Structurally, the freezer generally includes a box, a refrigeration system, and an electrical system.
The basic function of the freezer is to refrigerate and keep the inside of the box at an appropriate low temperature. The refrigeration system generally consists of four basic components: compressor, condenser, capillary or thermal expansion valve, and evaporator. Refrigerant is a liquid that can boil at low temperature and at low pressure. It absorbs heat when it boils. The refrigerant circulates continuously in the refrigeration system. The compressor increases the gas pressure of the refrigerant, resulting in liquefaction conditions. When passing through the condenser, it condenses and liquefies, and releases heat. , and then reduce the pressure and temperature when passing through the capillary, and then boil and vaporize to absorb heat when passing through the evaporator. In addition, the use of refrigeration diodes is now developed. There is no complicated mechanical device, but the efficiency is poor, and it is used in small refrigerators.
The freezer originally used F12 (Freon 12) as the refrigerant, but now it uses R600a/R134a/R404 and other refrigerants because it will destroy the ozone layer of the atmosphere.
In addition, due to the inevitable existence of some moisture and impurities in the system, a drying filter is generally installed at the inlet end of the capillary.
Refrigerators use electricity as the main energy source, rely on electric motors to drive compressors or use refrigeration diodes, and are generally equipped with relay protectors and thermostats.
According to different starting methods, refrigerator motors using compressors can be divided into resistance split-phase starting type, capacitor starting type, and capacitor starting capacitor running type. The motor of the fully hermetic compressor is installed inside the refrigeration system and is in contact with the refrigerant and refrigerating machine oil for a long time, and is subjected to pressure, high temperature, etc. Therefore, it must be resistant to refrigerant and refrigerating oil, have stable electrical performance, high-temperature resistance, vibration and shock resistance, Have a larger starting torque, and keep clean without moisture and other requirements.
The box body is composed of structural materials and thermal insulation materials, forming a space to store food and preventing heat transfer from inside and outside. The box generally includes an outer box, an inner tank, and a thermal insulation layer. The inner liner (lining) of the refrigerator is generally made of ABS or HIPS sheet by vacuum forming, with a thickness of less than 1 mm, white and smooth.