In order to reduce the irreversible losses of heat transfer, the heat transfer temperature difference of low - temperature heat exchangers is small, so heat exchangers are required to have a high specific surface area. In engineering, a heat exchanger with a heat transfer surface area of more than 700 square meters per cubic meter of volume is called a compact heat exchanger. The methods to make heat exchangers more compact are as follows:

(1) Select and develop new heat exchanger materials. Replace materials with low thermal conductivity with those with high thermal conductivity to enhance heat transfer.

(2) Improve the geometric shape of the heat transfer surface to enhance convective heat transfer. Among them, the geometric shape of the fins is of crucial importance to the performance of the compact heat exchanger. The research on fin performance (such as heat transfer performance, flow resistance performance, strength, etc.) is an important part of the research on compact heat exchangers.

(3) The flow channel layout is another important factor affecting its performance. This is because in multi - stream heat exchangers, the layout of the flow channels will affect the local thermal equilibrium inside each channel, thus affecting the performance of the heat exchanger. Compact heat exchangers use highly compact heat transfer surfaces, and the shape of the heat exchanger has a large frontal area and a short flow channel length. Therefore, the flow channel layout requires extremely high accuracy.