Comparison of R22, R410A, R32 and R290 refrigerants

At present, the refrigerant widely used in household air conditioning and heat pump is R22, which belongs to ozone depleting substance HCFC. According to the Montreal Protocol, China will eliminate the production and consumption of all manufacturing HCFC by 2030 [1]. The alternative refrigerants for R22 can be roughly divided into three categories:

The first type is HFC refrigerant, such as R410A (widely used) and R32 (potential refrigerant);

The second type is HC hydrocarbon refrigerant, such as R290 (potential refrigerant);

The third category is natural working medium carbon dioxide CO2 - it is generally not used in household air conditioning due to its high working pressure.

At present, the focus of household air-conditioning refrigerants mainly focuses on R22, R410A, R32 and R290. As the media of refrigeration industry, it is necessary for us to popularize their safety.

The safety of refrigerants mainly includes toxicity and flammability. The national standard refrigerant numbering method and safety classification GB / T 7778-2017 divides the toxicity of refrigerants into class A (low chronic toxicity) and class B (high chronic toxicity), and divides the flammability into class 1 (no flame propagation), class 2L (weak possibility), class 2 (possibility) and class 3 (flammability and explosion). According to GB / T 778-2017, refrigerant safety is divided into 8 categories: A1, A2L, A2, A3, B1, B2L, B2 and B3, of which A1 is the safest and B3 is the most dangerous.

R22: refrigerant to be eliminated

R22 is composed of chlorodifluoromethane (CHCLF2), which is non combustible and non explosive, with low toxicity and safety grade of A1. R22 ozone depleting potential ODP > 0, so it is not suitable for long-term use, and China will completely eliminate it by 2030.

R410A: alternative refrigerant for R22

R410A is composed of R32 and R125 in the proportion of 50% by mass. Among them, R32 (difluoromethane, CH2F2, A2L), R125 (pentafluoroethane, cf3chf2, A1) and a410a are safety grade A1. They also belong to non combustion, non explosion and low toxicity working fluids.

Compared with R22, R410A belongs to high-pressure refrigerant, which has higher requirements for equipment and system pressure strength, but it is conducive to reducing compressor displacement, reducing heat exchange copper pipe diameter and saving raw materials; R410A has better heat transfer and flow characteristics than R22, which is conducive to improve the operation efficiency of air conditioning and has obvious energy-saving effect. At present, it has been widely used.

ODP of R410A = 0, no ozone consumption; However, the global warming potential of R410A is GWP = 1730 (as a comparison, GWP of CO2 = 1), which plays a great role in promoting global warming. Therefore, R410A is not the final environmental protection refrigerant solution.

R32: future refrigerant competitors

The chemical composition of R32 is difluoromethane CH2F2, which has low toxicity, slight combustion and safety grade of A2L. R32 has the possibility of explosion, and its explosion limit is 14.4% - 29.3% [3]. The problem of low flammability needs to be solved in the application of household air conditioning.

The refrigeration performance of R32 is close to that of R410A. Under the same refrigeration capacity, the filling capacity of R32 is less than R410A (about 30% reduction), but the exhaust temperature is higher than R410A. R32 has ODP = 0 and GWP = 675. It is a green refrigerant and an important substitute for R22. At present, it has been widely used in household air conditioners in Europe, America, Japan and other countries.

R290: future refrigerant competitors

The chemical composition of R290 is propane (ch3ch2ch3), with little toxicity and flammability, and the safety grade is A3. The explosion limit of R290 is 2.1% - 10.0% [3], and the explosion point is much lower than R32.

ODP = 0 and GWP = 20 of R290 have little effect on global warming. It belongs to natural organic matter and can be obtained directly from liquefied petroleum gas with low price. R290 has good thermal performance, large gasification latent heat and less liquid filling capacity of the system. Under the same working conditions, the exhaust temperature can be 20 ℃ lower than R22, which is conducive to prolonging the service life of the compressor.

Last year, R290 gradually entered the field of vision. Many domestic enterprises have established R290 air conditioning production lines, and the national environmental protection department is also sparing no effort to promote the marketization process of R290 products [4]. At present, domestic support for R290 is greater than R32.

The biggest obstacle to the popularization and application of R290 is flammability. During use, safety measures need to be increased to ensure that its filling amount is controlled within the specified value of relevant regulations (standard iec60335-2-24: 2007) - at present, R290 is safe and controllable when used in household air conditioners < 1.5p; In addition, the leakage shall be reduced and the ability of leakage detection and response shall be improved.

Reference:

Source: Jianhuan world

[1] China Ozone Layer Protection Action Network: Notice on submitting the letter of intent for HCFC elimination and transformation project in industrial and commercial refrigeration and air conditioning industry in 2013

[2] Numbering method and safety classification of refrigerants (GB / T 7778-2017)

[3] Shi Lin, Zhu Mingshan. Reanalysis of R32 replacing R22 in household / commercial air conditioners [J]. Journal of refrigeration, 2010,01:1-5

[4] China home appliance network: the first batch of R290 air conditioners in China were officially listed in Shenzhen