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1、斯特林發(fā)動(dòng)機(jī)斯特林發(fā)動(dòng)機(jī)是一種閉循環(huán)活塞式熱機(jī),閉循環(huán)的意思是工作燃?xì)庖恢北4嬖跉飧變?nèi),而開(kāi)循環(huán)則如內(nèi)燃機(jī)和一些蒸氣機(jī)需要與大氣交換氣體。斯特林發(fā)動(dòng)機(jī)一般被歸為外燃機(jī)。切圖以外的菱形驅(qū)動(dòng)器測(cè)試配置斯特林發(fā)動(dòng)機(jī)的設(shè)計(jì):*粉紅-熱筒壁*深灰色-冷筒壁(與冷卻進(jìn)排氣管在黃色)*暗綠色-熱絕緣分開(kāi)的兩個(gè)汽缸結(jié)束*淺綠色-置換活塞*深藍(lán)色-功率活塞*淡藍(lán)色-曲柄連桿和飛輪沒(méi)有表明:熱源和熱匯。在此設(shè)計(jì)了置換活塞構(gòu)造沒(méi)有專(zhuān)門(mén)建造的再生。介紹斯特林發(fā)動(dòng)機(jī)在熱機(jī)中的效率目前是最高的,有時(shí)可以達(dá)到80%。Intheconversionofheatintomechanicalwork,theStirlingeng

2、inehasthepotentialtoachievethehighestefficiencyofanyheatengine.ItcantheoreticallyperformuptothefullCarnotefficiency,althoughnotyetinpractice.Thepracticallimitationsincludethenon-idealpropertiesoftheworkinggas,andmaterialpropertiessuchasfriction,thermalconductivity,tensilestrength,creep,rupturestreng

3、th,andmeltingpoint.TheStirlingenginecanrunonanyheatsource,includingchemical,solar,geothermalandnuclear.TherearemanypossibleimplementationsoftheStirlingengine.Mostfallintothecategoryofreciprocatingpistonengine.Incontrasttointernalcombustionengines,Stirlingengineshavethepotentialtouserenewableheatsour

4、cesmoreeasily,tobequieter,andtobemorereliablewithlowermaintenance.Theyarepreferredforapplicationsthatvaluetheseuniqueadvantages,particularlyifthethecostperunitenergygenerated($/kWh)ismoreimportantthanthecapitalcostperunitpower($/kW).Onthisbasis,Stirlingenginesarecostcompetitiveuptoabout100kW.3Compar

5、edtoaninternalcombustionengineofthesamepowerrating,Stirlingenginescurrentlyhaveahighercapitalcostandareusuallylargerandheavier.Theirlowermaintenancerequirementsmaketheoverallenergycostcomparable.Thethermalefficiencyisalsocomparable(forsmallengines),rangingfrom15%-30%.3Forapplicationssuchasmicro-CHP,

6、aStirlingengineisoftenpreferabletoaninternalcombustionengine.Otherapplicationsincludewaterpumping,space-basedastronautics,andelectricalgenerationfromplentifulenergysourcesthatareincompatiblewiththeinternalcombustionengine,suchassolarenergy,andbiomasssuchasagriculturalwasteandotherwastesuchasdomestic

7、refuse.StirlingshavealsobeenusedasamarineengineinSwedishGotlandclasssubmarines.4HoweverStirlingsaregenerallynotprice-competitiveasanautomobileengine,duetohighcostperunitpower,lowpowerdensityandhighmaterialcosts.Inrecentyears,theadvantagesofStirlingengineshavebecomeincreasinglysignificant,giventheris

8、einliquidfuelpricesandconcernssuchaspeakoilandclimatechange.Stirlingenginesaddresstheseissuesbybeingverycompatiblewithallrenewableenergyandfuelsources.ThesegrowinginterestsinStirlingtechnologyhavefosteredtheongoingresearchanddevelopmentofStirlingdevices,andR&Dbreakthroughshaveinturnincreasedinterest

