Alternatives to HCFC-22 for air conditioners

Some selected fluids have been assessed for their suitability as alternatives to HCFC-22 for air conditioners. Only those refrigerants with zero ozone depletion potential are considered. NIST CYCLE_D has been used for the comparative thermodynamic analysis. Among the refrigerants studied (HFC-134a, HC-290, R-407C, R-410A, and three blends of HFC-32, HFC-134a and HFC-125), HFC-134a offers the highest COP, but its capacity is the lowest and requires much larger compressors. The characteristics of HC-290 are very close to those of HCFC-22, and compressors require very little modification. Therefore, HC-290 is a potential candidate provided the risk concerns are mitigated as had been accomplished for refrigerators. For retrofitting, R-407C is probably the best candidate.