High frequency welding finned tube
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Murphy Thermal Energy Technology was founded in 1992 and has been committed to the development of thermal energy in HVAC industry.
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High frequency welding finned tube is widely used in petrochemical, machinery, metallurgy, rubber, printing and dying, medicine, food, power plants, passenger cars, drying and other industrial heating and cooling industry
Why we use high frequency welding finned tube?
What is high frequency welding finned tube
The basic principle of high frequency welding finned tube is to take the seamless steel tube on the outer packing band with a certain distance (strip perpendicular to the outer surface of the tube) and high-frequency current welding as the heat source.
By using the skin effect and electrical effect of high-frequency current, the local heating tube, the steel strip and the contact surface area to be welded can be plastically welded.
At the same time, the forging force of finned tube is applied to the metal oxide and the plastic form of the contact outside of the excess melt, so as to realize the combination of solid atoms between the steel tube and the finned material.
welding finned tube features
The high-frequency welding finned tube uses the skin effect and proximity effect of the high-frequency current to heat the steel strip and the outer surface of the steel tube while the steel strip is wound around the steel tube until it is in a plastic state or melted.
Under a certain pressure of winding the steel strip Finish welding. This high-frequency welding is actually a solid phase welding. Compared with inlay, brazing (or overall hot-dip galvanizing) and other methods, it is more advanced in terms of product quality (high fin welding rate, up to 95%), productivity and automation .
(1) High production efficiency, continuous winding production;
(2) Low cost, it depends on the characteristics of high-frequency welding itself — skin effect heating workpiece surface, to achieve the purpose of welding, welding process does not need to add any filler metal materials;
(3) Since the high-frequency current only passes on the shallow surface of the steel tube, the welding heat affected zone is small, so the additional wall thickness caused by this need not be considered in the design calculation; No heat treatment is required after the workpiece is welded.
(4) Solid welding, in the equipment configuration reasonable, process parameters perfect under the circumstances, can achieve between the fin and steel pipe welding firm, can withstand frequent open, shutdown caused by the thermal shock wave.
High frequency welding finned tube Material Standard
Fin material: Aluminum 1060, 1050, 1070, 6063,6061,3003
High frequency finned tube specifications:
Product specification: ∮ 25-219mm
Fin thickness: 0.8-2.5mm
Fin pitch: 4-35mm
Fin width: 10-25mm
Effective welding length: ≤15 m
Bending radius of finned tube: 50-300mm
Finned tube welding rate: more than 95%
How to accurately calculate the efficiency of high-frequency welding finned tube
In current applications, spiral finned tubes made by high-frequency resistance welding technology are widely used and are favored by users. The finned tube is usually made of carbon steel or alloy steel, and its structure can be divided into two categories: continuous type and zigzag type. At the same time, it can be divided into I type and L type according to its wing root shape. Among them, the root of the I-type fin still retains a continuous fin of a certain height, that is, the height of the serration is smaller than the height of the fin.
The main characteristics of the spiral heat pipe with the L-shaped fin structure can be summarized as: the height of the middle serration is the same as the height of the fin, and the serration extends to the root of the fin. In the research work, the focus is on the heat transfer and resistance characteristics.
At the same time, in this process, different calculation methods can be adopted to calculate the efficiency of the steel spiral radiator. For the continuous spiral radiator, it is usually considered that the fin efficiency is calculated according to the annular fin. If the heat dissipation at the fin end is neglected and the heat transfer coefficient of the fin surface is assumed to be uniform, then the calculation is carried out according to the formula.
We know that finned tubes are widely used at present. Because the calculation process is more complicated, in order to facilitate engineering calculations, the fin efficiency calculation formula of rectangular flat fins can be applied to ring fins to increase the height of the fins. The influence of different lengths of inner and outer perimeters is calculated based on the principle. This calculation method is simple and easy to use, and has been widely used and recommended.
How to choose high frequency welding finned tubes
This is the most important factor. If this point cannot be satisfied, no one will use it. What is not guaranteed for personal safety is a contraband and cannot appear on the market. Therefore, it is generally only necessary to purchase from a formal machinery factory. It won’t happen.
