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【正文】 英文翻譯 Chilled Water Systems[1] Chilled water systems were used in less than 4% of mercial buildings in the . in 1995. However, because chillers are usually installed in larger buildings, chillers cooled over 28% of the . mercial building floor space that same year (DOE, 1998). Five types of chillers are monly applied to mercial buildings: reciprocating, screw, scroll, centrifugal, and absorption. The first four utilize the vapor pression cycle to produce chilled water. They differ primarily in the type of pressor used. Absorption chillers utilize thermal energy (typically steam or bustion source) in an absorption cycle with either an ammoniawater or waterlithium bromide solution to produce chilled water. Overall System Figure shows a simple representation of a dual chiller application with all the major auxiliary equipment. An estimated 86% of chillers are applied in multiple chiller arrangements like that shown in the figure (Bitondo and Tozzi, 1999). In chilled water systems, return water from the building is circulated through each chiller evaporator where it is cooled to an acceptable temperature (typically 4 to 7176。C) (39 to 45176。F). The chilled water is then distributed to watertoair heat exchangers spread throughout the facility. In these heat exchangers, air is cooled and dehumidified by the cold water. During the process, the chilled water increases in temperature and must be returned to the chiller(s). The chillers shown in Figure are watercooled chillers. Water is circulated through the condenser of each chiller where it absorbs heat energy rejected from the high pressure refrigerant. The water is then pumped to a cooling tower where the water is cooled through an evaporation process. Cooling towers are described in a later section. Chillers can also be air cooled. In this configuration, the condenserwould be a refrigeranttoair heat exchanger with air absorbing the heat energy rejected by the high pressure refrigerant. Chillers nominally range in capacities from 30 to 18,000 kW (8 to 5100 ton). Most chillers sold in the . are electric and utilize vapor pression refrigeration to produce chilled water. Compressors for these systems are either reciprocating, screw, scroll, or centrifugal in design. A small number of centrifugal chillers are sold that use either an internal bustion engine or steam drive instead of an electric motor to drive the pressor. [1]節(jié)選自 James B. Bradford et al. “HVAC Equipment and Systems”.Handbook of Heating, Ventilation, and . Jan F. Raton, CRC Press LLC. 2020 浙 江 海 洋 學(xué) 院 畢 業(yè) 設(shè) 計(jì) 2 FIGURE A dual chiller application with major auxiliary systems (courtesy of Carrier Corporation). The type of chiller used in a building depends on the application. For large office buildings or in chiller plants serving multiple buildings, centrifugal pressors are often used. In applications under 1000 kW (280 tons) cooling capacities, reciprocating or screw chillers may be more appropriate. In smaller applications, below 100 kW (30 tons), reciprocating or scroll chillers are typically used. Vapor Compression Chillers Table shows the nominal capacity ranges for the four types of electrically driven vapor pression chillers. Each chiller derives its name from the type of pressor used in the chiller. The systems range in capacities from the smallest scroll (30 kW。 8 tons) to the largest centrifug
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