Progress in the use of air cycle technology in food refrigeration and especially retail display

摘要

Due to growing international concern over ozone depletion and global warming there is a real need to severely restrict the production and use of a whole range of CFC and HCFC refrigerants. In some specific applications no alternatives are available. In others chemical companies have had to try to develop new refrigerants to act as 'drop in' replacements for those currently used. In many cases there are viable, but often old fashioned, alternatives such as ammonia, butane, propane, carbon dioxide, water and air, which have much to offer in a food environment. The use of air as a refrigerant is based on the principle that when a gas expands isentropically, its temperature is reduced. The resulting cold air can then be used as a refrigerant, either directly in an open system, or indirectly by means of a heat exchanger in a closed system. This paper outlines the use of air cycle technology in food refrigeration and especially for display cabinets for chilled and frozen foods.