Finned tube features and application

Murphy finned tube in warehouse

Classification of finned tubes

There are many types of finned tubes, and new varieties are constantly emerging. Generally, it can be classified according to the following aspects:

1. Classified by processing technology

1) extruded fin tube;

2) Welding and forming finned tubes (high-frequency welding finned tubes, submerged arc welding finned tubes);

3) Roll forming finned tube;

4) the finned tube is fitted and formed;

5) Casting finned tube;

6) Tension-wound finned tube;

7) Insert tube.

Classified by fin shape

1) Square finned tube (Square finned tube);

2), round finned tube;

3) spiral finned tube (spiral finned tube);

4) Longitudinal Finned Tube (Longitudinal Finned Tube)

5) Corrugated finned tube;

6) Helical Serrated Finned Tubes;

7) Needle-shaped finned tube;

8) Tonghao overall plate finned tube (plate fin);

9) inner finned tube (inner finned tube). and many more.

3. According to whether the fin material of the fin tube is the same as that of the base tube, it can be divided into:

1) single metal finned tube

2) bimetal composite finned tube

Single metal finned tubes are classified by material

1) copper finned tube;

2) aluminum finned tube;

3) Carbon steel finned tube;

4) stainless steel finned tube;

5) cast iron (cast steel) finned tube; etc.

Classified by purpose

1) Finned tubes for air conditioning;

2) Finned tubes for air cooling;

3) Boiler: finned tube used by water wall, economizer and air preheater;

4) Finned tubes for industrial waste heat recovery;

5) other special purpose finned tubes; etc.

Finned tube features and application

Murphy finned tube in warehouse

The heat exchange principle of finned tube and the application of finned tube

The characteristics of finned tube 
In order to improve the heat exchange efficiency, fins are usually added on the surface of the heat exchange tube to increase the heat exchange.
The outer surface area (or inner surface area) of the tube, so as to achieve the purpose of improving the heat exchange efficiency, so
The heat exchange tubes are called finned tubes.
The finned tube is used as a heat exchange element and works under high temperature flue gas conditions for a long time, such as a pot
The finned tubes for furnace heat exchangers are used in harsh environments, high temperature and pressure, and corrosive atmosphere.
The finned tube should have a high performance index.
1) Anti-corrosion
2) Wear resistance (Anti-wear)
3) Low contact resistance (lower contact resistance)
4) High stability (Higher Stability)
5) Anti-fouling ability
High-frequency welding spiral finned tube is one of the most widely used spiral finned tubes.
It is widely used in power, metallurgy, cement industry preheat recovery and petrochemical industries. High
The frequency welding spiral fin tube uses the skin effect of high frequency current while the steel strip is wound around the steel tube.
And proximity effect, heating the steel strip and the outer surface of the steel pipe until the plastic state or melting, in the winding
The welding is completed under a certain pressure around the steel belt. This kind of high frequency welding is actually a solid phase welding.

Murphy copper finned tube

Compared with inlaying, brazing (or overall hot-dip galvanizing) and other methods, whether it is in product quality (fin’s

The welding rate is high, up to 95%), and the productivity and the degree of automation are more advanced.

Second, the principle of finned tube heat transfer

Below we discuss the heat transfer of the lower fin tube through an example of a specific heat transfer device thermal principle.

There is a heat exchanger that uses hot water to heat the air. The hot water flows in the tube and the air is outside the tube.

flow. For example, the hot air curtain for heating or the radiator on the car belong to this

A type of heat transfer, that is, the heat of the hot water is transferred through the tube wall to the cold fluid outside the tube—air.

It can be seen that the heat transfer process is closely related to the two convective heat transfer processes on both sides of the partition wall.

For the above example: the convective heat transfer coefficient on the water side of the tube is about 5000, while the

convective heat transfer coefficient on the air side is about 50, and the difference between the two is 100 times. Due to the heat exchange on the air side the “capacity” is much lower than the water side, which limits the performance of the heat exchange “capacity” of the water side and makes the air the side becomes the “bottleneck” of the heat transfer process, limiting the increase in heat transfer. 

To overcome the air side for the bottleneck effect, adding fins on the outer surface of the air side will be the most sensible choice.

After installing the fins, the original heat transfer area on the air side has been greatly expanded to make up for overcome the shortcomings of low heat transfer coefficient on the air side, the heat transfer is greatly improved.

The effect of adding fins can also be illustrated by the following more vivid example:

The immigration department at the border port assumes that Party A’s port has ten inspection ports and can be released every hour

5000 people, but there is only one ticket gate at Party B’s port, and it is very slow. It can only be released every hour.

Line 50 people. In this way, Party B’s side becomes a bottleneck for passenger clearance, making Party A’s “ability”

Can’t play. In order to increase the flow of customs clearance, the most effective way is to open a few more on the side of Party B.

Inspection port. This is the same as the principle of installing fins.

