SectionFour

Unit10:CondensationUnit11:EvaporationUnit12:MechanicalRefrigerationPrincipleUnit11:EvaporationNewWords&ExpressionsTextNotestothe

TextExerciseNewWords&Expressions華氏度數(shù)coilv.盤繞,卷absorbedadj.全神貫注的,一心一意的contentn.容[含]量heatcontent焓，熱含(量)，熱容量gainvt.vi.得到,增進,賺到,增加establishvt.建立，形成wherebyadv.憑什么,為何sensiblea.可感覺的，明顯的sensibleheat顯熱的casen.（外)殼，(封閉)罩，(機)箱；情況，事例thecaseofacoppercoil銅盤管箱asinthecaseof象在……情況下那樣，比如，就……來說correspondvi.符合,協(xié)調(diào),通信,相當,相應delivervt.遞(運，傳，輸)送，遞交，提供，交付drain

n.排水管Fahrenheitn.華氏(溫度)F=degreeFahrenheitNewWords&Expressionsevolvevt.vi.發(fā)展,進化,演變,放(釋)出evolveinto發(fā)展，（進化,演變）成vaporizevi(使)汽化,(使)蒸發(fā)retain

vt.保持(不變)remainvi.保持……狀態(tài),仍然referencen.參考,查閱,涉及,引用referencebemadeto提到,涉及preventv.防止,預防refervt.vi.提交,談及；提到,涉及,查閱,咨詢

referto查閱,提到,談到,打聽converselyadv.倒地,逆地,相反地similarlyadv.同樣地,類似于influencevt.影響,改變Text

制冷循環(huán)的第一步是液體制冷劑的蒸發(fā)。它是制冷劑完成實際功的過程（也就是制冷劑沸騰的過程）構成這種完整系統(tǒng)的一部分設備和進行蒸發(fā)的設備叫做蒸發(fā)器或冷卻盤管。為了使溫度降低必須從物體中除去熱，因而除去的熱不是損失掉了，而是被環(huán)境介質(zhì)吸收了，環(huán)境介質(zhì)熱含量與所吸收的熱量成正比例增加。從而形成了損耗的熱等于獲得熱量的規(guī)律。Thefirststepintherefrigerationcycleistheevaporationoftheliquidrefrigerant.Itisduringthisphasethatactualworkofrefrigerationisperformed.Theequipmentwhichformsapartofthecompletesystemandinwhichevaporationtakesplaceiscalledtheevaporatororthecoolingcoil.Toeffectadecreaseintemperature,heatmustberemovedfromabody.Theheatthusremovedisnotlost,butisabsorbedbyasurroundingbodywhoseheatcontentincreasesinproportiontotheamountabsorbed.Therulethatheatlostequalsheatgainedisthusestablished..Text

制冷系統(tǒng)的冷卻盤管或蒸發(fā)器，用來把熱量從傳熱壁面，或冷卻介質(zhì)通過盤管傳遞給制冷劑。使用的介質(zhì)應該通過下列兩種方法之一，或兩種方法相結合促使熱量流動。（1）溫差，制冷劑的溫度應低于傳熱壁面或冷卻介質(zhì)的溫度。

（2）制冷劑蒸發(fā)，利用汽化潛熱把被冷卻區(qū)域，或被冷卻物質(zhì)的熱量帶走。使制冷劑蒸發(fā)。

Thecoolingcoilortheevaporatorofarefrigerationsystemisdesignedtoaffectaheatflowfromtheareaorthesubstancetobecooledtoafluidmedium(refrigerant)forcedthroughthecoil.1Themediumemployedshouldinducesuchaflowofheatbyoneofthefollowingtwomethods,oracombinationofboth:(1)temperaturedifferential,wherebytherefrigerantislowerintemperaturethantheareaorthesubstancetobecooled;(2)evaporationoftherefrigerant,wherebythelatentheatofvaporizationisutilizedtoremoveheatfromtheareaorthesubstancetobecooled.2Text

1、溫差如果采用一種方法使溫度降低，那么被轉(zhuǎn)換的熱量只是一種顯熱的形式存在。換熱方法的實例是銅殼光管浸在熱水或鹽水箱內(nèi)、盤管的一端連接到一個輸送涼水的泵上，而另一端連在一個排水管上，然而熱流通過光管，促進熱物質(zhì)向冷水流動、結果暖物質(zhì)的溫度下降而冷卻水的溫度相應地升高。(1)TemperatureDifferentialIftemperaturereductioniseffectedbymeansofthefirstmethodalone,theheatthustransferredisthatofsensibleheatonly.Anexampleofthismethodofheatexchangeisthecaseofacoppercoilsubmergedinabodyofwarmsubstancewithoneendofthecoilconnectedtoapumpdeliveringcoldwaterandtheotherendconnectedtoadrain.Heatflowwouldthenbeinducedfromthewarmersubstancetothecoldwaterflowingthroughthecoil,resultinginadecreaseintemperatureofthewarmsubstanceandacorrespondingincreaseintemperatureofthecoldwater.3Text

