Fin heat exchanger cleaning

Murphy high frequency finned tube 1

You will need to keep the fin heat exchanger clean every once in a while. You will find that you are able to keep it clean and take care of it with proper maintenance and cleaning, the longer it will make it last longer, which will be the better job.

Step 1 Open

The first thing you will do is open the lid of the air cooler. Due to the cooling process of the air cooler, fresh air from outside circulates throughout the office or home. Every air cooler is different, so unless you have to open it before, you may need to look at the instructions and check to see exactly how to do it. Improper doing so may cause damage to your evaporative air conditioner.

Step 2 Check

The air in your room will never be out of date. This even allows you to enjoy a free operating unit, even if the doors and windows are open. After the cooler has been turned on, it is a good idea to take the pad and double check. If they want to be in good condition without debris or molds, then they will have to be replaced. 

Make these judgments before moving on to the next step. If it does need to be replaced, then make sure you get the correct measurement, so the size you get is a usable one.

Step 3 Float valve

Take a good look at your float valve and make sure it does not stick at all. If you find it, then you will need to get cleaned up. The moisture that the air cooler injects into your indoor air uses the cooling and evaporation technology. This enhanced moisture content can prevent the sun from getting out of your skin and eyes due to the heat. Many times, you will find that hard water deposits and debris are the main reason why you have a problem. If you don’t think that something clean can solve this problem, then it’s something else, and you might want to consider replacing everything.

Step 4 Belt

Make sure you check the belt on the fan. It can be very loose because this thing may cause problems. Please make sure it is tight and only slightly push when moving. If the belt moves too much, then it will need to be replaced.

Step 5 Oiling    

It is a good idea to oil the motor parts to ensure that it can run smoothly and longer, not to mention quiet.

Step 6 Cleaning

After you have done the proper inspection, you are ready to start cleaning. At first you will be panned and scrubbed with hard water until all the stains are gone. Make sure they are all cleaned before putting it back. Look inside, there must be a lot of dust anywhere, if there is, then scrub them until they are all washed away. 

Once you are done, you will only need to simply replace the necessary parts, it is best to put them back together to complete. Now, if you are running the air conditioner, you don’t have to be surprised when you receive high electricity bills. Detector air coolers are cost-effective and efficient devices that run on air conditioners with considerably less power. 

In fact, they are not only cost-effective operations, but they can also be maintained for long hours. In addition, they are quite cheap to install and all they need is minimal maintenance. They definitely consume less electricity compared to A/C units.

Murphy fin tube boiler economizer high frequency fin tube

Technical request for finned tube heat exchanger:

 1. Thermal performance requirements The higher the heat transfer coefficient K value of the finned heat exchanger, the better the heat transfer performance. 

To improve the heat dissipation capacity of the heat exchanger and increase the heat transfer coefficient of the finned heat exchanger, it is possible to increase the heat dissipation area of the outer wall to increase the air movement speed around the finned heat exchanger and increase the outward radiation intensity of the heat exchanger. .

 2. Economic requirements, the less metal consumption per unit heat of the finned heat exchanger to the room, the lower the cost, the better the economy. The metal thermal strength of the finned heat exchanger is a sign of weighing the economics of the heat exchanger. 

The thermal strength of metal refers to when the difference between the uniform temperature of the heat medium in the heat exchanger and the temperature of the indoor air is 1°C. 

The heat output per kilogram of mass heat exchanger per unit time. This index can be used as an index to weigh the economics of the heat exchanger of the same material. For various finned heat exchangers of different materials, the economic evaluation criteria should be weighed by the cost of heat exchanger unit heat dissipation (yuan/w).

 3. The finned heat exchanger should be equipped with equipment application and process requirements

 It has a certain mechanical strength and pressure capability; the construction method should be easy to combine into the required heat dissipation area, the construction size should be small, and the room area and space should be less occupied. The production process of the fin heat exchanger should meet the requirements of mass production.

 4. Hygiene and aesthetic requirements, the surface is lubricated, does not accumulate dust and is easy to clean, the installation of the fin heat exchanger should not affect the look and feel of the room.

 5. For service life requirements, finned heat exchangers should not be easily corroded and damaged, and have a long service life.

 Heat exchangers can be widely used in light industry, construction, machinery, textiles, printing and dyeing, electronics, food, starch, medicine, metallurgy, painting and other industries in hot air heating, air conditioning, cooling, condensation, dehumidification, drying, etc. .

 Heating heat exchanger: one of the uses including heaters and radiators.

 Finned heat exchanger structure: heat exchange tube, inlet and outlet header, frame.

 Among them, the heat exchange tube is composed of a heat exchange tube bundle, and the heat exchange tube is composed of a base tube and a fin. The quality of the heat exchange tube determines the heat exchange effect, the arrangement of the heat exchange tube affects the air resistance, and the installation method of the heat exchange tube determines the ability to withstand the temperature difference (thermal expansion and contraction).

 Commonly used heat exchange tube installation methods: fixed frame type (SRZ type, SRL type, S type), frame support type (GL type, U type). Among them, the frame is fixed, the heat exchange tube is directly welded to the frame box, the structure is simple, generally used for heat or refrigerant below 180 ℃; ) Welding, generally used for heat medium above 180℃.

 Commonly used heat exchange tube types: steel heat exchange tube (steel tube wrapped around steel fins, hot-dip galvanizing treatment), steel-aluminum composite heat transfer tube (steel tube rolled aluminum fin), copper heat transfer tube (copper tube wrapped around copper fin) , Tin lining treatment), copper-aluminum composite heat exchange tube (copper tube rolled aluminum fin), stainless steel heat exchange tube (stainless steel tube around stainless steel fin, high-frequency welding).

 Among them, the steel heat exchange tube, hot-dip galvanizing is the key, which can fill gaps, stabilize the fins, efficiently transfer heat, and efficiently prevent corrosion; copper radiator tubes, tin lining is the key. The main technical parameters of the heat exchanger: heat exchange area, ventilation net cross-sectional area, heat transfer coefficient. 

Among them, the heat exchange area affects the heat exchange, which is also the main cost parameter of the heat exchanger; the ventilation net cross-sectional area affects the ventilation resistance; the heat transfer coefficient affects the heat transfer effect. Selection parameters of drying radiator: heat medium (steam, hot water), hot air, materials. 

Among them: steam (pressure, temperature), hot water (inlet water temperature, outlet water temperature, flow rate), hot air (flow rate, inlet air temperature, humidity (water content), outlet air temperature, air resistance), materials (heat consumption, evaporation).

Water quantity) heat preservation heat exchanger selection parameters: heat medium (steam, hot water), space, region, heat preservation. Among them: steam (pressure, temperature), hot water (inlet water temperature, outlet water temperature, flow rate), space (length, width, height).

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Fin tube in heat exchanger

Murphy heat exchanger finned tube heat exchanger aluminum in workshop

Under normal circumstances, the spacing and height of the fin tube heat exchanger mainly affect the fining ratio, which has a great relationship with the film heat transfer coefficient of the medium inside and outside the tube. If the heat transfer coefficients of the inner and outer films of the tube differ greatly, a fin tube with a larger fin ratio should be selected, such as steam heating air. When there is a phase change in one side of the medium, the difference in heat transfer coefficient will be greater, such as the exchange of hot and cold air. 