When should finned tubes be used for heat exchange?

After understanding the principle and function of finned tubes, where to choose finned tubes, there are the following principles:

(1) If the heat transfer coefficients on both sides of the tube are very different, the heat transfer coefficient should be small

Fins are installed on one side.

Example 1: The boiler economizer has water in the tube and flue gas out of the tube, and fins should be used on the flue gas side.

Example 2: Air cooler, liquid is in the tube, air flows out of the tube, fins should be added to the air

side.

Example 3: In the steam generator, water is boiled inside the tube, and flue gas flows outside the tube. Fins should be added to the

Smoke side. It should be noted that in the design, the side with the smaller heat transfer coefficient should be placed outside the tube as much as possible to facilitate the installation of fins.

(2) If the heat transfer coefficients on both sides of the tube are very small, in order to enhance heat transfer, the same

When installing fins, if there are structural difficulties, no fins can be added on both sides. under these circumstances,

If only fins are added to one side, there will be no obvious effect on the increase in heat transfer.

Example 1: The traditional tubular air preheater uses air inside the tube and flue gas outside the tube. because

It is the heat transfer of gas to gas, the heat transfer coefficients on both sides are very low, and it is difficult to add fins in the tube, so I had to use a bare tube.

Example 2: Heat pipe air preheater, although the flue gas still heats the air, but due to the flue gas and

The air flows outside the tube, so finned tubes can be conveniently used on both the flue gas side and the air side, so that

the heat transfer is greatly increased.

(3) If the heat transfer coefficients on both sides of the tube are large, there is no need to use finned tubes.

Example 1: Water/water heat exchanger, when hot water is used to heat cold water, the heat transfer coefficients on both sides are sufficiently high, there is no need to use finned tubes. But in order to further enhance heat transfer, threaded pipe or

the corrugated tube replaces the light tube.

Example 2: In the condenser of a power plant, water vapor is condensed outside the tube, and water flows inside the tube. On both sides.

The heat transfer coefficient is very high, under normal circumstances, no need to use finned tubes.

 For more information, contact us

 

Stainless steel fin tube features and application

Murphy Steel Aluminum Composite Finned Tube

Processing technology and temperature change of stainless steel finned tube

Stainless steel finned tube is mainly used in production process of 304 type stainless steel processing, when making use of it is mainly used for two kinds of medium of heat transfer, laser welding stainless steel finned tube sophisticated technology, excellent performance, is the boiler, power generation, petrochemical industry, hvac, refrigeration, air conditioning industry such as heat, waste heat recycling alternatives.

Stainless steel finned tube in use can effectively improve the efficiency of the heat exchanger, to a certain extent, effectively prolong its life, reduce the volume and save material, the overall rolling finned tube without contact thermal resistance, heat transfer performance is good, high strength, thermal vibration and mechanical vibration resistance, thermal expansion performance is good.

The thermal contact resistance of the stainless steel finned tube is low, the product can maintain a stable low value within a large range of temperature changes, the heat transfer coefficient of the whole product is high, and it has good resistance to temperature change and vibration when in use, the heat transfer area per unit length is large, the heat transfer is high, the structure is reliable and the life is long; Finned surface smooth no burr, no wrinkle, not easy to scale, easy to clean and remove surface water, low flow resistance, can maintain good heat transfer performance for a long time.

The finned stainless steel tube has the characteristics of high strength, small flow loss, strong anti-corrosion performance, not easy to deform under long-term hot and cold working conditions and long service life. The whole rolled fin is smooth without burr, wrinkle and easy to clean. It is easy to remove the condensation water on the outer surface of the fin when wet cooling in heating and air conditioning engineering. It is not easy to dust and scale in drying, heating and other heat exchange occasions.

Murphy stainless steel fin tube

Stainless steel finned tube is highly adaptable.

Stainless steel finned tube in the use of its high heat transfer efficiency, due to the fin of the fluid disturbance makes the boundary layer constantly broken, because of the relatively large heat transfer coefficient, stainless steel finned tube because of the partition, the fin is very thin, with high thermal conductivity, so the finned tube heat exchanger can achieve very high efficiency.

Due to its compact operation, Murphy Thermal Technology laser-welded stainless steel finned tubes have an extended secondary surface during use, allowing surface areas of up to 1000 m2 /m3. The whole product is light and lightweight, because it is compact and mostly made of aluminum alloy. Now steel, copper and composite materials have also been mass-produced.

Laser welding of stainless steel finned tube has strong adaptability, and it is very suitable for the heat transfer between gas-gas, gas-liquid, liquid-liquid, various fluids and the phase transfer heat of the set state change during the operation. Through the arrangement and combination of the flow channel, it can adapt to different heat transfer conditions such as countercurrent, cross-current, multi-stream and multi-channel flow.

