Working Principle Of Dryer

For example, drying of wood before making wooden molds and woodware can prevent product deformation, and drying of ceramic blanks before calcination can prevent finished products from cracking. In addition, the dried materials are also easy to transport and store, such as drying the harvested grain to a certain moisture content to prevent mildew. Since natural drying is far from being able to meet the needs of production development, various mechanized dryers are more and more widely used.

The amount of water vapor in the compressed air is determined by the temperature of the compressed air: while keeping the compressed air pressure basically unchanged, reducing the temperature of the compressed air can reduce the water vapor content in the compressed air, and the excess water vapor will condense Into liquid. The freeze dryer uses this principle to use refrigeration technology to dry compressed air. Therefore, the refrigeration dryer has a refrigeration system. The refrigeration system of the freeze dryer belongs to compression refrigeration, which is composed of four basic components: refrigeration compressor, condenser, evaporator, and expansion valve. They are connected in turn by pipes to form a closed system. The refrigerant continuously circulates in the system, changes its state, and exchanges heat with the compressed air and cooling medium. Compressed air dryers also have adsorption dryers and dissolving dryers.

The refrigeration compressor sucks the low-pressure (low-temperature) refrigerant in the evaporator into the compressor cylinder. The refrigerant vapor is compressed, and the pressure and temperature increase at the same time; the high-pressure and high-temperature refrigerant vapor is compressed to the condenser, in the condenser, The refrigerant vapor at a higher temperature exchanges heat with the cooling water or air at a lower temperature. The heat of the refrigerant is taken away by the water or air and condenses, and the refrigerant vapor becomes a liquid. This part of the liquid is then delivered to the expansion valve, throttling through the expansion valve into a low-temperature and low-pressure liquid and enters the evaporator; in the evaporator, the low-temperature, low-pressure refrigerant liquid absorbs the heat of the compressed air and vaporizes (commonly known as "evaporation") , And the compressed air is cooled and condenses a large amount of liquid water; the refrigerant vapor in the evaporator is sucked away by the compressor, so that the refrigerant passes through the four processes of compression, condensation, throttling, and evaporation in the system, thus Completed a cycle.

In the refrigeration system of the freeze dryer, the evaporator is a device that transports cold energy, in which the refrigerant absorbs the heat of the compressed air to achieve the purpose of dehydration and drying. The compressor is the heart, which plays the role of inhaling, compressing, and transporting refrigerant vapor. The condenser is a device that emits heat, and transfers the heat absorbed in the evaporator together with the heat converted from the input power of the compressor to the cooling medium (such as water or air). The expansion valve/throttle valve acts as a throttling and pressure reduction for the refrigerant, and at the same time controls and regulates the amount of refrigerant liquid flowing into the evaporator, and divides the system into two parts, a high pressure side and a low pressure side.