9、inthetechnology.Ifsuppliedwithmechanicalpower,Stirlingscanfunctioninreverseasaheatpumpforheatingorcooling.ExperimentshavebeenperformedusingwindpowerdrivingaStirlingcycleheatpumpfordomesticheatingandairconditioning.Inthelate1930s,thePhilipsCorporationoftheNetherlandssuccessfullyutilizedtheStirlingcyc

10、leincryogenicapplications.5Basicanalysisisbasedontheclosed-formSchmidtanalysisgoogle翻譯:斯特林發(fā)動(dòng)機(jī)是一個(gè)封閉的循環(huán)蓄熱式發(fā)動(dòng)機(jī),氣體工質(zhì)?!胺忾]循環(huán)”是指工作流體內(nèi)永久的發(fā)動(dòng)機(jī)。工作流體是氣體推動(dòng)活塞上。這種外部熱發(fā)動(dòng)機(jī)可以驅(qū)動(dòng)任何熱源?!霸偕笔侵咐靡粋€(gè)內(nèi)部換熱器稱(chēng)為再生這增加了發(fā)動(dòng)機(jī)的熱效率相比,類(lèi)似的,但簡(jiǎn)單的熱斯特林循環(huán)的值得注意的是,其完善的理論效率;然而這還沒(méi)有實(shí)現(xiàn)的理想仍然是一項(xiàng)巨大的工程挑戰(zhàn)。然而,目前的設(shè)計(jì),指出其效率高,操作安靜和方便,他們可以利用什么否則將廢熱。斯特林發(fā)動(dòng)機(jī)在目前激動(dòng)

11、人心的利益為核心的組成部分,國(guó)內(nèi)熱電聯(lián)產(chǎn)(熱電聯(lián)產(chǎn))單位,這可能產(chǎn)生重大影響全世界的能源消耗。12空軍是一個(gè)許多可能的氣體,可用于在一個(gè)斯特林發(fā)動(dòng)機(jī)。所謂“熱空氣引擎”一般用來(lái)包含任何熱空氣引擎的工作液。熱空氣引擎可以使用任何一個(gè)幾個(gè)不同的熱力循環(huán),包括布雷頓循環(huán),愛(ài)立信斯特林循環(huán)或周期。在斯特林發(fā)動(dòng)機(jī)已用于小型低功耗應(yīng)用了近兩個(gè)世紀(jì)。斯特林發(fā)動(dòng)機(jī)繼續(xù)使用他們的能力提供機(jī)械或電力,加熱或冷卻的應(yīng)用,熱源和散熱片可用。斯特林發(fā)動(dòng)機(jī)背景NameThoughithadbeensuggestedasearlyas1884thatallclosedcycleairenginesshouldbegener

12、icallycalledStirlingenginesaftertheinventorofthefirstpracticalexample,theideafoundlittlefavourandthevarioustypesonthemarketcontinuedtobeknownbythenameoftheirindividualdesignerormanufacturer.Then,inthe1940s,thePhilipscompanywassearchingforasuitablenameforitsversionoftheairenginewhichbythattimehadalre

13、adybeentestedwithothergases.Rejectingmanysuggestions,includinghotgasengine(gasenginewasalreadyingeneraluseforinternalcombustionenginesrunningongaseousfuels)andexternalcombustionengine(didnotdifferentiatebetweenopenandclosedcycles),PhilipseventuallysettledonStirlingengineinApril1945.Generalacceptance

14、ofthetermfollowedafewyearslater.8EarlyyearsIllustrationtoRobertStirlings1816patentapplicationoftheairenginedesignwhichlatercametobeknownastheStirlingEngine.TheStirlingengine(orStirlingsairengineasitiswasknownatthetime)wasinventedandpatentedbyReverendDr.RobertStirlingin1816.9Itfollowedearlierattempts

