Alternative refrigerant mixtures for cfc and HCFC refrigerants in transport refrigeration systems: Performance and implementation

The Montreal Protocol and subsequent regional regulations have lead to a phase-out of chlorofluorocarbon (CFC) refrigerants. Hydrochlorofluorocarbon (HCFC) refrigerants are now subject to regulation and are scheduled to be phased out in the 21(st) Century. This paper reviews the performance requirements of transport refrigeration, the test program developed to measure alternative refrigerant performance, the compressor and component modifications required to accommodate alternative refrigerants, and the laboratory evaluation of composition shifting of refrigerant blends in the liquid and vapor states during system operation. Test results indicate that R-404A (a near azeotropic mixture of HFC-125, HFC-143a and HFC 134a) best satisfies the selection criteria and possesses performance characteristics similar to CFC refrigerants.