2、制冷劑蒸發(fā)因為許多制冷劑具有沸點低的特性。它們在正常的大氣壓力溫度條件下，作為一種氣體。例如氨在大氣壓力下的沸點是—28F，如果在86F的室溫下，受到這樣壓力的作用，就會變成氣態(tài)（它將以蒸氣的形式釋放）。 為了把氣態(tài)氨轉(zhuǎn)變?yōu)橐后w，并保持液態(tài)必須采用兩種措施之一，或兩者相結合，即（1）把氨氣的溫度降到它的沸點以下，或者（2）施加一定的壓力，與周圍的氣體溫度成正比。。(2)EvaporationofRefrigerantBecauseofthelowboiling-pointcharacteristicsofmanyrefrigerants,theyexistasagasundernormalatmosphericpressure-temperatureconditions.Ammonia,forexample,hasaboilingpointof-28Fatatmosphericpressure,and,ifexposedtosuchpressureataroomtemperatureof86F，itwouldevolveinitsgaseousstate.4Totransformthegaseousorvaporizedammoniatoaliquidandtomaintainitinthatform,itisnecessarythatoneoftwosteps,oracombinationofboth,betaken,namely(1)reducethetemperatureoftheammoniagastoatemperaturebelowitsboilingpoint,and/or(2)exertsufficientpressureinproportiontothesurroundingtemperature.5Text

例如水在大氣壓力下，其溫度保持在212F沸點下，就能保持其液態(tài)。如果氨的溫度保持在—28F沸點以下，它可以保持液體狀態(tài)，因而形成了這樣的規(guī)律，即物質(zhì)的狀態(tài)取決于溫度。Asinthecaseofwater,theliquidstatecanberetainedifthetemperatureismaintainedbelowitsboilingpointof212Fandatatmosphericpressure.Ammoniawillalsoremainliquidatatmosphericpressureifitstemperatureismaintainedbelowitsboilingpointof-28F.Thusthelawisestablishedthatthestateofasubstancedependsonthetemperature.

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氨從氣態(tài)到液態(tài)轉(zhuǎn)換的第二方法是任何液體壓力的增大或減小都使沸點升高或降低的規(guī)律。如果對氨施加壓力增大，它的沸點也相應地增加，如果施加足夠的壓力，氨的沸點可以提高到室溫86F以上，從而阻止氨的蒸發(fā)。 查閱氨溫度——壓力表就可以知道在86F下要使氨保持液體狀態(tài)需要169.2磅/平方英寸的壓力。相反地對任何液體施加的壓力減少可以降低其沸點。

Inthesecondmethodof"gastoliquid"transformationofammonia,referenceismadetothelawthatanincreaseordecreaseinpressureonanyliquidresultsintheraisingorloweringofitsboilingpoint.Ifthepressureexertedonammoniaisincreased,itsboilingpointalsoincreasesproportionately.Ifsufficientpressureisexerted,theboilingpointoftheammoniacanberaisedabovetheroomtemperatureof86F,andthuspreventitsevaporation.

Referringtotheammoniatemperature-pressuretable,itisfoundthatapressureof169.2Psiaisrequiredtoretainliquidammoniaatthetemperatureof86F.6

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相反地，減少對任何液體施加的壓力就可以降低其沸點。實驗證明，14.7磅/平方英寸的水在大氣壓力下，沸點為212F。根據(jù)壓力溫度關系的規(guī)律，如果對水施加的壓力減少到10磅/平方英寸，水沸點會降到193.21F，在5lb/in2的壓力下，可降到162.25F。與氨相同，如果所施加的壓力降到10磅/平方英寸，在大氣壓下它的沸點可變成—413.4F。通過對制冷劑施加壓力，確定能控制它的沸點。在制冷系統(tǒng)的蒸發(fā)器里，在一定范圍內(nèi)控制壓力，控制的壓力受所用制冷劑沸點的影響。

Conversely,areductioninpressureexertedonanyliquiddecreasesitsboilingpoint.Ashasbeenstated,theboilingpointofwateris212Fwhenexposedtonormalatmosphericpressure(14.7psia).7

Accordingtothelawofpressureboilingrelationship,theboilingpointofwatercanbereducedto193.21Fifthepressureexertedonitisreducedto10psia,andto162.25Fat5psia,etc.Similarlywithammonia,whoseboilingpointbecomes-41.34Fifexertedpressureisreducedbelowatmosphericto10psia.Theboilingpointofarefrigerantdefinitelycanbecontrolledbycontrollingthepressureexertedonit.Intheevaporatorofarefrigerationsystem,thepressureiscontrolledatalevelinfluencedbytheboilingpointoftherefrigerantused.