15、atmakinganairenginebutwasprobablythefirsttobeputtopracticalusewhenin1818anenginebuiltbyStirlingwasemployedpumpingwaterinaquarry.10ThemainsubjectofStirlingsoriginalpatentwasaheatexchangerwhichhecalledaneconomiserforitsenhancementoffueleconomyinavarietyofapplications.Thepatentalsodescribedindetailthee

16、mploymentofoneformoftheeconomiserinhisuniqueclosed-cycleairenginedesignllinwhichapplicationitisnowgenerallyknownasaregenerator.SubsequentdevelopmentbyRobertStirlingandhisbrotherJames,anengineer,resultedinpatentsforvariousimprovedconfigurationsoftheoriginalengine.Theirpressurisationenhancementhadby18

17、43sufficientlyincreasedpoweroutputenoughtodriveallthemachineryataDundeeironfoundry.12Aswellassavingfuel,theinventorsweremotivatedtocreateasaferalternativetothesteamenginesofthetime,13whoseboilersfrequentlyexplodedcausingmanyinjuriesandfatalities.1415TheneedforStirlingenginestorunatveryhightemperatur

18、estomaximizepowerandefficiencyexposedlimitationsinthematerialsofthedayandthefewenginesthatwerebuiltinthoseearlyyearssufferedunacceptablyfrequentfailures(albeitwithfarlessdisastrousconsequencesthanaboilerexplosion16)-forexample,theDundeefoundryenginewasreplacedbyasteamengineafterthreehotcylinderfailu

19、resinfouryears.17LaternineteenthcenturydevelopmentsSubsequenttothefailureoftheDundeefoundryenginethereisnorecordoftheStirlingbrothershavinganyfurtherinvolvementwithairenginedevelopmentandtheStirlingengineneveragaincompetedwithsteamasanindustrialscalepowersource(steamboilerswerebecomingsafer18andstea

20、menginesmoreefficient,thuspresentinglessofatargettorivalprimemovers).However,fromabout1860smallerenginesoftheStirling/hotairtypewereproducedinsubstantialnumbersfindingapplicationswhereverareliablesourceoflowtomediumpowerwasrequired,suchasraisingwaterorprovidingairforchurchorgans.19Thesegenerallyoper

21、atedatlowertemperaturessoasnottotaxavailablematerials,sowererelativelyinefficient.Buttheirsellingpointwasthat,unlikeasteamengine,theycouldbeoperatedsafelybyanybodycapableofmanagingafire.20Severaltypesremainedinproductionbeyondtheendofthecentury,butapartfromafewminormechanicalimprovementsthedesignoft

22、heStirlingengineingeneralstagnatedduringthisperiod.21TwentiethcenturyrevivalPhilipsMP1002CAStirlinggeneratorof1951DuringtheearlypartofthetwentiethcenturytheroleoftheStirlingengineasadomesticmotor22wasgraduallyusurpedbytheelectricmotorandsmallinternalcombustionenginesuntilbythelate1930sitwaslargelyfo

23、rgotten,onlyproducedfortoysandafewsmallventilatingfans.23AtthistimePhilipswasseekingtoexpandsalesofitsradiosintoareaswhereelectricitywasunavailableandthesupplyofbatteriesuncertain.Philipsmanagementdecidedthatalow-powerportablegeneratorwouldfacilitatesuchsalesandtaskedagroupofengineersatthecompanysre

24、searchlab(theNat.Lab)inEindhoventoevaluatealternatives.AfterasystematiccomparisonofvariousprimemoverstheStirlingenginesquiet(bothaudiblyandintermsofradiointerference)operationandabilitytorunonavarietyofheatsources(commonlampoil-cheapandavailableeverywhere-wasfavoured),theteampickedStirling.24Theywer

25、ealsoawarethat,unlikesteamandinternalcombustionengines,virtuallynoseriousdevelopmentworkhadbeencarriedoutontheStirlingengineformanyyearsandassertedthatmodernmaterialsandknow-howshouldenablegreatimprovements.25Encouragedbytheirfirstexperimentalengine,whichproduced16wattsofshaftpowerfromaboreandstroke

