Refrigerator working principle
The working fluid that completes the thermodynamic cycle in the refrigerator. It draws heat from the object being cooled at low temperatures and then transfers it to cooling water or air at a higher temperature. In a vapor compression refrigerator, a refrigerant that can be liquefied at normal temperature or lower temperature is used as a refrigerant, such as Freon (fluorine, chlorine, and bromine derivatives of saturated hydrocarbons), and azeotropically mixed working fluid (by two a kind of azeotrope solution in which a certain amount of Freon is mixed, hydrocarbons (propane, ethylene, etc.), ammonia, etc.; in a gas compression type refrigerator, a gas refrigerant such as air, hydrogen, helium or the like is used. The gas is always in a gaseous state in the refrigeration cycle; in the absorption refrigerating machine, a binary solution composed of an absorbent and a refrigerant is used as a working medium such as ammonia and water, lithium bromide (molecular formula: LiBr, white cubic crystal or granular) Powder, very soluble in water) and water; steam jet refrigerators use water as a refrigerant. The main technical indicators of the refrigerant are saturated vapor pressure, specific heat, viscosity, thermal conductivity, surface tension and so on. Since 1960, a large number of experimental studies have been carried out on the application of non-azeotropic mixtures, and they have been used in the liquefaction and separation of natural gas. The application of non-azeotropic mixed working medium single-stage compression can obtain a very low evaporation temperature, and can increase the cooling capacity and reduce the power consumption. Its nature is directly related to the refrigeration effect, economy, safety and operation management of the refrigeration unit. Therefore, the understanding of the refrigerant property requirements cannot be ignored.