what is a finned tube heat exchanger?

Introduction to the principle and characteristics of finned tube heat exchanger

Finned tube heat exchanger - what is a finned tube heat exchanger

Finned tube heat exchangers are usually composed of baffles, fins, seals, and deflectors. Fins, deflectors and seals are placed between two adjacent partitions to form an interlayer, which is called a channel. Such interlayers are stacked according to different fluid methods and brazed into a whole to form a plate bundle. The plate bundle is a fin. The core of the finned tube heat exchanger, together with the necessary heads, connecting pipes, supports, etc., constitutes the finned tube heat exchanger.

Finned tube heat exchanger - working principle of finned tube heat exchanger

From the perspective of heat transfer mechanism, the finned 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 that the heat transfer process takes place not only on the primary heat transfer surface (baffles), but also on the secondary heat transfer surface at the same time. The heat of the medium on the high-temperature side is poured into the medium on the low-temperature side once, and part of the heat is transferred along the height direction of the fin surface, that is, along the height direction of the fin, there is a partition to pour heat, and then the heat is convectively transferred to the low-temperature side medium.

Since the fin height greatly exceeds the fin thickness, the heat conduction process along the fin height direction is similar to that of a homogeneous slender guide rod. At this time, the thermal resistance of the fin cannot be ignored. The highest temperature at both ends of the fin is equal to the temperature of the partition, and with the convective heat release between the fin and the medium, the temperature continues to decrease until the medium temperature in the middle of the fin.

Finned Tube Heat Exchanger - Features of Finned Tube Heat Exchanger

1. High heat transfer efficiency Because the disturbance of the fins to the fluid causes the boundary layer to continuously rupture, it has a large heat transfer coefficient; at the same time, because the partitions and fins are very thin and have high thermal conductivity, the heat transfer of the finned tubes device can achieve high efficiency.

2. Compact Due to the extended secondary surface of the finned tube heat exchanger, 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 finned tube heat exchanger can be applied to: gas-gas, gas-liquid, liquid-liquid, heat exchange between various fluids and phase-change heat with collective state change. Through the arrangement and combination of flow channels, it can adapt to different heat exchange conditions such as counter flow, cross flow, multi-stream flow, and multi-pass flow. The heat exchange needs of large-scale equipment can be met through the combination of series, parallel, and series-parallel connections between units. In the industry, it can be finalized and mass-produced to reduce costs, and the interchangeability can be expanded through building block combinations.

5. The manufacturing process requires strict and complicated process. It is easy to block, not resistant to corrosion, and difficult to clean and repair, so it can only be used in occasions where the heat exchange medium is clean, non-corrosive, difficult to scale, difficult to deposit, and difficult to block.