When the hot air drops below the dew point, a fin tube heat exchanger can be used. In the case of heat exchange between air and air without phase change, or heat exchange between water and water, a bare tube is usually more suitable. Of course, low-finned tubes can also be used, because at this time, the heat supply coefficient is weak, and strengthening either side of them will have a certain effect. However, the effect of too large fin ratio is not obvious. The perfect situation is that the contact area inside and outside the tube is strengthened at the same time, and threaded or fluted tubes can be used.

The fin pitch mainly considers factors such as dust accumulation, dust formation, and easy cleaning, and at the same time, it must strictly comply with the equipment’s pressure drop requirements. When arranging, the distance between the tubes is not easy to be too large, generally more than 1mm is suitable for tube layout. In the process of heat exchange, when air flows through the finned tube heat exchanger, the front and back sides of the fin are mainly involved in heat exchange. 

There is only a small amount of radiant heat transfer in the middle of the two finned tubes, and the heat transfer effect is not obvious. Since this part has no fins and resistance, the air is easy to penetrate. In the process of air heating, the unheated cold air will neutralize with the heated hot air passing through the middle of the fins, which reduces the heat exchange effect. Compared with foreign finned tube heat exchangers, tubes The spacing is only 0.5mm larger than the outer diameter of the fins, which shows the importance of the tube spacing when the fin tubes are arranged.

The tube arrangement of the fin tube heat exchanger should be arranged as an equilateral triangle as far as possible. The hot air passing through the first row encounters resistance in the second row and there is a certain rebound wind, so that the 360° heat exchange of the entire fin tube does not have a dead angle. Therefore, the isosceles triangle arrangement should be avoided, and the square arrangement should not be used as much as possible, unless there are special requirements.

The pressure drop on the air side is a very important parameter in the design, which has a great relationship with the arrangement of the fin tube. When designing the fin tube arrangement, the ratio of the narrow gap flow surface and the windward surface should be calculated, so as to calculate according to the front wind speed The air mass flow rate is calculated, and the friction coefficient is calculated for the dynamic viscosity of air at different temperatures

Murphy fin tube for fin tube heat exchanger

What is the effect of fin thickness on the performance of fin tube heat exchanger

Fin tube heat exchanger is a commonly used heat exchanger structure in air conditioners. In the air conditioning industry, the fins of fin tube heat exchangers have different thicknesses, usually 0.095mm and 0.105mm. What is the impact on the performance of the fin tube heat exchanger? Let’s take a look at the factors affecting the performance of finned tube heat exchangers.

1. The larger the heat exchanger tube diameter, fin width and fin pitch, the greater the influence of fin thickness on heat transfer performance;

2. Compared with flat fins, the thickness of the fins has a greater impact on the heat transfer performance; the thickness of the fins has no effect on the heat transfer performance corresponding to the number of rows;

3. The fin thickness of the heat exchanger with small pipe diameter and small pipe spacing has little effect on the heat exchange performance.

Several Methods to Improve the Total Heat Transfer Coefficient of Finned Tube Heat Exchanger

Fin tube heat exchangers are not suitable for all heat exchange occasions. When the heat transfer coefficients on both sides of the tube are equal, finned tube heat exchangers can be omitted, such as oil-oil, water-water, gas-gas The heat exchange.

When the heat transfer film coefficients on the two sides of the heat transfer surface are very different, it is suitable to use a finned tube heat exchanger, because at this time, the smaller side becomes the main aspect of heat transfer control. When designing finned tube heat exchangers, the heat transfer coefficient on the smaller side should be maximized. It is mainly advantageous to make the film coefficients on both sides roughly equal.

The methods to increase the film coefficient mainly include the following aspects:

1. Reduce the cross-sectional area of the passage to increase the flow rate, add baffles in the passage or promote the degree of turbulence, which is generally used in the tube side structure of the finned tube heat exchanger.

2; Adding fins on the tube wall can not only increase the degree of turbulence, but also increase the heat transfer area. The main heat transfer function of the finned tube heat exchanger is based on this.

3; Use enhanced heat transfer surfaces, such as groove surfaces of various shapes, or porous surfaces, which can obtain a considerable heat transfer film coefficient for heat transfer processes with phase changes such as condensation and boiling. . Since such enhanced heat transfer reduces metal consumption, but at the same time increases the processing difficulty and production cost, it is less used in finned tube heat exchangers, unless there is a specific installation space restriction.

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Everything you should know about U bend tube

Murphy U Bend Tube

Murphy can make U bend tube in our factory according to customer requirements. The elbow is heat treated according to the customer’s requirements, and then hydrostatic pressure test and dye penetration test are performed as needed.

U-shaped elbows are widely used in heat exchanger systems. Heat exchanger equipment based on stainless steel U bend tube plays an important role in the nuclear industry and petrochemical machinery manufacturing.

U bend tube heat exchangers are specially designed for high temperature applications, especially steam condensing or hot oil systems. When the differential expansion makes the fixed tube-sheet heat exchanger unsuitable, and in some cases the floating head type (HPF) cannot be selected, the U bend tube heat exchanger will be selected.

The surface of the finished U-shaped elbow should be free from scale and scratches after bending.

Dimensional tolerance U-bend pipes are in accordance with relevant regulations of TEMA R.C.B. and ASTM A566 and ASTM A688

U bend tube diameter

In the bending part of the U bend tube with R = 2×D or larger, the main diameter and the secondary diameter of the pipe shall not deviate from the nominal diameter by more than 10% before bending.

If the specified value is less than 2×D, the tolerance may be larger, which requires the customer to confirm before ordering.

Wall thickness of U bend tube curved part

The wall thickness of the tube in the U-shaped bend shall not be less than the value determined by the following formula:

 

Tf wall thickness after bending, inch [mm],
T specified minimum pipe wall thickness, unit: [mm]
R centerline bending radius, inch [mm]
D Nominal outside diameter pipe diameter, inches [mm].

U bend tube leg length

For U-shaped tubes, the distance from the tangent point of the bend and the tube leg to the end of the tube leg, the length of the leg should not be less than the specified value, but it can exceed the specified value as follows:

Leg length [mm]

Up to 6000 mm: -0 / +3.2 mm
Over 6000 mm to 9000 (inclusive): -0 / +4.0 mm
More than 9000 -0 / + 4.8 mm

Difference in leg length

Unless otherwise specified, the difference in the length of the pins of the U-shaped elbow shall not exceed 1⁄8 inch = 3.2 mm.

Tube end: right angle
The end of any tube shall not deviate from the square by more than:

0.25 mm, suitable for tubes up to 5/8″ [15.9 mm]
0.40 mm [15.9 mm] for pipes higher than 5/8 inches

Leg spacing

The distance between the legs measured between the tangent point of the bend and the distance between the legs should be no more than 1⁄16 inch [1.5 mm] from the value (2 R-specified outside diameter of the pipe), where R is the centerline bend radius.

 

Murphy U bend tubes packed

Curvature of the curved part

The curvature of the curved portion of the U-tube should be substantially uniform and must not exceed 6 1⁄16 inches (1.5 mm) of the nominal centerline radius.

Deviation from the plane of bend

The allowable deviation from the bending plane must not exceed 1⁄16 inch [1.5 mm], for example measured from a tangential angle.

The dimensions of special grade heat exchanger tubes may differ from the above dimensions.

