外文翻譯--空調(diào)與制冷技術(shù)

1、<p><b>　　附　錄</b></p><p><b>　　附錄A 外文翻譯</b></p><p>　　Air Conditioning and Refrigeration Technology</p><p>　　Air conditioning has rapidly grown over the p

2、ast 50 years, from a luxury to a standard system included in most residential and commercial buildings. In 1970, 36% of residences in the U.S. were either fully air conditioned or utilized a room air conditioner for cool

3、ing (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 (50.9%) of residences in the U.S. had central air conditioners (Census Bureau, 1999). A

4、n estimated 83%</p><p>　　Air conditioning in buildings is usually accomplished with the use of mechanical or heat-activated equipment. In most applications, the air conditioner must provide both cooling and

5、dehumidification to maintain comfort 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 equ

6、ipment in this chapter is limited to those commonly used in commercial and residential buildings. </p><p>　　Commercial buildings range from large high-rise office buildings to the corner convenience store. B

7、ecause of the range in size and types of buildings in the commercial 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

8、 design that includes items such as a piping system, air distribution system, and cooling tower. Proper design of these systems requires a qualified engineer. The residential buildi</p><p>　　The chapter star

9、ts with a general discussion of the vapor compression refrigeration cycle then moves to refrigerants and their selection. Chillers and their auxiliary systems are then covered, followed by packaged air conditioning equip

10、ment.</p><p>　　Even though there is a large range in sizes and variety of air conditioning systems used in buildings, most systems utilize the vapor compression cycle to produce the desired cooling and dehum

11、idification. This cycle is also used for refrigerating and freezing foods and for automotive air conditioning. The first patent on a mechanically driven refrigeration system was issued to Jacob Perkins in 1834 in London,

12、 and the first viable commercial system was produced in 1857 by James Harrison and D.E. </p><p>　　Besides vapor compression, there are two less common methods used to produce cooling in buildings: the absorp

13、tion cycle and evaporative cooling. These are described later in the chapter. With the vapor</p><p>　　compression cycle, a working fluid, which is called the refrigerant, evaporates and condenses at suitable

14、 pressures for practical equipment designs.</p><p>　　The four basic components in every vapor compression refrigeration system are the compressor, condenser, expansion device, and evaporator. The compressor

15、 raises the pressure of the refrigerant vapor so that the refrigerant saturation temperature is slightly above the temperature of the cooling medium used in the condenser. The type of compressor used depends on the appli

16、cation of the system. Large electric chillers typically use a centrifugal compressor while small residential equipment uses a </p><p>　　The condenser is a heat exchanger used to reject heat from the refriger

17、ant to a cooling medium. The refrigerant enters the condenser and usually leaves as a subcooled liquid. Typical cooling mediums used in condensers are air and water. Most residential-sized equipment uses air as the cooli

18、ng medium in the condenser, while many larger chillers use water. After leaving the condenser, the liquid refrigerant expands to a lower pressure in the expansion valve.</p><p>　　The expansion valve can be a

19、 passive device, such as a capillary tube or short tube orifice, or an active device, such as a thermal expansion valve or electronic expansion valve. The purpose of the valve is toregulate the flow of refrigerant to the

20、 evaporator so that the refrigerant is superheated when it reaches the suction of the compressor.</p><p>　　At the exit of the expansion valve, the refrigerant is at a temperature below that of the medium (ai

21、r or water) to be cooled. The refrigerant travels through a heat exchanger called the evaporator. It absorbs energy from the air or water circulated through the evaporator. If air is circulated through the evaporator, th

22、e system is called a direct expansion system. If water is circulated through the evaporator, it is called a chiller. In either case, the refrigerant does not make direct contact wi</p><p>　　The refrigerant i

23、s converted from a low quality, two-phase fluid to a superheated vapor under normal operating conditions in the evaporator. The vapor formed must be removed by the compressor at a sufficient rate to maintain the low pres

24、sure in the evaporator and keep the cycle operating.</p><p>　　All mechanical cooling results in the production of heat energy that must be rejected through the condenser. In many instances, this heat energy

25、is rejected to the environment directly to the air in the condenser or indirectly to water where it is rejected in a cooling tower. With some applications, it is possible to utilize this waste heat energy to provide simu

26、ltaneous heating to the building. Recovery of this waste heat at temperatures up to 65°C (150°F) can be used to reduce costs for space </p><p>　　Capacities of air conditioning are often expressed i

27、n 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 3.51 kW (12,000 Btu/hr). The kW of thermal co

28、oling 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.</p><p>　　Refrigerants Use and Selection&

