat transfer, better wear resistance, and reduced costs with 410 Martensitic Stainless Steel tubing.

410 Stainless Steel tubing offers significantly increased heat transfer and strengths, as well as a reduction in thermal expansion, when compared to typical austenitic Stainless Steel tubing grades such as 316L.

Thermal conductivity of 410 Stainless Steel tubing is 53% BETTER at the same wall thickness than 316L tubing (410 k=24.9 W/m-K; 316L k=16.3 W/m-K @ 100 degrees centigrade). Engineers will appreciate the ability to reduce the wall thickness of 410 Stainless Steel within their heat exchanger designs, while still maintaining burst pressure requirements. Overall heat transfer can be improved an additional 400% in hardened 410 designs relative to conventional heavy-wall 316L heat exchangers rated for identical maximum pressures.

Thermal stresses are also reduced as 410 has a Coefficient of Thermal Expansion (CTE = 9.9 um/m/K) 38% less than 316L (CTE = 15.9 um/m/K). As a result, thermal fatigue stresses are reduced and product durability is increased.

The introduction of 410 Martensitic Stainless Steel for the fabrication of heat exchanger tubing offers higher strength, increased hardness and wear resistance, as well as a lower cost alternative to Ferritic series Stainless Steel alloys, which include 410S.

The hardened strength of 410 Martensitic Stainless Steel is twice that of 410S. Heat exchanger tubing made out of 410 Stainless Steel will allow for thinner walled material to carry the same pressures, increasing heat transfer and making the heat exchanger much more effective. Using less material also reduces overall costs per tube, heat exchanger fabrication and shipping costs.

# Heat Exchanger Basics:

A shell and tube heat exchanger is just one type of heat exchanger design. It is suited for higher-pressure applications and markets such as: dairy, brewing, beverage, food processing, agriculture, pharmaceutical, bioprocessing, petroleum, petrochemical, pulp & paper, and power & energy.

As its name implies, this type of heat exchanger consists of an outer, elongated shell (large pressure vessel or housing) with a bundle of smaller diameter tubes located inside the shell housing. One type of fluid runs through the smaller diameter tubes, and another fluid flows over the tubes (throughout the shell) to transfer heat between the two fluids. The set of tubes is called a tube bundle, and may be composed of several types of tubes; round, longitudinally finned, etc. depending on the particular application and fluids involved.

There may be variations on the shell and tube design. Typically, the ends of each tube are connected to plenums or water boxes through holes in the tubesheets. The tubes may be straight or bent in the shape of a U, which are called U-tubes.

The selection of material for tubing is extremely important. To be able to transfer heat well, the tube material should have good thermal conductivity. Because heat is transferred from a hot to a cold side through tubes, there is a temperature difference through the width of the tubes. Because of the tendency of the tube material to thermally expand differently at various temperatures, thermal stresses occur during operation. This is an addition to any stress from high pressures from the fluids themselves. The tube material also should be compatible with both the shell and tube side fluids for long periods under the operating conditions (temperatures, pressure, pH, etc.) to minimize deterioration such as corrosion. All of these requirements call for careful selection of strong, thermal conductive, corrosion-resistant, high-quality tube materials. Typical metals used in the manufacturing of heat exchanger tubing include: carbon steel, stainless steel (austenitic, duplex, ferritic, precipitation-hardenable, martensitic), aluminum, copper alloy, non-ferrous copper alloy, Inconel, nickel, Hastelloy, tantalum, niobium, zirconium, and titanium.

## Stainless Steel Shell And Tube Heat Exchanger

The tubes used in heat exchanger systems work towards the transference of heat between two fluids or they may be involved in cooling processes in said applications. Moreover, many Stainless Steel Shell And Tube Heat Exchanger Manufacturers recommend them because they offer their user several benefits. In industries, a Stainless Steel Heat Exchanger Tube may be used in various operations ranging from the elimination of process heat and feed water preheating to the Evaporation process for liquid or steam. The high performance of the alloy, in combination with its corrosion resistance properties and high strength, makes the Spiral Heat Exchanger Manufacturers recommend their use to various industries such as the marine industry as well as applications involving hydraulics.

In hydraulic applications, Plate And Frame Heat Exchanger Manufacturers suggest using these tubes for the cooling of hydraulic and lube oil. In addition to the above mentioned tasks, the Stainless Steel Heat Exchanger Shell And Tube may be employed in applications such as the cooling of the turbine, compressor, and engine along with the condensation process vapor or steam. While Air Cooled Heat Exchanger Manufacturers have several options like copper, copper-nickel, carbon steel, brass alloys, or even titanium alloys to choose from, they prefer using stainless steel.

Since stainless steel is easily available, and they offer their user resistance to corrosion, the Stainless Steel Fin Tube Heat Exchanger may be manufactured in any grade, depending on the needs of the application. If, however, the need of the application is to lower the cost, the Stainless Steel Heat Exchanger Tube Suppliers may advise the buyer to purchase an exchanger tube produced from grade 304, which is an economical grade of stainless steel

## Shell and tube heat exchangers

This type of heat exchanger is used for transferring heat in order to obtain the appropriate temperature parameters of the media flowing through the heat exchanger.

We provide services of production of heat exchangers on the basis of the documentation received from the customer.

We are specialized in the production of shell and tube heat exchangers made of stainless steel.

We are capable of manufacturing heat exchangers that reach the mass of 20 tons and include more than 7,000 pipes welded on the floor tube sheet.

The aspect that distinguishes our offer is the fact of subjecting the entire heat exchanger under process of degreasing, pickling, passivation, rinsing and drying in a technological line specially adapted for this type of operation.

Performing this process ensures the elimination of corrosion processes and prolonged use of the device. For high demanding customers our heat exchangers are subjected to a process of shot peening with quartz beads.

After welding procedures, the heat exchanger ensures the tightness of 10-6 mbar l/s.

Leak test is performed with a helium detector. Exchangers are also subjected to leak test the water pressure control calculated individually for each project.

Heat exchangers are also subjected to water leak proof test pressure control which is calculated individually for each project.

## What is Stainless Steel Tube?

Stainless steel tube is a versatile structural material that may be utilized in a variety of ways. Stainless steel tube is widely utilized in a variety of industries, and their sizes and variations vary greatly based on the application requirements. Stainless steel has proved to be a very dependable and long-lasting material in this application. Stainless steel heat exchangers are very corrosion resistant, and deposits of limestone and other residues are reduced. Boiler and heat exchanger manufacturers, as well as water heater and air conditioning manufacturers, use exchanger tubes extensively. Corrosion resistance, ductility, lightweight, fatigue resistance, and low and high-temperature resistance are only a few of the benefits of stainless steel heat exchanger tubes. The stainless steel tube heat exchanger can carry a wide range of gases and liquids at extremely low and high temperatures. Stainless steel spiral heat exchangers are another name for them.

## Uses

• A stainless steel U tube is a particular shaped tube that is utilized in high heat and pressure applications. These are used to prevent welding connections from forming a curve or a direction change.
• The fins on the surface of the pipes are utilized to release heat from the Stainless Steel Fin Tube Heat Exchanger.
• Heat transmission is substantially more efficient as a result of this than with standard Stainless Steel Heat Exchanger Tubing. Materials engineers have a variety of alternatives to increase the performance of heat exchanger tubes.
• They include requesting better corrosion-resistant grades, choosing tube suppliers with improved tube production and finning techniques, and relying on cutting-edge manufacturers with improved non-destructive testing methods.
• The stainless steel tube heat exchanger is ideal for moving a wide range of gases and liquids at both low and high temperatures.
• Stainless steel is a durable material. Heat exchangers with a U-shaped tube are suited for high-temperature applications, such as hot oil or steam condensing systems.
• They are employed in the fields of chemistry and petrochemistry, energy production, recycled energy, pulp, and paper industry, industrial pipelines, mechanical work, pharmaceutical/petrochemical, food and beverage industry, and industrial pipelines.
• Stainless steel heat exchangers are especially useful since they do not require system inhibitors and are compatible with clean running water. This implies that the stainless steel heat exchanger requires very little maintenance to be in good working order. To avoid leaks from applications, stainless steel U-bending pipes and tubes are utilized.

## The Use of Duplex Stainless Steel Tubing in Heat Exchanger Service

To improve the performance of your industrial process heat exchanger, consider using duplex stainless steel tubing.

Heat exchangers are key components for many industries, particularly in chemical and oil and gas plants where they play a vital role in process control. Industry professionals — from design engineers and fabricators to the in-plant operators who work with the equipment daily — seek new ways to improve heat transfer performance and extend the life of these units in corrosive environments. Many times, improvements are closely related to the tubing specified for use in their heat exchangers. To improve the performance of heat exchanger tubing, materials engineers have a number of options. They include specifying higher corrosion-resistant grades, selecting tube suppliers with enhanced tube manufacturing and finning processes and using state-of-the-art manufacturers that have upgraded their methods of non-destructive testing.

Making the correct decision is not an easy task. When selecting a tube material for a heat exchanger, many different options are available, depending upon the application, design and operating conditions (such as temperature, pressure and the corrosive environment). In addition, to be viable candidate materials, those tubing options need to be available and affordable. Everything from raw material costs to the availability of off-the-shelf distribution can impact the tube selection process. And, all of these factors have the potential to affect the outcome of a project.

The table above provides a summary of some of the more frequently used ASME specifications for steel tubing for pressure applications. (To view this image larger and in a new window, click here. ) It shows the wide range of alternatives that engineers and fabricators are faced with when considering candidate tubing materials for heat exchanger, condenser, boiler and feedwater heater service.

Duplex stainless steels refer to a family of stainless steels alloyed to produce a microstructure consisting of approximately equal parts ferrite and austenite.

Heat exchangers are often faced with extreme temperatures, pressures and corrosive media. Duplex stainless steels are designed to have high strengths while maintaining good toughness, have excellent resistance to chloride pitting corrosion and be more resistant to stress corrosion cracking than the 300 series austenitic stainless steels.