Basic testing and processing:

1. High-pressure hydrostatic test: minimum: 10 Mpa-25Mpa.
2. Underwater air test after bending
3. U-tube wall thickness test
4. Eddy current test before U-shaped bend is formed
5. Ultrasonic test before U-shaped bend is formed
6. Heat treatment can relieve stress

Other details of U bend tube:

a. Cut all the pipes to the specified leg length, and use air for internal cleaning and deburring.
b. Before packaging, both ends of the U-shaped elbow are covered with plastic covers.
C. Vertical separator for each radius.
d. Each plywood box is equipped with a packing list covered with plastic to facilitate identification of order details, including an accurate list of internal radius and length.

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Fin tube for boiler economizer

Murphy G fin tube batches

H type fin tube waste heat recovery device (also called economizer)

The concept of economizer

The economizer  is the heating surface in the tail flue of the boiler that heats the boiler feed water into saturated water under the pressure of the steam drum. Because it absorbs relatively low temperature flue gas, it reduces the flue gas exhaust temperature and saves It improves energy and efficiency, so it is called an economizer.

Working principle of economizer

1. The economizer greatly saves fuel. The economizer absorbs the heat of the low-temperature flue gas, reduces the temperature of the flue gas, reduces the flue gas loss, and saves fuel.

Since the feed water is heated in the economizer before entering the steam drum, the heat absorption of the feed water on the heating surface is reduced, and the economizer can be used to replace part of the expensive evaporation heating surface.

2. The economizer can reduce the temperature of the flue gas, recover the heat of the flue gas, improve the thermal efficiency of the boiler, and save fuel. The temperature of the flue gas at the outlet of the superheater is about 700℃. 

Even if a large number of convection tube bundles are arranged behind the superheater, the temperature of the flue gas leaving the convection tube bundle is still as high as 250-350℃, even if a large number of convection tube bundles are arranged after the superheater. Contain a lot of calories.

3. The economizer can be combined with the circulating water pump to superimpose the water temperature over and over again to increase the boiler feed water temperature from 20 degrees Celsius to about 80 degrees Celsius to ensure that the boiler does not lose pressure or cavitation when replenishing water, and maintain the average water supply , to achieve the purpose of energy saving.

The role of economizer:

1. Absorb the heat of low-temperature flue gas, lower the exhaust temperature, reduce exhaust loss, and save fuel.

2. Since the feed water is heated in the economizer before entering the steam drum, the heat absorption of the feed water on the heating surface is reduced, and the economizer can be used to replace part of the expensive evaporation heating surface.

3. When the feed water temperature is increased, the wall temperature difference will be reduced when entering the steam drum, and the thermal stress will be correspondingly reduced, thereby prolonging the service life of the steam drum.

Classification of economizers:

1. According to materials, there are cast iron economizers and steel economizers;

2. According to the relative flow direction of flue gas and feed water, there are forward economizer and reverse economizer;

3. According to heating conditions, there are boiling economizers and non-boiling economizers;

4. According to the device, there are vertical economizer and horizontal economizer.

H-shaped finned tube economizer technology is a high-efficiency heat exchange economizer assembled with H-shaped fin tubes (also known as H-shaped fin tubes, fin tubes, and butterfly tubes).

Structure type:

The basic form is “H” type and double “H” type, arranged in series.

Performance characteristics

1) The economizer uses the H-shaped finned tube economizer to replace the bare tube economizer, which can increase the heat exchange area and reduce the number of pipe arrangements, thereby increasing the flue gas flow section, reducing the smoke velocity and reducing wear. 

Since the wear rate of the pipe is proportional to the 3.33 power of the flue gas flow rate, if the flue gas velocity is reduced from 9m/s to 7m/s, the wear rate will be reduced to 43% of the original. At the same time, the experiment shows that the finned tube itself has the function of making fly ash concentrate in the middle of the tube row, so the use of finned tube economizer can reduce the abrasion in the structure.

2) The H-shaped finned tube can be made into a double-tube “double H”-shaped finned tube. The rigidity of the structure is good and it can be applied to the occasions with long tube rows.

3) The H-shaped finned tube economizer is arranged in line. The H-shaped fin divides the space into several small areas, which has a flow equalizing effect on the airflow, and greatly reduces wear.

4) H-shaped fins can achieve the best soot blowing effect because of the straight passages formed on both sides.

5) The space is compact, the overall weight is greatly reduced, and the cost is reduced.

6) Energy saving and low power consumption: The economizer used in the generator set can reduce the heat loss of the generator exhaust by at least two-thirds, and consumes only 2 to 4 kW per ton of steam.

7) Simple operation and maintenance; labor saving: the economizer is assembled and shipped as a whole, with few moving parts, simple structure and easy installation. High level of automation, simple operation and maintenance, can reduce operating personnel.

Murphy fin tube high frequency welded aluminum fin tube for Boiler

Parameter

Steam pressure: 0.5~4.0 MPa
Steam form: saturated steam/superheated steam
4. Loop mode
Natural circulation/forced circulation
5. Scope of adaptation
It is suitable for various types of generator sets with a power range of 600kW to 15000kW and various waste heat resources with a temperature greater than 300°C.

Types of boiler economizer corrosion

1. Corrosion of boiler economizer includes internal corrosion and external corrosion. Corrosion in the pipe belongs to oxygen corrosion, also called oxygen absorption corrosion. It means that the boiler feed water still contains a certain amount of oxygen even though it has been treated. The chemical nature of oxygen is very active and can react with the iron element of steel equipment, causing damage to steel equipment. Corrosion produces iron oxides Fe2O3 and Fe3O4, which is called rust.

2. The boiler economizer is based on the above oxygen corrosion principle. When the feed water flows through the economizer tube, oxygen corrosion in the economizer tube is prone to occur due to the high temperature, and ulcer-like corrosion pits are formed on the inner wall of the tube, which endangers the boiler economy. Safe use of coal loader. Oxygen corrosion in boiler economizer tubes is usually lighter in the high temperature section than in the low temperature section, which is the result of the gradual consumption of oxygen in the feedwater.

3. The steel tube economizer is not limited by pressure and can be used as a boiling type. It is generally made of carbon steel pipes with an outer diameter of 32 to 51 mm. Sometimes fins and ribs are added to the tube to improve the heat transfer effect. The steel tube economizer consists of horizontally arranged parallel elbow tubes (usually called serpentine tubes).

The role of economizer recycling:

During the start-up process of the boiler (drum boiler), because the circulation of its steam and water pipes is not established, that is, the boiler feed water is in a stagnant state. At this time, the water in the economizer is in a non-flowing state. 

As the combustion of the boiler increases, the smoke With the increase of gas temperature, the water in the economizer is likely to vaporize, which makes the part of the economizer in an over-temperature state. 

In order to avoid this situation, connect a pipeline from the centralized downpipe of the steam drum to the inlet of the economizer , As a recirculation pipe, keep the water in the economizer in a flowing state. Avoid its vaporization.

Use effect and requirements of economizer

1. Economizer is an indispensable part of modern boilers. Its function is to use the heat of the flue gas at the tail of the boiler to heat the boiler feed water and reduce the heat loss of exhaust gas. The boiler economizer has been adopted in large boilers and has received good results.

2. The economizer can reduce the temperature of the flue gas, recover the heat of the flue gas, improve the thermal efficiency of the boiler, and save fuel. The temperature of the flue gas at the outlet of the superheater is about 700℃. 

Even if a large number of convection tube bundles are arranged behind the superheater, the temperature of the flue gas leaving the convection tube bundle is still as high as 250-350℃, even if a large number of convection tube bundles are arranged after the superheater. Contain a lot of calories.

