SectionThree

Unit7:HeatExchangerUnit8:TheReciprocatingCompressorUnit9:LiquidPumpUnit7:HeatExchangerNewWords&ExpressionsTextNotestothe

TextExerciseNewWords&Expressionsshell

n.貝殼,殼,外形,炮彈shell-and-tubeheatexchanger管殼式換熱器medium

n.adj.媒體,方法,媒介；中間的,中等的,chilln.adj.v.寒冷的；使冷,變冷,冷藏brinen.鹽水solutionn.解答,解決辦法,溶解,溶液freezev.凍結(jié)circulatev.（使)流通,(使)運(yùn)行,(使)循環(huán),(使)傳播air-cooledheatexchanger空冷器corrosiveadj.n.腐蝕的,腐蝕性的腐蝕物,腐蝕劑corrosionn.侵蝕,腐蝕狀態(tài)withstandvt.抵擋,經(jīng)受住horizontal

adj.地平線的,水平的NewWords&Expressionsverticalposition豎直位置nozzlen.管口,噴嘴drainingn.排水泄水排泄withdrawnadj.性格內(nèi)向的,偏僻的,孤獨的condensaten.冷凝物submergev.浸沒,淹沒,掩沒；vi.潛水a(chǎn)ssurevt.確告,保證,擔(dān)保fulfillvt.履行,實現(xiàn),完成(計劃等)customn.習(xí)慣,風(fēng)俗v.定制,承接定做活的calculation

n.計算,考慮automaticallyadv.自動地,機(jī)械地Text

如果物料需要冷卻，也可使用管殼式換熱器。冷卻介質(zhì)通常用水，冷卻水或者是冷的鹽水。用鹽水（鹽的水溶液）是因為鹽水的凍結(jié)溫度比水低。有時液體在暴露在空氣里的管路里循環(huán)冷卻，叫做空氣冷卻器。如果用風(fēng)機(jī)對管路快速吹冷風(fēng)，冷卻過程就加快。Ifamaterialistobecooled,ashell-and-tubeheatexchangercanalsobeused.Thecoolingmediumisnormallywater,chilledwater,orcoldbrine.Brine(asolutionofsaltinwater)isusedbecauseitfreezesatalowertemperaturethanpurewater.Sometimesliquidsarecooledbycirculatingthemthroughpipesexposedtheatmosphere;thisiscalledanair-cooledheatexchanger.1Thecoolingprocessisspeededifafanisusedtoblowcoolairrapidlyoverthetubes.Text

當(dāng)用管殼式換熱器來冷卻時，需要冷卻的物料或者走管內(nèi)或者走管外，而冷卻介質(zhì)走另一測。如果兩者之一比另一種腐蝕性強(qiáng)（如鹽水是腐蝕性的）則走管程。管子可以用耐腐蝕材料制造，而殼體用便宜的材料加工。如果腐蝕介質(zhì)走殼程，既與殼體內(nèi)表接觸，又與管子外表接觸，管子和殼體都必須抗腐蝕。

Whenashell-and-tubeheatexchangerisusedforcooling,thematerialtobecooledmaybeeitheronthetube-sideortheshell-side,withthecoolingmediumtheotherside.2Ifoneofthetwoliquidsismorecorrosivethantheothers(brine,forexample,canbecorrosive)itisusuallyonthetube-side.Thetubescanthenbemadeofacorrosion-resistantmaterial,withacheapermaterialfortheshell.Ifacorrosivematerialisusedontheshell-side—incontactwithboththeinnersurfaceoftheshellandtheoutersurfaceofthetubes---boththetubesandshellmustbeabletowithstandcorrosion.3Text

管殼式換熱器可以是臥式也可以是立式運(yùn)行，但常用臥式。當(dāng)用蒸汽加熱時，通常從上面的管口進(jìn)入殼體，從下部的管口排出冷凝水。如果冷凝液積聚在換熱器內(nèi)（通常是由于故障或疏水器尺寸不對）并且將管子浸沒了，那么傳熱效果受到影響，因為蒸汽的傳熱效果比熱水快很多。當(dāng)液體走殼程時，總是從下面的管口進(jìn)入，從上面的接管口引出。這樣工程師才能保證換熱器內(nèi)充滿液體，管子浸沒在液體中。Itispossibletooperateshell-and-tubeheatexchangersineitherthehorizontalorverticalposition,buthorizontalexchangersaremostcommon.Whensteamisusedforheating,itisalwaysintroducedthroughtheupperopening,ornozzle,intheshell,sothattheloweropeningcanbeusedfordrainingcondensate.Ifapoolofcondensatebuildsupinsuchanexchanger(usuallyduetomalfunctioningfunctioningorwronglysizedsteamtrap)andsubmergessomeofthetubes,theheattransfersuffersbecausecondensingsteamtransfersheatmorerapidlythandoeshotwater.4Whenaliquidisusedontheshell-side，itisalwaysintroducedthroughthelowernozzleandwithdrawnthroughtheuppernozzle.Inthiswaytheengineercanbeassuredthattheexchangerremainsfull,withliquidsurroundingallthetubes.Text

