Plate-fin heat exchanger is usually composed of baffle, fin, seal and guide plate. Fins, guides and seals are placed between two adjacent partitions to form a interlayer, called a channel. The interlayer is stacked according to different ways of fluid and brazed into a whole to form a plate bundle. The plate bundle is the core of the plate fin heat exchanger.
The emergence of the plate-fin heat exchanger has improved the heat exchange efficiency of the heat exchanger to a new level, and the plate-fin heat exchanger has the advantages of small size, light weight, and can handle more than two kinds of media. At present, plate-fin heat exchanger has been widely used in petroleum, chemical, natural gas processing and other industries.
Characteristics of plate-fin heat exchanger
(1) High heat transfer efficiency, due to the disturbance of the fin to the fluid, the boundary layer is constantly broken, so it has a large heat transfer coefficient; At the same time, because the partition and fin are very thin and have high thermal conductivity, the plate-fin heat exchanger 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 compact and mostly made of aluminum alloy. Now steel, copper, composite materials and so on have also been mass-produced.
(4) Strong adaptability, plate-fin heat exchanger can be applied to: gas - gas, gas - liquid, liquid - liquid, all kinds of fluid between the heat transfer and the phase transformation of the set state change heat. Through the arrangement and combination of the flow channel can adapt to: countercurrent, cross-current, multi-stream flow, multi-process flow and other different heat transfer conditions. The combination of series, parallel and series-parallel between units can meet the heat exchange needs of large equipment. In industry, it can be finalized and mass produced to reduce costs and expand interchangeability through building block combination.
(5) Strict manufacturing process requirements, complex process.
(6) Easy to plug, corrosion resistance, cleaning and maintenance is very difficult, so it can only be used for heat exchange medium clean, no corrosion, not easy to scale, not easy to deposit, not easy to plug the occasion.
Plate-fin heat exchanger structure:
It is usually composed of partitions, fins, seals and flow guides. Fins, guides and seals are placed between the two adjacent partitions to form a sandwich, called a channel. The sandwich is stacked according to the different ways of fluid and brazed into a whole to form a plate bundle. The plate bundle is the core of the plate fin heat exchanger, with the necessary head, nozzle, support and so on to form the plate fin heat exchanger.
Working principle of plate-fin heat exchanger
From the heat transfer mechanism, the plate-fin heat exchanger still belongs to the interwall heat exchanger. Its main feature is that it has an extended secondary heat transfer surface (fin), so the heat transfer process is not only carried out on the primary heat transfer surface (separator), but also on the secondary heat transfer surface at the same time. The heat of the medium on the high temperature side is not only poured into the medium on the low temperature side once, but also transferred part of the heat along the direction of the fin surface height, that is, along the direction of the fin height, the heat is poured into the partition, and then the heat is passed to the medium on the low temperature side. Since the fin height greatly exceeds the fin thickness, the heat conduction process along the fin height direction is similar to the heat conduction of a homogeneous elongated guide rod. In this case, the thermal resistance of the fin can not be ignored. The maximum temperature at both ends of the fin is equal to the temperature of the partition. With the convection and heat release between the fin and the medium, the temperature decreases continuously until the medium temperature in the middle region of the fin.
