Why is R-32 widely used as a refrigerant in heat pumps today? How is it better than the refrigerants of the past?

Refrigerants are the working fluids that are used in refrigeration cycles. They are often used in heat pumps and air conditioning systems. Other than the various types of heating and cooling systems, all refrigerants function similarly. In order to transfer undesirable heat from one place to another, refrigerants will circulate between the compressor, condenser, expansion device, and evaporator. In comparison to water, the typical refrigerant kinds will have a low boiling point. This will allow them to evaporate quickly and with the least amount of thermal energy. R-32 is a next-generation refrigerant that effectively transports heat while causing less damage to the environment.

Different types of refrigerants used in heat pumps

R-12

R12 was the first refrigerant that could be safely used to air condition a car as it was non-flammable and would not start a fire in a collision. Until 1975, when scientists learned that CFCs, including R12, were hazardous to the ozone layer, R12 refrigerant was the predominant refrigerant. Its harm to the environment outweighed the fact that it was valuable in so many ways.

R-22

R-22 is a hydrochlorofluorocarbon (HCFC) refrigerant that can be used in small, medium, and large heat pumps. It was mostly used in installations where the heat pump served as both the heating system and the cooling system.

R134a

R134a refrigerant is most commonly used in medium-sized and large heat pump systems. Its efficiency is higher than that of R407c and R410a, but it is lower than that of NH3 refrigerant. The cost of investing will be high since it has low pressure.

R407c and R410a 

These are often used in small and medium-sized heat pumps. Both refrigerants are often used in dual-purpose installations. R410a will enter a supercritical condition once the temperature reaches 71 °C. Compared to R134a, efficiency is better and the cost is lower.

R-32

R-32 is the next-generation refrigerant that efficiently transports heat while having a minimal negative impact on the environment. Compared to heat pumps that utilize the refrigerant R-22, R-32 can lower electricity consumption by up to 10% since it efficiently conveys heat. Additionally, R-32 is known for its low environmental impact and has a global warming potential (GWP) that is one-third lower than the commonly used refrigerants of today, such as R-22 and R-410A.

Why is R-32 better than other types of refrigerants?

Up until recently, a variety of refrigerants were employed in heat pumps. Since HFC R407c had pretty similar operating properties to R22, manufacturers originally responded by switching over to it as the preferred "in-service" refrigerant.

However, starting in 2006, the market shifted to R410A refrigerant (also an HFC) since it provided improved efficiency by running at higher pressures. R410A uses R-32 and R125, but R407c employs a combination of R-32, R125, and R134A refrigerants, allowing it to function at these higher pressures.

Due to increased environmental awareness brought on by the Montreal Protocol in 1987 and the Kyoto Protocol in 1997, regulations have become more stringent, which has led to a switch to refrigerants with even lower environmental impact.

The common refrigerant R-410A still has a problem with global warming despite having no ozone depletion potential (ODP). While R-32 has an ozone depletion potential of zero, it has only about one-third the global warming potential (GWP) of R-410A.

R-410A is the refrigerant that is currently most popular in developed countries. However, if R-410A were completely replaced with R-32, the impact of HFCs on global warming in 2030 would be reduced by the CO2 equivalent of about 800 million tonnes (19%) as opposed to R-410A's ongoing use.

Many considerations, including the impact on the environment, energy efficiency, safety, and cost-effectiveness, influence heat pump manufacturers' decisions to switch to a new refrigerant like R-32.

Benefits of R-32

The main advantages of R-32 over HCFCs like R-22 and refrigerant mixes like R-410A are its efficiency and lower environmental effect. Despite having around one-third the global warming potential of R-410A, it performs and operates quite similarly. From a performance perspective, R-32 and R-410A are very similar, but R-32 is much more efficient.

Since R-32 is a single-component refrigerant, it is simpler to recycle and reuse. Additionally, it uses well-known technology, is reasonably cheap to produce, doesn't split, and is simpler to handle.

R-32 has minimal toxicity, is difficult to ignite, and does not explode. R-32 offers higher efficiency, longer pipe runs, and requires less refrigerant volume per kW.

Cons of R-32

R-32 is slightly more combustible than R22 and R410A. The labeling of R-32 as a slightly flammable substance has caused less concern in recent years as millions of units have been installed and used safely and ignition of R-32 is very difficult, due to its low burning velocity. 

The uncertain future of R-32 is also a possible disadvantage, which will be discussed in the following section.

Future of R-32

R-32 refrigerant is not "untried" or "new," as it has been in use in Japan for more than two years and is currently being used in over 10 million installed and operational units. Therefore, R-32 will benefit the industry since it will let businesses keep creating cozy spaces for us to work, shop, and unwind while still using equipment that has a minimal impact on climate change. Daikin is employing AI technology to develop a new refrigerant with a GWP of 10 or less. This is hoped to be introduced in 2023. Plans for a new refrigerant are not shocking because R-32 was only ever seen as a short-term fix in the effort to reduce the impact of air conditioning on global warming. Even though R-32 has a lower GWP than older HFCs, its GWP of 675 is still very high compared to other refrigerants that have been created in the years since R-32 first entered the refrigerant market.