R134a alternatives

In addition to the flammable HFO refrigerants R1234yf and R1234ze(E) already described, non-flammable mixtures are now also available as R134a alternatives. As previously mentioned, the initial situation is most favorable for these.

They achieve GWP values of approx. 600 − less than half of 134a (GWP = 1430). In addition, this type of blends can have azeotropic properties, so they can be used like pure refrigerants.

For quite some time a blend has been applied on a larger scale in real systems – this was developed by Chemours and is called OpteonTM XP-10. Results available today are highly satisfactory.

This is also true for an R134a alternative designated Solstice® N-13 and offered by Honeywell which, however, differs regarding the blend composition.

The refrigerants are listed in the ASHRAE nomenclature under R513A (Chemours) and R450A (Honeywell).

The same category also includes the refrigerant blends R516A (ARKEMA ARM 42) and R456A (Koura/Mexichem AC5X).

All options show refrigerating capacity, power input, and pressure levels similar to R134a. Thus, components and system technology can be taken over, only minor changes like superheat adjustment of the expansion valves are necessary.

Polyolester oils are suitable lubricants which must meet special requirements, e.g. for the utilization of additives.

Prospects are especially favorable for supermarket applications in the medium temperature range in a cascade with CO2 for low temperature, just as in liquid chillers with higher refrigerant charges where the use of flammable or toxic refrigerants would require comprehensive safety measures.

A special case is the refrigerant R515B: an azeotropic mixture of R1234ze(E) and small amounts of R227ea. This combination, declared by the manufacturer Honeywell as an R134a alternative, is non-flammable (A1) despite the very low GWP of approx. 300.

However, as with the previously described R1234ze(E), this can only be considered an alternative under certain restrictions. The volumetric refrigerating capacity is also more than 20% lower than that of R134a or R1234yf.

This category of substitutes also includes R471A (Honeywell), a blend of R1234ze(E), R1336mzz(E) and R227ea. R1336mzz(E) is a non-flammable HFO low-pressure refrigerant which can also be used with turbo compressors and for high temperature heat pumps. Due to the two main HFO components, the GWP of the blend is < 150, but it is still non-flammable (A1).

A disadvantage, however, is the even lower volumetric refrigerating capacity compared to R515B.