Stainless steel finned tube manufacturing process requirements are strict, the process is complex, easy to plug and corrosion resistance and cleaning maintenance is very difficult, so it can only be used for heat transfer medium clean, no corrosion, not easy to scale, not easy to deposit, not easy to plug the occasion.

Stainless steel finned tube to a certain extent regularly check whether the finned tube has sediment, coking, rust layer and other scaling adhesion, and immediate cleaning. At the same time, it is necessary to check whether the adhesive between the finned tube and the rubber gasket is tight, and whether the rubber gasket itself is intact, so as to avoid the leakage caused by the rubber gasket degumming and damage.

Matters needing attention when choosing stainless steel finned tube:

 

1 stainless steel aluminum finned tube, in the selection of stainless steel grades, whether to pay attention to its surface temperature requirements?

Stainless steel aluminum finned tube, in the selection of stainless steel grades, is to pay attention to its surface temperature requirements, and this is also one of the factors that must be considered. So in this case, the answer is yes. Moreover, for different grades of stainless steel, its surface temperature is not the same. For example, 304 stainless steel, its surface temperature is about 450℃, and 321 stainless steel, is 600℃ – 700℃.

2. In the finned tube radiator, are the different types of finned tubes different in terms of base tubes and finned materials? Stainless steel aluminum finned tube this kind, can it be used?

In finned tube radiators, there are different choices for different types of finned tubes in terms of base tubes and finned materials. Therefore, the answer to question 1 is yes. Moreover, its base tube can be copper tube, steel tube, and stainless steel tube, etc., while the fin can be copper belt, aluminum belt, or stainless steel belt. So, from this point of view, stainless steel aluminum finned tube this kind, can be used.

3 stainless steel aluminum finned tube, if there is dust or dirt, then, how to clean up?

Stainless steel aluminum fin tube, if there is dust or dirt, then, it is possible to use professional cleaning agent, that is, acid lotion, to remove clean, specifically, is to use acid lotion for scrubbing, so as to get a good removal effect. However, it is important to note that there can be no residual, so as not to cause rust and corrosion of the finned tube.

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Fin tube working principle and application

Murphy High frequency welded fin tube 2

The application of fin tube 

The application of finned tubes is now very extensive. Its main purpose is to exchange heat, so it is mainly installed on the surface of the heat exchange tube in order to improve the heat exchange efficiency. However, for the finned tube, there are still certain requirements for its performance, mainly including wear resistance, stability, etc., especially when used in a harsh environment, its performance is required It is better, in addition to having low contact thermal resistance and good dust prevention ability.

What principles should we follow when we use finned tubes for heat transfer?

(1) If the heat transfer coefficients on both sides of the tube are very different, finned tubes should be installed on the smaller side.

(2) If the heat transfer coefficients on both sides of the tube are very small, finned tubes can be installed on both sides, but do not only install one side, which will not be effective.
(3) If the heat transfer coefficients on both sides of the tube are large, do not install finned tubes.

Murphy heat exchanger finned tube heat exchanger aluminum in workshop

Working principle of fin tube

To understand the heat transfer principle of finned tubes, let’s first understand what the heat transfer coefficient is. The heat transfer coefficient refers to the amount of heat transfer per unit temperature difference and unit heat transfer area, which can reflect the heat transfer capacity between the fluid and the wall.

The finned tube is a heat exchanger composed of round tubes or smooth tubes, so how can we increase the heat transfer of the round tubes? One of the most effective methods is to use an expanded surface on the outer surface of the tube, that is, on the flue gas side, that is, a finned tube. 

Assuming that the actual heat transfer area of the finned tube is several times the outer surface area of the original smooth tube, although the heat transfer coefficient of the flue gas is still very low, the heat transfer effect reflected on the outer surface of the smooth tube will be greatly increased, so that the entire The heat transfer process is enhanced, and under the condition of a certain total heat transfer, the metal consumption of the equipment is reduced and the economy is improved.

Applications of fin tube

(1) Heat pipe air preheater series

Application: absorb waste heat from flue gas and heat combustion-supporting air to reduce fuel consumption and improve combustion conditions, thereby achieving energy saving; it can also absorb waste heat from flue gas to heat other gaseous media such as coal gas.

(2) Heat pipe economizer series

Application: It absorbs heat from the flue gas and uses it to heat the feed water. The heated water can be returned to the boiler (as an economizer) or used alone (as a water heater) to improve energy efficiency and achieve the purpose of energy saving.

(3) Heat pipe waste heat boiler (evaporator) series

Application: Use heat pipes as heat transfer elements to absorb higher temperature flue gas waste heat to generate steam. The generated steam can be fed into the steam pipe network (the pressure of the pipe network must be reached), or it can be used for power generation (with relatively high steam volume). Large and stable heat source) or other purposes. For steel mills, petrochemical plants and industrial furnaces, this is the most popular form of waste heat utilization.