Secondly, when purchasing a finned tube, we must pay attention to its service life. The longer the service life, the lower the wear rate and the slower replacement, which will save money. The factory definitely hopes that the less money it can draw. Good, so durability has always been an important factor in the purchase of finned tubes.
- Environmental protection
Environmental protection and safety are similar, but environmental protection is more about the safety of ambient air, so when choosing finned tubes, we must choose green and environmentally friendly ones, and the formal security inspection department will often check the factory processing The release of gas and waste water from time to time, so don’t choose cheap ones because of the cheap price. Once the problem is found, you will face the serious problem of fines and closure of the factory.
Inspection of high frequency welding finned tube
When the air outlet temperature of the finned tube is higher or lower than the standard value, you should check and find out whether the following conditions have occurred:
- The inlet temperature of the high-temperature exhaust has exceeded the allowable value or has dropped to a too low value.
- Whether the flow rate of high temperature exhaust is over or under.
- Is the flow at the low temperature side insufficient or excessive?
- Whether there is dust accumulation in the fin tube.
When the air supply or exhaust is normal, or when there is no accumulation of ash, if a huge change in temperature or temperature efficiency is found, check and find out whether the following conditions have occurred:
- Is the fin tube damaged?
- Is there any blockage of the fin tube exhaust pipe?
- Whether the sealing baffle of hot and cold fluid is damaged, and whether two fluids are mixed.
How to improve the performance of high frequency welding finned tube
The high-frequency welding finned tube is a kind of high-efficiency heat transfer element. In comparison, its heat transfer area can be several times or even dozens of times that of a bare tube, which can enhance heat transfer, reduce flow resistance, and reduce metal consumption. Therefore, the economy and operational reliability of heat exchange equipment are improved. The high frequency welding finned tube is aimed at the shortcomings of the radiator made of series fins and wound fins, and an efficient heat dissipation element using high-frequency welding finned tubes is improved.
In actual processing, we can see that when preparing high-frequency welded finned tube products, strip steel with a thickness of 0.8 to 1 mm is used to wind the finned tube. At the same time, a high-frequency welding process is used to The fins are welded firmly on the tube to ensure the bonding strength between the tube and the fins. Therefore, its metal thermal strength can reach 1.10 to 1.20w/kg℃, and it has the advantages of high heat exchange efficiency, large heat dissipation area, long service life, wide temperature range and high pressure resistance.
Because of these advantages, the current high-frequency welded finned tube products are widely used in the production of air preheaters and the production of energy-saving radiators in factories and residences, and they are also used in the post-winding of heat pipes. Finned tubes are widely used in waste heat recovery, petrochemicals, power station boilers, economizers, ships, passenger cars, industrial and civilian buildings, heating, refrigeration, medicine, wood and grain drying and other national economic fields.
In order to further improve the heat transfer performance of high-frequency welding finned tube products, we can achieve this goal through some improvement methods. In fact, the research on the high-frequency finned tube is mainly focused on how to improve its heat transfer performance. Therefore, the requirements for enhancing the heat transfer performance of high-frequency finned tubes can be achieved by optimizing the design and improvement of the finned tube structure.
In general, there are currently two ways to effectively improve the heat transfer performance of high-frequency welded finned tubes. One of them is to use high-frequency finned tubes (evaporator) finned tubes that are prone to frost under low temperature conditions. Designed as a variable-pitch fin structure, another method is to design the equal-pitch internally threaded tube of the high-frequency finned tube under air conditioning conditions into a variable-pitch internally threaded tube to increase the disturbance of the airflow in the tube and improve the heat transfer coefficient.
High frequency welding finned tube maintenance
High frequency finned tubes are widely used and trusted in many fields due to their own characteristics and performance, such as petroleum pipelines, flower greenhouses, construction projects and so on. In Murphy’s many years of production and sales, many users have raised questions about the short service life of high-frequency welded finned tubes due to careless maintenance during the use: how to maintain the finned tube to last longer? The following is the solution:
The high-frequency welding finned tube uses high-frequency welding technology to add scaly fins, so do not collide and squeeze during installation and use. This will easily deform, and even affect the heat dissipation effect.
