Refrigerants are also called refrigeration working fluids. Refrigerants mainly including Refrigerant R134a for automotive , Refrigerant R410a for air conditioner, Refrigerant R1234yf, etc. It is a working substance that continuously circulates in the refrigeration system and achieves refrigeration through its own state changes. The refrigerant absorbs the heat of the cooling medium (water or air, etc.) in the evaporator and vaporizes, and transfers the heat to the surrounding air or water in the condenser to condense.
The selection of refrigerant is a more complicated technical and economic issue. There are many factors to be considered. When selecting, an overall technical analysis should be carried out according to the specific situation.
1. Consider the requirements of environmental protection. Choose refrigerants that comply with national environmental protection regulations.
2. Consider the requirements of refrigeration temperature. According to different refrigerant temperature and cooling conditions, high temperature (low pressure), medium temperature (medium pressure), and low temperature (high pressure) refrigerants are selected. Usually the standard evaporating temperature of the selected refrigerant is 10°C lower than the refrigerating temperature. The choice of refrigerant should also consider the cooling conditions and use environment of the refrigeration device. The condensing pressure during operation should not exceed the specified value of the compressor's safe use conditions. Automobile air conditioners can only use the air outside the car as the cooling medium. The temperature, wind speed, solar radiation, heat radiation and other factors that affect it frequently change. Its operating conditions determine that it can only use high temperature (low pressure) refrigerants. In the past R12 is used, and R134a is mostly used when posting.
3. Consider the nature of the refrigerant. According to the thermodynamic, physical and chemical properties of the refrigerant, select those refrigerants that are non-toxic, non-explosive, and non-combustible; the selected refrigerant should have good heat transfer, low resistance, and good compatibility with the materials used in the refrigeration system.
4. Consider the type of compressor. Different refrigeration compressors work differently. The volumetric compressor increases its pressure by reducing the volume of the refrigerant vapor. Generally, refrigerants with large refrigeration capacity per unit volume, such as R134a, R22, etc., are used. There are many types of refrigerants, with the advancement of science and technology. New working fluids are constantly appearing to suit different refrigeration devices.