26、of30 x25mm,26Phillipsbeganadevelopmentprogram.ThisworkcontinuedthroughoutWorldWarIIandbythelate1940shandedovertheType10toPhilipssubsidiaryJohandeWittinDordrechttobeproductionisedandincorporatedintoageneratorset.Theresult,ratedat200wattsfromaboreandstrokeof55x27mm,wasdesignatedMP1002CA(knownastheBung

27、alowset).Productionofaninitialbatchof250beganin1951,butitbecameclearthattheycouldnotbemadeatacompetitivepriceandtheadventoftransistorradioswiththeirmuchlowerpowerrequirementsmeantthattheoriginalrationaleforthesetwasdisappearing.Approximately150ofthesesetswereeventuallyproduced.27Somefoundtheirwayint

28、ouniversityandcollegeengineeringdepartmentsaroundtheworld28givinggenerationsofstudentsavaluableintroductiontotheStirlingengine.PhilipswentontodevelopexperimentalStirlingenginesforawidevarietyofapplicationsandcontinuedtoworkinthefielduntilthelate1970s,butonlyachievedcommercialsuccesswiththereversedSt

29、irlingenginecryocooler.Theydidhowevertakeoutalargenumberofpatentsandamassawealthofinformationwhichtheylicensedtoothercompaniesandwhichformedthebasisofmuchofthedevelopmentworkinthemodernera.29在將熱變成機(jī)械功的轉(zhuǎn)換上,史特林引擎在真實(shí)的熱機(jī)中可達(dá)最高的熱效率,至多80%,僅受工作氣體和引擎材料的不理想性質(zhì)限制,例如摩擦、熱傳導(dǎo)性、抗張強(qiáng)度、緩慢、熔點(diǎn)等。此引擎理論上可用任何足量的熱源運(yùn)行,包括太陽(yáng)能、化學(xué)能

30、和核能。與內(nèi)燃機(jī)相比,史特林引擎往往維修需求較低,更高效、更安靜、而且更可靠。它們傾向被應(yīng)用于某些特殊用途以發(fā)揚(yáng)其獨(dú)特優(yōu)點(diǎn)。特別是首要目標(biāo)非減低每單位功率的投資成本(金錢(qián)/千瓦),而是減低引擎產(chǎn)生每單位能量的成本(金錢(qián)/度)的時(shí)候。在額定功率下,史特林引擎的投資成本目前比內(nèi)燃機(jī)引擎高,而且通常更大更重,因此這引擎科技很少單獨(dú)以此作為競(jìng)爭(zhēng)基準(zhǔn)。然而在一些用途上,適當(dāng)?shù)谋疽娣治隹闪钍诽亓忠鎯?yōu)于內(nèi)燃機(jī)引擎。近年來(lái),鑒于能源成本普遍上漲,能源短缺和氣候變遷之類(lèi)的環(huán)境問(wèn)題,史特林引擎的優(yōu)點(diǎn)愈來(lái)愈顯著。對(duì)史特林引擎科技提高興趣促進(jìn)了史特林裝置的研發(fā)。其應(yīng)用涵蓋借由不相容于內(nèi)燃機(jī)的豐富能源抽水、宇基太空航

31、行、發(fā)電,像是太陽(yáng)能、農(nóng)業(yè)廢料還有家庭垃圾。另一個(gè)史特林引擎的潛力是,若供應(yīng)機(jī)械功,它可以作為一種熱泵。已有實(shí)驗(yàn)利用風(fēng)能驅(qū)動(dòng)史特林熱泵作為家用冷暖空調(diào)。斯特林發(fā)動(dòng)機(jī)功能描述EngineoperationSincetheStirlingengineisaclosedcycle,itcontainsafixedmassofgascalledtheworkingfluid,mostcommonlyair,hydrogenorhelium.Innormaloperation,theengineissealedandnogasentersorleavestheengine.Novalvesarerequ

