外文翻譯-供熱站溫度壓力實時檢測

PAGEPAGE8HeatingtemperatureandpressuretestThermistorsareinexpensive,easily-obtainabletemperaturesensors.Theyareeasytouseandadaptable.Circuitswiththermistorscanhavereasonableoutoutvoltages-notthemillivoltoutputsthermocoupleshave.Becauseofthesequalities,thermistorsarewidelyusedforsimpletemperaturemeasurements.They'renotusedforhightemperatures,butinthetemperaturerangeswheretheyworktheyarewidelyused.Thermistorsaretemperaturesensitiveresistors.Allresistorsvarywithtemperature,butthermistorsareconstructedofsemiconductormaterialwitharesistivitythatisespeciallysensitivetotemperature.However,unlikemostotherresistivedevices,theresistanceofathermistordecreaseswithincreasingtemperature.That'sduetothepropertiesofthesemiconductormaterialthatthethermistorismadefrom.Forsome,thatmaybecounterintuitive,butitiscorrect.Hereisagraphofresistanceasafunctionoftemperatureforatypicalthermistor.Noticehowtheresistancedropsfrom100kW,toaverysmallvalueinarangearoundroomtemperature.Notonlyistheresistancechangeintheoppositedirectionfromwhatyouexpect,butthemagnitudeofthepercentageresistancechangeissubstantial.TemperatureSensor-TheThermocoupleYouareat:Elements-Sensors-ThermocouplesReturntoTableofContentsAthermocoupleisajunctionformedfromtwodissimilarmetals.Actually,itisapairofjunctions.Oneatareferencetemperature(like0oC)andtheotherjunctionatthetemperaturetobemeasured.Atemperaturedifferencewillcauseavoltagetobedevelopedthatistemperaturedependent.(ThatvoltageiscausedbysomethingcalledtheSeebeckeffect.)Thermocouplesarewidelyusedfortemperaturemeasurementbecausetheyareinexpensive,ruggedandreliable,andtheycanbeusedoverawidetemperaturerange.Inparticular,othertemperaturesensors(likethermistorsandLM35sensors)areusefularoundroomtemperature,butthethermocouplecanTheThermocoupleWhyUsethermocouplesToMeasureTemperature?Theyareinexpensive.Theyareruggedandreliable.Theycanbeusedoverawidetemperaturerange.WhatDoesAThermocoupleLookLike?Hereitis.Notethetwowires(oftwodifferentmetals)joinedinthejunction.Whatdoesathermocoupledo?Howdoesitwork?Thejunctionoftwodissimilarmetalsproducesatemperaturedependentvoltage.Forabetterdescriptionofhowitworks,clickhere.HowDoYouUseAThermocouple?Youmeasurethevoltagethethermocoupleproduces,andconvertthatvoltagetoatemperaturereading.Itmaybebesttodotheconversiondigitallybecausetheconversioncanbefairlynonlinear.ThingsYouNeedToKnowAboutThermocouplesAjunctionbetweentwodissimilarmetalsproducesavoltage.Inthethermocouple,thesensingjunction-producesavoltagethatdependsupontemperature.Wherethethermocoupleconnectstoinstrumentation-copperwires?