3. The economizer can also generate a small amount of steam. The feed water entering the boiler economizer comes from the deaerator. The water temperature of the low-pressure deaerator is generally 104°C, and the water temperature of the high-pressure deaerator is about 158°C. 

The saturation temperature of the medium-pressure furnace (4.4Mpa) is about 256°C, and the saturation temperature of the high-pressure furnace (11 Mpa) is 317°C, which is much higher than the temperature of deoxygenated water.

4. The staff of the economizer must pass the medical examination, have enough lighting for night work, turn off the electric welder when leaving the scene after work, protect welding, and save electricity. 

Wear work clothes, wear glasses when welding insulated shoes, and wear glasses. When entering the site, wear a helmet and fasten your seat belt when working at heights.

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5 Tips how to choose your most suitable fin tube heat exchanger?

15130628085a2f6eb5b74c8966

What is fin tube heat exchanger

Fin tube heat exchanger  is a kind of heat exchange equipment used in gas and liquid heat exchangers. It achieves the purpose of enhancing heat transfer by adding fins to the ordinary base tube.

The  fin tube heat exchanger is one of the earliest and most successful discoveries in the process of improving tube heat transfer. This method is still the most widely used method among all tube heat transfer surface enhancement methods.

 It is not only suitable for single-fin tube heat exchangers, which are widely used in power, chemical, petrochemical, air-conditioning engineering and refrigeration engineering.

Structure of  fin tube heat exchanger

The basic heat transfer element of the fin tube heat exchanger is a finned tube, a finned tube mountain base tube and a fin combination. The base tube is usually a round tube, but there are also oval tubes and flat tubes. The surface structure of the fins includes flat fins, interrupted fins, corrugated fins and perforated fins.

The base pipe can be steel pipe; stainless steel pipe; copper pipe, etc. The fin can also be made of steel belt; stainless steel belt, copper belt, aluminum belt, etc. The fin tube heat exchanger is a device in which air is used as the heat exchange medium, and the temperature is transferred from one object to another.

There are two types of steam heat exchangers, heating air and cooling air. The heat exchange process is divided into two stages. First, the heating or cooling medium heats or cools the surrounding air under the action of the finned tube, and the heated or cooled air transfers the heat to other objects to achieve the purpose of heating and cooling.

Such as drying room drying and air cooling system. It is the main equipment in the hot air device. The heat medium used in the fin tube heat exchanger can be steam or hot water, or heat transfer oil. The working pressure of steam is generally not more than 0.8Mpa, and the temperature of hot air is below 150°C.

Classification of finned tubes in fin tube heat exchanger:

1. Classified by structure

From the structural type, the finned tube can be divided into two basic types: longitudinal and radial. 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 radial The shapes of the fins are round, rectangular and needle-shaped. In addition, the fin can be arranged outside the tube, called an outer finned tube; it can also be arranged inside the tube, called an inner fin tube or both.

2. Classified by manufacturing process

According to the manufacturing process, finned tubes can be classified into integral finned tubes, welded finned tubes, high-frequency welded finned tubes and mechanically connected finned tubes.

(1) The integral fin tube is made by casting, machining or rolling, and the fin and the tube are a whole.

(2) 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 such finned tubes.

(3) High-frequency welding of finned tubes uses high-frequency electric induction generated by a high-frequency generator to generate high temperature at the contact point between the tube surface and the fins.

Melt the two in the left and right depth range, and then pressurize to connect the fin and the tube as a whole. No flux, no solder, simple manufacturing, high productivity, excellent heat transfer and mechanical properties. This is the most ideal type of finned tube, which is being recognized and adopted by the majority of users.

(4) The finned tubes are mechanically connected, usually in three types: winding type, inlaid type, sleeve type or string type. The winding fin 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 the 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.

  

Murphy heat exchangers

 

The basic equation of heat transfer calculation for  fin tube heat exchanger is the same as that of other tube heat exchangers:

 In the equation:

 -Heat transfer, W;

 Total heat transfer coefficient based on the heat transfer area of the inner surface of the base pipe, W/(m2·℃);

 Total heat transfer coefficient based on the heat transfer area on the outer surface of the fin side, W/(m2·℃);

 The heat transfer area of the inner surface of the base pipe, m2;

 The heat transfer area of the outer surface of the fin side, m2;

 Logarithmic average temperature difference, ℃.

Simplify the above formula to get


Heat transfer characteristics of fin tube heat exchanger

From the perspective of heat transfer mechanism, the fin tube heat exchanger is still a shoulder-arm heat exchanger. Its main feature is that it has an extended secondary heat transfer surface (fins), so the heat transfer process is not only performed on the primary heat transfer surface (baffle), but also on the secondary heat transfer surface.

The heat of the medium on the high temperature side is poured into the medium on the low temperature side once on the surface, and part of the heat is also transferred along the height of the fin surface, that is, along the height of the fin, there is a partition to pour the heat, and then the heat is transferred to the low temperature side medium.

Since the height of the fin greatly exceeds the thickness of the fin, the heat conduction process along the height of the fin is similar to that of a homogeneous elongated guide rod. At this time, the thermal resistance of the fin cannot be ignored.

The temperature at both ends of the fin is at most equal to the temperature of the partition. With the convection and heat release of the fin and the medium, the temperature continues to decrease until the temperature of the medium in the middle of the fin.

1. High heat transfer efficiency. Due to the continuous rupture of the boundary layer due to the disturbance of the fins to the fluid, it has a large heat transfer coefficient; at the same time, because the partitions and fins are very thin and have high thermal conductivity, plate-fin heat transfer is made The device can achieve high efficiency.

2. Compact Because the plate-fin heat exchanger has an extended secondary surface, its specific surface area can reach 1000/m3.

3. Lightweight The reason is that it is compact and mostly made of aluminum alloy. Now steel, copper, composite materials, etc. have also been mass-produced.

4. Strong adaptability The fin tube heat exchanger can be applied to: heat exchange between gas-gas, gas-liquid, liquid-liquid, various fluids, and phase-change heat that undergoes concentration changes. Through the arrangement and combination of runners, it can be adapted to different heat exchange conditions such as counter-flow, cross-flow, multi-stream, multi-pass flow. The combination of series, parallel, series and parallel between the units can meet the heat exchange needs of large equipment. Industrially, it can be finalized and mass-produced to reduce costs, and interchangeability can be expanded through modular combination.

 Selection parameters of fin tube heat exchanger

How to choose a fin tube heat exchanger is indeed a question that consumers need to think about.

Some focus on thermal efficiency and care about whether they can obtain obvious results in a short time; some focus on corrosion resistance due to environmental factors; and whether the shape is beautiful in accidents. Such all kinds. So which ones are the most basic and cannot be ignored?

First: The working pressure of the finned tube radiator should meet the working pressure of the system and comply with the current national product standards;

Second: Industrial buildings with high requirements for dust emission or dust prevention should use finned tube radiators that are easy to clean;

Third: Corrosion-resistant finned tube radiators should be used in industrial buildings with corrosive gases or in environments with high relative humidity;

Fourth: When using steel finned tube radiators, a closed system should be adopted and meet the product’s water quality requirements.

Fifth: When using aluminum finned tube radiators, internal anti-corrosion aluminum finned tube radiators should be used, and meet the product’s water quality requirements;

Sixth: Choose a regular finned tube radiator manufacturer, with better after-sales guidance, installation, and technical support. Our company specializes in manufacturing various radiator equipment, heat exchangers, oil coolers, surface air coolers, and radiators. , Finned tube.  