There are several groups of duplex stainless steels that are categorized by the level of alloying elements present. Lean duplex stainless steels have low amounts of alloying elements while duplex and super duplex stainless steels have higher amounts of alloying elements. The composition of a duplex stainless steel directly affects the corrosion resistance of the alloy. This is most often quantified by the pitting resistance equivalent number (PREn): PREn = %Cr + 3.3 x %Mo + 16 x %N).

Duplex stainless steels are useful in applications where strength is of great importance. They can help reduce the weight of components due to their increased strengths (about twice as high as typical 300 series austenitic stainless steels). The higher strength equates to thinner sections of duplex stainless steel being required to accommodate a load as opposed to lower strength materials (like carbon or austenitic stainless steels).

By comparison, many alternative stainless steel options fall short in corrosion resistance. For instance, austenitic stainless steels are readily susceptible to stress corrosion cracking under certain conditions. This limits the recommended operating temperatures of austenitic stainless steel components in stress corrosion cracking environments. Conversely, duplex stainless steels are more resistant to stress corrosion cracking and, therefore, can be used in many environments where austenitic stainless steel is not adequate. In fact, duplex stainless steels also have much improved resistance to chloride pitting corrosion as compared to austenitic stainless steels. This is of great importance when trying to find an alloy that is adequate for chloride-containing environments, where austenitic stainless steels are not suited for service.

Strength and corrosion resistance aren’t the only factors that engineers weigh in their decision-making processes. Cost and availability often come into play. Many times, manufacturers and distributors can provide duplex stainless steels at a much more stable price as compared to austenitic stainless steels due to their lower content of nickel and molybdenum. Of course, this offers some protection from the volatility of raw material pricing that other candidate materials face.

As well as it performs in many operating environments, duplex stainless steel tubing does have potential drawbacks and fabrication complexities. It requires much more precise and careful heat treatment plans as compared to austenitic stainless steels due to the tendency to form detrimental intermetallic phases. Inter metallics, which can form in duplex stainless steels, can cause the material to become brittle and impair corrosion resistance. Welding or other fabrication processes that impart high heat inputs into the material can also promote intermetallic phases to form. However, with a proper Welding Procedure Specification (WPS) and heat treating/cooling processes, detrimental intermetallic phases can be avoided.

Duplex stainless steels also have limits on the temperatures in which they can be used in service. They have the tendency to form a low-temperature intermetallic phase (alpha prime), which causes embrittlement of the material. The industry-recommended temperature range that duplex stainless steels can be used at is –22 to 617°F (-30 to 325°C). Welding duplex stainless steels can also be challenging because care must be taken to ensure that the weld has the proper phase balance. The ferrite content of the weld must fall within a specified range provided. If the phase balance of the weld does not fall within the specification, the corrosion and mechanical properties of the weld could be compromised. A proper WPS, which has been verified to yield the proper phase balance, should be used to avoid complications.

Manufacturers who are experienced at working within duplex stainless steels’ limitations are able to maximize their many potential benefits, providing end users with superior performance. Like less corrosion-resistant carbon steel or copper alloy products, duplex stainless steel tube can also be integral finned to improve heat transfer by providing an increase in its surface area.

Finning duplex stainless steels is an extremely challenging process due to the high strength of these materials. Achieving the desired number of fins and fin height without damaging them requires skill, experience and extensive research and development. Heat treatment after the finning or U-bending manufacturing steps also requires precise process control.

Utilizing corrosion-resistant duplex stainless steel tubing in place of traditional carbon steel or austenitic stainless steel can be beneficial to the performance of heat exchangers. These unique alloys have the ability to extend the lifetime of the tubing in the right applications. Yet duplex is not always the answer. Pinpointing the ideal tubing for an application — one manufactured by an experienced supplier that can meet tight turnaround requirements —  can be a challenge. But finding that knowledgeable source is well worth the effort because getting the materials-selection process right or wrong impacts everything from budgets to production schedules.

## What is a Condenser Coil and How Does It Work?

An air conditioning system is widely considered to be an essential appliance in the entire country of Singapore. From household residences to different industry offices, this dependable cooling machine is needed by many to survive the warm weather and increase total productivity. While it may be a simple piece of cooling machinery on the outside, the internal parts that make up an aircon are all sorts of complicated.

Enter the condenser coil, a device that transfers heat from one medium to another. The condenser coil is just one of the many components that allow an aircon to remove warmth from the outside and vent it inside. Not to be confused with the evaporator coils responsible for indoor air, which are usually located indoors compared to the condenser coils’ outdoor unit setting.

## How Does An Air Conditioner Condenser Coil Work?

For you to understand how an aircon condenser coil works, it is important to point out its main function first: a place where all the warm air gets removed. The aircon condenser coil is responsible for the heat transfer process. This is where much of the absorbed heat is transferred from your house and into the open outdoors.

An AC condenser coil is made up of different tubes that are filled with refrigerant liquid. In order for it to fully function, a chiller inside the coil cools the fluid and moves through the condenser tubing. Once this process is done, it’s further converted into gas. Afterwards, the converted gas is distributed through the entire cooling system.

After this conversion process is done, the refrigerant then releases the heat and returns to a liquid state. From here, the cycle will continue in a closed system.

Looking into a condenser coil closely throughout this process will also show you the process of the refrigerant vapor. This vapor is usually processed through a cycle of warm trading loop, allowing it to be turned into a fluid and making the heat from the cold indoor zone get dismissed in the process.

From this condenser coil process, the aircon is able to provide the quality breeze that every homeowners and office workers expect.

## Caring For Your Air Conditioning Condenser

It shouldn’t take an air conditioning expert to know that AC machines deserve  proper and regular check-up and maintenance. Whether you’re having problems with your overall AC system, condenser unit or evaporator coil, knowing when to call for help is very important. For your machine to continue performing at its absolute best, you need to schedule frequent appointments with an aircon technician. If done regularly, this allows you to save a lot of money by preventing any bigger performance issues down the line.

## CONDENSER COIL

Heat Exchanger (Coils) for Condensers

Condenser coil or heat exchanger in HVAC/R system cools up the substances (i.e. refrigerants) and in turn let out latent heat from the system.

In a typical A/C system, the condenser coil is the one located outdoor letting out heat, while the other coil–the evaporator coil–is located indoor chilling the space.

Our condenser coils can be customized and designed to match any system requirements–air conditioning, refrigeration, or industrial processes. Circuiting can be matched to heat transfer volume requirements and coil face area can be split to your particular requirements.

Available Tube Material

• Copper
• Aluminum
• Copper nickel

Additional tube material available upon request

Available Fin Material

• Copper
• Precoated aluminum
• Copper nickel

## Condenser (heat transfer)

In systems involving heat transfer, a condenser is a heat exchanger used to condense a gaseous substance into a liquid state through cooling. In so doing, the latent heat is released by the substance and transferred to the surrounding environment. Condensers are used for efficient heat rejection in many industrial systems. Condensers can be made according to numerous designs, and come in many sizes ranging from rather small (hand-held) to very large (industrial-scale units used in plant processes). For example, a refrigerator uses a condenser to get rid of heat extracted from the interior of the unit to the outside air.

Condensers are used in air conditioning, industrial chemical processes such as distillation, steam power plants and other heat-exchange systems. Use of cooling water or surrounding air as the coolant is common in many condensers.

## History

The earliest laboratory condenser, a “Gegenstromkühler” (counter-flow condenser), was invented in 1771 by the Swedish-German chemist Christian Weigel.[2] By the mid-19th century, German chemist Justus von Liebig would provide his own improvements on the preceding designs of Weigel and Johann Friedrich August Göttling, with the device becoming known as the Liebig condenser.

### Principle of operation

A condenser is designed to transfer heat from a working fluid (e.g. water in a steam power plant) to a secondary fluid or the surrounding air. The condenser relies on the efficient heat transfer that occurs during phase changes, in this case during the condensation of a vapor into a liquid. The vapor typically enters the condenser at a temperature above that of the secondary fluid. As the vapor cools, it reaches the saturation temperature, condenses into liquid and releases large quantities of latent heat. As this process occurs along the condenser, the quantity of vapor decreases and the quantity of liquid increases; at the outlet of the condenser, only liquid remains. Some condenser designs contain an additional length to sub cool this condensed liquid below the saturation temperature.

Countless variations exist in condenser design, with design variables including the working fluid, the secondary fluid, the geometry and the material. Common secondary fluids include water, air, refrigerants, or phase-change materials.

Condensers have two significant design advantages over other cooling technologies:

• Heat transfer by latent heat is much more efficient than heat transfer by sensible heatonly
• The temperature of the working fluid stays relatively constant during condensation, which maximizes the temperature difference between the working and secondary fluid.

Examples of condensers

Surface condenser

surface condenser is one in which condensing medium and vapors are physically separated and used when direct contact is not desired. It is a shell and tube heat exchanger installed at the outlet of every steam turbine in thermal power stations. Commonly, the cooling water flows through the tube side and the steam enters the shell side where the condensation occurs on the outside of the heat transfer tubes. The condensate drips down and collects at the bottom, often in a built-in pan called a hotwell. The shell side often operates at a vacuum or partial vacuum, produced by the difference in specific volume between the steam and condensate. Conversely, the vapor can be fed through the tubes with the coolant water or air flowing around the outside.

Chemistry

In chemistry, a condenser is the apparatus which cools hot vapors, causing them to condense into a liquid. Examples include the Liebig condenserGraham condenser, and Allihn condenser. This is not to be confused with a condensation reaction which links two fragments into a single molecule by an addition reaction and an elimination reaction.

In laboratory distillationreflux, and rotary evaporators, several types of condensers are commonly used. The Liebig condenser is simply a straight tube within a cooling water jacket, and is the simplest (and relatively least expensive) form of condenser. The Graham condenser is a spiral tube within a water jacket, and the Allihn condenser has a series of large and small constrictions on the inside tube, each increasing the surface area upon which the vapor constituents may condense. Being more complex shapes to manufacture, these latter types are also more expensive to purchase. These three types of condensers are laboratory glassware items since they are typically made of glass. Commercially available condensers usually are fitted with ground glass joints and come in standard lengths of 100, 200, and 400 mm. Air-cooled condensers are unjacketed, while water-cooled condensers contain a jacket for the water.