29、lt;/p><p>　　Up until the mid-1980s, refrigerant selection was not an issue in most building air conditioning applications because there were no regulations on the use of refrigerants. Many of the refrigerants h

30、istorically used for building air conditioning applications have been chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). Most of these refrigerants are nontoxic and nonflammable. However, recent U.S. federa

31、l regulations (EPA 1993a; EPA 1993b) and international agreements (UNEP, 1987) hav</p><p>　　The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) has a standard numbering sys

32、tem (Table 4.2.1) for identifying refrigerants (ASHRAE, 1992). Many popular CFC, HCFC, and HFC refrigerants are in the methane and ethane series of refrigerants. They are called halocarbons, or halogenated hydrocarbons,

33、because of the presence of halogen elements such as fluorine or chlorine (King, 1986). </p><p>　　Zeotropes and azeotropes are mixtures of two or more different refrigerants. A zeotropic mixture changes s

34、aturation temperatures as it evaporates (or condenses) at constant pressure. The phenomena is called temperature glide. At atmospheric pressure, R-407C has a boiling (bubble) point of –44°C (–47°F) and a conden

35、sation (dew) point of –37°C (–35°F), which gives it a temperature glide of 7°C (12°F). An azeotropic mixture behaves like a single component refrigerant in that the saturation temperat</p><

36、p>　　ASHRAE groups refrigerants (Table 4.2.2) by their toxicity and flammability (ASHRAE, 1994).Group A1 is nonflammable and least toxic, while Group B3 is flammable and most toxic. Toxicity is based on the upper safet

37、y limit for airborne exposure to the refrigerant. If the refrigerant is nontoxic in quantities less than 400 parts per million, it is a Class A refrigerant. If exposure to less than 400 parts per million is toxic, then t

38、he substance is given the B designation. The numerical designations</p><p>　　Refrigerant 22 is an HCFC, is used in many of the same applications, and is still the refrigerant of choice in many reciprocating

39、and screw chillers as well as small commercial and residential packaged equipment. It operates at a much higher pressure than either R-11 or R-12. Restrictions on the production of HCFCs will start in 2004. In 2010, R-22

40、 cannot be used in new air conditioning equipment. R-22 cannot be produced after 2020 (EPA, 1993b).</p><p>　　R-407C and R-410A are both mixtures of HFCs. Both are considered replacements for R-22. R-407C is

41、expected to be a drop-in replacement refrigerant for R-22. Its evaporating and condensing pressures for air conditioning applications are close to those of R-22 (Table 4.2.3). However, replacement of R-22 with R-407C sho

42、uld be done only after consulting with the equipment manufacturer. At a minimum, the lubricant and expansion device will need to be replaced. The first residential-sized air conditio</p><p>　　Ammonia is wide

43、ly used in industrial refrigeration applications and in ammonia water absorption chillers. It is moderately flammable and has a class B toxicity rating but has had limited applications in commercial buildings unless the

44、chiller plant can be isolated from the building being cooled (Toth, 1994, Stoecker, 1994). As a refrigerant, ammonia has many desirable qualities. It has a high specific heat and high thermal conductivity. Its enthalpy o

45、f vaporization is typically 6 to 8 times high</p><p>　　Research is underway to investigate the use of natural refrigerants, such as carbon dioxide (R-744) and hydrocarbons in air conditioning and refrigerati

46、on systems (Bullock, 1997, and Kramer, 1991). Carbon dioxide operates at much higher pressures than conventional HCFCs or HFCs and requires operation above the critical point in typical air conditioning applications. Hyd

47、rocarbon refrigerants, often thought of as too hazardous because of flammability, can be used in conventional compressors and ha</p><p>　　From:Composite Index Ashrae Handbook Series</p><p><b

48、>　　空調(diào)與制冷技術(shù)</b></p><p>　　過去50年以來，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)。在 1970 年的美國(guó)， 36% 的住宅不是全空氣調(diào)節(jié)就是利用一個(gè)房間空調(diào)器冷卻；到1997年，這一數(shù)字達(dá)到了 77%，在那年作的第一次市場(chǎng)調(diào)查表明，在美國(guó)有超過一半的住宅安裝了中央空調(diào) (人口普查局, 1999)。在1998年，83%的新建住