32、ired,unlikeothertypesofpistonengines.TheStirlingengine,likemostheat-engines,cyclesthroughfourmainprocesses:cooling,compression,heatingandexpansion.Thisisaccomplishedbymovingthegasbackandforthbetweenhotandcoldheatexchangers,oftenwitharegeneratorbetweentheheaterandcooler.Thehotheatexchangerisinthermal

33、contactwithanexternalheatsource,suchasafuelburner,andthecoldheatexchangerbeinginthermalcontactwithanexternalheatsink,suchasairfins.Achangeingastemperaturewillcauseacorrespondingchangeingaspressure,whilethemotionofthepistoncausesthegastobealternatelyexpandedandcompressed.Thegasfollowsthebehaviordescr

34、ibedbythegaslawswhichdescribehowagasspressure,temperatureandvolumearerelated.Whenthegasisheated,becauseitisinasealedchamber,thepressurerisesandthisthenactsonthepowerpistontoproduceapowerstroke.Whenthegasiscooledthepressuredropsandthismeansthatlessworkneedstobedonebythepistontocompressthegasontheretu

35、rnstroke,thusyieldinganetpoweroutput.Whenonesideofthepistonisopentotheatmosphere,theoperationisslightlydifferent.Asthesealedvolumeofworkinggascomesincontactwiththehotside,itexpands,doingworkonboththepistonandontheatmosphere.Whentheworkinggascontactsthecoldside,itspressuredropsbelowatmosphericpressur

36、eandtheatmospherepushesonthepistonanddoesworkonthegas.Tosummarize,theStirlingengineusesthetemperaturedifferencebetweenitshotendandcoldendtoestablishacycleofafixedmassofgas,heatedandexpanded,andcooledandcompressed,thusconvertingthermalenergyintomechanicalenergy.Thegreaterthetemperaturedifferencebetwe

37、enthehotandcoldsources,thegreaterthethermalefficiency.ThemaximumtheoreticalefficiencyisequivalenttotheCarnotcycle,howevertheefficiencyofrealenginesisonlyafractionofthisvalue,eveninhighlyoptimizedengines.Sterlingenginesmallclear.oggPlayvideoVideoshowingthecompressoranddisplacerofaverysmallStirlingEng

38、ineinactionVerylow-powerengineshavebeenbuiltwhichwillrunonatemperaturedifferenceofaslittleas7C,forexamplebetweenthepalmofahandandthesurroundingair,orbetweenroomtemperatureandmeltingwaterice.303132editPressurizationInmosthighpowerStirlingengines,boththeminimumpressureandmeanpressureoftheworkingfluida

39、reaboveatmosphericpressure.Thisinitialenginepressurizationcanberealizedbyapump,orbyfillingtheenginefromacompressedgastank,orevenjustbysealingtheenginewhenthemeantemperatureislowerthanthemeanoperatingtemperature.Allofthesemethodsincreasethemassofworkingfluidinthethermodynamiccycle.Alloftheheatexchang

40、ersmustbesizedappropriatelytosupplythenecessaryheattransferrates.Iftheheatexchangersarewelldesignedandcansupplytheheatfluxneededforconvectiveheattransfer,thentheenginewillproducepowerinproportiontothemeanpressure,aspredictedbytheWestnumber,andBealenumber.3334Inpractice,themaximumpressureisalsolimite

41、dtothesafepressureofthepressurevessel.LikemostaspectsofStirlingenginedesign,optimizationismultivariate,andoftenhasconflictingrequirements.35editLubricantsandfrictionAStirlingengineandgeneratorsetwith55kWelectricaloutput,forcombinedheatandpowerapplications.Athightemperaturesandpressures,theoxygeninai