Industrial distillation

Larger condensers are also used in industrial-scale distillation processes to cool distilled vapor into liquid distillate. Commonly, the coolant flows through the tube side and distilled vapor through the shell side with distillate collecting at or flowing out the bottom.

Air conditioning

Condenser unit for central air conditioning for a typical house

condenser unit used in central air conditioning systems typically has a heat exchanger section to cool down and condense incoming refrigerant vapor into liquid, a compressor to raise the pressure of the refrigerant and move it along, and a fan for blowing outside air through the heat exchanger section to cool the refrigerant inside. A typical configuration of such a condenser unit is as follows: The heat exchanger section wraps around the sides of the unit with the compressor inside. In this heat exchanger section, the refrigerant goes through multiple tube passes, which are surrounded by heat transfer fins through which cooling air can circulate from outside to inside the unit. There is a motorized fan inside the condenser unit near the top, which is covered by some grating to keep any objects from accidentally falling inside on the fan. The fan is used to pull outside cooling air in through the heat exchanger section at the sides and blow it out the top through the grating. These condenser units are located on the outside of the building they are trying to cool, with tubing between the unit and building, one for vapor refrigerant entering and another for liquid refrigerant leaving the unit. Of course, an electric power supply is needed for the compressor and fan inside the unit.

Direct-contact

In a direct-contact condenser, hot vapor and cool liquid are introduced into a vessel and allowed to mix directly, rather than being separated by a barrier such as the wall of a heat exchanger tube. The vapor gives up its latent heat and condenses to a liquid, while the liquid absorbs this heat and undergoes a temperature rise. The entering vapor and liquid typically contain a single condensable substance, such as a water spray being used to cool air and adjust its humidity.

Equation

For an ideal single-pass condenser whose coolant has constant density, constant heat capacity, linear enthalpy over the temperature range, perfect cross-sectional heat transfer, and zero longitudinal heat transfer, and whose tubing has constant perimeter, constant thickness, and constant heat conductivity, and whose condensible fluid is perfectly mixed and at constant temperature, the coolant temperature varies along its tube according to:

{\displaystyle \Theta (x)={\frac {T_{H}-T(x)}{T_{H}-T(0)}}=e^{-NTU}=e^{-{\frac {hPx}{{\dot {m}}c}}}=e^{-{\frac {Gx}{{\dot {m}}cL}}}}

where:

• is the distance from the coolant inlet
• is the coolant temperature, and T(0) the coolant temperature at its inlet
• is the hot fluid’s temperature
• is the number of transfer units
• is the coolant’s mass (or other) flow rate
• is the coolant’s heat capacity at constant pressure per unit mass (or other)
• is the heat transfer coefficient of the coolant tube
• is the perimeter of the coolant tube
• is the heat conductance of the coolant tube (often denoted)
• is the length of the coolant tube

## An Introduction to Coil Heat Exchangers

Coil heat exchangers in their simplest form, use one or more tubes that run back and forth a number of times. The tube separates the two fluids. One fluid flows inside the tube and another flows on the outside. Let us have a look at a heating example. Heat is transferred from the hot inner fluid to the tube wall via convection, it then conducts through the pipe wall to the other side and the outer fluid carries this away also through convection.

The Coil Type Heat Exchanger produced by metal industries are suitable to transfer heat in a wide variety of operating conditions and to refuse to accept decay for the longest period of time possible under the harshest operating circumstances. Coil-type exchangers are more efficient than shell and tube exchangers for low flow rates. Due to their simple construction, they are low in price and easy to clean on the shell side. Thermal efficiency approximates that of a true countercurrent flow type exchanger.

Condensers are used for condensation vapors cooling liquids. Condensers are made by fusing a number of parallel coils in a glass shell. Coil Type Heat Exchangers are artificial to special requirements as to dimensional tolerances, finish and tempers for use in condensers and heat exchangers.

Copper heat exchanger tubes are normally supplied in straight length in annealed half-hard temper. Coil Type Heat Exchangers shaped by are metal industries not only have stiff tolerances the most dependable dimensions throughout the tube length. The tube surface is clean both inside. Coils are made in different diameters using tubes different bores.

## The Applications of Coil Heat Exchangers

When it comes to heat exchangers, coil heat exchangers specifically are ideal for applications including boiler air preheating, pulp dryers, unit heaters, condensing and cooling as well as high-pressure, air tempering, and dryer applications. Depending on the application, there are many types and styles of coil heat exchangers to choose from.

Some of these include stainless tube bundles, double-pip heat exchangers, stainless steel tube immersion coil, bare tube immersion cooler, gas to water cooler, copper coil heat exchangers, combination ambient air/chiller water cooler, or coil tube-in-shell design to name a few. Each of these may also come in a variety of sizes and each has specific advantages. However, coil heat exchangers, in general, can be expected to have many advantages overall as well.

The Advantages of Coil Heat Exchanger?

Some advantages of coil heat exchangers include high efficiency, flexibility, low-pressure drop, they require little maintenance, are compact and lightweight, and are also easy and inexpensive to install. Coil heat exchangers tend to have higher efficiency than other types because of the large number of closely aligned tubes. This design aspect enlarges the heat transfer area, which results in a higher heat transfer co-efficient overall.

This efficiency equates to higher production while using less energy and that means big savings both upfront and in the long run. The coil-type heat exchanger is also known for being compact and lightweight due again to the closely packed tubes. The exchangers’ compact, lightweight design as well as their unique vertical orientation also means that they will take up less space and will be easier and less expensive to install. Their lightweight and compactness also lend to the flexibility mentioned earlier.

Another advantage of these heat exchangers is that there are many options when it comes to model types and configurations, which means they can be used with a wide variety of temperatures, flows, and pressures.

This flexibility equates to greater value overall. In addition to the benefits I just mentioned, coil heat exchangers also have low-pressure drops and require little maintenance as the structure of the tubes allows for turbulent fluid flow, which minimizes fouling and scales build-up. They can also be easily removed from the piping system to be flushed if that is necessary. Saving time and money both on installation and maintenance can go a long way for your business, and allows for overall smoother operations and less hassle and frustration.

## Cooper Finned Tube

#### Detailed Product Description

 Material: C12200 / C12000 / C70600 Outer Diameter: 47mm Inner Diameter: 22mm Wall Thickness: 1.5mm Fin Height: 11mm FPI: 8 High Light: spiral finned tubes, spiral tube heat exchanger, Copper Spiral Finned Tube

## Heat Exchanging Copper Spiral Finned Tube with Extruding Process

#### Quick Details:

1. Roll forming process
2. Higher heat transfer ability comparing to HF welding and Wrapped fin tube
3. Save cost and assembling space due to higher efficiency
4. ISO 9001:2008 quality certified
5. Well sold in USA, Australia, Germany, etc.

#### Tube Number Code System

Take Tube Number M-11045.180100.00 as example

 M 11 045 180 100 00 M=Medium HeightH=HighL=Low Minimum fins per Inch Fin Height in 1/10 mm Minimum Root Diameter in 1/10 mm Root Wall-thickness in 1/100 mm Code of Inner Surface00=plain01=Undulated02=Grooved

Descriptions:

Process Flow:

1. Order raw material based on customers’ request.
2. Inspection on raw material when arrived
3. Roll forming the fin tube, while monitoring the whole process
4. Cut into customized length
5. Inspection on specification of finned tube
6. If required, we provide de-fin process, soft annealing, bending and coiling, welding connectors
7. Clean procedure, pressure test, drying and packing

Finned tube:

The finned tube provide by us is Extruded Type, which is different from the ones through HF Welding and Wrapping method. The fins are obtained by roll forming the outer surface of a soft seamless plain tube. The technology simply squeezes the wall thickness transforming into straight fins on the tube. So the fin and the tube are integrated and inseparable, which avoids the heat resistance between fin and tube, and optimizes heat exchange efficiency. Based on this structure, the Extruded type can survive more severe working conditions than other finned tubes. Also it, on the other hand, shows several unique features such as enhanced physical structure, resistance to vibration, anti-corrosion ability, and long service life, etc.

Under this technology, there are two major types of finned tubes available with us, Single metal tubes and Bimetallic tubes. The former uses Copper, Aluminum, and Copper Nickel alone. The later has a core tube on the inside made of harder material. In this case, the outer tube is rolled onto the core tube in order to provide for a tight bond and good thermal contact between the two tubes.

Customized finned tube is available. The specification table is followed below. If required, the fin tube can be made into various forms after soft annealing process. They can be used for cooling and heating in a large scale of conditions. For example, coils in water heater, oil cooler in large machines, heat transfer part in boiler and heat recovering system, air-conditioning and refrigeration industry as condenser part or evaporator part, etc.

The material for our fin tube covers Copper(C10200, C12000, C12200), Copper Nickel(C70600), Aluminum(1060), Aluminum alloy, Aluminum-Steel(bimetallic), Aluminum-Stainless Steel(bimetallic), Aluminum-Copper(bimetallic), Aluminum-Copper Nickel(bimetallic), Copper-Copper Nickel(bimetallic).

Specifications:

 Customized Outside diameter and Inside Diameter Fin Height 0~12mm Fins per Inch 5~26 Fin Thickness 0.3~0.5mm Wall thickness 0.7~2mm

1. Optimized inner to outer surface ratio
2. High heat exchange rate
3. Enhanced structure due to the roll forming process
4. Flexible as straight tube or bent or coiled heat exchangers
5. Low heat resistance between fins and tube
6. Strong resistance to shock and thermal expansion and contraction
7. Cost and energy saving due to long service life and high exchange rate

Applications:

The fin tubes are mainly used in heating(gas-fired boilers, condensing boilers, flue gas condensers), in mechanical and automotive engineering(oil coolers, mine coolers, air coolers for diesel engines), in chemical engineering(gas coolers and heater, process cooler), in power plants(air cooler, cooling tower), and in nuclear engineering(uranium enrichment plants).

