Like condenser, evaporator is also a kind of heat exchanger, also known as cooler, which is a direct device to obtain cold air in refrigeration cycle. The shape is similar to the condenser, but narrower, smaller and thicker than the condenser. Its function is to let the low-temperature and low-pressure liquid refrigerant absorb heat and evaporate in its pipeline, so as to reduce the temperature of the evaporator and the surrounding air, so as to output more cold air when the wind of the blower passes through it.
The evaporator has three structures: segment type, tube belt type and laminated type, as shown in Figure 6.13, 6.14 and 6.15. The segment type has the advantages of simple structure and convenient processing, but the heat exchange efficiency is poor. The process of tube belt type is more complex than that of segment type, and the efficiency can be increased by about 10%. The laminated processing is the most difficult, but its heat exchange efficiency is also the highest and its structure is the most compact.
The low-temperature and low-pressure liquid refrigerant entering the evaporator discharge pipe absorbs the heat of the air passing through the heat transfer surface of the evaporator through the pipe wall to cool it. At the same time, the moisture contained in the air condenses on the surface of the evaporator due to cooling, and is collected and discharged to dehumidify the air. The cooled and dehumidified air is blown into the car room by the blower to obtain cold air in the car.