Trade-offs in refrigerant selections: past, present, and future

Recent attention to depletion of stratospheric ozone, by chemicals containing bromine and chlorine, resulted in an international accord to halt their production. The most widely used refrigerants are among them. Chemical and equipment manufacturers mounted aggressive research and development programs to introduce alternative and transition refrigerants, associated lubricants and desiccants, and redesigned equipment. The already difficult criteria became even more complex, with subsequent linkage of chemical emissions from human activities to global climate change. The very successful response to protect the ozone layer has led some regulators and users to assume that ideal substitutes will be found. Such chemicals should be free of all environmental and safety concerns, be chemically and thermally stable, and perform efficiently. The analyses presented in this paper demonstrate that the outlook for discovery or synthesis of ideal refrigerants is extremely unlikely. Trade-offs among desired objectives, therefore, are necessary to achieve balanced solutions. The paper also shows that fragmented regulation of the chemicals involved. to address individual issues, jeopardizes the prospect of solving subsequently addressed problems. The paper reviews the history of refrigerants, their roles in ozone depletion and global climate change, and necessary trade-offs in refrigerant selections. (C) 1998 Elsevier Science Ltd and IIR. All rights reserved.