NotestotheTextNotestotheText

1、Thecoolingcoilortheevaporatorofarefrigerationsystemisdesignedtoeffectaheatflowfromtheareaorthesubstancetobecooledtoafluidmedium(refrigerant)forcedthroughthecoil.制冷系統(tǒng)的冷卻盤管或蒸發(fā)器用來產(chǎn)生一個從被冷卻區(qū)域或物質(zhì)到強制通過盤管的流體介質(zhì)(制冷劑)的熱流動.bedesignedto+inf.設計成能(做),用來,目的是使theplanismerelydesignedtomaintaintheirnuclearsuperiority.制定這個計劃,只是為了保持他們的核優(yōu)勢.forcedthroughthecoil迫使通過盤管的(過去分詞短語,做medium的定語)NotestotheText使用的介質(zhì)應該通過下列兩種方法之一,或兩種方法相結合促使熱量流動:(1)溫差,制冷劑的溫度應低于傳熱壁面或冷卻介質(zhì)的溫度;(2)制冷劑的蒸發(fā)借此利用汽化潛熱除去傳熱壁面或冷卻介質(zhì)的熱量whereby在此句中充當關系副詞,引出定語從句,意為"借此",相當于bywhich.2、Themediumemployedshouldinducesuchaflowofheatbyoneofthefollowingtwomethods,oracombinationofboth:(1)temperaturedifferential,wherebytherefrigerantislowerintemperaturethantheareaorthesubstancetobecooled;(2)evaporationoftherefrigerant,wherebythelatentheatofvaporizationisutilizedtoremoveheatfromtheareaorthesubstancetobecooled.NotestotheText熱便會從比較熱的物質(zhì)傳給流經(jīng)盤管的冷水,使熱物質(zhì)的溫度降低,冷水的溫度相應增加。would表示按照某種判斷“應當會……”之意，但語氣較為婉轉(zhuǎn)，屬虛擬語氣。3、Heatflowwouldthenbeinducedfromthewarmersubstancetothecoldwaterflowingthroughthecoil,resultinginadecreaseintemperatureofthewarmsubstanceandacorrespondingincreaseintemperatureofthecoldwater.NotestotheText例如，氨在大氣壓下的沸點是—28F，如果在86F的室溫下受到這樣的壓力的作用，就會變成氣態(tài)。-28F讀成negativetwentyeightdegreesFahrenheit.and在此表示因果關系，故譯成“所以”。Coldwaterisheavierthanwarmwaterandgoesunderit.冷水比溫水重，所以流向溫水下面。ifexposedto…of86F是過去分詞短語，做條件狀語。

4、Ammonia,forexample,hasaboilingpointof-28Fatatmosphericpressure,and,ifexposedtosuchpressureataroomtemperatureof86F，itwouldevolveinitsgaseousstate.NotestotheText為了把氣態(tài)氨轉(zhuǎn)變?yōu)橐后w并保持液體，有必須采用兩種措施之一或兩者相結合，即把氨氣的溫度降到它的沸點以下，或施加一定的壓力與周圍的氣體溫度成正比。在betaken前省略了should.and/or和（或）takeMand/orN取M和（或）N（或取M，或取N，或者兩者都取）5、Totransformthegaseousorvaporizedammoniatoaliquidandtomaintainitinthatform,itisnecessarythatoneoftwosteps,oracombinationofboth,betaken,namely(1)reducethetemperatureoftheammoniagastoatemperaturebelowitsboilingpoint,and/or(2)exertsufficientpressureinproportiontothesurroundingtemperature.NotestotheText查閱氨溫度——壓力表可知在86F的溫度下保持液態(tài)氨要求169.2磅/英寸2的壓力。在apressureof169.2psia和thetemperatureof86F兩個短語中，介詞of表示同位關系，引出同位語。Thislightbulbhasaresistanceof120ohms.這個燈泡有120歐姆的電阻。（120ohms是resistance的同位語）6、Referringtotheammoniatemperature-pressuretable,itisfoundthatapressureof169.2Pisaisrequiredtoretainliquidammoniaatthetemperatureof86F.NotestotheText業(yè)已表明，在正常大氣壓力（14.7磅/英寸2

）下，水的沸點為212F。ashasbeenstated業(yè)已表明as為關系代詞，代替整個主句，在從句中做主語，引入非限制性定語從句，類似插入語。這類非限制性定語從句常見的有：asweknown我們知道ashasbeensaidbefore如上所述asmaybeimagined如可想象出來的那樣asiswellknown眾所周知aswecansee正如我們大家都能見到的那樣asmightbeexpected正如所料asoftenhap