In the heat exchanger, the cold and hot fluids are separated by the partition, and there is a certain temperature difference, and a certain heat exchange will be formed between the two; It makes use of the heat balance knowledge of junior high school physics. The heat of high temperature objects will always be transferred to low temperature objects, thus transferring the heat from the hot side to the cold side. It is a device that can transfer heat energy from one fluid to another. It is widely used in chemical industry.