49、宅安裝了中央空調(diào) ( 人口普查局, 1999)。中央空調(diào)在商業(yè)建筑物中也得到了快速的發(fā)展，從 1970年到1995年，有空調(diào)的商業(yè)建筑物的百分比從54%增加到 73%(杰克森和詹森,1978)。</p><p>　　建筑物中的空氣調(diào)節(jié)通常是利用機(jī)械設(shè)備或熱交換設(shè)備完成.在大多數(shù)應(yīng)用中，建筑物中的空調(diào)器為維持舒適要求必須既能制冷又能除濕，空調(diào)系統(tǒng)也用于其他的場(chǎng)所，例如汽車、卡車、飛機(jī)、船和工業(yè)設(shè)備，然而，在本章中，

50、僅說明空調(diào)在商業(yè)和住宅建筑中的應(yīng)用。 </p><p>　　商業(yè)的建筑物從比較大的多層的辦公大樓到街角的便利商店，占地面積和類型差別很大，因此應(yīng)用于這類建筑的設(shè)備類型比較多樣，對(duì)于比較大型的建筑物，空調(diào)設(shè)備設(shè)計(jì)是總系統(tǒng)設(shè)計(jì)的一部分，這部分包括如下項(xiàng)目：例如一個(gè)管道系統(tǒng)設(shè)計(jì)，空氣分配系統(tǒng)設(shè)計(jì)，和冷卻塔設(shè)計(jì)等。這些系統(tǒng)的正確設(shè)計(jì)需要一個(gè)有資質(zhì)的工程師才能完成。居住的建筑物(即研究對(duì)象)被劃分成單獨(dú)的家庭或共有式公寓，

51、應(yīng)用于這些建筑物的冷卻設(shè)備通常都是標(biāo)準(zhǔn)化組裝的，由空調(diào)廠家進(jìn)行設(shè)計(jì)尺寸和安裝。</p><p>　　本章節(jié)首先對(duì)蒸汽壓縮制冷循環(huán)作一個(gè)概述，接著介紹制冷劑及制冷劑的選擇，然后介紹冷卻設(shè)備及附屬系統(tǒng)，最后介紹組合式空調(diào)機(jī)組。</p><p>　　雖然空調(diào)系統(tǒng)應(yīng)用在建筑物中有較大的尺寸和多樣性,大多數(shù)的系統(tǒng)利用蒸汽壓縮循環(huán)來制取需要的冷量和除濕，這個(gè)循環(huán)也用于制冷和冰凍食物和汽車的空調(diào)，在18

52、34年，一個(gè)名叫Perkins的人在倫敦獲得了機(jī)械制冷系統(tǒng)的第一專利權(quán)，在1857年，詹姆士Harrison和D.E. Siebe生產(chǎn)出第一個(gè)有活力的商業(yè)系統(tǒng)(Thevenot 1979)，除了蒸汽壓縮循環(huán)之外 , 有兩種不常用的制冷方法在建筑物中被應(yīng)用: 吸收式循環(huán)和蒸發(fā)式冷卻，這些將在后面的章節(jié)中講到。對(duì)于蒸汽壓縮制冷循環(huán)，有一種叫制冷劑的工作液體，它能在適當(dāng)?shù)墓に囋O(shè)備設(shè)計(jì)壓力下蒸發(fā)和冷凝。</p><p>

53、　　每個(gè)蒸汽壓縮制冷系統(tǒng)中都有四大部件，它們是壓縮機(jī)、冷凝器、節(jié)流裝置和蒸發(fā)器。壓縮機(jī)提升制冷劑的蒸汽壓力以便使制冷劑的飽和溫度微高于在冷凝器中冷卻介質(zhì)溫度，使用的壓縮機(jī)類型和系統(tǒng)的設(shè)備有關(guān)，比較大的電冷卻設(shè)備使用一個(gè)離心式的壓縮機(jī)而小的住宅設(shè)備使用的是一種往復(fù)或漩渦式壓縮機(jī)。</p><p>　　冷凝器是一個(gè)熱交換器，用于將制冷劑的熱量傳遞到冷卻介質(zhì)中，制冷劑進(jìn)入冷凝器變成過冷液體，用于冷凝器中的典型冷卻介質(zhì)是

54、空氣和水，大多數(shù)住宅建筑的冷凝器中使用空氣作為冷卻介質(zhì)，而大型系統(tǒng)的冷凝器中采用水作為冷卻介質(zhì)。</p><p>　　液體制冷劑在離開冷凝器之后，在膨脹閥中節(jié)流到一個(gè)更低的壓力。膨脹閥是一個(gè)節(jié)流的裝置，例如毛細(xì)管或有孔的短管，或一個(gè)活動(dòng)的裝置，例如熱力膨脹閥或電子膨脹閥，膨脹閥的作用是到蒸發(fā)器中分流制冷劑以便當(dāng)它到壓縮物吸入口的時(shí)候, 制冷劑處于過熱狀態(tài)，在膨脹閥的出口，制冷劑的溫度在介質(zhì)(空氣或水) 的溫度以下

