Refrigerants are also called refrigeration working fluids, commonly known as refrigerants in some areas in the south. It is a working substance that continuously circulates in the refrigeration system and realizes refrigeration through its own state changes. The refrigerant absorbs the heat of the cooling medium (water or air, etc.) in the evaporator to vaporize, and transfers the heat to the surrounding air or water in the condenser to condense.
In gas compression refrigerators, gas refrigerants such as air, hydrogen, helium, etc. are used. These gases are always gaseous in the refrigeration cycle; in absorption refrigerators, a binary composition composed of absorbent and refrigerant is used. Solution is used as working fluid, such as ammonia and water, silver bromide and water, etc.; steam jet refrigerator uses water as refrigerant. The main technical indicators of refrigerants include saturated vapor pressure, specific heat, viscosity, thermal conductivity, surface tension, etc. After 1960, people have conducted a large number of experimental studies on the application of non-azeotropic mixtures, and they have been used in the liquefaction and separation of natural gas. The application of single-stage compression of non-azeotropic mixed working fluid can obtain very low evaporation temperature, and can increase refrigeration capacity and reduce power consumption. Its nature is directly related to the refrigeration effect, economy, safety and operation management of the refrigeration device.
