How Many Features do You Know About the Finned Tube

1. The concept of film tube

Fin tube is a heat exchange element, mainly in order to improve the heat exchange efficiency, usually by adding fins on the surface of the heat exchange tube, increase the outer area of the heat exchange tube (or internal surface area), so as to achieve the purpose of improving the heat exchange efficiency of the heat exchange tube.

2. Classification of finned tubes

At present, the most common and widely used type at home and abroad is the partition type. The design and calculation of other types of heat exchangers are often based on the partition type heat exchanger. As a general equipment, heat exchangers are classified according to their working principles and can be divided into partition type, hybrid type and regenerative type.

When finned tube is used in evaporator of low temperature refrigeration system working under low temperature condition (below 0℃), there is a common problem of frost on its surface. The effect of frost formation on the performance of heat exchanger is manifested in the reduction of heat transfer coefficient and the increase of air resistance, and the reasonable structure of heat exchanger should reduce the influence of both. When frost begins to form, the surface roughness of the evaporator increases, causing the heat transfer area to increase, while the gas flow rate also increases, so the heat transfer coefficient K increases in the initial frost formation, but with the continuous thickening of the frost layer, the thermal resistance of heat transfer increases, and the final heat transfer coefficient K decreases.

When the air flow through the evaporator, due to the water vapor in the air continuously deposited on the surface of the finned tube, the relative humidity of the air decreases, and the amount of frost on the surface of the finned coil gradually decreases along the direction of the air flow, so the frost of the first few rows of finned tubes in the evaporator is more serious, and the frost of the last few rows of tubes is relatively light.

If the structure of variable pitch fins is adopted, the fin spacing downstream along the wind direction is smaller and smaller, it can maintain its high heat transfer efficiency under frost conditions, and extend its frost flushing time. After the evaporator adopts the variable pitch fin tube structure, when the air is longitudely grazing the staggered fin tube, the staggered distribution of fin tubes makes the upstream fin tube have a flow effect on the downstream fin tube, which strengthens the heat transfer capacity of the front half of the fin tube, and the distribution of the rear fin tube Narrows the flow channel and increases the flow rate, so that the heat transfer of the rear half of the fin tube is also strengthened.

3. Finned tube radiator structure and characteristics

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

4. What are the advantages of hot-dip galvanized finned tube radiators and ordinary finned tubes

Hot-dip galvanized finned tube radiator is on a high-quality seamless steel pipe, through a special winding machine, the high-quality steel strip is tightly and evenly wound on the outer surface of the base pipe by mechanical force, and the two ends are spot-welded and fixed; Then the whole steel wound finned tube is hot-dip galvanized. The galvanized layer can form a special metallurgical structure that can withstand mechanical damage during transportation and use; Every part of the plating can be zinc plated, even in dents, sharp corners and hidden places can be fully protected. It is relatively stronger in corrosion resistance and protection than ordinary fin radiators.

5. What are the advantages of stainless steel finned tube radiators over carbon steel? Which one is more affordable?

There is not much difference between the two thermal conductivity properties, but their main differences are:

Stainless steel: beautiful appearance, super corrosion resistance, expensive, several times more expensive than carbon steel.

Carbon steel: cheap but prone to oxidation and corrosion in the air.

As for whether the material should be stainless steel or carbon steel when designing a heat exchanger, it needs to be selected according to the applicable location.

You can click here to know more about the difference between stainless steel finned tube and carbon steel finned tube.