R474A

What is R474A refrigerant?

R474A is a refrigerant blend composed of R1132(E) and R1234yf, both of which are classified as hydrofluoroolefins (HFOs). It is being developed as a potential successor to R1234yf, a single-component refrigerant widely used in heat pumps and air conditioning systems for electric vehicles (EVs).
While R1234yf offers an extremely low global warming potential (GWP) of less than 1, there remains scope for further performance improvements in EV heat pump applications due to its relatively low vapor pressure and limited volumetric cooling performance. In particular, maintaining sufficient heating performance in cold climates has been recognized as a challenge.
By blending R1132(E), which has a higher vapor pressure than R1234yf, R474A achieves improved cooling and heating performance compared with R1234yf alone. It was developed to improve heat pump performance under low-temperature operating conditions.

Comparison of Heating Performance: R474A vs. R1234yf

In a heat pump system, heating is achieved by the refrigerant absorbing heat from the outside air as it evaporates in the evaporator and then releasing that heat indoors. In general, refrigerants with lower boiling point and higher vapor pressure can absorb heat more effectively even under low ambient temperatures which can contribute to improved heating performance in cold climates.
The boiling points of R474A and R1234yf are compared below:

R1234yf has a boiling point of -29.4℃ and relatively low vapor pressure, making it challenging to maintain sufficient heating performance in cold climates. In contrast, R474A has a lower boiling point of -44.6℃ and a higher vapor pressure than R1234yf. These properties enable R474A to absorb heat more efficiently from cold ambient air, which is expected to contribute to improved heating performance in cold climates.

Comparison of Cooling and Refrigeration Performance: R474A vs. R1234yf

R474A demonstrates higher heating and refrigeration performance compared with R1234yf. This is primarily due to its higher vapor pressure.
At 25℃, the saturation pressure of R1234yf is approximately 0.68 MPa, whereas that of R474A reaches approximately 1.07 MPa. The higher vapor pressure allows a greater mass flow rate of refrigerant to be drawn into the compressor. As a result, more heat can be transferred through the refrigeration cycle, increasing the system's overall performance.

This effect contributes not only to improved heating performance but also to enhanced cooling and refrigeration performance.

Environmental Impact of R474A

With an ozone depletion potential (ODP) of zero and a global warming potential (GWP) of less than 1, R474A has a very low environmental impact.

Challenges of Using R474A

Because R474A is a refrigerant blend consisting of R1132(E) and R1234yf, refrigerant leakage may alter its composition. As a result, it may be necessary to recover the entire refrigerant charge and refill the system rather than simply topping it up after a leak has occurred.
In addition, R474A is classified as an A2L refrigerant (lower toxicity and mildly flammable). Therefore, its use requires compliance with applicable safety standards, including measures such as leak detection and adequate ventilation.
Furthermore, because R474A contains R1234yf, a fluorinated refrigerant, ongoing regulatory actions related to PFAS substances, particularly those under consideration in Europe, could influence its future market adoption.