 Application of  fin tube heat exchanger

Fin tube heat exchangers are widely used in power, chemical, petrochemical, air conditioning engineering and refrigeration engineering, such as surface air coolers, air heaters, and fan coils used in air conditioning engineering.

The air cooler evaporator and frost-free refrigerator evaporator used in refrigeration engineering are not only suitable for the flow of single-phase fluid, but also have great value for phase change heat.

Most of the fin-tube heat exchangers used for clean gas use a new and efficient fin surface structure, which has achieved a significant heat transfer enhancement effect.For more information, contact us!

What you better know G type fin tube

Murphy finned tube aluminum high frequency welded for HVAC 20 scaled

What is G type fin tube

 

Finned tube is a kind of heat exchange element. In order to improve the heat exchange efficiency, fins are usually added to the surface of the heat exchange tube to increase the external surface area (or internal surface area) of the heat exchange tube to achieve the purpose of improving the heat exchange efficiency. Such a heat exchange tube.

The outer surface of the fin tube is covered with small fins. The role of these fins is to act as a transfer process and filter. Heat transfer is usually from the inside to the outside and then in the reverse direction.

 

 G type fin tube, also known as embedded finned tube, where g means slotted. It is formed by screwing fin strips made of copper or aluminum into machined grooves and backfilling to secure the lock. Fill the base tube material. Compared with other finned tubes,  G type fin tubes are firmer. Therefore, it is widely used in places where high-temperature heat transfer is required.

The G type fin tube is a circumferential finned tube in which the fin is mechanically embedded in the groove, the groove is plowed into the tube, and the roller is locked in place, thereby forcing the groove to tightly surround the fin base.

The aluminum fin strip is wound and embedded in the groove, and is firmly locked by closing the groove with the bottom tube metal. This ensures maximum heat transfer at high temperatures.

The maximum operating temperature of G fins is 450 degrees Celsius. Commonly used heat sink materials are aluminum (or) copper, pipes-carbon steel, stainless steel, copper, copper alloys, etc.

 

G type fin tube manufactruring process

Specifically, the  G type fin tube is a spiral groove with a certain width and depth that is pre-processed on the steel tube, and then the aluminum strip is inlaid on the steel tube on the equipment. During the winding process, due to a certain pre-tightening force, the steel strip will be tightly pinched in the spiral groove, thus ensuring a certain contact area between the steel strip and the steel pipe. 

In order to prevent the steel strip from rebounding and falling off, both ends of the steel strip should be welded to the steel pipe. In order to facilitate the inlay, there should be a certain backlash between the steel strip and the spiral groove. If the backlash is too small to form an interference, the inlay process is difficult to proceed smoothly.

 In addition, the wound steel belt will always have a certain rebound, as a result, the steel belt and the bottom surface of the spiral groove cannot be well joined. Inlay fins can be carried out on general equipment, and the cost is not high.

 

G type fin tube processing requirements

Embedded depth and stability

1.1 Pull-off force test: more than 8kg or the aluminum strip is torn

1.2 Mosaic depth: 0.35~0.5 according to the wall thickness of the furnace tube

1.3 Mounting stability: the first pull-off test specimen of each class meets the requirements of 1.1

1.4 The embedded tube is made of stainless steel and carbon steel, and the wall thickness of the pipe shall not be less than 2mm

1.5 The diameter of the inlaid pipe is dn20~38 (the British American standard is based on 1.5 requirements)

1.6 No cracks or cracks on the surface of the pipe after inlay

1.7 The height of the inlaid piece is calculated based on the diameter of the pipe-generally half of the diameter of the pipe, but not higher than 57 plus or minus

G type fin tube product size accuracy

2.1 The overall length of the wing segment -5mm ~ +5mm, segmental motion accuracy -0.3mm ~ +0.4mm

2.2 Film pitch +0.21mm or more

2.3 Verticality of fin and steel pipe -1 degree ~ +1 degree

2.4 Mounting flatness -0.1mm ~ +0.1mm except for the height difference caused by the thickness tolerance of the fin itself

2.5 Mounting height difference -0.1mm ~ +0.1mm Except for height difference caused by fin size tolerance

2.6 Under the same steel tube material, the same spacing and number of fins, the length of the different fin tubes after inlaying is the same.

 

Murphy G type fin tube
Advantages of G type fin tube

Compared with other fin tubes, G type fin tube has a compact design, high performance, easy installation, and requires less space

Less wiring, more optimized surface, good corrosion resistance, less energy consumption, higher reliability, simple routine maintenance and high mechanical resistance.

In the G type fin tube, the fin is prepared by embedding a metal strip in a groove. The latter is formed on the base tube. Place the heat sink on it to complete the backfill-resulting in the heat sink firmly fixed to the base tube. Therefore, the name G type fin tubeappeared. The above three processes are carried out simultaneously. Since the fins are firmly fixed on the base tube, it is expected to maximize heat transfer from the g-fin tube.

G type fin tube usually work at high temperatures (about 400 degrees Celsius). These heat sinks are made of copper, carbon or aluminum and have relatively low resistance to atmospheric corrosion. On the other hand, mechanical resistance is acceptable. Stainless steel and carbon steel fin materials can also be used, but special processing and processing of steel fins is necessary. Air coolers, radiators, etc. use G type fin tube.

Parameters of G type fin tube

1) Outer diameter: 25mm~82.5mm

2) Length: 130mm~18m

3) Heat sink height: 0mm-16mm

4) Fin pitch: 2.0-5.0mm

5) Length of fin tube: 0.5m~14m

6) Single metal rolled fin tube: pure aluminum 1060 / aluminum alloy 6063 6061 material

7) Bimetal rolled finned tube: the tube base is protected from the outer layer of the aluminum tube, and it is corrosion resistant;

8) Bottom tube material: carbon steel tube/stainless steel tube/copper tube/titanium alloy tube.

9) Packaging: The aluminum finned tube is packed with plastic film on the inside and steel frame on the outside.

Application of G type fin tube

G type fin tubes are widely used in rubber factories, power plants, petroleum industry, chemical industry and other industries

For more details, please contact us!

5 Tips how to choose your most suitable aluminum finned tube?

Murphy finned tube aluminum high frequency welded for HVAC 20 scaled

Aluminum is the common material of finned tube. Today this article will introduce the details of all aspects of finned tube.

Development of aluminum finned tubes

Aluminum finned tube in form is the, the base tube more common with several kinds of stainless steel, carbon steel and copper material, after extrusion forming professional equipment, made into the finned tube, we need this kind of finned tube in the position of the base, is a must and the walls of the tube for a tight fit, this is to compare the obvious advantages of aluminum fin tube.

And aluminum finned tube on the heat transfer coefficient is quite high, and the heat transfer performance is good, major is its surface without burr, and wrinkle, the appearance is very bright and beautiful, also is more convenient in cleaning, main is to use the heater, or the surface of the condenser, the discharge of water effectively.

If the aluminum fin tube is used in drying and heating, it will definitely not scale and dust and other adverse phenomena, because the aluminum fin tube in the cross section is mainly trapezoidal shape, therefore, its strength will be higher, but also the heat dissipation area for diffusion, and to ensure the use of products get big talk.