55、。</p><p>　　之后制冷劑經(jīng)過一個(gè)熱交換器叫做蒸發(fā)器，它吸收通過蒸發(fā)器的空氣或水的熱量，如果空氣經(jīng)過蒸發(fā)器在流通,該系統(tǒng)叫做一個(gè)直接膨脹式系統(tǒng)，如果水經(jīng)過蒸發(fā)器在流通,它叫做冷卻設(shè)備，在任何情況下，在蒸發(fā)器中的制冷劑不直接和空氣或水接觸，在蒸發(fā)器中，制冷劑從一個(gè)低品位的兩相液體轉(zhuǎn)換成在正常的工藝條件下過熱的蒸汽。蒸汽的形成要以一定的足夠速度被壓縮機(jī)排出以維持在蒸發(fā)器中低壓和保持循環(huán)進(jìn)行。</p>

56、;<p>　　所有在生產(chǎn)中的機(jī)械冷卻產(chǎn)生的熱量必須經(jīng)過冷凝器散發(fā)，在許多例子中，在冷凝器中這個(gè)熱能被直接散發(fā)到環(huán)境的空氣中或間接地散發(fā)到一個(gè)冷卻塔的水中。在一些應(yīng)用中，利用這些廢熱向建筑物提供熱量是可能的，回收這些最高溫度為65℃(150°F)的廢熱可以減少建筑物中采暖的費(fèi)用。</p><p>　　空調(diào)的制冷能力常用冷噸或千瓦 (千瓦) 來表示，冷噸是一個(gè)度量單位，它與制冰廠在 24小時(shí)內(nèi)

57、使1噸 (907 公斤)的水結(jié)冰的能力有關(guān)，其值是3.51千瓦 (12,000 Btu/hr)，空調(diào)的冷卻能力不要和產(chǎn)生冷量所需的電能相互混淆。</p><p>　　直到20世紀(jì)80年代中葉，制冷劑的選擇在大多數(shù)的建筑物空調(diào)設(shè)備中不是一個(gè)問題，因?yàn)樵谥评鋭┑氖褂蒙线€沒有統(tǒng)一的的標(biāo)準(zhǔn)，在以前，用于建筑物空調(diào)設(shè)備的大多數(shù)制冷劑是氟氯碳化物和氟氯碳?xì)浠?，且大多?shù)的制冷劑是無毒的和不可燃的，然而，最近的美國(guó)聯(lián)邦的標(biāo)準(zhǔn)

58、(環(huán)保署 1993a；環(huán)保署 1993b) 和國(guó)際的協(xié)議 (UNEP,1987) 已經(jīng)限制了氟氯碳化物和氟氯碳?xì)浠锏闹圃旌褪褂茫F(xiàn)在，氟氯碳化物和氟氯碳?xì)浠镌谝恍﹫?chǎng)合依然被使用，對(duì)制冷劑的理解能幫助建筑物擁有者或者工程師更好的了解關(guān)于為特定的設(shè)備下如何選擇制冷劑，這里將討論不同制冷劑的使用并給出影響它們使用的建筑空調(diào)設(shè)備和標(biāo)準(zhǔn)。 </p><p>　　美國(guó)社會(huì)的供暖、制冷和空調(diào)工程師學(xué)會(huì)(ASHRAE)有一個(gè)

59、標(biāo)準(zhǔn)的限制系統(tǒng) (表 4.2.1)用來區(qū)分制冷劑，許多流行的氟氯碳化物，氟氯碳?xì)浠锖头蓟锏闹评鋭┦窃诩淄楹鸵彝榈闹评鋭┫盗兄?，因?yàn)辂u素元素的存在他們被叫作碳化鹵或鹵化的碳化氫，例如氟或氯。 </p><p>　　Zeotropes 和 azeotropes 是混合二種或更多不同的制冷劑，一種zeotropic混合物能改變飽和溫度在它在不變的壓力蒸發(fā) ( 或冷凝)。這種現(xiàn)象被稱溫度的移動(dòng)，在大氣壓力下，R-4

60、07 C的沸點(diǎn)(沸騰)是–44 °C(– 47° F)和一個(gè)凝結(jié)點(diǎn) (露點(diǎn))是–37°C(–35°F), 產(chǎn)生了7°C的溫度移動(dòng) (12°F)，一個(gè) azeotropic 混合物的性能像單獨(dú)成份制冷劑那樣，它在不變的壓力下蒸發(fā)或冷凝它們的飽和溫度不會(huì)有少許變化。R-410有微小的足夠溫度滑動(dòng) (少于5.5 C,10°F)，可以認(rèn)為接近azeotropic混合制冷劑。&

