The selection of refrigerant is a complicated technical and economical problem, the factors which need to be considered are many, and the comprehensive technical analysis should be carried out according to the specific situation.
1. Consider environmental protection requirements.
Must choose the refrigerant conforming to the national environmental protection regulations.
2. Consider the refrigeration temperature requirements.
According to the refrigerant temperature and cooling conditions, the selection of high temperature (low pressure), Zhong Wen (medium voltage), low temperature (high-pressure) refrigerant. The standard evaporation temperature of the refrigerant usually chosen is lower than the refrigeration temperature 10 ℃. The refrigerant should also consider the cooling conditions, the use environment and so on. The condensation pressure in operation should not exceed the stipulated value of the compressor's safe use condition. Automotive air-conditioning can only use the outside air to do cooling media, the impact of the temperature, wind speed, solar radiation, thermal radiation and other factors in the frequent changes, its operating conditions decided that it can only choose high-temperature (low-voltage) refrigerant, used to choose R12, most currently selected R134a.
3. Consider the nature of refrigerant.
According to the thermodynamic properties, physical properties and chemical properties of refrigerant, the refrigerant is not poisonous, non-explosive, non-combustion, and the refrigerant should be used for good heat transfer, low resistance, and good compatibility with the refrigeration system.
4. Consider the type of compressor.
The working principle of different refrigeration compressors varies. Volumetric compressor is by reducing the volume of refrigerant vapor to improve its pressure, the general selection of unit volume refrigeration volume of large refrigerant, such as R134a,R22. Many kinds of refrigerant, along with the progress of science and technology. The new working quality is constantly appearing to fit the different refrigeration devices.