42、r-pressurizedcrankcases,orintheworkinggasofhotairengines,cancombinewiththeengineslubricatingoilandexplode.Atleastonepersonhasdiedinsuchanexplosion.36Lubricantscanalsoclogheatexchangers,especiallytheregenerator.Forthesereasons,designersprefernon-lubricated,low-coefficientoffrictionmaterials(suchasRul

43、on(plastic)orgraphite),withlownormal-forcesonthemovingparts,especiallyforslidingseals.Somedesignsavoidslidingsurfacesaltogetherbyusingdiaphragmsforsealedpistons.ThesearesomeofthefactorsthatallowStirlingenginestohavelowermaintenancerequirementsandlongerlifethaninternal-combustionengines.發(fā)動(dòng)機(jī)運(yùn)行由于斯特林發(fā)動(dòng)機(jī)

44、是一個(gè)封閉的循環(huán),它包含一個(gè)固定的大規(guī)模的天然氣被稱(chēng)為“工作流”,最常見(jiàn)的空氣,氫氣或氦氣。在正常運(yùn)作,引擎是密封的,沒(méi)有氣體進(jìn)入或離開(kāi)發(fā)動(dòng)機(jī)。無(wú)閥是必要的,不像其他類(lèi)型的活塞式發(fā)動(dòng)機(jī)。在斯特林發(fā)動(dòng)機(jī),最喜歡熱引擎,通過(guò)4個(gè)周期的主要過(guò)程:冷卻,壓縮,加熱和擴(kuò)張。這是通過(guò)移動(dòng)的氣體之間來(lái)回?zé)崂錈峤粨Q器,往往與再生之間的加熱器和冷卻器。熱換熱器的熱與外部的熱源,如燃料燃燒器,和冷戰(zhàn)式換熱器是在接觸熱與外部散熱片,如空氣魚(yú)翅。改變氣體溫度會(huì)引起相應(yīng)的變化,氣體壓力,而運(yùn)動(dòng)的活塞造成的天然氣將輪流擴(kuò)大和壓縮。氣體的行為如下描述了天然氣的法律,說(shuō)明氣體的壓力,溫度和體積是有關(guān)系的。當(dāng)氣體被加熱,因?yàn)樗?/p>

45、是在一個(gè)密封的房間,壓力上升,這對(duì)當(dāng)時(shí)行為的權(quán)力活塞產(chǎn)生動(dòng)力中風(fēng)。當(dāng)冷卻氣體的壓力下降,這意味著較少的工作需要做的活塞壓縮氣體返回中風(fēng),從而產(chǎn)生了凈功率輸出。當(dāng)一方活塞開(kāi)放的氣氛中,操作稍有不同。由于密封貨量工作氣體接觸的熱點(diǎn)方面,它的擴(kuò)大,是做人的工作的活塞和氣氛。當(dāng)工作氣體接觸冷戰(zhàn)一方,其壓力低于大氣壓力的氣氛推的活塞和不工作的天然氣??傊?,使用斯特林發(fā)動(dòng)機(jī)的溫度差異其熱端和冷端建立一個(gè)周期的一個(gè)固定數(shù)量的天然氣,加熱和擴(kuò)大,冷卻和壓縮,從而熱能轉(zhuǎn)換為機(jī)械能。更大的溫度差異的熱點(diǎn)和冷源,更大的熱效率。最高理論效率相當(dāng)于卡諾循環(huán),但效率的真正的發(fā)動(dòng)機(jī)是只有一小部分的價(jià)值,即使是在高度優(yōu)化的引

