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a unit used to treat and circulate air in air-conditioning systems. Conditioners are classified as self-contained, fan-and-coil, and terminal units. Self-contained units have built-in refrigeration machines and electric air heaters. Fanand-coil units are provided with heating and cooling from external sources. Terminal units are supplied with air from a central conditioner and with heating and cooling from external sources (for example, from central heating and refrigeration plants).
Self-contained units. Among the components of self-contained conditioners are one or more refrigeration compressors with electric motors, an air-cooling evaporator, a condenser, an air filter, and fans with electric motors, as well as apparatus that automatically controls the operation of the refrigeration machine and maintains specified parameters of the room air.
Self-contained conditioners are classified according to their layout as horizontal, divided, or vertical units. Horizontal units are usually window-mounted and are intended for service in a single room with an area up to 50 sq m. Their air delivery is 450–1,000 m3/hr; their cooling capacity, 6.7–18.8 megajoules per hr (MJ/hr), or 1,600–4,500 kcal/hr; their power consumption, 1.1–2.6 kilowatts (kW). Selfcontained horizontal conditioners are equipped with an air-cooled condenser. Conditioners with divided units are made up of two housings connected by pipelines through which the refrigerant circulates. One housing contains the compressor-condenser unit; the other contains the evaporator-fan unit. The first housing is mounted outside the building; consequently, the noise level is greatly reduced. The second housing is installed inside the building. Conditioners with divided units are intended to serve one or more rooms with an area up to 300 sq m. Their air delivery is 1,600–7,000 m3/hr; their cooling capacity, 32.7–127 MJ/hr (7,800–30,000 kcal/hr); their power consumption, 4.5–19.0 kW. They are equipped with a condenser with air cooling or air-evaporative cooling. Self-contained vertical conditioners are built as upright cabinets. They are used for one or more rooms with an area up to 1,700 sq m. Their air delivery is 1,300–1,600 ml’hr; their cooling capacity, 25.2–314 MJ/hr (6,000–75,000 kcal/hr); their power consumption, 2.7–36 kW. They are equipped with water-cooled condensers.
Self-contained horizontal and divided conditioners are used in residential, public, and industrial buildings; vertical units are used in public and industrial buildings. Vertical conditioners cause more noise within a room. All types of self-contained conditioners are delivered ready for installation and thus can be used in existing buildings. Self-contained conditioners are also used to provide ventilation and sometimes heating, dust removal, cooling, and dehumidification. To provide heating, self-contained conditioners are sometimes equipped with built-in electric air heaters or have provisions for switching the refrigerating machine to operation as a heat pump. Refrigeration machines of self-contained conditioners are filled with a harmless refrigerant (Freon 12 or Freon 22). Self-contained conditioners for surgical operating rooms have two-stage air-cleaning apparatus that includes humidifying and bactericidal stages. As of 1972, research and development were under way in the USSR and in a number of other countries on self-contained heating and cooling conditioners including a semiconductor heat pump. Such conditioners are switched from cooling to heating by changing the direction of electric current. One advantage of such conditioners is the absence of refrigeration machines with reciprocating motion of inertial masses, which results in a reduction in room noise to an insignificant level. Self-contained conditioners with absorption refrigeration machines heated by gas or electricity are also in use.
Fan-and-coil units. Fan-and-coil conditioners are classified as horizontal and vertical units. Horizontal fan-and-coil conditioners are delivered by factories in the form of sections or standardized components for on-site assembly according to a specified or standard design. The air delivery of horizontal conditioners is 10,000–500,000 m3/hr; their cooling capacity is 0.21–12.6 GJ/hr (50,000–3,000,000 kcal/hr).
Vertical fan-and-coil conditioners are delivered from factories as ready-to-install units equipped with all necessary devices for automatic regulation, control, and monitoring. The air delivery of vertical conditioners is 1,500–20,000 m3/hr; their cooling capacity is 31.4–418.6 MJ/hr (7,500–100,000 kcal/hr).
Terminal units. Terminal conditioners may be of the fan or induction types. Conditioners manufactured in the USSR are mainly of the induction type; they are most often used in office buildings, hotels, and staterooms of oceangoing and river ships. They are mounted below windows and are connected to air ducts that convey primary conditioned air from the central conditioner and to pipelines supplying water to heat exchanges. In terminal conditioners of the induction type the primary air is discharged through a nozzle array at high velocity, inducing circulation of secondary (room) air, which, in passing through the heat exchanger, is cooled (in summer) or heated (in winter). The mixture of primary and secondary air subsequently passes through a grille and enters the room. The heating and cooling capacity of terminal conditioners is regulated by adjusting the supply of the heating or cooling agent or by letting some part of the airflow bypass the heat exchanger through a bypass duct equipped with a damper. The operation of terminal conditioners of the induction type is virtually noiseless.
Special types of conditioners, mainly of the self-contained type, are used in railroad cars, aircraft, cranes, automobiles, tractors, combines, and excavators. Such conditioners are driven by the main engine or an auxiliary engine.
REFERENCESpravochnik proektirovshchika promyshlennykh, zhilykh i obshchestvennykh zdanii i sooruzhenii, part 2. Moscow, 1969.
E. E. KARPIS