Guide to R32, R290, R410A, and R22 Refrigerants

Currently, R22 is widely used in household air conditioners and heat pumps. As an HCFC (hydrochlorofluorocarbon), it is categorized as an ozone-depleting substance. Under the Montreal Protocol, the production and consumption of HCFCs in manufacturing industries will be phased out by 2030. Alternatives to R22 can be classified into three main categories:

• HFC Refrigerants: Such as R410A (already widely used) and R32 (a promising refrigerant).
• HC Hydrocarbon Refrigerants: Such as R290 (a potential alternative).
• Natural Working Fluids: Like carbon dioxide (CO2), which, due to its high working pressure, is generally unsuitable for household air conditioning.

R22 Refrigerants

R22 was one of the most commonly used refrigerants due to its high cooling efficiency and low cost. However, as an HCFC, it damages the ozone layer and contributes to global warming. Developed countries have largely ceased using R22, and developing countries are gradually phasing it out in compliance with the Montreal Protocol.

Strict measures are required to control leaks when servicing existing equipment. Due to environmental regulations, R22 usage is rapidly decreasing, and it is being replaced by more sustainable alternatives.

R410A Refrigerants

R410A is a blend of 50% R32 (difluoromethane, CH2F2, A2L) and 50% R125 (pentafluoroethane, CF3CHF2, A1) by mass. Its safety classification is A1, indicating it is non-flammable, non-explosive, and has low toxicity.

Compared to R22, R410A is a high-pressure refrigerant, requiring equipment and systems to withstand greater pressure. However, it reduces compressor displacement, decreases heat exchanger copper tube diameters, and saves raw materials. R410A’s superior heat transfer and flow characteristics enhance air conditioner efficiency, delivering significant energy savings.

• ODP (Ozone Depletion Potential): 0, meaning it does not deplete the ozone layer.
• GWP (Global Warming Potential): 1730 (for comparison, CO2 has a GWP of 1), meaning it significantly contributes to global warming. Over time, it is likely to be replaced by lower-GWP refrigerants.

R32 Refrigerants

R32 is a single-component HFC refrigerant with a GWP approximately half that of R410A. It offers similar cooling efficiency to R410A but has a lower environmental impact.

R32 is flammable, with a safety classification of A2L. It has an explosion limit of 14.4%–29.3%. R32’s refrigerating performance is comparable to R410A, but it requires approximately 30% less charge for the same cooling capacity. However, its discharge temperature is higher than R410A’s.

• ODP: 0
• GWP: 675, making it an environmentally friendly refrigerant.
  R32 is a key alternative to R22 and has been widely adopted in household air conditioners in Europe, Japan, and the United States.

R290 Refrigerants

R290, chemically known as propane (CH3CH2CH3), is a natural refrigerant with very low toxicity. It is flammable, with a safety classification of A3, and has an explosion limit of 2.1%–10.0%, which is lower than R32.

• ODP: 0
• GWP: 20, meaning it has minimal impact on global warming.
  R290 is a natural organic compound derived directly from liquefied petroleum gas, making it cost-effective. Its excellent thermodynamic properties, high latent heat of vaporization, and lower refrigerant charge requirements improve energy efficiency. Additionally, under the same operating conditions, its discharge temperature is up to 20°C lower than R22, which benefits compressor longevity.

Challenges:
The primary barrier to R290’s adoption is its flammability. Rigorous safety measures are essential during use to ensure the refrigerant charge remains within regulatory limits. Efforts are also needed to minimize leakage and enhance detection and response capabilities.