## 4 Types of Heat Exchangers and Applications

Have you ever been driving down the highway and seen smoke drifting up from a smokestack? The truth is, all that smoke is wasted energy that could be used for another purpose. That’s why heat exchangers exist. A heat exchanger allows the heat from a fluid (liquid or gas) to pass through a second fluid without the two ever coming into direct contact with each other. For example, a heating furnace burns natural gas that is carried over water by pipes. If the gas and the water came into direct contact, the heat exchange would stop and the water would never warm up.

Even though all heat exchangers perform the same function, there are different types that have varied applications. Learning about these different heat exchangers will help you determine what the right equipment is for your business. Let’s take a look at the 4 types of heat exchangers and their applications below:

1. Double Tube Heat Exchangers:

Double tube heat exchangers use what is known as a tube within a tube structure. There are two pipes where one is built inside the other. Just like the example above, one fluid flows through the inner pipe while the second fluid flows around the first fluid in the outer pipe. This type of heat exchanger is known for being the most basic and affordable of all. Its size makes it ideal for tight spaces, allowing for some extra flexibility in the layout of the manufacturing process.

2. Shell and Tube Heat Exchangers:

Out of all the types of heat exchangers, shell and tube heat exchangers are the most versatile. A shell and tube heat exchanger is designed with a number of tubes placed inside a cylindrical shell. The popular design of this type of heat exchanger allows for a wide range of pressures and temperatures. If you need to cool or heat a large amount of fluids or gases, the application of the shell and tube heat exchanger is an option to consider. While smaller in size compared to some of the other types, a shell and tube heat exchanger can be easily broken-down, making cleaning and repairs easy.

3. Tube in Tube Heat Exchangers:

Similar to the other types of heat exchangers, a tube in tube heat exchanger is comprised of two tubes, one for each fluid. However, the tubes are coiled together to form an outside and inside pattern. The application for a tube in tube design can get fairly creative. Since the tubes are coiled together, most designs for this type are compact. Applications for a tube in tube heat exchanger center around high temperature and high pressure. Since it runs at a higher output, a tube in tube heat exchanger tends to have greater efficiency.

4. Plate Heat Exchangers:

While all of the types of heat exchangers discussed so far have a similar design, the plate heat exchanger is the exception. Metal plates are used to transfer heat between two fluids. The plate is a metal shell, with spaces inside each plate that act as hallways for fluids to travel through. With a plate heat exchanger, there is a greater surface area in contact with the fluids, so it has better rates of heat transfer compared to all other types. Although plate heat exchangers can be more expensive, the efficiency gained by the design is a big plus. This type of heat exchanger is best used in places like power plants because of its durability and low repair rates.

## WHAT ARE THE DIFFERENT TYPES OF HEAT EXCHANGERS?

Most heat exchangers in hygienic processing transfer heat indirectly from warmer fluids to cooler fluids without the fluids mixing together. Heat exchanger types vary to meet requirements for processing efficiency, cost of ownership, and maintenance. In this blog, we describe plate and frame, shell and tube, and scraped surface heat exchangers used in food, beverage, dairy, and pharmaceutical processing.

With supply change challenges among the latest high-priority concerns for contractors and system operators, our Guide to Choosing the Right Heat Exchanger is an invaluable tool for processors, production managers, and mechanical engineers. In this article, we introduce the types of heat exchangers used in food, dairy, beverage, and pharmaceutical processing.

## PLATE AND FRAME HEAT EXCHANGER

Plate and frame designs feature corrugated parallel plates separated from each other by gaskets that control the alternating flow of hot and cold fluids over the plate surfaces.

A frame plate and a pressure plate compress gasketed plates together with tightening bolts. Gasketed plates and the pressure plate suspend between an upper bar and a lower guiding bar. The simple mechanical design enables easy cleaning and capacity changes by adding or removing plates.

Hot or cold media flows in alternating channels with processed fluids, and heat transfers from the warmer channel to the cooler channel.

Because of the relatively narrow path between plates and the corrugated design of plates, which create turbulence, plate and frame designs are well-suited to heating fluids of low to medium viscosity.

When fluids are moderately viscous (thick) or include small amounts of particulates, wider gaps between plates can help maintain flow requirements. Wide gaps between plates allow particulates to pass between plates without obstructing flow.

Standard plates typically feature a chevron pattern to maximize plate strength at high pressures. Plates may have different chevron angles to optimize heat transfer for specific pressure drops.

Wider-stream plates have fewer contact points, so they help prevent blockages. They are especially effective for raw juice applications with heating by liquid or steam.

When used for fibrous liquids, viscous, or fluids with particulates, two features of wide-gap plates may ease the flow of fluids or particles:

1. Wider gaps between plates than standard designs
2. Plate pattern

Double-walled plates consist of two sheets formed together to prevent media from mixing in the event a crack forms in one of the plates.

Gaskets between plates seal the channels to keep fluids separate, to guide flow, and to prevent leaks. Gaskets fit into specially designed plate grooves

Gaskets can be clipped or glued to plates. Clips secure gaskets to the plate to prevent gaskets from moving and to prevent misalignments and leaking. Clip-on gaskets reduce the time required for re-gasketing.

Regasketing of clip-on gaskets is a process of taking off the old one and clipping on a new one.

For glued gaskets, the process is to remove the old one, clean the sealing surface, glue and heat-treating to set glue.

Plates hang from a carrying bar and a guide bar keeps plates vertically aligned. Operators compress the plates between the end plate and pressure with tightening bolts and nuts.

##### Typical applications for plate-and-frame heat exchangers include:
• Low to medium viscosity products with little to no particulate: milk, cream, ice cream mixes, beverages, beer, beer wort.

Standard Plate Gap
Channels are all consistent size

Single-sided WideGap
One extra wide channel for fibrous/dirty fluid (A) and one channel for non-fibrous fluids (B)

Double-sided WideGap
Two wide channels for fibrous/dirty fluids (C)

## SHELL AND TUBE HEAT EXCHANGER

Shell and tube heat exchangers transfer heat between fluids that pass through a bundle of tubes and fluids within a large shell vessel that surrounds the tubes. Tubes inside the shell can enable processing of fluids that are more viscous or contain more particulate than a plate and frame heat exchanger.

Because applications differ widely, shell and tube designs have evolved to meet specific processing requirements.

Monotube heat exchangers — also called tube-in-tube, and jacketed tube — consist of an external shell and a single inner tube. Monotube designs are used in heat-treating applications for products that many times include large particles or have high-pulp or high-fiber ingredients.

Annular models of tube heat exchangers apply heat to product from the inside and outside simultaneously to prevent layering. Annular space designs typically have three to four concentric tubes.

Multitube types have a bundle of inner tubes. They are designed for processing heating, cooling, and heat recovery of low viscosity products that include pulp, fibers, and particulates.

Single tubesheet design: Tubesheets hold tubes in place at one end of the shell. When tubes are placed inside a shell, tubesheets cap one end of the shell to contain heating or cooling fluids. In addition to the tubesheet, baffles hold tubes in place within the body of the shell.

Double tubesheet design: For applications where detecting leaks or mixing of the tube-side fluid with the shell-side fluid is especially warranted, double tubesheet designs afford easy spotting of both.

The risk of mixing between product and heating/cooling fluid is greatly reduced because as product flows through the tubes, the heating/cooling fluid is sealed in the shell by the first tube sheet, and the second tube sheet seals the product.

The gap between the two tubesheets is open to view for easy leak detection. While typically a feature of pharmaceutical processing, double-tubesheet designs can be used in any application utilizing a shell and tube heat exchanger.

##### Typical applications for shell-and-tube heat exchangers include:
• Low to medium viscosity products: depending on specific product selected can contain varying size of particulate. Beverages with pulp, purees, WFI, lotions, gels, high fouling dairy products.

## SCRAPED SURFACE HEAT EXCHANGER

Some applications require heat transfer to highly viscous and/or sticky products. In those applications, scraped surface heat exchangers are the best method to provide effective heat transfer due to the scraping blades that keep product from settling on the interior surfaces.

Product enters a cylinder at the bottom of the scraped surface tube. Heating or cooling fluids travel in a counter-current flow in a cylinder surrounding the product channel.

Blades inside the product channel remove product from the channel wall to ensure uniform heat transfer to the product.

The scraping blades are made a variety of materials to meet different processing requirements, and are designed specifically for gentle product handling to avoid compromising product quality and consistency.

Scraped surface exchangers can be mounted vertically or horizontally. Inside, an electric motor turns a rotor fitted with scraping blades.

To prevent damage to product, rotors turn and product the move through the heat exchanger in the same direction, with product entering at the bottom and exiting at the top.

The heating surface is polished to a high finish on the inner surface.

The seals are made of single carbon mechanical, carbon flushed / aseptic, hard face and hard face flushed / aseptic. Suitable materials will be selected for special applications.

##### Typical applications for scraped surface heat exchangers include:
• Viscous products: Ketchup, mayonnaise, hummus, peanut butter, puddings, salad dressings, bread dough, gelatine, baby food, skin lotions, and shampoos.
• Heat-sensitive products: Egg products, fruit purées, cream cheeses, and fishmeal.
• Crystallizing and phase changing products: Coffee/tea extracts, icings and frostings, sugar concentrates, margarines, shortening, spreads, gelatine broth, lard, fondant, and, beer and wine.
• Particulate products: Meats, poultry, pet foods, jams and preserves, and rice puddings.
• Sticky products: Caramel, cheese sauces, processed cheese, gums, gelatine, mascara, and toothpaste.

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## What is u-tube heat exchanger? An undeniable advantageous system

Many heat exchangers are U-shaped to maximize tube surface and heat exchange in a confined room. A u-tube heat exchanger or let’s say a u-tube configuration also makes it simple to enter the package. This article will provide readers with an introduction to one of the most common heat exchangers, the u-tube heat exchanger.

