the branch of engineering that deals with the production and use of refrigeration in the temperature range from 10° to – 150°C. The production of temperatures below – 150°C is the task of cryogenic engineering.
Refrigerating machines, whose refrigerating capacities range from several hundred watts to a few megawatts, are the most widely used and versatile sources of refrigeration in engineering. Freezing mixtures, water ice, dry ice, and liquefied gases—such as liquid nitrogen—are also used to produce temperatures below the environmental temperature. Thermoelectric cooling is employed for low refrigeration loads.
Refrigeration is widely used in the food industry for the cooling, freezing, and storage of perishable food products (seeCOOLING OF FOOD PRODUCTS and FREEZING OF FOOD PRODUCTS). In most cases, the shipment of perishable products also requires the use of refrigeration. In addition, refrigeration is required for the production of water ice and dry ice (seeICE MACHINE), as well as in the manufacture of, for example, ice cream and certain confectioneries.
The modern chemical and petroleum-refining industries also use refrigeration. In the chemical industry, refrigeration is employed in the synthesis of ammonia and dyes, for the liquefaction and separation of gas mixtures, and for the precipitation of salts from solutions. In the petroleum-refining industry, refrigeration is required in the production of, for example, high-octane gasolines and certain grades of lubricants. Refrigeration has been used extensively in the gas industry, for example, to liquefy natural gas and to remove condensable components from natural gas during preliminary processing. The refrigerating systems for the chemical, petroleum-refining, and gas industries are often heavyduty systems, with capacities of up to a few megawatts, and produce cooling over a very wide temperature range.
Refrigeration is also used in machine building (for example, for contraction fits), construction (seeFREEZING OF SOIL), and medicine; it is also employed in such activities as the construction of artificial skating rinks for year-round use and the desalination of seawater.
In the overwhelming majority of cases, air conditioning in public, industrial, and residential buildings is carried out by means of refrigerating machines, which are used both to reduce the temperature of the conditioned air and to dehumidify the air.
REFERENCESKholodil’naia tekhnika: Entsiklopedicheskii spravochnik, vols. 1–3. Moscow, 1960–62.
Rozenfel’d, L. M., and A. G. Tkachev. Kholodil’nye mashiny i apparaty, 2nd ed. Moscow, 1960.
A. N. FOMIN