A review of alternative working fluids in transport refrigeration systems

CFC refrigerants R-12 and R-502, and HCFC refrigerant R-22 have been important refrigerants in the commercial and transport refrigeration industries for both medium and low temperature applications. The early phase-out of CFC refrigerants presented industry with a pressing challenge to search for suitable alternative refrigerants for both retrofit (short term) and new unit (long term) applications. The CFC phase-out schedules presented by the Montreal Protocol and subsequent regional regulations prompted chemical manufacturers to develop new single compound refrigerants and numerous different blends of HCFC and HFC compounds for testing and evaluation in both retrofit and new unit applications. During the past several years, Thermo King has extensively tested and evaluated these alternative replacement refrigerants and blends for use in transport refrigeration systems. A rigorous regiment of laboratory testing component development work, and field testing of replacement refrigerants has now been completed for both retrofit and new unit applications. This paper reviews the performance requirements of transport refrigeration, the test program developed to measure alternative refrigerant performance, and compressor and other component modifications made to accommodate alternative refrigerants. The performance of hydrochlorofluorocarbon (HCFC) blends based on R-22 is presented and evaluated for suitability of use in retrofit applications. The performance of hydrofluorocarbon (HFC) blends is also presented and evaluated for suitability of use in new unit applications.