空調(diào)系統(tǒng)外文翻譯-文庫(kù)吧資料
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【正文】 hazardous because of flammability, can be used in conventional pressors and have been used in industrial applications. R290, propane, has operating pressures close to R22 and has been proposed as a replacement for R22 (Kramer, 1991). Currently, there are no mercial systems sold in the . for building operations that use either carbon dioxide or flammable refrigerants. 外文翻譯 空調(diào)系統(tǒng) 內(nèi)蒙古科 技大學(xué)畢業(yè)設(shè)計(jì)說(shuō)明書 7 過去 50 年以來(lái)，空調(diào)得到了快速的發(fā)展，從曾經(jīng)的奢侈品發(fā)展到可應(yīng)用于大多數(shù)住宅和商業(yè)建筑的比較標(biāo)準(zhǔn)的系統(tǒng)。C, 10176。C (12176。C (–35176。C (–47176。F) can be used to reduce costs for space heating. Capacities of air conditioning are often expressed in either tons or kilowatts (kW) of cooling. The ton is a unit of measure related to the ability of an ice plant to freeze one short ton (907 kg) of ice in 24 hr. Its value is kW (12,000 Btu/hr). The kW of thermal cooling capacity produced by the air conditioner must not be confused with the amount of electrical power (also expressed in kW) required to produce the cooling effect. Refrigerants Use and Selection Up until the mid1980s, refrigerant selection was not an issue in most building air conditioning applications because there were no regulations on the use of refrigera nts. Many of the refrigerants historically used for building air conditioning applications have been chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). Most of these refrigerants are nontoxic and nonflammable. However, recent . federal regulations (EPA 1993a。內(nèi)蒙古科 技大學(xué)畢業(yè)設(shè)計(jì)說(shuō)明書 1 外文翻譯 來(lái)源 : 外文文獻(xiàn)一 Air Conditioning Systems Dennis L. O’Neal and John A. Bryant Air conditioning has rapidly grown over the past 50 years, from a luxury to a standard system included in most residential and mercial buildings. In 1970, 36% of residences in the . were either fully air conditioned or utilized a room air conditioner for cooling (Blue, et al., 1979). By 1997, this number had more than doubled to 77%, and that year also marked the first time that over half (%) of residences in the . had central air conditioners (Census Bureau, 1999). An estimated 83% of all new homes constructed in 1998 had central air conditioners (Census Bureau, 1999). Air conditioning has also grown rapidly in mercial buildings. From 1970 to 1995, the percentage of mercial buildings with air conditioning increased from 54 to 73% (Jackson and Johnson, 1978, and DOE, 1998). Air conditioning in buildings is usually acplished with the use of mechanical or heatactivated equipment. In most applications, the air conditioner must provide both cooling and dehumidification to maintain fort in the building. Air conditioning systems are also used in other applications, such as automobiles, trucks, aircraft, ships, and industrial facilities. However, the description of equipment in this chapter is limited to those monly used in mercial and residential buildings. Commercial buildings range from large highrise office buildings to the corner convenience store. Because of the range in size and types of buildings in the mercial sector, there is a wide variety of equipment applied in these buildings. For larger buildings, the air conditioning equipment is part of a total system design that includes items such as a piping system, air distribution system, and cooling tower. Proper design of t
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