Carbon Dioxide as a Refrigerant
CO2 as a refrigerant. Basic principles. The Montreal Protocol regulations on gases that deplete the earth’s ozone layer have led to a phase-out of chlorofluoro-carbons (CFCs) as refrigerants in industrialized countries. Moreover, hydrochlorofluorocarbons (HCFCs) are only an interim solution in industrialized countries until the year 2020 and certain national regulations prescribe an even earlier phase-out date (for instance, by the end of the year 1999 for R22 in Germany). Another environmental concern regarding these refrigerants is their behaviour as greenhouse gases in the atmosphere and this also applies for CFC and HCFC substitutes, the newly developed hydrofluorocarbons (HFCs). For this reason, these new refrigerants are placed in a basket with five other gases covered by the Kyoto Protocol on greenhouse gases. This situation has led to increased use of the “old” refrigerants ammonia and hydrocarbons. Although both are environmentally benign, they can exhibit a certain degree of local danger because of their flammability and/or toxicity. Therefore, carbon dioxide (CO2), an “old” refrigerant used in industrial and marine refrigeration, was proposed by the late Prof. Gustav Lorentzen in 1990 to be used as an alternative refrigerant, mainly because of its non-flammability.
Author: International Institute of Refrigeration