-youhavetwomorejunctionsandtheyalsoproduceatemperaturedependentvoltage.Thosejunctionsareshowninsidetheyellowoval.Whenyouuseathermocouple,youneedtoensurethattheconnectionsareatsomestandardtemperature,oryouneedtouseanelectronicallycompensatedsystemthattakesthosevoltagesintoaccount.Ifyourthermocoupleisconnectedtoadataacquisitionsystem,thenchancesaregoodthatyouhaveanelectronicallycompensatedsystem.Onceweobtainareadingfromavoltmeter,themeasuredvoltagehastobeconvertedtotemperature.Thetemperatureisusuallyexpressedasapolynomialfunctionofthemeasuredvoltage.Sometimesitispossibletogetadecentlinearapproximationoveralimitedtemperaturerange.Therearetwowaystoconvertthemeasuredvoltagetoatemperaturereading.Measurethevoltageandlettheoperatordothecalculations.Usethemeasuredvoltageasaninputtoaconversioncircuit-eitheranalogordigital.Letuslookatsomeothertypesofbase-metalthermocouples.TypeTthermocouplesarewidelyusedasaretypeKandTypeN.TypeK(Ni-Cr/Ni-Al)thermocouplesarealsowidelyusedintheindustry.Ithashighthermopowerandgoodresistancetooxidation.TheoperatingtemperaturerangeofaTypeKthermocoupleisfrom-269oCto+1260oC.However,thisthermocoupleperformsratherpoorlyinreducingatmospheres.TypeT(Cu/Cu-Ni)thermocouplescanbeusedinoxidizingofinertatmospheresoverthetemperaturerangeof-250oCto+850oC.Inreducingormildlyoxidizingenvironments,itispossibletousethethermocoupleuptonearly+1000oC.TypeN(Nicrosil/Nisil)thermocouplesaredesignedtobeusedinindustrialenvironmentsoftemperaturesupto+1200oC.Apolynomialequationusedtoconvertthermocouplevoltagetotemperature(oC)overawiderangeoftemperatures.Wecanwritethepolynomialas:Thecoefficients,anaretabulatedinmanyplaces.HerearetheNBSpolynomialcoefficientsforatypeKthermocouple.(Source:T.J.Quinn,Temperature,AcademicPressInc.,1990)TypeKPolynomialCoefficientsnan00.226584602124152.10900267233.424832210340.6824-860963914.954.83506x10106-1.18452x101271.38690x10138-6.33708x1013WhatIfTheSurroundingTemperatureExceedsLimits?Therearereallynothermocouplesthatcanwithstandoxidizingatmospheresfortemperaturesabovetheupperlimitoftheplatinum-rhodiumtypethermocouples.Wecannot,therefore,measuretemperatureinsuchhightemperatureconditions.Otheroptionsformeasuringextremelyhightemperaturesareradiationorthenoisepyrometer.Fornon-oxidizingatmospheres,tungsten-rheniumbasedthermocouplesshowsgoodperformanceupto+2750oC.Theycanbeused,forashortperiod,intemperaturesupto+3000oC.Theselectionofthetypesofthermocoupleusedforlowtemperaturesensingisprimarilybasedonmaterialsofathermocouple.Inaddition,thermopoweratlowtemperatueisratherlow,someasurementofEMFwillbeproportionallysmallaswell.MoreFactsOnVariousThermocoupleTypesAvarietyofthermocouplestodaycoverarangeoftemperaturefrom-250oCto+3000oC.Thedifferenttypesofthermocouplearegivenletterdesignations:B,E,J,K,R,S,TandNTypesR,SandBarenoblemetalthermocouplesthatareusedtomeasurehightemperature.Withintheirtemperaturerange,theycanoperateforalongerperiodoftimeunderanoxidizingenvironment.TypeSandtypeRthermocouplesaremadeupofplatinum(Pt)andrhodium(Rh)mixedindifferentratios.AspecificPt/Rhratioisusedbecauseitleadstomorestableandreproduciblemeasurements.TypesSandRhaveanuppertemperaturelimitof+1200oCinoxidizingatmospheres,assumingawirediameterof0.5mm.TypeSandtypeRthermocouplesaremadeupofplatinum(Pt)andrhodium(Rh)mixedindifferentratios.AspecificPt/Rhratioisusedbecauseitleadstomorestableandreproduciblemeasurements.TypesSandRhaveanuppertemperaturelimitof+1200oCinoxidizingatmospheres,assumingawirediameterof0.5mm.TypeBthermocoupleshaveadifferentPt/RhratiothanTypeSandR.Ithasanuppertemperaturelimitof+1750oCinoxidizingatmospheres.Duetoanincreasedamountofrhodiumcontent,typeBthermocouplesarenoquitesostableaseithertheTypeRorTypeS.TypesE,J,K,T,andNarebase-metalthermocouplesthatareusedforsensinglowertemperatures.Theycannotbeusedforsensinghightemperaturesbecauseoftheirrelativelylowmeltingpointandslowerfailureduetooxidation.TypeBthermocoupleshaveadifferentPt/RhratiothanTypeSandR.Ithasanuppertemperaturelimitof+1750oCinoxidizingatmospheres.Duetoanincreasedamountofrhodiumcontent,typeBthermocouplesarenoquitesostableaseithertheTypeRorTypeS.wewilllookintosomedifferencesbetweendifferentbase-metalthermocouples.TypeE(Ni-Cr/Cu-Ni)thermocoupleshaveanoperatingtemperaturerangefrom-250oCto+800oC.Theiruseislesswidespreadthanotherbase-metalthermocouplesduetoitslowoperatingtemperature.However,measurementsmadebyaTypeEhaveasmallermarginoferror.1000hoursofoperationinairofaTypeEthermocoupleat+760oC,having3mmwires,sholdnotleadtoachangeinEMFequivalenttomorethan+1oC.TypeJ(Fe/Cu-Ni)thermocouplesarewidelyusedinindustryduetotheirhighthermopowerandlowcost.Thistypeofthermocouplehasanoperatingtemperaturerangefrom0oCto+760oC.LinkstoRelatedLessonsTemperatureSensorsThermistorsThermocouplesLM35sOtherSensorsStrainGagesTemperatureSensorLaboratoriesReturntoTableofContentsExperimentsWithTemperatureSensors-DataGatheringMeasuringtemperatureisthemostcommonmeasurementtask.Therearenumerousdevicesavailableformeasuringtemperature.Manyofthemarebuiltusingoneofthesecommonsensors.ThermistorThermocoupleLM35IntegratedCircuitTemperatureSensorYoucangetmoreinformationaboutthesesensorsbyclickingthelinksabove.LaboratoryThepurposeofthislaboratoryistogettimeresponsedataforthethreesensorsyouwereintroducedtolabsweek.HerearelinkstoLabVIEWprogramsyoucanuse.NTempsHydra.vi-tomeasuretemperaturefromtheHydra.NVoltsHydra.vi-tomeasurevoltagefromtheHydra.ResetHydra.vi-A"sub-vi"youneedtoresettheHydra.1Temp.vi-Asub-vithatwilltakeonetemperaturemeasurementontheHydra.1VoltHydra.vi-Asub-vithatwilltakeonevoltagemeasurementontheHydra.Youshouldhaveallthefilesaboveonyourdesktop.Youcanclickoneachlinkandsavetothedesktop,oryoucanfindtheNMeasfolderinmypublicspaceandcopytheentirefoldertothedesktop(best).YouonlyneedtodoubleclicktheNTempsorNVoltsfilestostartandruntheminLabVIEW-buttheyhavetobetakenoutofthenetworkfolder!Onceyouhavethefilestogetherinasinglefolderonyourdesktop,StartNTempsHydra.vitomeasuretemperatureusingthethermocoupleattachedtoterminals21(yellowlead)and22(redlead).Notethattheseterminals(21and22)aretheconnectionsforchannel1fortheHydra.(Forexample,ifyouweredoingamanualtemperaturereadingusingthefrontpanel,youwouldneedtosettochannel1.)YouneedtoconnecttheyellowleadofthethermocoupletothetopconnectorforChannel#1(Terminal#21)andtheredleadofthethermocoupletothebottomconnector(ground?)forChannel#1(Terminal#22).BothofthoseconnectionsaremadetotheconnectorstriponthetopoftheHydraDataAcquisitionUnit.StartNVoltsHydra.vitomeasurevoltagesusingtheLM35andthevoltagedividercircuitforthethermistor.BothsetsofmeasurementsshouldbetakenfromthefrontpanelconnectionpointsontheHydra.ForboththeLM35andthethermistorcircuit,youneedtosupply5vtothecircuitboard.Inyourlabnotebookrecordanycircuitryyouuse,andanypertinentpointsregardingtheequipmentyouuse.Noteanyotherfeaturesofeachsensorthatwillhelpyouforyourprojectormakethingsmoredifficult.Dothefollowing:Connecteachsensor.Herearelinkstousingeachsensorinameasurement.ThermocouplesLM35sThermistorsForeachsensoryouneedtogetdataintwosituations:Asthesensorheatsup(risingtimeconstantbehavior)Asthesensorcoolsdowntoambienttemperature(decayingtimeconstantbehavior)Thatdatashouldbestoredinacomputerfile.Useadifferent,understandablenameforeachfile.Theprogramwillpromptyouforafilename.SuggestedfilenamesarethingslikeThermistorUp.txt,etc.BeforeyouleavelabbesurethatyoucanbringyourdataupinExcel(totestthatyouhaveagooddatafile)andthatyoucanplotthedatatoseethatitlookslikewhatyouexpect.Estimatethefollowingforeachsensor.Thetimeitwilltakeforthesensortogetwithin1oCwhenthesensorisingoodthermalcontactwiththetemperatureenvironmentbeingmeasuredandthetemperaturesensorstartsat25oCandgoesto50oC.(Thatmeanstomeasurethetimeittakestogettobetween49oCand51oC.)Thetimeitwilltakeforthesensortogetwithin1oCofthefinalvaluewhenthesensorisinairataconstanttemperatureandthetemperaturesensorstartsat25oCandgoesto50oC.Inotherwords,whenwillthetemperaturesensorreach49oC?Thetimeitwilltakeforthesensortogetwithin0.1oCforthetwosituationsabove.(i.e.,between49.9oCand50.1oC.)Thetimeitwilltakeforthesensortogetwithin1oCwhenthesensorisingoodthermalcontactwiththetemperatureenvironmentbeingmeasuredandthetemperaturesensorstartsat50oCandgoesto25oC.Explainwhythereisadifferenceinthespeedoftheresponseinthevarioussituationsabove.Yourreportshouldshowcalculationsforthetimeconstant(s)foreachdevice,andshouldshowtheresultsusingthethreemethods.Tabularpresentationoftheresultsisbest.Finally,youshould-asbestpossible-explainyourresults.Whywouldthetimeconstantbedifferentgoingupandgoingdown.