Features of aluminum finned tubes

Aluminum finned tube are basically use aluminum pipe, copper and iron are or after rolling, and so on the thermal resistance is small, and the heat transfer performance is higher, and the anticorrosion performance is very strong, the main or on the flow loss is small, even in the uneven and under the condition of long-term processing, it also won’t appear deformation.

After the manufacture of aluminum finned tube using the whole aluminum tube, it will not have contact with thermal resistance, and the strength is also very high, not only mechanical vibration resistance is also very heat resistant shock, in the whole thermal expansion performance is relatively good, the main or heat transfer area can be expanded.

In addition, according to the relevant requirements of customers, aluminum finned tubes can be manufactured and produced into various pipe materials. The manufacturing technology of aluminum finned tubes should be successful and extensive in terms of development. Therefore, Murphy will focus on innovation and research and development regardless of future development and current use

Technological characteristics of aluminum finned tube

Extrusion aluminum finned tube technology features, using the form of base tube sleeve aluminum tube, (base tube can be carbon steel, stainless steel, copper) through machine extrusion, forming a fin, the fin base and tube outer wall close fitting, high heat transfer coefficient, excellent heat transfer performance.

Rolling plate finned tube fin smooth and no burr, no fold, beautiful and bright, easy cleaning, as air heater and puts forward the components easy to eliminate surface when the condensate, the drying heat and other places is not easy to dust, scale, rolling plate finned tube fin transection and a trapezoid, and fin high intensity, and expanded the cooling surface, thus make maximum use of the material.

The extruded finned tube is made of iron or copper or aluminum tube by compound rolling, which has the advantages of tight bonding, small thermal resistance, good heat transfer performance, high strength, small flow loss, strong anti-corrosion performance, not easy to deform under long cold and hot working conditions, long working life and so on.

The integral rolled fins are smooth without burring and easy to be cleaned. The fins are easy to condense water on the surface during wet cooling in heating and air conditioning engineering. The surfaces are anodized under drying heating and other hot intersections, with beautiful and elegant color, and can effectively prevent surface corrosion.

Aluminum rolled finned tube is made by rolling aluminum tube as a whole, no contact thermal resistance, high strength, heat resistance and mechanical vibration, good thermal expansion performance, and has considerable expansion heat exchange surface, the effect of this finned tube heat exchanger is ahead of the series or wound heat exchanger.

Aluminum finned tube adopts CNC L finned pipe through digital control to keep segment binding force in the best condition, rolling forming of the trapezoidal cross-section with heat flux density distribution size, aluminum finned tube on the basis of material saving, greatly improving the thermal efficiency, is apart from the uniform, good heat transfer, wing than high, base tube can be protected from air erosion. It is mainly used in air coolers, air heaters in petrochemical, electric power, papermaking, tobacco, building heating and other industries, and air heaters in spray drying systems of plant protein powder and starch in food industry.

Efficiency of aluminum finned tubes

Aluminum finned tube is usually finned on the surface of heat exchange tube to increase the outer area (or inner surface area) of the heat exchange tube, so as to improve the heat exchange efficiency. L type, double L type finned tube: working temperature: 230 ℃, aluminum finned tube adopts the most advanced CNC L finned pipe through digital control to keep segment binding force in the best condition, rolling forming of the trapezoidal cross-section with heat flux density distribution size, on the basis of material saving, greatly improving the thermal efficiency, put an end to the string type finned tube for segment gap cannot eliminate the contact thermal resistance.

Aluminium finned tubes are formed by aluminium alloy plates and aluminium tubes in a single row to form flaky fin tubes, which are separated by 100mm intervals by screw rods to form rows of different lengths and widths. The space of 100mm forms several longitudinal parallel channels. When the refrigeration system is working, the cool air sinks and the hot air rises, and the cold air in the channel forms a flue effect, which accelerates the convection, accelerates the cooling speed, and shortens the running time of the compressor.

Compared with traditional steel tube direct-cold evaporator, aluminum alloy fin tube has much higher thermal conductivity than steel tube. The evaporation temperature of refrigerant in the tube and the temperature in the warehouse decrease, which increases the energy efficiency ratio in the compressor. If it is applied in the construction of cold storage, the load on the roof of the storage can be greatly reduced, the construction cost can be saved, a large number of supporting pipe fittings and steel needed in the hoisting of steel row can be reduced, the cost of hoisting materials and labor cost can be reduced, and the installation efficiency can be improved.

The steel and aluminum composite finned tube is formed by cold rolling of the pressure-resistant base tube and aluminum tube on the special machine tool, which overcomes the defect that aluminum and other metals cannot be welded. Also known as heat exchange tube, heat transfer tube, rolled sheet tube. It makes use of the pressure resistance of the base tube and the high efficiency of aluminum heat transfer, plasticity, highlighting the characteristics of the two materials in the process.

Because the specific gravity of aluminum is the smallest of the commonly used nonferrous and ferrous metals, the finned material of light metals determines the lightweight nature of the heat exchanger manufactured with it.

Steel-aluminum composite finned tube has the advantages that other types of finned tube can not compare.

 

Murphy carbon steel high frequency fin tube HVAC scaled

 

Steel – aluminum composite finned tube

Steel – aluminum composite finned tube has high heat transfer performance. The thermal conductivity of aluminum is about 211.9W/m.K, which is lower in cost and higher in cost performance compared with silver and copper. Objects with good thermal conductivity tend to absorb heat quickly and dissipate heat quickly.

The steel – aluminum composite finned tube also has low air resistance. The finned surface of steel – aluminum composite finned tube is smooth without fold. Air can be easily penetrated between the fins; Low contact thermal resistance; With a large heat dissipation area, the finning ratio of steel-aluminum composite finned tube can reach up to 22.7, and the unit heat dissipation area is much larger than that of conventional wound heat dissipation tube. Long service life, steel and aluminum composite finned tube in the process of processing, the base tube and aluminum finned into a compact composite.

A 0.5mm thick coating layer is formed on the surface of the base pipe to protect the base pipe from contact with the ambient air, which can improve its service life. ; Steel-aluminum composite finned tube is also not easy to dust, not easy to scale. Easy to clean and remove surface water, has a good resistance to temperature changes, can maintain good heat transfer performance for a long time.

Cleaning and maintenance of aluminum finned tube

In order to extend the service life of aluminum finned tubes, it is necessary to regularly check whether all aluminum finned tubes are intact, whether there are deposits, coking, rust layer and other scale adhesion, and immediately clean them. At the same time must also check whether the finned tube and rubber gasket adhesion is precise, whether the rubber gasket itself is ready, in order to avoid rubber gasket degumentation and damage caused by leakage.

As a heat exchange element, finned tube works under the condition of high temperature flue gas for a long time. Finned tube is divided into integral finned tube, welded finned tube, high-frequency finned tube and mechanically connected finned tube. Plate heat exchanger pressing nut and up and down guide rod, should be lubricated frequently with lubricating grease.

The adjustment of each instrument should be operated by a special person, and the operation and maintenance should be carried out in strict accordance with the operating rules; Each time the finned tube is pressed again, the scale position of the last pressing should be recorded. Do not make the rubber gasket press too much, which will reduce the service life of the rubber ring.

When replacing the finned tube rubber gasket, the whole section should be updated to avoid uneven clearance of each piece, affecting the heat transfer result. In short, gas furnace special finned tube in use to pay attention to maintenance and maintenance, will reduce the occurrence of early failure, extend the service life, improve the effectiveness of the operation, bring more benefits.

