1. Our commonly used R22 refrigerant is pure difluoro-chloromethane, which is a single-component refrigerant. It can be either gaseous or liquid during charging. It is a non-environmentally friendly refrigerant, so it has been phased out in many places;

　　2. R404A refrigerant is a mixed refrigerant, which is generally liquid when charged. It belongs to an environmentally friendly refrigerant and is used with POE lubricating oil;

　　3. Reasons for using R404A air conditioning refrigerant in low-temperature refrigeration system:

　　1. The latent heat of R404A refrigerant is much larger than that of R22, so its thermal efficiency and refrigeration efficiency are higher, and the circulation volume of the system is small, so its filling amount is also smaller than that of R22, and the cooling speed is faster;

　　2. Some friends who do not know very well think that the evaporation temperature of R404A refrigerant is lower. This understanding is wrong. The evaporating temperature is the temperature in the evaporator and when the heat produces boiling, so we can say that the temperature of R404A air conditioning refrigerant is lower than that of R22 under a certain pressure condition; do not ignore the pressure factor;

　　4. What are the differences between R22 refrigerant and R404A?

　　1. The compatibility of R404A refrigerant, lubricating oil, and water is relatively good. Therefore, the R404 refrigeration system has much higher requirements for moisture and residues, and the cleanliness of the system than the R22 refrigeration system. The control of moisture and impurities in the R404A system is a very important indicator, so the filter device configuration of the R404A refrigeration system is higher;

　　2. The exhaust pressure of R404A refrigerant is about 1.2 times that of R22 refrigerant. The mass flow rate is about 1.5 times that of R22 refrigerant. The exhaust flow rate will also increase and the drag will also increase accordingly. In general, the heat exchange capacity of the condenser is about 20%-30% higher than that of Chlorodifluoromethane R-22.