Wood in the production of wood mold, wood before the drying can prevent the deformation of the product, ceramic billet drying before calcination can prevent the finished product cracking. In addition, dry materials are also easy to transport and store, such as drying the harvested grain to a certain wet content below, to prevent mildew.
Because natural drying is far from meeting the needs of production development, a variety of mechanized dryers are more and more widely used. The amount of water vapor in compressed air is determined by the temperature of the compressed air: reducing the temperature of the compressed air can reduce the amount of water vapor in the compressed air while keeping the compressed air pressure largely unchanged, while the excess water vapor condenses into a liquid. Freeze-Drying machine is the use of this principle using refrigeration technology to dry compressed air. Therefore, the cold dryer has a refrigeration system. The refrigeration system of the freeze-drying machine belongs to the compressed refrigeration, which is composed of four basic components, such as refrigeration compressor, condenser, evaporator and expansion valve. The pipes are connected in turn to form a closed system in which the refrigerant circulates continuously in the system, changes in state and heat exchange with compressed air and cooling media.
Compressed air dryer also has adsorption dryer and dissolved dryer. The refrigeration compressor inhales the low pressure (low temperature) refrigerant in the evaporator into the compressor cylinder, the refrigerant steam is compressed, the pressure and temperature rise at the same time, the high pressure refrigerant steam is pressed to the condenser, in the condenser, the cooler steam with high temperature is hot exchange with the cooling water or air with low temperature, The heat of the refrigerant is taken away by water or air and condensed, and the refrigerant steam becomes a liquid. This part of the liquid is then transported to the expansion valve, through the expansion valve throttling into a low-temperature low-pressure liquid and into the evaporator, in the evaporator low temperature, low pressure refrigerant liquid absorbs the heat of compressed air and vaporization (commonly known as "evaporation"), while compressed air is cooled to condense a large amount of liquid water; refrigerant steam in the evaporator is sucked away by the compressor, so that the refrigerant in the system through the compression, condensation, throttling, evaporation and so on four processes, thus completing a cycle. In the refrigeration system of the freeze-drying machine, the evaporator is the equipment that transports the cold quantity, in which the refrigerant absorbs the heat of the compressed air and realizes the purpose of dehydration and drying. Compressor is the heart, plays the role of inhalation, compression, transport refrigerant steam. A condenser is a device that emits heat, passing the heat absorbed in the evaporator along with the heat converted by the compressor input power to the cooling medium (such as water or air) to take away.
The expansion valve/throttle valve acts as a throttling and antihypertensive effect on the refrigerant, simultaneously controls and regulates the amount of refrigerant liquid flowing into the evaporator, and divides the system into two parts, the high pressure side and the low pressure side.