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Why we use fin tube heat exchanger

Murphy High frequency welded fin tube

The application of fin tube heat exchangers

Today, Murphy team introduced you a heat exchanger, which is widely used in various fields such as textile, printing and dyeing, petroleum, chemical industry, electric power and so on, namely finned tube heat exchanger.

What is finned tube heat exchanger

The finned tube heat exchanger achieves the purpose of enhancing heat transfer coefficient by adding fins to the ordinary base fin tubes, and can have a heating effect. When heating is required, it can use high-temperature water, steam or high-temperature heat transfer oil to heat the air. When cooling is required, low-temperature water (such as chilled water) can be used to cool the air. Fin tubes heat exchangers are very popular in the industry and are widely used by enterprises.

Murphy heat exchanger finned tube heat exchanger aluminum in workshop

What should be paid attention to when choosing a finned heat exchanger?

Murphy will give you some suggestions. Of course, the specific matters depend on the specific situation and are for reference only. If the requirements for thermal performance are relatively high, a higher heat transfer rate value should be selected. The higher the value, the better the heat dissipation performance; if economic issues are taken into consideration, we can choose less metal consumption, which can reduce costs.

If you need more sanitation, we can choose a smooth surface and easy to clean; in terms of service life, finned heat exchanger can choose metal, which is not easy to be corroded and damaged. The service life is longer; then, we must also pay attention to protection during use to extend its use time and bring more convenience to our lives.

How to increase the heat transfer capacity of the heat exchanger

Finned tube heat exchangers are still shoulder-arm heat exchangers to some extent. The main feature of the surface is that it has an extended heat transfer surface area. Therefore, the process is not only a one-time transfer. On the hot surface, but also on the secondary heat transfer surface area.

In addition to pouring the heat of the medium fluid on the high temperature side into the medium on the low temperature side, part of the heat is also transferred along the height of the fin surface, that is, along the height of the fin. It is a partition that pours heat into, and then the heat is transferred to the low temperature side by convection.

Maintenance method of finned tube

1. Regularly check whether the cleaning of each fin tube is completed, whether there are deposits, coking, scale, etc., and clean it immediately.

2. When you need to replace the rubber gasket or repair the degummed parts, you need to remove the fin tubes, put it on the table, remove the old gasket, or use fine sandpaper to polish the glue marks in the groove of the fin tube.

3. Every time you re-tighten the fin tube, pay attention to the position of the scale during the last tightening, and do not over tighten the rubber gasket, which may reduce the service life of the gasket.

4. When replacing the rubber gasket of the fin tube, all parts must be updated to avoid uneven gaps between the fins and affect the heat transfer effect.

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Fin tube pipe material and application

Murphy finned tube copper material

Classification of carbon steel pipes

Hot-rolled carbon steel pipes are divided into general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other steel pipes.

Cold-rolled (dial) carbon steel pipes are divided into general steel pipes, low- and medium-pressure boiler steel pipes, high-pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, and other steel pipes, as well as carbon thin-wall steel pipes, alloy thin-wall steel pipes, and stainless steel pipes. Rusty thin-walled steel pipes, special-shaped steel pipes. The outer diameter of hot-rolled seamless pipe is generally greater than 32mm, and the wall thickness is 2.5-75mm. The outer diameter of cold-rolled seamless steel pipe can be up to 6mm and the wall thickness can be up to 0.25mm. The outer diameter of thin-walled pipe can be up to 5mm and the wall thickness is less than 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.

General carbon steel pipe: It is made of 10, 20, 30, 35, 45 and other high-quality carbon steels such as 16Mn, 5MnV and other low-alloy structural steels or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steels by hot rolling or cold rolling. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid transportation pipelines. Seamless pipes made of medium carbon steel such as 45 and 40Cr are used to manufacture mechanical parts, such as stressed parts of automobiles and tractors. Carbon steel pipes are generally used to ensure the strength and flattening test. Hot-rolled steel pipes are delivered in hot-rolled state or heat-treated state; cold-rolled steel pipes are delivered in heat-treated state.

Preparation method of carbon steel pipe

The raw material of the carbon steel pipe is a round tube blank. The round tube blank is cut by a cutting machine into a blank of about 1 meter in length, and then sent to the furnace for heating via a conveyor belt. The billet is fed into the furnace and heated at a temperature of approximately 1200 degrees Celsius. The fuel is hydrogen or acetylene. The temperature control in the furnace is a key issue. After the round billet is out of the furnace, it must be pierced through a pressure punching machine. Generally, the more common piercing machine is the tapered roller piercing machine. This type of piercing machine has high production efficiency, good product quality, large perforation diameter expansion, and can wear a variety of steel types.

After piercing, the round tube billet is cross-rolled, tandem-rolled or squeezed by three rolls successively. After squeezing, take off the tube and calibrate. The sizing machine uses a tapered drill to rotate at a high speed into the steel blank to punch holes to form a steel pipe. The inner diameter of the steel pipe is determined by the length of the outer diameter of the drill bit of the sizing machine. After the steel pipe is sized, it enters the cooling tower and is cooled by spraying water. After the steel pipe is cooled, it will be straightened.