## What is u-tube heat exchanger?

U-tube heat exchanger is a form of tube and shell heat exchanger that is used in petroleum and chemical machinery. The tube box, casing, and tube buddle are the key components of a u-tube heat exchanger. Furthermore, drying is simple following the hydro test of the u-tube heat exchanger.

Both of the front header types may be used in a u-tube heat exchanger, and the rear header is usually an M-Type. The U-tubes allow for limitless thermal expansion, the tube bundle may be removed for cleaning, and small bundle-to-shell clearances are possible. However, since mechanical cleaning of the tubes is difficult, this type is normally used only when the tube side fluids are clean. The u-tube design has the drawback of not being able to provide pure counter-flow unless an F-Type Shell is used. Besides, u-tube designs are limited to an odd number of tube passes. This can be one of the disadvantages of u-tube heat exchanger.

On the other hand, about u tube heat exchanger advantages we need to say that the benefits stem from its compact size, which is also very powerful. Because of the U-shape, heat stress can be accounted for. A heat exchanger with U-tube packages takes up slightly less volume than a straight tube heat exchanger of the same design due to the bent individual tubes. Here also the concept of u tube vs straight tube heat exchanger comes to the scene. During the action, u-tube heat exchanger often provides only a low-pressure loss. Stainless steel can help to reduce corrosion and deposits. As a result, the number of repair cycles is greatly decreased. Additionally, a worn tube package may be replaced. If the input temperatures of the two media are very different, the material and construction must withstand extremely high heat stresses. As a result of the temperature differential, the metal expands at different points and to different extents, and cracks will form if the design is flawed. Because of the U-shape of the tube bundle, the heat exchanger can adjust for certain heat pressures very well and is hence well suited for operation with two output media at very different temperatures. Baffles are used in tube package heat exchangers to improve heat exchange.

Yes! There are more about u tube vs straight tube heat exchanger. Any manufacturer would have to decide whether to use a straight tube or a u-tube exchanger. The construction of the tube is important. If a manufacturer selects a tube design that is not appropriate for the application, it can result in exchanger damage or difficult-to-clean fouling. Both u-tube heat exchanger and straight heat exchanger are widely used in a variety of sectors, including food and beverage, chemical, and pharmaceuticals, and each has its own set of benefits and drawbacks. Except for the tube configuration and the rear bonnet, they are similar.

Let’s discover the advantages of straight tube heat exchanger first.

## Advantages of straight tube heat exchanger

One of the most significant advantages of the straight tube heat exchanger is its simplicity. Straight tube exchanger is also common because of its flexibility. Straight tube exchanger allows for pure countercurrent flow within the exchanger without the need for a second one to be connected in series to the first. An F-type two-pass shell with a longitudinal baffle is favored over an E-type in these situations. The baffle divides the two currents. As the cold and heat streams travel in opposite directions, this is referred to as countercurrent movement. For all stages in the exchanger, the hot stream should be colder than the cold stream, though the cold stream’s exit temperature might be greater than the hot stream. Co current flow, on the other hand, defines the passage of hot and cold streams in the same direction. The cold stream must always be lower than the hot stream in this setting. This means that the cold stream’s outlet temperature must be slightly lower than the other. This is impossible to do when the streams are going in the same direction, so many manufacturers resist co current designs.

## u tube heat exchanger advantages

Although straight tube heat exchanger has many advantages, it can fall short in certain ways. This is one of the reasons why the u-tube heat exchanger is so popular. While a straight tube design is safer since the tubing does not need to be curved, as with U-tubes, it can become very expensive when other necessary additions are considered. U-tubes, for example, need only one tube sheet and bonnet, resulting in significant cost savings.

Straight tube heat exchanger is vulnerable to the thermal expansion effect. As the tubes heat at varying speeds and pressures, it does not necessarily spread in sync. Since the tubes are attached to these other critical materials, this may cause damage to the tube layer and shell in a straight tube exchanger. This problem can be alleviated with an extension joint, but these additions are not inexpensive. A u-tube heat exchanger, on the other side, is only attached to the tube sheet and shell on one end, allowing for thermal expansion without causing damage to the rest of the system. Tube packets can also be conveniently separated from the exchanger thanks to U-tube designs. This makes it easier to examine and disinfect the shell and exterior of the tube bundle.

Cleaning is another important factor for designers to remember when designing an exchanger. Straight tubes are the simplest to vacuum when there are no twists to contend with. However, some straight tube designs make testing and cleaning of the shell more complicated because the tubes cannot be.

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U bend tubes for heat exchangers applied mostly in oil and gas plants, chemical and petrochemical plants, refineries, power plants and renewable energy plants. Low fin tubes can be supplied in the form of U bends.

Each U bend tube of our range is rigorously quality checked by our team of talented professionals on every stage of production to deliver the clients defect free best quality products. These U bend tubes can be custom designed in various diameters as per the requirements of our clients.

## U tube heat exchanger

U-bend tubes are widely used in heat-exchanger systems. Heat-exchanger equipment on the basis of seamless stainless U-tubes is essential in strategically important and critical fields — nuclear and petrochemical machine building.

##### “U bend tubes for heat exchangers applied mostly in Oil & Gas plants, Chemical & Petrochemical plants, Refineries, Power plants, Renewable energy plants.”
• Object medium: 10%sodium hydroxide+5%sodium hypochlorite
• Shell Diameter: ø 800
• Working Pressure: 1.5mpa
• Working Temperature: 40º C~90º C
• Heat Exchange Surface Area: 100M2
• Material: Gr1\Gr2

## Fin tube

Fin tubes are used in applications involving the transfer of heat from a hot fluid to a colder fluid through a tube wall. Furthermore, finned tubes are used when the heat transfer coefficient on the outside of the tubes is appreciably lower than that on the inside.

Note:
We produced condenser tube, carbon steel by the material out into the condenser tube, stainless steel condenser tube and carbon steel and stainless steel tubular mixed condensation out of three, according to the form of fixed tube plate, floating head type, U-tube heat exchanger, according to the structure into a single tube, twin-tube and multi-way tube, heat transfer area of 1 ~ 500m2, can be customized according to user needs.

## U Tube Heat Exchanger

U tube heat exchanger is a kind of tube and shell heat exchanger, belongs to the petroleum and chemical equipments. This kind of heat exchanger is named after the‘U’shape tube. U tube heat exchanger is composed of some main components like the tube box, shell, and tube buddle. What’s more, it is easy to drying after the U tube heat exchanger hydrotest.

## U Tube Heat Exchanger Advantages

• The tube buddle can expand or contract freely, and they will not produce thermal stress due to the temperature difference between the tube and shell, which leads a good thermal compensation performance.
• The structure is simple, with only one tubesheet and less sealing surface, thus,the price is low.
• It is easy to make the u tube heat exchanger cleaning and maintenance, which is because the tube buddle can be drawn from the shell body.
• This kind of heat exchanger has a light quality, is suitable for the situation with high temperature and high pressure.

## U Tube Heat Exchanger Design

The biggest difference about u tube heat exchanger compared with other types of heat exchanger is the tube buddle structure, the longer the tube diameter is , the longer the minimum bending radius is. And the u tube heat exchanger bending radius should not less than two times the outer diameter of the heat exchanger tube.
U tube heat exchanger usually designed according to the ASME Code, Section VIII, Division 1. This high load U tube heat exchanger can prevent the stress damage caused by container inflation during the process of heating or cooling. As one end of the tube bundle is float, the heat exchanger can be guaranteed safety even under the extreme heat cycle. It is a ideal design method when the heat medium is steam.
ANSON can manufacture U tube heat exchanger in accordance with the ASME standard, TEMA, and API for 1, 2, or 4 pass U tube heat exchanger, other special requirements are also available.

 TEMA Designations for Shell-and-Tube Heat Exchangers Stationary Head Types Shell Types Rear Head Types A channel and removable cover E one pass shell L fixed tubesheetlike ‘A’ stationary head B bonnet (integral cover) F two pass shellwith longitudinal baffle M fixed tubesheetlike ‘B’ stationary head C channel integral withtubesheet and removable cover G split flow N fixed tubesheetlike ‘C’ stationary head N channel integralwith tubesheet and removable cover H double split flow P outside packed floating head D special high pressure closure J divided flow S floating headwith backing device (split_ring) K kettle type reboiler T pull through floating head X cross flow U u tube bundle W packed floating tube sheetwith lantern ring

Ordering Information:

• Please specify the type or standard you need, ASME standard or TEMA type. If you want a TEMA type heat exchanger please specify the type according to the above TEMA designation table, like TEMA Type BEM.
• Please specify the material you need, we provide material from Steel, Stainless Steel to Copper Alloys. Other material options are also available.
• Please specify the size you need. Like 1, 2, 4 or 6 pass and shell diameter, or other important dimensions you think

## Products

### U-Bend Stainless Steel Tubes Package

‘U’ Bend Stainless Steel Tubes are manufactured in our plant as per the customer requirements. Bends can be Heat Treated in accordance with Clients’ requirements followed by hydrostatic testing and dye penetrant testing if required.

U bent tubes are widely used in heat-exchanger systems. Heat exchanger equipment on the basis of stainless U-tube is essential in strategically important and critical fields nuclear and petrochemical machine building.

U-tube heat exchangers Designed for high temperature applications, especially steam condensing or hot oil systems. Thïs model is selected when differential expansion makes a fixed tube sheet exchanger unsuitable and when conditions preclude a floating head type (HPF) selection.

Surface condition Finished U-tubes shall be free of scale, without scratches after bending

Dimensional tolerances U-tubes acc. to TEMA R.C.B.

