Compression, Condensation, Throttling, Evaporation

- Apr 10, 2019-

A dryer is a mechanical device that uses heat to reduce the moisture of a material and is used to dry the object. The dryer vaporizes the moisture (usually referred to as moisture or other volatile liquid components) in the material by heating to obtain a solid material having a specified moisture content. The purpose of drying is for the purpose of material use or further processing. According to the operating pressure, the dryer is divided into two types: atmospheric pressure dryer and vacuum dryer. According to the operating pressure, it can be divided into normal pressure and pressure reduction (pressure dryer is also called vacuum dryer). The entry also details the dryer, freeze dryer and microwave dryer during adsorption.

The amount of water vapor in the compressed air is determined by the temperature of the compressed air: reducing the temperature of the compressed air reduces the amount of water vapor in the compressed air while maintaining the constant pressure of the compressed air, and the excess water vapor condenses. Into a liquid. The freeze dryer uses this principle to use refrigeration technology to dry compressed air. Therefore, the dryer has a refrigeration system. The refrigeration system of the freeze dryer is a compression type refrigeration system consisting of four basic components: a refrigeration compressor, a condenser, an evaporator, and an expansion valve. They are connected in series by pipes to form a closed system in which the refrigerant circulates continuously in the system, undergoes state changes and exchanges heat with compressed air and cooling medium. Compressed air dryers also have adsorption dryers and dissolution dryers.

The refrigeration compressor draws the low-pressure (low-temperature) refrigerant in the evaporator into the cylinder of the compressor, and the refrigerant vapor is compressed, and the pressure and temperature are simultaneously increased; the high-pressure high-temperature refrigerant vapor is pressed to the condenser, and in the condenser, The higher temperature refrigerant vapor exchanges heat with the cooler water or air, and the heat of the refrigerant is taken away by water or air to condense, and the refrigerant vapor becomes a liquid. This part of the liquid is then sent to the expansion valve, which is throttled into a low-temperature and low-pressure liquid through the expansion valve and enters the evaporator; in the evaporator, the low-temperature, low-pressure refrigerant liquid absorbs the heat of the compressed air and vaporizes (commonly called "evaporation") The compressed air is cooled to condense a large amount of liquid water; the refrigerant vapor in the evaporator is sucked away by the compressor, so that the refrigerant undergoes four processes of compression, condensation, throttling, and evaporation in the system, thereby Completed a loop.