Because of the spiral distribution of high-frequency welding fin tube scales, there will be some deposits and scales in long-term use, we must clean and clean in time.
Check whether the joints are loose and the foot pads fall off.
The high-frequency welding finned tube is exposed to the outside to avoid low rain, try to keep it dry, and not too close to the ground, to avoid corrosion of the finned tube by irrigation in the greenhouse.
Through the maintenance of finned tubes, the service life of high frequency welding finned tubes will be greatly increased.
- Regularly check whether each fin tube is intact, whether there are deposits, coking, scales, etc., and wash it immediately. At the same time, it is necessary to check whether the adhesion of each fin tube and the rubber gasket is precise, and whether the rubber gasket is complete, so as to avoid leakage caused by degumming and damage of the rubber gasket.
- The compression nut and upper and lower guide rods of plate heat exchanger should be lubricated with lubricating grease.
- Each instrument adjustment should also be debugged by a dedicated person, and the operation rules should be strictly implemented for operation and maintenance.
- Every time the fin tube is re-tightened, the scale position during the last pressing must be carefully noted, and the rubber gasket shall not be pressed too much, so as to reduce the service life of the gasket.
- When replacing the rubber gasket of the fin tube, all the sections must be updated to avoid uneven gaps between the fins and affect the heat transfer results.
High frequency finned tube applications
High frequency welding fin tube is widely used in petrochemical, machinery, metallurgy, rubber, printing and dying, medicine, food, power plants, passenger cars, drying and other industrial heating and cooling, is the convection section of cracking furnace, transform furnace, heat exchanger, air preheater and economizer, crystallizer, radiator, and the optimal heat transfer of heat pipe technology components. The advantages of high frequency welded fin tube, especially the steel fin radiator is widely used in office buildings, residential buildings, hotels, workshops and other industrial and civilian construction industry, with good heating effect, is the traditional cast iron, plate radiator replacement products.
Practical application case of high frequency welding finned tube
- It is not appropriate to use a fin cooler in high frequency welding, unless the temperature is higher than 500℃.
- However, due to its better anti-corrosion effect, such as stainless steel fin-stainless steel base tube, methanol synthesis evaporative cooling applications can be used, but the heat transfer efficiency is greatly reduced, only about 45% of aluminum (the area is only 60% of aluminum, The total heat transfer efficiency of aluminum is only 70%, and the total effect is 0.6×0.7 = 0.45), so the water quality is poor. If you want a good preservative user, we can produce it.
In the process of high frequency welding finned tubes for heat transfer, an important process parameter must be considered, that is, the heat transfer coefficient. The so-called 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. High-frequency welding finned tubes are heat exchangers composed of round tubes or smooth tubes, so how can we increase the heat transfer of the round tubes?
For now, the use of high frequency welding finned tubes can effectively increase the heat transfer. This is because 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. The entire 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.
In practical applications, high frequency welding finned tubes have achieved ideal results in heat pipe air preheaters. Applicable occasions are: absorb waste heat from flue gas and heat combustion 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 gas media such as coal gas.
Secondly, in the series of heat pipe waste heat boilers (evaporators), high frequency welding finned tubes can also be seen. It is mainly to 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 plants, petrochemical plants and industrial kilns, this is a form of waste heat utilization.
In addition, it can also be used in the heat pipe economizer series. At this time, the function of the high frequency welding finned tube is to absorb heat from the flue gas to heat the feed water. The heated water can be returned to the boiler (as an economizer). It can be used alone (as a water heater) to improve energy utilization and achieve energy saving purposes.
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High frequency welding finned tube quantity
Base tube parameters: diameter, thickness, length and material specifications.
Fin parameters: material specifications, type (solid or serrated), height, thickness,
spacing, fin length and unfinned. Welding preparation details (if required).
The delivery period is required.