Length of straight part -0/+5 mm
Flattening (also called “ovality”) at the bend shall not exceed 10% of the nominal tube outside diameter.
Wall thickness in bending part acc. to TEMA RCB 2.31 Minimum tube wall thickness in the bend part (T min)T(min) ≥ (SW × (2×R + D))/( 2× (R+D)where:

SW is smallest wall thickness D Nominal outside diameter R radius
Radius tolerance 1) for R 100 mm +/- 3 mm

2) for R ≥ 100 mm +/- 5 mm
Straightness tolerance max. 1,5 mm per 1 m
U-Tube ends: plain, vertically cut to the tube axis

Tube-bending line, installed at 2007, will allow to produce U-tubes as per such standards:

1. ASTM A688/A688M-08
2. ASTM A803/A803M
3. ASTM A556/A556M, ASME SA556
4. ASME SA-688

Initial Length
Maximum lengths of 27000mm can be supplied on request

Dimensions
Tubes OD in mm can be bent upon agreement: 15,8 – 16,0 – 17,0 – 18,0 – 19,05 – 20,0 – 21,3 – 25,4 -26,7 – 31,8 -38,1

Minimum: 1.5×OD
Maximum: 1500 mm

Heat treatment of the bend
U-bends with a bending radius up to maximum of 1500mm can be heat treated on request

The basic Testing and processing:
1. High Pressure Hydrostatic Test:Minimum:10 Mpa-25Mpa.
2. Air Under Water Test After Bending
3. U Tubes Wall Thickness Test
4. Eddy Current Test before U bend Formed
5. Ultrasonic Test before U bend Formed
6. Heat treatment to stress relieved
7. Ball passing test

The below sizes are those most frequently used,other sizes can be produced upon request.

 Grade(UNS): Austenitic Stainless Steel:304/304L/304H(1.4301/1.4306/1.4948); 316/316L(1.4401/1.4404); 316Ti(1.4571); 321(1.4541); 309S(1.4833); 310S(1.4845); 317L(1.4438)321H(1.4878); 347H (1.4550);Duplex Stainless Steel:S32001, S32003, S31500, 2205(1.4462); S32304,(1.4362);S31803,2507 (S32750),S32760(1.4501);S32101(1.4162);Super Austenitic Stainless Steel: 904L, S30432, S31042, 6Mo (S31254, N08367)Nickel Base Alloys:Alloy 20 (UNS N08020), Monel 200 (UNS 02200), Monel 400 (UNS N04400),Incoloy 800 (UNS N08800), Incoloy 800H (UNS N08810), Incoloy 800HT (UNS N08811), Incoloy 825 (UNS N08825),Inconel 600 (UNS N06600), 4J29, 4J36, GH3030, GH3039, C276 (UNS N10276)Martensitic Stainless Steel:410(1.4006), 410S(1.4000), 420(1.4021)Ferritic Stainless Steel:405(1.4002), 430(1.4016) Outside Diameter: 6 – 830mm Wall Thickness: 0.50 – 60mm Standards(Norm): EN 10216-5; DIN 17456, DIN 17458, DIN 2462, DIN 17455 GB/T14975; T14976; T13296; GB5310; ASTM A213, A269, A312, A511, A789, A790, A928, A999, A1016, ASTM B161, ASTM B163, ASTM B165, ASTM B167, ASTM B338, ASTM B407, ASTM B423, ASTM B444,ASTM B619, ASTM B622, ASTM B626, ASTM B668, ASTM B677, ASTM B829 JIS G3459, JIS G3463, JIS G3446, JIS G3447, JIS G3448, JIS G3468 GOST 9940;GOST 9941;

Your best solution in Heat Exchange solution!
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## L/LL/LK Finned Tube

Fin Type: Fin Tube
Tube Material: Carbon steel, stainless steel, copper, aluminum
Fin Material: Copper, aluminum
Fin Tube Length: No Limit
Product description/LL/KL finned tube: Working temperature: 230?. Features: Adopting the winding process, the production efficiency is high, the lamella distance is uniform, the heat transfer is good, the finization ratio is high, the base tube can be protected from air erosion.

## L/LL/KL Finned Tube

Finned tube is a tube with small finned fins around its outer surface. These fins act as a filter and a mechanism for transferring heat from the material inside the tube to or from the outer space. Finned tubes are used in applications where heat is transferred from a hot fluid to a cooler fluid through the wall of the tube. The rate at which this heat transfer occurs depends on three factors:

The difference in temperature between the two fluids.

The coefficient of heat transfer between each fluid and the wall.

Surface area of fluid exposure.

L type finned tube. Adopting the winding process, the production efficiency is high, uniform lamella distance , good heat transfer, high finization ratio, the base tube can be protected from air erosion. The aluminum fin or copper fin is folded into an L shape and continuously spirally wound on the outer surface of the base tube under the action of tension.

Maximum working temperature-150°C (302°F), acceptable for atmospheric corrosion resistance, poor mechanical resistance. Commonly used heat sink materials are aluminum and copper.

LL typefinned tube: Under the L-shaped foundation, the fin root completely covers the outer surface of the base tube; to some extent, this fin type guarantees better corrosion resistance. Maximum working temperature-180°C (356°F), acceptable for atmospheric corrosion resistance, poor mechanical resistance. Commonly used heat sink materials are aluminum and copper

KL type finned tube: Before the fins are continuously wound on the surface of the steel pipe, the outer surface of the base pipe needs to undergo a knurling process; after the fins are wound, the root of the fin attached to the steel pipe will also be knurled to strengthen the steel pipe and Combination of fins. For this reason, this fin type ensures better heat transfer characteristics under the fins of L and LL. Maximum working temperature-260°C (500°F), acceptable for atmospheric corrosion resistance, poor mechanical resistance. Commonly used heat sink materials are aluminum and copper

## L/LL/KL Finned Tube applications

Application: Mainly used in air coolers in petrochemical, electric power, paper making, tobacco, building heating and other industries, air heaters and air heaters in spray drying systems such as vegetable protein and starch in the food industry. Blast furnace and converter systems, power generation: condensate exhaust gas discharged from steam turbines, condensate contact cycle cooling condensation, fossil and nuclear power plants, air conditioners (Freon, ammonia, propane), waste incineration equipment, compressor coolers, etc.

## ‘L’ FIN TUBE, ‘LL’ FIN TUBE, ‘KLM’ FIN TUBE (WRAP AROUND FIN TUBE):-

The L’ FIN TUBE, ‘LL’ FIN TUBE, ‘KLM’ FIN TUBE also known as Wrap Around Fin Tube. This type of Fin Tube widely finds acceptance where the Heat Transfer Temperature is relatively lower and the cost needs to be controlled. These type of Fin Tubes are relatively lesser in cost as compared to the ‘G’ Type Fin Tube and the Extruded Type Fin Tube.

In ‘L’ Type Fin Tube or also known as ‘L’ Foot Fin Tube the finning is done by wrapping around the Fin stock spirally around the base tube. This is as reason also known as spirally wound Fin Tube. The base of the fin stock is Shaped in to and ‘L’ shape which gives a base for the fin to stand on firmly. Also the ‘L’ shape provides a certain protection against the atmospheric corrosion.

The next version of wrap around Fin Tube and also of ‘L’ Fin Tube is ‘LL’ Fin Tube. The process is similar to the L Fin Tube type. However, the improvement is that the ‘L’ Foot of the previous fin is completely overlapped by the ‘L’ Foot of the next fin. This gives the Fin base a shape of tow ‘L’ foot simultaneously. It provides excellent corrosion resistance.

The last and the most widely used type of wrap around Fin Tube is ‘KLM’ Fin Tube or ‘Knurled L’ Foot Fin Tube.

This is currently one of the most widely type used and preferred Fin Tubes. This type of Fin Tube is manufactured similar to the ‘L’ Fin Tube. However, the process involves Knurling the Tube and at the same time the ‘L’ base of the fin stock to firm a frim bond and much better contact between the Fin and the Tube.

In all the above type of wrap around Fin Tubes the fins are held by Spiral Tension, The ends are required to be firmly held to gather by means of Mechanical Bonding, Brazing etc. This tube also has an added benefit of using Much Lower Thickness of the Base tube thereby reducing the cost considerably.

These Fin Tubes find application in AIR FIN COOLERS, RADIATORS etc. and are preferred in Industries like Power Plants, Chemical Industries, Petroleum Refineries, Chemical process Plants, Rubber Plants, etc.

Properties of ‘L’ FIN TUBE, ‘LL’ FIN TUBE, ‘KLM’ FIN TUBE (WRAP AROUND FIN TUBE):-

1. Manufacturing Process: – Wrap Around the Base Tube with various iterations of the Fin Base
2. Fin To Tube Bond:- Moderate
3. Heat Transfer Efficiency:- Moderate
4. Mechanical Resistance: – Moderate
5. Corrosion Protection: – Good
6. Temperature Range:- Up to Maximum 175 Deg C

Manufacturing Range ‘L’ FIN TUBE, ‘LL’ FIN TUBE, ‘KLM’ FIN TUBE (WRAP AROUND FIN TUBE):-

 Sr. No Particulars Range 1 Base Tube Material Stainless Steel, Carbon Steel, Alloy Steel, Titanium, Copper, Duplex Stainless Steel, Inconel etc. (all material in the theoretical limit) 2 Base Tube Outside Diameter 12.70 mm to 38.10 mm 3 Base Tube Thickness 1.25mm And Above 4 Base Tube Length 500 mm Min To 15000 mm 5 Fin Material Aluminum, Copper, Stainless Steel, etc. 6 Fin Thickness 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.55mm, 0.60mm, 0.65mm 7 Fin Density 236 FPM (6 FPI) to 433 FPM (11 FPI) 8 Fin Height 9.8 mm to 16.00 mm 9 Bare Ends As per Client Requirement 10 Manufacturing Capacity 5,00,000 Meter Per Annum

We can supply material on urgent delivery basis because of large stock and relations with raw material suppliers. We use only Prime Quality base tube and Aluminum Material.

The Extruded Fin Tubes can be supplied with EN 10204 EN 3.1 and EN 3.2 certifications. We can provide Third Party Inspection from any reputed inspection agency.

## L/LL/KL/KLM Type Fin Tube, Wrapped Tension L Type Finned Tube For Heat Exchanger

Manufacturing process:

The fin strip (normally aluminum and copper) is folded into an L SHAPE and wound onto the base tube surface under tension. The feet of the fins are joined together and cover the finned surface.

