The most basic and main use of refrigerant is to use it as a part of the refrigeration system, such as for refrigeration in refrigerators and freezers; Use of air conditioning and refrigeration system; Cooling air or cooling water in refrigeration (low temperature) equipment and instruments; Cryogenic industry, low-temperature medicine and low-temperature scientific research, freeze-drying (freezing) equipment, and the production of gaseous refrigerants and liquid chemicals. The commonly used refrigerants of air source heat pump include R22, R134a, R407C and R410a.

R22 (difluorochloromethane) is widely used for refrigeration in low-temperature industries such as refrigerators and air conditioners, with a melting point of - 146 ℃ and a boiling point of - 38.1 ℃. According to the Montreal Protocol, its use and production have been stopped in developed countries, and it can still be produced in developing countries, but its production and use deadline is 2030.

R134a (tetrafluoroethane) is an environmentally friendly refrigerant approved and recommended by most countries at present, and is also a mainstream environmentally friendly refrigerant. It is widely used in the initial installation and re-adding of new refrigeration and air-conditioning equipment during maintenance. Melting point - 101 ℃, boiling point - 26.5 ℃

R407C is composed of R32 refrigerant and R125/ The refrigerant is mixed with R134a refrigerant in a certain proportion. It is an environmentally friendly refrigerant that does not destroy the ozone layer. R407c is also characterized by cleanness, low toxicity, incombustibility and good cooling effect, and is widely used in the air conditioning industry.

R410A is a new type of mixed environment-friendly refrigerant, which is composed of two quasi-azeotropic mixtures R32 and R125, 50% each. It does not destroy the ozone layer. The working pressure is about 1.6 times of that of ordinary R22 air conditioners, and the cooling (heating) efficiency is high. Melting point - 155 ℃, boiling point - 51.6 ℃.