Refrigerant Ice Vapor Heat Cycle Refrigeration System Gas Cycle Liquid Refrigerators Refrigeration Cycle Gas Cyclic Vapor-compression Refrigeration Vapor Compression Cycle Compressed Air Compression Absorption Patent Heat Sink Refrigerator Substance Compressor Ammonia Condenser Fluid Food Refrigerants HFC A1 Fluorocarbons Toxicity Air-conditioning HFC-134a Mixtures Azeotropic Safety Classification Cold Storage Refrigerant Blends R-134a Replacement