46、擎。斯特林引擎小clear.ogg視頻顯示壓縮機(jī)和置換的一個(gè)非常小的斯特林發(fā)動(dòng)機(jī)在行動(dòng)非常的低功率發(fā)動(dòng)機(jī)已建成這將運(yùn)行在溫差只有7C,例如棕櫚油之間的手和周?chē)諝庵g,或室溫和融化水冰。303132加壓在大多數(shù)高功率斯特林發(fā)動(dòng)機(jī),無(wú)論是最低壓力和平均壓力的工作流體高于大氣壓力。這一初步增壓發(fā)動(dòng)機(jī)可實(shí)現(xiàn)泵,或填補(bǔ)了發(fā)動(dòng)機(jī)的壓縮天然氣罐,甚至只是發(fā)動(dòng)機(jī)密封時(shí)的平均溫度低于平均溫度。所有這些方法提高質(zhì)量的工作液中的熱力循環(huán)。所有的換熱器的尺寸必須適當(dāng)提供必要的傳熱率。如果換熱器是精心設(shè)計(jì),可供應(yīng)熱通量所需的對(duì)流換熱,然后將發(fā)動(dòng)機(jī)產(chǎn)生電力中所占的比例平均壓力,因?yàn)轭A(yù)測(cè)的一些西方國(guó)家和一些比爾。3334

47、在實(shí)際上,最大的壓力也是有限的安全壓力,壓力容器。如同大多數(shù)方面的斯特林發(fā)動(dòng)機(jī)的設(shè)計(jì),優(yōu)化多元,而且往往有矛盾的要求。35潤(rùn)滑油和摩擦斯特林發(fā)動(dòng)機(jī)和發(fā)電機(jī)組55千瓦的電力輸出,為熱電聯(lián)產(chǎn)的應(yīng)用。在高溫度和壓力,氧氣在空氣加壓曲軸箱,或在工作氣體的熱空氣引擎,可以結(jié)合發(fā)動(dòng)機(jī)的潤(rùn)滑油和爆炸。至少有一人已死于這種爆炸。36潤(rùn)滑油也可以堵塞換熱器,特別是再生。由于這些原因,設(shè)計(jì)者寧愿不潤(rùn)滑,低摩擦系數(shù)材料(如盧倫(塑料)或石墨),低正常部隊(duì)的運(yùn)動(dòng)部件,尤其是滑動(dòng)密封。一些設(shè)計(jì),避免滑動(dòng)表面完全采用隔膜密封活塞。這些都是一些因素,使斯特林引擎有較低的維修要求和更長(zhǎng)的壽命比內(nèi)燃機(jī)斯特林循環(huán)Mainarti

48、cle:StirlingcycleTheidealizedortextbookStirlingcycleisathermodynamiccyclewithtwoisochores(constantvolume)andtwoisotherms(constanttemperature).Itisthemostefficientthermodynamiccyclecapableofpracticalimplementationinanengine-itstheoreticalefficiencyequalingthatofthehypotheticalCarnotcycle.Howeverreal-

49、worldissuesreducetheefficiencyofactualengines,duetolimitsofconvectiveheattransfer,andviscousflow(friction).Therearealsopracticalmechanicalconsiderations,forinstanceasimplekinematiclinkagemaybefavoredoveramorecomplexmechanismneededtoreplicatetheidealizedcycle.主要文章:斯特林循環(huán)在理想化或“文字書(shū)”斯特林循環(huán)是一個(gè)熱力循環(huán)有兩個(gè)isocho

50、res(恒容)和兩個(gè)等溫線(xiàn)(恒定的溫度)。這是最有效的熱力循環(huán)能夠切實(shí)執(zhí)行的引擎-其理論效率相當(dāng)于這一虛構(gòu)的卡諾循環(huán)。然而現(xiàn)實(shí)世界的問(wèn)題,降低效率,實(shí)際的發(fā)動(dòng)機(jī),由于界限的對(duì)流換熱和粘性流動(dòng)(摩擦)。也有實(shí)際的機(jī)械因素,比如一個(gè)簡(jiǎn)單的運(yùn)動(dòng)聯(lián)系起來(lái)可能是有一個(gè)更復(fù)雜的機(jī)制需要復(fù)制的理想化的周期斯特林改進(jìn)Mainarticle:RegenerativeheatexchangerInaStirlingengine,theregeneratorisaninternalheatexchangerandtemporaryheatstoreplacedbetweenthehotandcoldspacessu