After straightening, the steel pipe is sent to the metal flaw detector (or hydraulic test) by the conveyor belt for internal flaw detection. If there are cracks, bubbles, etc. inside the steel pipe, it will be detected. After the quality inspection of steel pipes, strict manual selection is required. After the quality inspection of the steel pipe, paint the serial number, specification, production batch number, etc. with paint. It is hoisted into the warehouse by a crane.

Murphy copper fin tube pipe pipes

Connection method of copper pipe

 

Copper tube is also called red copper tube. A kind of non-ferrous metal pipe, which is pressed and drawn seamless pipe. Copper pipe has the characteristics of good electrical conductivity and thermal conductivity. It is the main material of electrical and heat-dissipating accessories for electronic products, and has become the choice of modern contractors for the installation of water pipes, heating and cooling pipes in all residential commercial buildings. The following is the connection method.

 

Non-processing compression type connection, the use of non-processing compression type pipe fittings to implement mechanical connection of copper pipes is a relatively simple construction method, simple operation and easy to master, construction personnel only need a little training to master the operating skills. It is a commonly used connection method in current engineering.

 

When connecting, as long as the end surface of the pipe cut can be kept perpendicular to the pipe axis, and the burrs at the cut are cleaned, the pipe fitting is assembled with the correct position of the snap ring and the nut is tightened to achieve a tight connection of the copper pipe. However, this connection method relies on the pressing force of the thread on the snap ring to keep the joint tight. Therefore, the joint should not be directly buried in the wall. It is advisable to lay the joint in a repairable position, so that once the compression force is loosened When leakage occurs, the nut can be tightened further to maintain the necessary pressure.

 

Cleaning of copper pipe

 

Copper pipe has the characteristics of good electrical conductivity and thermal conductivity. It is the main material of electronic products and heat dissipation accessories. It has become the choice of modern contractors for the installation of water pipes, heating and cooling pipes in all residential commercial buildings. Copper pipe has poor corrosion resistance, is easy to oxidize, and chemically reacts with some liquid substances, and is easy to bend and shape.

 

It is generally required that the hardness value of the heat exchange tube material is generally lower than the hardness value of the tube sheet. When there is stress corrosion, local annealing of the tube head should not be used to reduce the hardness of the heat exchange tube; the heat exchange tube with an outer diameter of less than 14mm Expansion joints should not be used for tube sheet connection. Expansion length: the nominal thickness of the tube sheet minus the smaller value of 3mm or 50mm.

 

Spiral copper pipes Spiral copper pipes are generally stronger than straight-sealed copper pipes, and can produce copper pipes with a larger diameter from a narrower blank. The standard of copper pipe material can also use blanks with the same width to produce copper pipes with different diameters. Smaller diameter copper pipes mostly use straight seam welding, and large diameter copper pipes mostly use spiral welding.

 

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Fin tube maintenance and comparison

Murphy Aluminum Composite Finned Tube

The long-term use of any item can not be separated from the care and maintenance. Murphy laser welding fin tube is no exception. So what are the specific aspects of fin tube maintenance?

Generally, when water is used for circulation at the beginning of operation, there may be slight leakage. When the temperature rises to the sterilization temperature, the leakage will disappear by itself. If the leakage does not stop, the finned tube must be compressed a little more. If it is still ineffective, it is necessary to open and check the rubber gasket. It is also possible that the finned tubes are arranged in the order of numbers on the fins, which should be corrected.

  1. Regularly check whether the finned tubes are complete, whether there are deposits, coking, rust layer and other scaling adhesion, and clean them immediately. At the same time, it is also necessary to check whether the adhesion between each fin tube and the rubber washer is tight, and whether the rubber washer itself is in good condition, so as to avoid leakage caused by rubber washer degumming and damage.
  1. The plate heat exchanger pressing nut and upper and lower guide rods shall be lubricated with lubricating grease frequently.
  1. Each instrument shall be regulated by a specially assigned person and operated and maintained in strict accordance with the operating procedures.
  1. When the rubber gasket needs to be replaced or the degummed part needs to be repaired, the finned tube shall be removed and placed on the table, and the old gasket shall be removed, or the glue traces in the groove of the finned tube shall be wiped out with fine sandpaper at the degumming position, and then the oil traces in the groove shall be wiped out with carbon tetrachloride or trichloroethylene, and then the back of the new rubber gasket shall be wiped out with fine sandpaper, similarly with carbon tetrachloride or trichloroethylene the alkene solvent wiped out the oil.                                                                                                  Then, apply a thin layer of glue on the back of the groove and rubber washer. Let it dry a little, but it still sticks. That is to say, the rubber washer is embedded in the groove, flattened around, and coated with a layer of talcum powder. Then install the fin tube and clamp it gently. According to the glue instructions, it can be used after a period of time.
  1. When recompressing the laser welded composite fin tube, pay attention to the scale position during the last compression. Do not over press the rubber gasket, so as to reduce the service life of the gasket.
  1. When replacing the rubber gasket of the finned tube, it is necessary to update all the segments so as to avoid uneven clearance between the fins and affect the heat transfer effect.
Murphy Steel Aluminum Composite Finned Tube