管殼式換熱器應(yīng)用廣泛，所以在許多制造廠商的產(chǎn)品單上都有。工業(yè)生產(chǎn)中有一些工業(yè)通用的標(biāo)準(zhǔn)設(shè)計類型?？墒牵瑳]有任何一組標(biāo)準(zhǔn)的換熱器能滿足所有的要求。所以很多換熱器是根據(jù)需要設(shè)計和制作的。任何特殊需要的換熱器的尺寸主要根據(jù)要傳送的熱量以及處理的流體的體積而定。大多數(shù)工程師在大學(xué)里學(xué)習(xí)換熱器的設(shè)計計算，而現(xiàn)在可以用計算機(jī)來自動完成。Shell-and-tubeheatexchangersaresowidelyusedthattheyareavailableasstockitemsfrommanymanufacturers.Thereareanumberofstandarddesignsusedthroughouttheindustry.However,nogroupofstandardexchangerscouldfulfillallneeds,somanyexchangerarecustomdesignedandmanufactured.Thesizeoftheshell-and-tubeheatexchangerneededforanyparticularjobdependsmainlyontheamountofheattobetransferredandthevolumeoffluidtobehandled.5Thecalculationsarelearnedincollegebymostengineers,butcomputerprogramsnowdothemautomatically.NotestotheTextUnit1NotestotheText

1、Sometimesliquidsarecooledbycirculatingthemthroughpipesexposedtheatmosphere;thisiscalledanair-cooledheatexchanger.

Sometimesliquidsarecooledbycirculatingthemthroughpipesexposedtheatmosphere與thisiscalledanair-cooledheatexchanger是并列句。在前一句中l(wèi)iquids是主語，arecooled是謂語部分，bycirculatingthemthroughpipesexposedtheatmosphere是現(xiàn)在分詞短語作狀語，其中的exposedtheatmosphere是過去分詞短語做定語修飾pipe.Unit1NotestotheText在句中Whenashell-and-tubeheatexchangerisusedforcooling是狀語從句,thematerial是主語tobecooled是不定式做定語修飾thematerials，maybeeitheronthetubesideortheshellside是謂語部分,withthecoolingmediumtheotherside是介詞短語作伴隨狀語，省略了

介詞on，即withthecoolingmediumontheotherside。

2、Whenashell-and-tubeheatexchangerisusedforcooling,thematerialtobecooledmaybeeitheronthetube-sideortheshell-side,withthecoolingmediumtheotherside.Unit1NotestotheTextIf引導(dǎo)條件狀語從句acorrosivematerialisusedontheshellside，“incontactwithboththeinnersurfaceoftheshellandtheoutersurfaceofthetubes”是插入語，做補(bǔ)充說明。boththetubesandshellmustbeabletowithstandcorrosion是主句。3、Ifacorrosivematerialisusedontheshellside—incontactwithboththeinnersurfaceoftheshellandtheoutersurfaceofthetubes---boththetubesandshellmustbeabletowithstandcorrosion.

Unit1NotestotheText

本句中Ifapoolofcondensatebuildsupinsuchanexchanger(usuallyduetomalfunctioningfunctioningorwronglysizedsteamtrap)andsubmergessomeofthetubes是條件狀語從句，theheattransfersuffers是主句，becausecondensingsteamtransfersheatmorerapidlythandoeshotwater為原因狀語從句，譯為蒸汽冷凝比熱水要快的多。

4、Ifapoolofcondensatebuildsupinsuchanexchanger(usuallyduetomalfunctioningfunctioningorwronglysizedsteamtrap)andsubmergessomeofthetubes,theheattransfersuffersbecausecondensingsteamtransfersheatmorerapidlythandoeshotwater.Unit1NotestotheText這是一個單句，Thesizeoftheshell-and-tubeheatexchangerneededforanyparticularjob是主語，其中neededforanyparticularjob是