61、lt;/p><p>　　ASHRAE組制冷劑根據(jù)它們的毒性和易燃性(ASHRAE,1994)劃分的。A1組合是不燃燒的和最沒有毒的，而B3組是易燃的和最有毒的，以空氣為媒介的制冷劑最高安全限制是毒性，如果制冷劑在少于每百萬分之400是無毒的，它是一個(gè)A級(jí)制冷劑，如果對(duì)泄露少于每百萬分之400是有毒的,那么該物質(zhì)被稱B級(jí)制冷劑，這幾個(gè)級(jí)別表示制冷劑的易燃性，表 4.2.1 的最后一欄列出了常用的制冷劑的毒性和易燃的等級(jí)

62、。因?yàn)樗麄兪菬o毒的和不燃燒的 , 所以在A1組中制冷劑通常作為理想的制冷劑能基本滿足舒適性空調(diào)的需求。在A1中的制冷劑通常用在建筑空調(diào)設(shè)備方面的，包括 R-11，R-12，R-22，R-134a,和R-410A。R-11，R-12，R-123和R-134a是普遍用在離心式的冷卻設(shè)備的制冷劑，R-11，氟氯碳化物, 和R-123, HCFC, 都有低壓高容積特性，是用在離心式壓縮機(jī)上的理想制冷劑。在對(duì)氟氯碳化物的制造的禁令頒布之前, R-

63、11和R-12已經(jīng)是冷卻設(shè)備的首選制冷劑，在已存在的系統(tǒng)維護(hù)中，現(xiàn)在這兩種制冷劑的使用已經(jīng)被限制，現(xiàn)在，R-123 和 R-134a都廣泛的用在新的冷卻設(shè)備中。R-</p><p>　　制冷劑22 屬于HCFC，在多數(shù)的相同設(shè)備中被用，也是在多數(shù)往復(fù)和螺旋式冷卻設(shè)備和小型商業(yè)和住宅的集中式設(shè)備中的首選制冷劑，它可以在一個(gè)更高的壓力下運(yùn)行，這一點(diǎn)要優(yōu)于R-11或R-12中的任何一個(gè)。從2004開始，HCFCs的制造

64、將會(huì)受到限制。在2010年，R-22不能在新的空調(diào)設(shè)備中被使用。 2020年之后，R-22不允許生產(chǎn)(環(huán)保署,1993b)。</p><p>　　R-407C和R-410A是 HFCs的兩種混合物，兩者都是R-22的替代品，|R-407C預(yù)期將很快地替換R-22，在空調(diào)設(shè)備中，它的蒸發(fā)和冷凝壓力接近R-22 (表格4.2.3)。然而，用R-407C來替換R-22應(yīng)該在和設(shè)備制造者商議之后才能進(jìn)行，至少潤(rùn)滑油和膨脹

65、裝置將需要更換。在1998年，第一個(gè)使用R-410A的空調(diào)設(shè)備的住宅在美國(guó)出現(xiàn)。使用R-410A的系統(tǒng)運(yùn)作中，壓力大約比R-22高50%；因此，R-410A不能夠用于當(dāng)作速凍制冷劑來替代 R-22。R-410A系統(tǒng)利用特定的壓縮機(jī)，膨脹閥和熱交換器來利用該制冷劑。</p><p>　　氨廣泛地被在工業(yè)的冷卻設(shè)備和氨水吸收式制冷中用，它具有可燃性并且分毒性等級(jí)為B，因此在商業(yè)建筑物中使用受到限制，除非冷卻設(shè)備的制造

66、工廠獨(dú)立于被冷卻的建筑物之外。作為制冷劑，氨有許多良好的品質(zhì)，例如，它有較高的比熱和高的導(dǎo)熱率，它的蒸發(fā)焓通常比那普遍使用的鹵化碳高6到8倍，而且氨和鹵化碳比較來看，它能提供更高的熱交換量，而且它能用在往復(fù)式和離心式壓縮機(jī)中。</p><p>　　天然制冷劑的使用, 例如二氧化碳 (R-744) 和碳化氫在空調(diào)和制冷系統(tǒng)中的使用正在研究之中，二氧化碳能在高于傳統(tǒng)的HCFCs或HFCs的壓力下工作和在超過臨界點(diǎn)的典