The difference between high frequency finned tube and laser welded stainless steel finned tube

At present, there are many kinds of fin tube, mainly high frequency welded fin tube. Although it is more advanced in product quality and production automation compared with inlay, brazing and other methods, due to the factors such as the root of high frequency welded finned tube is difficult to be welded through and there are wrinkles at the root, there are still many shortcomings in heat exchange efficiency and dust prevention convenience of high frequency welded finned tube.

Fin tube is a kind of heat exchange element. In order to improve the heat exchange efficiency, usually add fins on the surface of the heat exchange tube to increase the surface area (or internal surface area) of the heat exchange tube, so as to achieve the purpose of improving the heat exchange efficiency.

As a heat exchange element, fin tube works in the condition of high temperature flue gas for a long time, such as the working environment of finned tube for boiler heat exchanger is bad, high temperature and pressure, and it is in corrosive atmosphere, which requires the finned tube to have high performance index.

1) anti corrosion

2) anti wear

3) low contact resistance

4) high stability

5) dust prevention capacity

Advantages of Murphy thermal technology laser welding stainless steel fin tube:

  1. Using pulse laser welding technology, the welding of the winding piece is completed synchronously, and the welding adhesion rate of the segment piece reaches 100%.
  1. Laser welding is metallurgical combination, and the welding strength of segment can reach more than 600MPa.
  1. The laser welding machine adopts the servo drive system, and the transmission accuracy can reach the level of hundredth meter.
  1. The distance between laser welded fins and tubes can be ≤ 2.5mm, and the heat dissipation area is increased by nearly 50% compared with that of high frequency welded tubes (the distance between fins and tubes is ≥ 4.5mm). The consumption per unit area is less, and the volume of heat exchanger can be greatly reduced.
For more information, contact us hier.

Knowledge about fin tube fins

Murphy fin tube in wooden box

Why use aluminum fins?

There are various materials according to the application and operation of the heat exchange.

Common ones are aluminum, alloys, copper, brass, nickel, titanium, stainless steel, carbon steel, etc. Among them, aluminum and alloys are the most commonly used.

The basic performance of finned tube heat exchange should have good welding ability and forming ability, high mechanical strength, good corrosion resistance and thermal conductivity. Nevertheless, aluminum and alloys are also ductile, and their tensile strength increases at lower temperatures. They are widely used all over the world, especially in low temperature and compact heat exchange.

Let’s take a look at the characteristics of aluminum

1. Low density

Through alloying and heat treatment, the structure of building steel can be achieved. It is suitable for all kinds of transportation, especially small vehicles, which reduces weight and consumption.

2. Good corrosion resistance

Under harsh conditions, aluminum oxides are non-toxic. Using aluminum for heat exchange, there is no need to worry about oxides destroying the air or liquid inside for a long time.

3. Good thermal conductivity,

Especially suitable for heat sinks, heat transfer evaporators and condensers. To

4. High yield and die cutting resistance.

It is easy to process and shape.

As a professional finned tube manufacturer, our leading product is aluminum finned tube. If you have any interest, please contact us for more information.

The ratio of fin tube is affected by fin height, fin thickness and fin spacing.

When the root of the fin is exposed on the base bare tube, if heat is transferred from the inside to the outside, the heat will be transferred from the root of the fin along the height of the fin. It is also continuously transferred to the surrounding fluid through convective heat transfer. 

As a result, the temperature of the fin gradually decreases along the height. This also shows that the difference between the temperature of the fin and the temperature of the ambient fluid is gradually decreasing, and the change in heat per unit is shrinking. Therefore, the effect of the fin surface area on the enhanced heat transfer is diminishing. The higher the fin, the smaller the contribution of the increased area to the heat exchange.

Murphy G type fin tube

Fin height

Generally speaking, for high-frequency welded finned tubes used in engineering projects, when the fin height is 15mm, the fin efficiency is about 0.8. When the fin height is 20mm, the fin efficiency drops to 0.7. 

 

Based on this, the optimal height is 15mm. If the fin height exceeds 20mm, the fin efficiency will be poor, so it is generally not used. However, for the aluminum fins on the air cooler, since the thermal conductivity of aluminum is much better than that of carbon steel, the height of 22-25mm is always used.

 

How will the fin spacing affect the fin ratio?

 

Usually a smaller pitch can effectively increase the fin ratio. When considering the nature of the flowing gas and the ash deposition, the following factors should be noted.