51、chthattheworkingfluidpassesthroughitfirstinonedirectionthentheother.Itsfunctionistoretainwithinthesystemthatheatwhichwouldotherwisebeexchangedwiththeenvironmentattemperaturesintermediatetothemaximumandminimumcycletemperatures,37thusenablingthethermalefficiencyofthecycletoapproachthelimitingCarnoteff

52、iciencydefinedbythosemaximaandminima.TheprimaryeffectofregenerationinaStirlingengineistogreatlyincreasethethermalefficiencybyrecyclinginternallyheatwhichwouldotherwisepassthroughtheengineirreversibly.Asasecondaryeffect,increasedthermalefficiencypromisesahigherpoweroutputfromagivensetofhotandcoldendh

53、eatexchangers(sinceitisthesewhichusuallylimittheenginesheatthroughput),though,inpracticethisadditionalpowermaynotbefullyrealizedastheadditionaldeadspace(unsweptvolume)andpumpinglossinherentinpracticalregeneratorstendstohavetheoppositeeffect.Theeasiestwaytounderstandtheregenerator,istoseeitasalumpofm

54、atterplacedintheflowpathoftheworkinggasthattheworkinggasheatsandcoolsasitflowsfromonesideofthestirlingenginetotheother.Asthegasleavesthehotsideoftheengine,thenextgoalofthedesigneristocoolthegas.Iftheregeneratormassiscoolatthatpoint,thehotgaswillbecooledslightlybytheregeneratorasitpassesitandthenfurt

55、hercooledwhenthegasgetstotheheatsinkheatexchanger.Theworkingfluidhasthenbeencooledbytwomethods,theregeneratorandthecoldsinkheatexchanger.Thisprocesshaslefttheregeneratorwarm,thatissomeheathasbeenretainedwithintheengineandnotlosttothecoldheatsink.Thefluidmustthenleavethecoldsideoftheengineandthedesig

56、nersgoalistoheatthefluidasmuchaspossible.Thegaspassesthroughthewarmregenerator,whichheatsthegasalittle,andthenthegasgoesontothehotsideoftheenginewhereitheatsupfurther.Asthecoldgasmovedpasttheregeneratoritcooledtheregeneratoralittleleavingitcoolerandreadyforthenextcycle.Theregeneratoristhereforeamass

57、thatisheatedandcooledbetweentheheatsourceandheatsinktemperaturesastheworkingfluidmovesbackandforth.Theregenerator,asaworkingfluidpre-heater,pre-cooler,improvestheabilitytoheatandcooltheworkingfluid.Thisreducestheburdenontheheatsourceandsinkheatexchangersinmovingtheworkingfluidtothemaximumhighandlowt

58、emperatures.Theregeneratorshouldnotlimittheflowoftheworkingfluidasitmovesabouttheengine,anditshouldnotaddadditionalvolumeofworkingfluid,justforthesakeofaddingaregenerator.Designingasuccessfulregeneratorisabalancebetweenhighheattransferwithlowviscouspumpinglossesandlowdeadspace.Theseinherentdesigncon

59、flictsareoneofmanyfactorswhichlimittheefficiencyofpracticalStirlingengines.Atypicaldesignisastackoffinemetalwiremeshes,withlowporositytoreducedeadspace,andwiththewireaxesperpendiculartothegasflowtoreduceconductioninthatdirectionandtomaximizeconvectiveheattransfer.38InanalphaStirlingenginetheregenera

60、torwouldbeplacedintheflowbetweenthehotandcoldcylinders.Inbetaandgammaenginestheregeneratorisusuallyincorporatedintheheadofthedisplacerpiston.Oftenthedisplacerpistonheaditselfactsasalowefficiencyregeneratorwithoutanyadditionaldesignfeatures.TheregeneratoristhekeycomponentinventedbyRobertStirlingandit

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