Refrigerants will change the way forward (2/2)

Second,Differences in application characteristics of R22 and R134A
Selecting a suitable refrigerant substitute is very difficult and must take into account many factors and conduct a comprehensive assessment, both to meet the requirements of ODP, Global Warming Potential(GWP), as well as thermal performance, toxicity, flammability, compatibility, investment and operating costs. . The application characteristics of R22 and R134a are analyzed as follows.
1, the global warming potential(GWP)of R134a is 0.25, and R22 is 0.36, which belongs to greenhouse gases. .
2. The ODP of R134a is 0 and R22 is 0.06, which is why R134a becomes an environmentally friendly refrigerant. .
3. The specific volume of R134a is 1.47 times of R22, and the latent heat of evaporation is small, so the refrigeration capacity of R134a is only 60%of the R22 unit. According to the unit cooling capacity price, the price of R22 unit is about 60%of the R134a unit. .
4. The thermal conductivity of R134a is reduced by 10%than that of R22, so the heat exchange area of R134a unit needs to be larger. .
5. The water absorption of R134a is very strong, which is 20 times that of R22. Therefore, the requirement for dryer in the unit system is higher to avoid ice blocking. .
6. R134a has stronger swelling effect than R22 on rubber substances, and refrigerant leakage rate is higher in actual operation. In addition, it is very corrosive to copper, and``copper plating‘‘ will occur during use, so additives must be added in the system. .
7. R134a system requires special compressor and special grease lubricating oil. Due to its high water absorption, high foaming property and high diffusivity, the stability of the system is inferior to the mineral oil used in R22 system. .
8, R134a and other HFCs refrigerants and their special lipid oils are higher than R22, and the equipment has higher operation and maintenance cost. . Other refrigerants of HFCs called environmental refrigerants, such as R410A, R440A and R407C, although the efficiency is better than R134a, there is also too high working pressure, the optimisation and pressure resistance requirements for pipeline components, so it is necessary to improve the design of heat exchanger and unit and high cost of investment operation and maintenance.

At present, the application of large refrigerating units still does not adapt to the basic national conditions in China, which is the reason why the years of using HCFCs for developing countries in the international convention, and the result of collective efforts of developing countries. . To sum up, the ideal refrigerant does not exist in the short term. At present stage, R22 refrigerant still has the advantages of high efficiency, stability and low price compared with R134a environmental protection refrigerant. The application of large refrigeration unit will also be in the advantage. Before the ideal refrigerant is born, R22 refrigerant can be consumed until 2040. 
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