 

A. Severe heavy ash deposition

 

For example, the exhaust of electric furnaces and converters in steel plants and industrial kilns has high ash content. If finned tubes are used for heat exchange, a larger fin pitch is recommended. For example, if the pitch is greater than 10mm, you need to increase the air discharge and choose a blower.

 

B. Attention should be paid to occasions with little ash.

 

Take the exhaust of factory boilers and industrial boilers as an example. A fin pitch of 8mm is appropriate, but it should be designed to have self-blowing capability.

 

C. Dust-free or lightly dusty occasions.

 

For example, the exhaust from natural gas burning equipment or air cooler, the fin spacing is 4-6mm. For aluminum air coolers, 3mm is also selected as the fin pitch.

 

Fin thickness

The choice of the thickness of the heat sink depends on the corrosion and wear of the fluid gas. Under normal circumstances, thicker heat sinks will be used in severely corroded sites.

 

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Composite fin tube features and advantages

Copper fin tube murphy

The laser welded composite fin tube is a highly efficient heat transfer element. Its heat transfer area is several to several tens of times that of a light pipe, which can enhance heat transfer, reduce flow resistance, and reduce metal consumption, thereby improving the economy and operational reliability of heat exchange equipment. At present, laser-welded composite finned tubes have been widely used in chemical, electric power, metallurgy, petrochemical, boiler, building materials, textile, environmental protection, drying, medical and other fields.

 

Advantages of laser welding composite fin tube:

 

1. The laser power has a high density. During use, the temperature of the workpiece will rise rapidly after absorbing the laser and melt or vaporize. Even materials with high melting point, high hardness and brittleness (such as ceramics, diamonds, etc.) can be processed by laser. .

2. The laser head of the laser welded composite fin tube does not contact the workpiece, and there is no problem of tool wear.

3. The workpiece is not subject to stress and is not easy to be polluted.

4. It can process the moving workpiece or the material sealed in the glass shell.

5. The divergence angle of the laser beam can be less than 1 milliarc, the spot diameter can be as small as micrometers, and the action time can be as short as nanoseconds and picoseconds. At the same time, the continuous output power of high-power lasers can reach kilowatts to ten kilowatts. Therefore, the laser is suitable for both precision micro processing and large-scale material processing.

6. The laser beam of the laser welding composite fin tube is relatively easy to control, achieving a high degree of automation and high processing accuracy.

7. In harsh environments or places where other people are inaccessible, robots can be used for laser processing.

 

Advantages of composite fin tube processing

 

1. The installation is simple and economical. The length of the laser-welded composite fin tube can reach 12 meters, which reduces the connection points, makes the installation more economical and faster, and reduces the probability of water leakage at the connection. To

2. Maintenance is simple. After the laser welded composite fin tube is installed, maintenance is basically no longer needed. To

3. High efficiency, laser welding composite fin tube is full contact welding of fin and steel pipe winding. The heat dissipation area is more than 8 times that of the light tube, the interior is smoother, and the internal water flow resistance is small. 

4. Long service life, high mechanical strength of the combination of fins and pipes, tensile strength above 600Mpa, and hot-dip galvanizing both inside and outside of the pipe. Weldable fin material: carbon steel, corrosion-resistant steel, stainless steel, alloy steel. Weldable fin form: solid tooth, open tooth.

Aluminum copper composite fin tube Murphy for boiler

The laser welding composite fin tube can effectively realize its automatic operation during operation, so it can be controlled by a computer when welding. Generally, two different materials of metal can be welded, which is difficult for some ordinary welding. The material to be welded can be easily welded using a stainless steel laser welding machine.

 

Application of laser welding composite fin tube:

Laser welding composite finned tubes are used in civil wall-hung boilers, industrial boilers, etc. The advantage is that the contact thermal resistance is zero. Compared with high-frequency welding, it has the characteristics of large fin ratio, light weight, compact heat exchanger assembly, and more energy saving. Environmental protection.

 

Laser-welded composite finned tubes are made of stainless steel, titanium, copper, carbon steel, and other domestic finned tubes. Although it is more advanced in terms of product quality and production automation than methods such as inlay and brazing.

 

1: The thickness of the base tube can be 0.8-1.5 mm, and the thickness of the fin can be 0.3-1 mm, which greatly saves material costs compared to other processes.

2: High penetration rate, can prevent crevice corrosion, prolong service life, and reduce heat transfer resistance.

3: Break through the material limit and use different materials for processing.

4: Easy secondary processing, can be directly coiled and bent.

5: The welding heat-affected zone is small, and the metallographic change is small, making it possible to process small-diameter finned tubes. The materials used for heat exchange tubes and condenser tubes should have good heat transfer performance, and more importantly, have good corrosion resistance, erosion resistance, and abrasion resistance. They should also have good strength, rigidity and plasticity, and be easy to process and manufacture.

