It is very difficult to choose a suitable refrigerant replacement, many factors must be considered and a comprehensive evaluation must be carried out, not only to meet the requirements of ozone depletion potential (ODP), global warming potential (GWP), etc., but also to Consider thermal performance, toxicity, flammability, compatibility, investment and operating costs, etc. The application characteristics of R22 and R134a are analyzed as follows:

1. The global warming potential (GWP) of R134a is 0.25 and that of R22 is 0.36, both belonging to greenhouse gases.

2. The ozone depletion potential value (ODP) of R134a is 0, and R22 is 0.06, which is the reason why R134a is an environmentally friendly refrigerant.

3. The specific volume of R134a is 1.47 times that of R22, and the latent heat of evaporation is small, so the refrigeration capacity of R134a unit is only 60% of that of R22 unit. According to the price of unit cooling capacity, the price of R22 unit is about 60% of that of R134a unit.

4. The thermal conductivity of R134a is 10% lower than that of R22, so the heat exchange area of ​​the heat exchanger of the R134a unit needs to be larger.

5. The water absorption of R134a is very strong, which is 20 times that of R22, so the requirements for the dryer in the unit system are higher to avoid ice blockage.

6. R134a has stronger swelling effect on rubber substances than R22, and the refrigerant leakage rate is higher in actual operation. In addition, it is highly corrosive to copper, and "copper plating" will occur during use, so additives must be added to the system.

7. The R134a system needs a special compressor and special grease lubricating oil. Due to its high water absorption, high foaming and high diffusivity, the grease lubricating oil is inferior to the R22 system in terms of system performance stability. mineral oil.

8. The price of HFCs refrigerant such as R134a and its special lipid oil is higher than that of R22, and the operation and maintenance cost of the equipment is higher. Other refrigerants such as HFCs, known as environmentally friendly refrigerants, such as R410A, R440A, and R407C, although they are better than R134a in terms of efficiency, they also have too high working pressure, high requirements for optimization of piping components and high pressure resistance, and need to be improved. Heat exchanger and unit design, investment, operation and maintenance costs are high, and the application of large-scale refrigeration units is not suitable for my country's basic national conditions at this stage. The result of the collective efforts of the nation. To sum up, the ideal refrigerant does not exist in the short term. Compared with R134a environmental protection refrigerants, R22 refrigerant still has the advantages of high efficiency, stability and low price at the current stage in my country. It is widely used in large refrigeration units. It will also be in an advantageous position in terms of the R22 refrigerant can be consumed until 2040 before the ideal refrigerant is born.