This handbook of the series "Refrigeration" presents the sections of physical and technical sciences on which the development and use of refrigeration machines and installations are based. The basics of thermodynamic theory are described, various refrigeration cycles of steam and gas (air) machines are described, cycles of heat-using refrigerating machines are considered. Information on working substances used in compression and absorption refrigerating machines is given. The basics of heat exchange calculation for cases typical for refrigeration equipment are described.