Surface Protection:

Both bare ends shall be Zinc or Aluminum metalized applied by an electro spray arc system coating.

HFW Solid Finned Tubes short for High Frequency Welded Helical Spiral Solid Finned Tube

Helical Finned Tubes provide the designer with high thermal efficiency and compact design solutions for a whole range of heat exchangers where clean flue gases are used. Helical finned Tubes are manufactured in both Solid and Serrated type.

Helical Solid Finned Tubes are manufacturer by helically wrapping continuous fin strip on tube. HF Resistance Welding Usually Employs Frequency Of 400 kHz. The fin wound around the tube And Continuous weld. The fin strip is wounded spirally onto the tube and welded continuously with a high frequency electrical process to the base tube along the spiral root. The fin strip held under tension and confined laterally as it is formed around the tube, thereby ensuring that the strip is in forceful contact with the base tube surface. A continuous weld is applied at the point where the fin strip first begins to bend around the tube diameter, using the gas metal arc welding process.

For a given tube or pipe size, the desired heat transfer surface area per unit length of tube can be obtained by specifying the appropriate fin height, fin thickness and /or number of fins per meter of length.

HFW Solid Finned Tube

This welded steel finned tube configuration can be used for any practically heat exchanger application, and is particularly suited to high temperature and high pressure applications. The important features of this configuration are efficient, effective bond of fin to tube under all conditions of temperature and pressure, and ability to withstand high fin-side temperatures.

A continuous helical fin is attached to the base tube by high frequency electric resistance welding in order to give an efficient and thermally reliable bond.

Technical Details/Base Tube Details

Tube Diameter : 20 mm OD Min to 219 mm OD Max.

Tube Thickness : Minimum 2 mm up to 16mm

Tube Material : Carbon Steel, Stainless Steel, Alloy Steel, Corten steel, duplex Steel, Super Duplex Steel, Inconel, High Chrome High Nickle & Incolloy, CK 20 material and some other material.

Fin Details

Fins Thickness : Min. 0.8 mm to Max. 4 mm

Fins Height : Min 0.25” (6.35 mm) To Max.1.5” (38 mm)

Fin Density : Min 43 Fins Per Meter To Max. 287 Fins Per Meter

Material : Carbon Steel, Stainless Steel, Alloy Steel, Corten steel, Duplex Steel and Incolloy.

For a rapid quotation, plz send with following requirement:

Number of pieces,

base tube: Diameter, thickness, length and material specification.

Fins: material specification, type (solid or serrated), height, thickness, spacing, finned length and unfinned sections. Weld prep details if required.

Delivery period required.

Keywords: Fin tubes, Finned tube, Finned Pipe Helical Finned Tubes, Solid fin tubes, Serrated finned tube, Helical Serrated Finned Tubes, Tubos Aletados

 * These are the most common fin/tube patterns. We have more than 20 different plate fin and tube combinations. Contact me for more information and options. Helical Fin Surface(Tube OD – Available Helical Fin Height on the Tube) 5/8″ – 3/8″, 1/2″ and 7/16″ 1″ – 3/8″, 1/2″ , 7/16″ and 5/8″ 1 1/4″ – 3/8″, 1/2″ , 7/16″ and 5/8″ 15.875mm – 9.525mm, 12.7mm and 11.113mm 25.4mm – 9.525mm, 12.7mm, 11.113mm and 15.875mm 31.75mm – 9.525mm, 12.7mm, 11.113mm, and 15.875mm “L” Footed, Embedded and other helical fin attachment options are available.Contact me about the availability of 1 1/4″ (31.75mm) tube material

The common application fields are:

1. Heat exchangers units for power plant(electric, nuclear, thermal and geothermal power plants);
2. High corrosive systems (condensers, evaporators, sea water desalinations, fertilizing, urea systems, ammonia, gas, corrosive acids);
3. The petroleum, chemical and petrochemical industries;
4. The food processing and refrigeration industries;
5. Natural gas treatment;

## ‘L’ Finned Tubes

One common type of finned tube is the ‘L’ fin. Receiving its name from the letter it creates from the cross-sectional view, the ‘L’ fin relies on maximum surface contact between fin and tube which is ensured by tension-forming a fin strip helically around the base tube.

This type of connection maximizes the heat transfer capacity and enhances the corrosion protection of the tube. The ‘L’ fin accommodates temperatures between 150 to 170 °C and comes in mainly ductile metals such as aluminum or copper which are capable of withstanding the compression around the base of the fin and allow stretching on the outside during installation.

Fig. 9: Typical Heavy-Duty Dry Air Cooler or Condenser – commonly using copper, aluminium or carbon steel tubes with helical aluminium or galvanized fins.
Note the removable bolts in the header box which allow for inspection and cleaning of the tubes.

Fig. 10: Copper finned tubes copper tubes

Fig. 11: Cross-sectional schematic of L fin

## 4. ‘LL’ Finned Tube

Manufactured in the same way as the ‘L’ finned tube, the ‘LL’ fin has overlapping feet to completely enclose the base tube, resulting in excellent corrosion resistance. The maximum operating temperature is approximately the same as the ‘L’ fin. This type of fin commonly available in aluminum and copper. The Overlapped “L” fin design has interlocking fins that are wound together to prevent movement and separation. The fins protect the entire tube and the designation works well for the applications where corrosion is an issue.

## 5. ‘KL’ Finned Tube

‘KL’ Fin Tubes are also called knurled finned tubes. The fin is wrapped around the tube and the foot is rolled into the outer surface of the pre knurled tube and secured at each end. The fins are manufactured from a strip of metal which is machined into an accurately controlled L shape foot, similar to the L type fin, then it is rolled into a taper causing it to curl. The tube surface is knurled by a rotating tool, then the foot of the fin is knurled into the base tube providing a tight bond that optimizes thermal transfer.

## L/Ll /Kl Type Finned Tube/Heat Exchanger/ Fin Tube

Aluminum Finned Tubes type including: L/ KL/ LL type finned tube, Extruded finned tube, “G” embedded finned tube,HF spiral welding fin tube ,bend ,radiator. If you are interested in our products, please tell us the detail information or send your drawing, we will produce as your drawing.

Features:
1)Tube material: Stainless steel as ASME ASTM 213, 312 — 304L, 304, 316, 316L, 321 etc, . Carbon steel as ASME ASTM– 106, 179, 192, etc, alloy, Aluminum, and copper.

2)Fin material: Carbon steel, alloy, Aluminum, and copper, etc.

3)Bare tube size: OD 15.85mm-168mm.

L type finned tube:Adopting the winding process, the production efficiency is high, uniform lamella distance , good heat transfer, high finization ratio, the base tube can be protected from air erosion. The aluminum fin or copper fin is folded into an L shape and continuously spirally wound on the outer surface of the base tube under the action of tension.

Maximum working temperature-150°C (302°F), acceptable for atmospheric corrosion resistance, poor mechanical resistance. Commonly used heat sink materials are aluminum and copper.

LL typefinned tube: Under the L-shaped foundation, the fin root completely covers the outer surface of the base tube; to some extent, this fin type guarantees better corrosion resistance. Maximum working temperature-180°C (356°F), acceptable for atmospheric corrosion resistance, poor mechanical resistance. Commonly used heat sink materials are aluminum and copper

We can supply material on urgent delivery basis because of large stock and relations with raw material suppliers. We use only Prime Quality base tube and Aluminum Material.

The Extruded Fin Tubes can be supplied with EN 10204 EN 3.1 and EN 3.2 certifications.

## Benefits & Tradeoffs of All-Stainless Steel Coi

Oftentimes, using stainless steel components seems like a simple solution to corrosion on coils. You may see fins or tubes or other parts of the system show signs of corrosion, and it seems that the best option is to change the coil to stainless steel, solving the corrosion problem permanently. While this seems like a simple solution to a significant problem in the HVAC, industrial, and commercial systems where coils are found, the answer to the question “should I make an all-stainless coil?” is far moare complex.

While it’s true that stainless steel has excellent corrosion resistance properties, when used in a heat exchanger it can have poor heat transfer characteristics. So, it’s possible that by solving the corrosion problem using stainless, other system issues could result. Performance reduction, exceeding fan or motor capacities, and exceeding space or structural limitations of the existing unit are all possibilities when changing a system’s materials to stainless. Finally, there are the economics – is the stainless steel solution a viable commercial option for the installation?

As the system engineer, you are faced with a dilemma: meet the overall system constraints, solve the corrosion problem, and maintain a budget so the project moves forward. These priorities often conflict with each other, but the evaluation and balancing of these objectives are where Super Radiator can lend a hand.

To better understand the potential impact of using an all stainless steel heat exchanger, let’s evaluate an example 400,000 BTU/HR (33 tons or 119 kW) cooling coil. For the example, we’ll use 45° F water and a 36” x 45” coil with standard copper tubes and aluminum fins. The coil for this installation will be 12” deep, weigh 320 pounds and have a cost factor of 1.0. This is our base unit and is the component currently installed in the system.

The question is what is the impact of changing the heat exchanger to all stainless steel? There are two ways to evaluate the case: keep the same unit capacity or fit the space of the current unit.

Here are the results of using all stainless steel:

• Maintaining capacity: Air pressure drop = increased 2.3x; Weight increase= 6x; Depth increase= 2.2x ; Cost Factor = 6.8x.
• Air pressure drop= no change; weight increase 1.5x; Capacity Decrease = 40%; Cost Factor = 4.

To summarize, changing the coil from the copper and aluminum to all stainless steel will be a cost increase between 4 and 7 times the original coil. Moreover, it will either not fit in the existing unit, or short the system capacity by 40%.

If the system being designed is new, the larger size or different capacity could be reconciled with adjustments to other system components, such as changing the fan to accommodate the higher levels of air friction or altering the unit design to create more space for the larger coil. However, for an existing system, this may not be possible.

