R-32, a mildly flammable (A2L) lower GWP refrigerant, is widely used in the EU and Asia as an alternative to R-410A for residential and commercial air-conditioning ranges. However, other lower GWP mildly or non-flammable fluorocarbon alternatives to R-410A are reported as being selected or evaluated for some air-conditioning applications. A very low GWP HFO non-flammable refrigerant together with a change in compressor technology may have the potential at some point in the future to provide an option for air-conditioning systems.
The mildly flammable A2L refrigerant R-454B has been selected by an equipment manufacturer for future use in ducted residential and light commercial air-conditioning systems for the United States. This type of air-conditioning system is not typically used in the EU, where split and multi-split systems are used for domestic air-conditioning. The planned future use of HFO/HFC blend R-454B with a GWP of 466, is 78% lower than R-410A and is more efficient when compared to R-410A.
The non-flammable A1 refrigerant R-466A (provisional ASHRAE designation) has been evaluated for use in VRF air-conditioning systems. The promising initial performance testing showed very similar efficiency, cooling and heating capacity to R-410A. The HFC based refrigerant has a GWP of 733, which is 65% lower than R-410A, and the overall life-cycle climate performance (LCCP) including direct and indirect emissions is 30% lower than R-410A. Reliability testing is being carried out in VRF systems.
Domestic and small commercial air-conditioning systems typically use scroll or rotary compressors, which require high pressure (low boiling point) refrigerants such as R-410A or R-32 to achieve the required cooling capacities within a small equipment footprint. An equipment manufacturer is evaluating an innovative mini screw compressor which has the potential to be used for similar air-conditioning requirements. Screw compressors achieve high volumetric throughputs allowing the use of a wider range of low and medium pressure refrigerants including higher boiling point non-flammable HFO based refrigerants.
Source: Cooling Post