Aluminum finned tube has been widely used in the major fan heating equipment, it is mainly on the steel pipe to pre-process a certain width and depth of the spiral groove, and then the steel strip embedded in the steel pipe on the lathe. During the winding process, due to a certain pretension force, the steel strip of high-frequency aluminum fin tube will be tightly squeezed in the spiral groove, thus ensuring a certain contact area between the steel strip and the steel tube.

In order to prevent the steel strip from springback and falling off, the two ends of the steel strip should be welded to the steel tube, and there should be a certain side gap between the steel strip and the spiral groove for easy enchase. If the side gap is too small and interference is formed, the Mosaic process is difficult to proceed smoothly. In addition, the wound steel strip always springs back to a certain extent, so that the steel strip and the bottom of the spiral groove can not be well joined.

The main application of aluminum finned tube is these, I believe that with the continuous improvement of our technology, the performance of aluminum finned tube will continue to increase, its application range will be more extensive. For more information, contact us!

Hot story about heat exchanger components this week

Murphy finned tubes display 2 scaled

There are many heat exchanger components and materials on the market now, so this week I will share with you a widely used classic heat exchanger component-finned tube.

Heat exchanger component-finned tube

Finned tube is a kind of heat exchange component, often used in high temperature and flue gas space. In our daily work, it can be seen everywhere, for example, the boiler needs to use finned tubes for heat exchange. For daily operations in such a harsh environment, the finned tube itself must have corrosion resistance and stability.

As a typical heat exchange component, in order to improve the heat exchange efficiency of the finned tube, fins are usually added on the surface of the heat exchange tube to increase the outer surface area of the heat exchange tube, thereby improving the heat exchange efficiency. In order to improve efficiency, heat exchange tubes are used.

As a finned tube manufacturer, Murphy has made great improvements to the corrosion resistance of the finned tube as heat exchanger component following long-term feedback from customers. In order to improve corrosion resistance, corrosion-resistant materials such as stainless steel and aluminum alloy are used in the manufacturing process of finned tubes. These materials have better corrosion resistance. Can effectively improve the service life of the heat exchanger and heat exchanger component.

Murphy finned tubes display 7 scaled
Murphy finned tubes display 4 scaled

Some customers report that the cost of these raw materials is generally high, and we have also taken corresponding countermeasures. Some corrosion inhibitors are used. The corrosion inhibitors have an effective protective effect on the metal surface of the fin tube. Substances can significantly reduce the corrosion rate of metal materials in the medium to zero. At the same time, the original physical and mechanical properties of metal materials can be kept unchanged.

Wear resistance is also a notable feature of finned tubes. If the finned tube suffers from abrasion, the heat exchange efficiency will be affected to a certain extent, so choose a finned tube with strong wear resistance. As a professional finned tube manufacturer, Murphy recommends that you consider using a kind of heat exchanger component-an integral finned tube, which has remarkable wear resistance. Because the integral fin tube fin and the base tube are integrally formed, the crystal structure is consistent, and the performance is stable.

Moreover, the fin is in the shape of a sand dune, which matches the shape of the temperature gradient when heated. Uniformity, no concentration, and no weak points of strength (and the main reason for wear is due to high temperature points, which should be low σ). In addition, the fins have a diversion effect on the flue gas. Make the various indicators of the flue gas (temperature, flow rate, ash content, etc.) more uniform, will not produce the flue gas flow, and will not cause the flue gas to scour a certain area or a certain part. Therefore, it is more wear-resistant.

Similarly, when choosing a finned tube, you need to pay attention to stability. Only when the stability is strong, the finned tube can be used in a high temperature environment without affecting the heat transfer performance.

In general, the finned tube has the functions of high heat exchange efficiency and large heat dissipation area. The whole heat exchanger component product has the advantages of long service life and wide temperature range. Users of Murphy finned tubes also come from various industries, such as petrochemicals, economizers, waste heat recovery, greenhouses, power station boilers, wood drying and so on. That’s it for the content of the finned tube shared this week. If you want to know more product information, please contact us.

Why we choose stainless steel finned tube

Stainless steel finned tube murphy

Sophisticated processing technology for stainless steel finned tubes

In the production process, the laser welding stainless steel finned tube is mainly made of 304 stainless steel. It is mainly used for the heat exchange of two media when it is used. The 304 stainless steel finned tube has excellent technology. It is an alternative product for heat exchange and waste heat recovery in boiler, power generation, petrochemical, HVAC, refrigeration, air conditioning and other industries.

 

Laser welded stainless steel finned tube can effectively improve the efficiency of its heat exchanger during use, to a certain extent, effectively extend its life, reduce volume and save materials, the whole rolled finned tube has no contact thermal resistance, heat transfer Good performance, high strength, heat resistance vibration and mechanical vibration, good thermal expansion performance.

 

Laser welded stainless steel finned tube has the characteristics of high strength, small flow loss, strong anti-corrosion performance, easy deformation and long working life under long-term cold and hot working conditions. The integrally rolled fins are smooth, free of burrs, wrinkles, and easy to clean. It is easy to remove condensate on the outer surface of the fins during wet cooling in heating and air conditioning projects. It is not easy to form dust and scale in drying and heating and other heat exchange occasions.

 

The laser-welded stainless steel finned tube has low contact thermal resistance, the product can maintain a stable low value within a large temperature change range, the entire product has a high heat transfer coefficient, and has good resistance to sudden changes in temperature and vibration during use. Units The length of the heat exchange area is large, the heat transfer is high, the structure is reliable, and the life is long; the surface of the fin is smooth without burrs, no wrinkles, and is not easy to scale, easy to clean and exclude surface water, low flow resistance, and can maintain good heat transfer performance for a long time. .

 

Stainless steel finned tube temperature

In the selection of stainless steel grades, we must pay attention to the surface temperature requirements, and this is also one of the factors that must be considered. So on this question, the answer is yes. Moreover, the surface temperature of different stainless steel grades is different. Moffi Thermal Technology reminds you here, for example, 304 stainless steel, its surface temperature is about 450 ℃, and 321 stainless steel, it is 600 ℃-700 ℃.

 

Stainless steel finned tube has strong adaptability

 

The stainless steel finned tube has high heat transfer efficiency when it is used. The disturbance of the fin to the fluid causes the boundary layer to rupture continuously. Because of the relatively large heat transfer coefficient, the stainless steel finned tube is thin because of the separator and the fin. , With high thermal conductivity, so that the finned tube heat exchanger can achieve high efficiency.

 

Due to the compactness of the laser welded stainless steel finned tube of Murphy Thermal Energy Technology in operation, its equipment has an extended secondary surface when it is used, so that its surface area can reach 1000㎡/m3. The whole product is light and compact, the reason is compact and mostly made of aluminum alloy, and now steel, copper, composite materials, etc. have also been mass produced.

 

The laser welded stainless steel finned tube has strong adaptability, and it is very suitable for the heat exchange between gas-gas, gas-liquid, liquid-liquid, various fluids, and the phase change heat that occurs in the state change during operation. . Through the arrangement and combination of flow channels, it can adapt to different heat exchange conditions such as counter-current, cross-flow, multi-stream and multi-pass flow.

 

The manufacturing process of the stainless steel finned tube is strict, the process is complicated, it is easy to be clogged during operation, and it is difficult to clean and repair, so it can only be used for the heat exchange medium is clean, non-corrosive, not easy to scale, not easy to deposit, not easy Occasions.