Stainless steel or other high corrosion-resistant material may be the only option in some systems: high temperatures, abrasive environments, extreme caustic chemical solution. For many cases, a basic coil with a high-quality coil coating can solve most coil corrosion issues. Let’s evaluate the impact of this option.

Based on Super Radiator research, using a coil coating has little impact to the thermal performance of the coil. However, coating does incur additional cost compared to an uncoated coil. Electro-deposition (E-coat) and baked phenolic (such as Heresite P413) are the most common, quality coil coatings. The example coil, with the coating will have cost factor of 1.3. The price is higher than the bare coil, but coating is a great option to solve the corrosion issue, meet the performance needs of the system, and fit the space.

Copper fin and tube are often considered for corrosive, abrasive, or harsh environments. For select installations, an all-copper construction is a good option. Adding to our example from earlier in the document, a copper coil will have a cost factor of 1.5. However, the copper construction does have the benefit of 3.5% increased capacity. Using copper fins keeps the air friction the same as with aluminum fins. The coil weight does increase by 1.8x.

Is all stainless steel construction the best option to solve the corrosion issue on your finned tube coil? It may be. But there may be better options.

## Stainless steel: The ideal material for heat exchanger construction

Stainless steel has proven to be a particularly reliable and durable material here. Heat exchangers made of stainless steel are particularly resistance to corrosion and deposits of limestone and other residues are minimized.

Common tube bundle heat exchangers and special heat exchangers can be realized using stainless steel without problem. If single parts are welded to each other, each welded seam always marks a possible weak spot. Always rely on an experienced manufacturer due to reasons of reliability during operation. We have the necessary expertise and experience to perform welded seams cleanly and reliably according to the WIG and/or MIG procedure. Naturally we are certified according to DIN EN ISO 3834-3:2005.

Austenitic stainless steels such as Type 304 (UNS $30400) and Type 316 (UNS 31600) are frequently selected for heat exchangers placed in cooling water service. These alloys generally perform well in clean water and are expected to give a long service life with minimal problems. Unfortunately the assumption that cooling waters will be clean is often misleading, and unexpected failures can result from localized corrosion mechanisms such as pitting, crevice corrosion, microbiologically influenced corrosion (MIC), and stress-corrosion cracking (SCC). Localized corrosion may be associated with water chemistry parameters such as temperature and chlorides, deposits that accumulate in the system, microbiological activity, operational factors such as low water velocity and stagnant water after hydrotesting, and variations in steel chemistry at inclusions and welds. An overview of localized corrosion mechanisms for stainless steel is presented along with corrosion tendencies for modem versions of Types 304/316 stainless steels. 300-series stainless steel (SS) alloys are often used in exchangers at power plants, refineries, chemical plants, and paper mills. Types 304 (UNS$30400) and 316 (UNS 31600) are popular and cost-effective choices for general purpose stainless steels in cooling water service (Table 1). Austenitic SS alloys are ductile, tough and most importantly, easy to form and weld. Type 304, also known as “18/8,” is the most widely used SS alloy in the world. Typical applications would include shell and tube heat exchangers, plate and flame exchangers, piping, and water jackets for process reactors. With shell and tube heat exchangers, cooling water can be on the shell side or tube side, and the exchanger orientation can be horizontal or vertical. When the environmental conditions are conducive for localized corrosion, Type 316 is recommended because the addition of molybdenum increases resistance to pitting and crevice corrosion.

A wide variety of higher alloyed specialty stainless steels are available environments or critical stand-by water systems, but at a premium price. For example, 6% Mo superaustenitic SS alloys such as AL6XN will not suffer pitting or crevice corrosion when immersed in ambient temperature seawater. AL6XN heat exchanger tubing costs nearly four times as much as Type 304, based on 2002 prices 1.

Today’s 300-series Stainless Steels

Modem versions of products are usually thought to be equal or better than the old ones they replace. This, however, does not hold true for 300-series stainless steels. Types 304/316 alloys being produced today are not as corrosion resistant as those produced 20 to 30 years ago ~. Because of advances in SS melting practices, ladle refining, and economic competition between manufacturers, typical 300-series SS alloys now have chemistries very near the absolute minimum of the ASTM requirement. This is largely due to the widespread use of argon-oxygen decarburization (AOD), which has facilitated pinpoint control over both major and minor alloying elements (Ni, Cr, Mo, C, N, S) 2. For example, 20 years ago typical Type 304 had a chromium level of approximately 19% and Type 316 had a molybdenum content close to 2.6% 1. Modem Type 304 has chromium levels just above 18%, and the molybdenum content of Type 316 now runs below 2.1%. The nickel content of Type 304 has also dropped nearly 1% over the years, while Type 316L is leaner by more than 2% nickel and 1-1/2% chromium 2.

## The Introduction of Stainless steel coil

Stainless steel capillary
First, the definition of stainless steel coil
Stainless steel coil, generally diameter of 0.5 to 20mm, thickness of 0.1 to 2.0mm plate mounted or mosquito coils installed; widely used in chemical, mechanical, electronic, electrical, textile, rubber, food, medical Equipment, aviation, aerospace, communications, petroleum and other industrial fields.
Stainless Steel Coil Picture Picture provided by Jiangsu Yeqing Stainless Steel Co., Ltd
Second, the type of stainless steel coil
Stainless steel industrial pipe, ultra-long coil, U-tube, pressure pipe, heat transfer tube, fluid pipe, spiral coil Features: high temperature steam, impact corrosion, ammonia corrosion; anti-fouling, Safe and reliable; pipe wall is uniform, wall thickness of only 50-70% of the copper, the overall thermal conductivity is better than the total thermal conductivity is better than, Brass; the old unit is the transformation and manufacture of new equipment ideal heat exchanger products. In the petrochemical industry, electric power, nuclear industry, medicine, food and other industries can be widely used.
Third, the use of stainless steel coil
Industrial stainless steel coil: heat exchangers, boilers, petroleum, chemical, fertilizer, chemical fiber, pharmaceutical, nuclear power and so on.
Stainless steel coils for fluids: Beverages, beer, milk, water systems, medical equipment, etc.
Stainless steel coil for mechanical structure: printing and dyeing, printing, textile machinery, medical equipment, kitchen equipment, automotive and marine accessories, construction and decoration.
Bright stainless steel coil: welded by a good stainless steel strip and then reduce the wall, from thick to thin wall, this process can make the wall thickness uniform, smooth, and reduce the wall of the wall to form a seamless tensile effect. Seamless in accordance with the naked eye, but the process is the pipe. Reduce the wall with the process of bright annealing, so that the inner and outer walls will not form oxide, inside and outside the bright, beautiful, this is really medical products needed. The next process needs sizing, that is, a small pull process to determine the diameter, diameter tolerance can generally be positive and negative 0.01m
Specifications:
3/8 “* 0.049 * (1 ~ 2000m)
1/8 “* 0.035 * (1 to 3500 m)
1/4 “* (0.035” to 0.049) * (1 to 1800 m)
1/2 “* 0.049 * (1 to 1000 m)
Φ3 * 0.9 * (1 ~ 3500m)
Φ4 * 0.9 * (1 ~ 2500m)
Φ6 * 0.9 * (1 ~ 1700m)
Φ8 * 1 * (1 ~ 1000m)
Φ10 * 1 * (1 ~ 8000m)
Φ (10-26) ★ (1-2) length (1-800m) diameter according to customer requirements
Material: 201,202,304,304 L, 316L, 317L, 321 (also according to user requirements)
Pressure: 60-100MPa
Implementation of the standards: in line with ASTM A269-2002.JIS G4305
Technical requirements

## What Kind of Savings Come from a Stainless Steel Heat Exchanger?

Waste-oil combustion is an environmentally friendly and efficient way to power your boiler, space heater, or furnace. Waste-oil combustion helps you save money, energy, and the planet, all while staying more comfortable in your home or office. At the heart of waste-oil combustion technology is the heat exchanger – the component that transfers energy from the oil into heat. The heat exchanger is crucial for cooling and heating purposes. The heat exchanger most affects the safety and performance of your unit, making it an important piece to optimize. A stainless steel heat exchanger offers a range of benefits compared to other materials.

Higher Product Quality

Stainless steel is one of the toughest and most durable materials in the world. It is better equipped for handling high temperatures and resisting corrosion than aluminum, iron alloys, or steel alloys are. Stainless steel heat exchangers have 10.5% more chromium than alloys, making it incredibly resistant to corrosion and rust – two common problems with boilers, heaters, and furnaces.

Stainless steel also offers quality in terms of thermal conductivity. Thermal conductivity is the measure of how well a unit can transfer heat. The higher the thermal conductivity, the better the unit performs. While aluminum’s thermal conductivity is greater than any kind of steel, aluminum will corrode and warp over time. Stainless steel, on the other hand, will never lose its shape or ability to conduct heat.

Manufacturers of stainless steel heat conductors overcome the problem of lower thermal conductivity by making the walls of the component thinner. Thinning the walls maximizes heat exchange while retaining the lasting strength of the original material. Thinner, more durable stainless steel heat exchangers offer better performance than even galvanized steel. The high tensile strength of stainless steel means it can withstand high pressures despite thin walls – something other metals cannot manage.

Better Reliability

The properties and capabilities of stainless steel give it a lasting reliability that one cannot enjoy with heat exchangers made from other materials. Temperature tolerance and corrosion resistance are two major factors for waste-oil combustion, where traces of sulfur cannot mix with water condensation anywhere within the chimneystack for optimal performance. Stainless steel heat exchangers are best in class for both these factors, beating out the competition by a long shot.

Stainless steel heat exchangers carry a lifetime warranty. By comparison, copper alloy heat exchangers have warranties of just five to 10 years, and aluminum ones may have warranties of up to 15 years. Manufacturers offer lifetime warranties on stainless steel heat exchangers, because they’re confident the units will last for life. Stainless steel won’t crack under pressure as other materials do – important for performance and long life, but also for personal safety. A cracked heat exchanger can release deadly carbon monoxide gas into your home. Stainless steel protects your investment and your family.