 

Laser welding composite fin tube structure:

 

 

Laser welded composite fin tube is a fin form that takes two different treatment methods to strengthen the heat exchange of the fin. When the laser welded composite fin tube is installed on other equipment, its installation structure can be divided into the following There are several ways: there are a series of methods such as winding type, string type, soldering type, rolling type and so on.

 

Performance advantages:

1. Strong anti-corrosion

2. Good wear resistance

3. Low thermal contact resistance

4. High stability

5. Anti-ash accumulation ability.

 

The materials commonly used in the production of composite fins are steel, stainless steel, copper, and aluminum. The finned tube fan heater is to add fins to the heat exchange tube of the air conditioner to better perform fan heating. The laser welding composite fin tube plays a role in the air conditioner, which improves the working efficiency of the air conditioner and greatly reduces the cost.

 

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Fin tube technology and industry features

20201223141018

Fin tube manufacturing process and welding classification:

The fin tube can be divided into two basic types: longitudinal and radial. The other types are the development and deformation of these two types. For example, the large spiral angle fin tube is close to the longitudinal direction, and the small spiral angle fin tube is close to the longitudinal direction. The shapes close to the radial fins are round, rectangular and needle-shaped. In addition, the fin can be arranged outside the tube, called an outer fin tube; it can also be arranged inside the tube, called an inner fin tube or both.

The fin tube manufacturing process can classify finned tubes into integral finned tubes, high-frequency welded finned tubes, mechanically connected finned tubes and laser welded finned tubes. Under normal circumstances, the overall finned tube is in the process of making The middle is mainly made by casting, machining or rolling, and the fin and the tube are integrated. Welding finned tubes, using brazing or inert gas shielded welding and other processes to manufacture. Modern welding technology can connect fins of different materials together, and can make finned tubes simple and economical, with good heat transfer and mechanical properties, and has been widely used. Since the residue in the welding seam is not conducive to heat transfer and may even cause fracture, the quality of the welding process must be ensured when producing this type of finned tube.

The high-frequency welding finned tube mainly uses the frequency induction generated by its high-frequency generator, so that high temperature can be generated at the contact between the tube surface and the fin, and the two are melted within a depth of about 10μm, and then pressurized to make The fin and the tube are connected as one body. No flux, no solder, simple manufacturing, high productivity, excellent heat transfer and mechanical properties. This is an ideal type of finned tube, which is being recognized and adopted by the majority of users.

Finned tubes usually have three types: inlay type, sleeve type, wound type, or string type. The winding finned tube is simple to manufacture. The metal band is fixed on one end of the tube by mechanical or welding method, and the metal belt is tightly wound on the outer wall of the tube by means of tube rotation torque, and the other end is fixed to form a wound fin tube. The material of the winding sheet can be copper strip, steel strip or aluminum strip.

The finned tube of Murphy uses the most advanced laser welding technology.

The perfect combination between the fin and the tube improves the efficiency of heat transfer and corrosion resistance, resulting in clean welded fin tube joints and completely straight fins (no corrugations).

New material combination and production range

Our laser fin process allows a wider range of tube and fin combinations. The feasible height, thickness and pitch of the fin exceeds any conventional fin process.

In addition, the increased range of material combinations of tubes and fins (steel, aluminum, copper, titanium) provides new advantages and alternatives to the industry.

Price savings, lower energy consumption, reduced consumable costs and increased efficiency enable Murphy to provide very competitive prices.

Murphy fin tube aluminum high frequency welded for hvac

The performance characteristics of finned tubes in different industries:

Murphy finned tube is a device that converts heat power and effectively increases the area of heat. In our daily life, the use of finned tubes is very common, mainly by using intelligent design to realize its in life , And the protective use in the environment, and has been unanimously recognized in the industry.

At the same time, Murphy laser welded stainless steel finned tube also has better anti-corrosion performance characteristics. In many different industry movements, the finned tube presents relatively unique advantages, and in many different environments It can be used in both, and has many additional functions, mainly on the basis of the original, the entire function of the piece has been significantly improved.

Laser-welded stainless steel finned tubes are available, and the performance is very good. It can effectively carry different performances. Therefore, it should also belong to a relatively special performance, and the finned tubes can also be used in air conditioners and industrial radiators Among them, the effect is very obvious, and it can bring considerable benefits to the enterprise.

And to ensure that the laser welded stainless steel finned tube can be better used in our daily life. Among them, the wear resistance is also the more prominent advantage of the finned tube. When assembling its parts, the finned tube has a better High wear resistance, so it has a longer service life. If it is matched with ordinary equipment, it can also exert greater performance.

Laser welding of stainless steel finned tubes can also significantly improve the actual recognition function of the equipment, and directly reflect this advantage in the protection of the environment. Its advantages are not comparable to other equipment. The main thing is that the finned tube still exists. The function of preventing dust accumulation is impossible in many traditional equipment.

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