 

Stainless steel finned tubes should be regularly checked to a certain extent for deposits, coking, scale deposits and other scale deposits on each finned tube, and immediately cleaned. If there is dust or dirt on the stainless steel aluminum finned tube, you can use a professional cleaning agent, that is, pickling agent, to clean it. Specifically, it is scrubbed with pickling agent, so that you get a good Removal effect. 

However, it should be noted that there must not be any residues, so as not to cause rust and corrosion of the finned tube. At the same time, it is also necessary to check whether the adhesion of each fin tube and the rubber gasket is tight, and whether the rubber gasket itself is intact, so as to avoid leakage caused by the rubber gasket being degummed and damaged.

 

Adhesion of rubber gasket of stainless steel finned tube

When re-tightening the finned tube each time the stainless steel finned tube is used, pay attention to the position of the scale when the finned tube is pressed back. During the operation, the rubber gasket must not be overpressed. As a result, the ring life is shortened.

 

When replacing the rubber gasket of the finned tube of the stainless steel finned tube, all the segments need to be updated during the operation process, so that the unevenness of the spacer gap can be effectively avoided, which will directly affect its The effect of heat transfer.

 

Under normal circumstances, the stainless steel finned tube should be cleaned with water to start the operation. There should be no slight leakage during the use. When the temperature rises to the sterilization temperature during the use, its product leaks. The situation will disappear by itself, if the leakage is still uninterrupted, the finned tube must be compressed a little more. If it still fails, the rubber gasket must be opened for inspection, and the end of the finned tube is generally arranged in the order of the number on the chip, which should be corrected.

 

The stainless steel finned tube can be divided into stringed tube (sleeved tube), tension wound finned tube, insert tube, rolled finned tube with no dead angle, cast finned tube, Laser welding composite finned tube, which is divided into high frequency welding finned tube, submerged arc welding finned tube, etc.

What’s right about laser welded finned tube working principle?

laser welded fin tubes murphy

Laser welded finned tube

Laser welding spiral finned tube is processed by laser welding machine.

Stainless steel laser welded spiral finned tube

In traditional spiral finned tubes, high frequency welding, resistance welding and other techniques are used to attach stainless steel fins to the steel tube. Laser welding finned tube, the welding process has its shortcomings that cannot be overcome.

The laser welding  finned tube has a fully automatic welding process, which saves labor costs; secondly, the laser welding fins are firm and strong, and the high tensile strength test is qualified; laser welding has higher efficiency advantages.

Laser welding machine is the most advanced laser welded  finned tube laser welding equipment. Because the welding process is fully automatic and mechanical, the scientific and technological content and quality of laser welded finned tubes are superior to traditional cooling tubes.

Laser welding principle

Laser welding is a welding method that irradiates a high-intensity laser beam onto the surface of a metal, and through the interaction of the laser and the metal, the metal absorbs the laser light into heat and melts the metal to form a cooling crystal.

Stainless steel laser welded finned tube:

  1. High degree of automation, the automatic fin laser welding machine can complete welding at one time, and the synchronous winding enables the welding depth of the fin feet and the tube to be realized.

        2 Laser welding, high firmness and high binding force. Laser welding is a metallurgical combination with a welding strength greater than 600MPa.

  1. The laser welding machine has high precision, which can weld 8-meter-long laser welded finned tubes with an accuracy of 0.05mm.
  2. Laser welding can greatly improve the heat transfer coefficient.
  3. The length of the laser welding fin section is less than or equal to 2.5 mm, and the heat dissipation area is increased by nearly 50% compared with the high-frequency welded tube (the distance is greater than or equal to 4.5 mm), which greatly reduces the material of the tube and can also reduce the volume of the heat exchanger Variety.

Why use aluminum fins for stainless steel laser welded finned tubes?

According to the application and operation of heat exchange, there are various materials. Common are aluminum, alloys, copper, brass, nickel, titanium, stainless steel, carbon steel, etc., among which aluminum and alloys are the most commonly used.

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

 

Murphy finned tubes factory workshop
Murphy carbon steel high frequency fin tube HVAC A 1 scaled

 

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, reducing weight and consumption.

  1. Good corrosion resistance

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

  1. Good thermal conductivity,

Especially suitable for heat sink, heat transfer evaporator and condenser.

  1. High yield and die-cut resistance.

It is easy to process and shape.

As a professional laser welded finned tube manufacturer, our leading product is aluminum laser welded finned tube. If you are interested, please contact us for more information.

Fin tube ratio is affected by fin height, fin thickness and fin spacing

When the root of the fin is exposed on the bare base 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 fin temperature gradually decreases along the height. 

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

Fin height

In general, for high-frequency laser welded  finned tubes used in engineering projects, the fin efficiency is about 0.8 when the fin height is 15 mm. When the fin height is 20mm, the fin efficiency drops to 0.7. Based on this, the optimal height is 15 mm. If the fin height exceeds 20mm, the fin efficiency will be very 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 pitch affect the fin ratio?

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

  1. Severe heavy ash deposition

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

  1. For occasions with little ash, but also pay attention.

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

  1. No dust or light dust.

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

Fin thickness

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

How to improve the production efficiency of laser welded finned tubes and reduce production costs: The production efficiency of finned tubes is still very low at present, and there is much room for improvement. As long as the development is good, the production cost will be greatly reduced. There are many factors that affect the production efficiency of finned tubes, mainly including the following factors:

  1. Impedance matching problem: We all know that the electron tube is a voltage amplifying element, the output impedance is very high, and the contact welding is a current heating welding process, which requires a low-impedance power supply. Therefore, the impedance of the two does not match and it is difficult to output more Large electric power. Only by changing the ratio of the tank circuit and adjusting the relative position of the contacts properly can a large output be obtained.
  2. Reduce the standby time: the tube must provide a basic power consumption to work, that is to say, whether you are soldering or not, this part of the power must be consumed, so reducing the standby time will save power and thus reduce production costs. The actual standby time in the production process of finned tubes is more than 50%, and the power loss in this part cannot be ignored. The use of high-performance equipment will greatly reduce the standby time, resulting in higher efficiency and lower cost. Automatic loading, automatic unloading, pneumatic clamping of steel pipe, high production efficiency.

  3. Reduce the probability of breaking the band: For the same strip steel, the welding structure affects the probability of breaking the band. At present, there are three types of welding structures: spring structure, hydraulic series spring structure and pneumatic structure. The first two principles are the same, mainly relying on the pressure of the spring to achieve the forging force. 

When the pipe jumps, the spring is also used to buffer, because the elastic potential energy E=-KX2 means that the elastic potential energy is proportional to the square of the displacement. When the displacement changes by 5 mm, the change of upset energy is 25 times, so it is easy to break the steel strip, and the pressure roller is more likely to be damaged. However, there is no spring in the pneumatic structure, which mainly relies on the pressure of the gas to achieve the forging force. When the pipe jumps, it is buffered by the air pressure. When the displacement changes by 5 mm, because the length of the cylinder is 125 mm, the variation is only 4%.

Advantages of laser welded finned tube:

  1. Thin and continuous wet seam
  2. Small heat affected zone
  3. Short heating time
  4. The tube and fins have only slight microstructure changes
  5. High heat forms seams
  6. High welding speed
  7. Laser welding is carried out in a protective atmosphere, so the weld is free of impurities

Laser welded finned tube application

  • Power plant
  • Chemical industry
  • Heat recovery plant
  • Thermal Industry