供熱站溫度壓力實時檢測熱敏電阻很便宜，易于得到的溫度傳感器。它們易于使用和適應(yīng)性。與熱敏電阻的電路可以有合理outout電壓-而不是產(chǎn)出熱電偶毫伏的。由于這些優(yōu)勢，熱敏電阻廣泛用于簡單的溫度測量。它們不是用于高溫，但在他們的工作溫度范圍在那里，他們被廣泛使用。熱敏電阻溫度敏感電阻器。所有的電阻隨溫度，但熱敏電阻的半導(dǎo)體材料建造，是一個電阻對溫度特別敏感。但是，與大多數(shù)其他電阻器，熱敏電阻的一個隨溫度降低。這是由于半導(dǎo)體材料制成的熱敏電阻的特性。一些人認(rèn)為，這可能是違反直覺，但它是正確的。這里是一個電阻作為溫度函數(shù)的圖像為一典型的熱敏電阻。請注意阻力從100千瓦下降到一個很小的值在1左右房間溫度范圍。不僅是從你期望相反的方向電阻的變化，但其電阻變化率的幅度是可觀的。

溫度傳感器-熱電偶您現(xiàn)在的位置：元素-傳感器-熱電偶返回目錄熱電偶表是由兩個不同的金屬組成的交界處。其實，這是一個路口對。一位在參考溫度0oC的像（）和其他交界處的溫度進行測量。阿溫差會引起電壓要發(fā)展是溫度而定。（該電壓是由一些被稱為塞貝克效應(yīng)引起的。）熱電偶廣泛用于溫度測量，因為它們價格便宜，堅固可靠，而且可以在很寬的溫度范圍內(nèi)使用。特別是，其他如熱敏電阻溫度傳感器和傳感器LM35（）周圍室溫有用的，但為什么熱電偶熱電偶可以使用熱電偶測量溫度？他們是廉價的。他們是堅固，可靠。它們可用于在很寬的溫度范圍。熱電偶是什么樣子？在這里。注意兩條線兩種不同的金屬（）參加了路口。熱電偶是什么呢？它是如何工作的？兩種不同的金屬交界處產(chǎn)生電壓的溫度依賴性。對于如何更有效的描述，請點擊這里。你是如何利用熱電偶？您測量熱電偶產(chǎn)生的電壓，并轉(zhuǎn)換成的電壓，溫度讀數(shù)。這可能是最好的進行轉(zhuǎn)換，因為轉(zhuǎn)換的數(shù)字可以相當(dāng)非線性的。事情你需要知道關(guān)于熱電偶的兩種不同金屬之間的交界處產(chǎn)生電壓。在熱電偶，傳感交界處-產(chǎn)生的電壓時的溫度而定。凡熱電偶連接到儀器-銅導(dǎo)線？-你有兩個路口，同時也產(chǎn)生電壓的溫度依賴性。顯示這些路口內(nèi)的黃色橢圓形。當(dāng)您使用熱電偶時，您需要確保連接是在一些標(biāo)準(zhǔn)的溫度，或者你需要使用一個電子補償系統(tǒng)，考慮到這些電壓。如果您的熱電偶連接到數(shù)據(jù)采集系統(tǒng)，然后有很好的機會，你有一個電子補償制度。一旦我們獲得了由電壓表讀數(shù)，測得的電壓必須轉(zhuǎn)換為溫度。溫度通常表示為多項式函數(shù)的測量電壓。有時有可能獲得超過一有限的溫度范圍內(nèi)像樣的線性近似。有兩種方法來測量電壓轉(zhuǎn)換為溫度讀數(shù)。測量電壓，讓經(jīng)營者做計算。以此作為一個轉(zhuǎn)換電路-無論是模擬或數(shù)字輸入電壓的測量。讓我們看看基本金屬熱電偶一些其他類型。T型熱電偶被廣泛用作是K型和K型型北路（Ni-Cr/Ni-Al）熱電偶也廣泛應(yīng)用在工業(yè)中使用。它具有較高的熱電勢和良好的抗氧化作用。一個K型熱電偶的工作溫度范圍為攝氏從-2691260℃。然而，這種熱電偶表現(xiàn)不佳而在減少大氣。T型（銅/銅鎳）熱電偶可以在惰性氣氛氧化以上的-250oC的溫度范圍為850oC的使用。在減少或輕度氧化環(huán)境中，可以使用熱電偶至接近1000℃。N型（Nicrosil/Nisil）熱電偶的設(shè)計可在溫度高達1200oC的工業(yè)環(huán)境下使用。一個多項式方程用于熱電偶電壓轉(zhuǎn)換溫度（℃）以上的溫度范圍。我們可以寫多項式為：系數(shù)，一個是在許多地方表列。下面是一個K型熱電偶國家統(tǒng)計局多項式系數(shù)。（來源：勺奎恩，溫度，學(xué)術(shù)出版社有限公司，1990年）K型?多項式系數(shù)1100.22658460224152.10900267233.424832210340.6824-860963914.954.83506x101061.18452x101271.38690x101386.33708x1013什么如果周邊溫度超過限制？真的有沒有能抵御氧化熱電偶以上的鉑銠熱電偶型大氣溫度的上限。我們不能，因此，在如此高的溫度測量環(huán)境溫度。測量溫度非常高輻射或其他選項的噪音高溫計。對于非氧化性氣氛，鎢錸熱電偶具有良好的性能高達2750℃。他們可以使用，很短的時間，在溫度高達3000℃。作者：熱電偶溫度傳感器采用低類型的選擇主要是基于一個熱電偶材料。此外，在低受熱熱電相當(dāng)?shù)?，所以將EMF測量比例太小了。更多的事實在不同類型的熱電偶熱電偶品種涵蓋了從今天-250oC的溫度范圍為3000℃。不同類型的熱電偶，給出英文字母代號：二，電子，強，鉀，俄，西，T和N型度R，S和B是貴金屬，用于測量高溫?zé)犭娕?。其溫度范圍?nèi)，他們可以經(jīng)營了一段較長時間的氧化環(huán)境下。S型和R型熱電偶是由白金注冊（鉑）和銠（銠）在不同的比例混合。一個具體的鉑/銠比為使用，因為它會導(dǎo)致更加穩(wěn)定和可重復(fù)性測量。S型和R在氧化氣氛的1200oC的溫度的上限，假設(shè)一個線徑為0.5mm。S型和R型熱電偶是由白金注冊（鉑）和銠（銠）在不同的比例混合。一個具體的鉑/銠比為使用，因為它會導(dǎo)致更加穩(wěn)定和可重復(fù)性測量。S型和R在氧化氣氛的1200oC的溫度的上限，假設(shè)一個線徑為0.5mm。B型熱電偶具有不同的Pt/S型和R比它在氧化氣氛的1750oC的溫度的上限Rh的比例。由于對銠含量，B型熱電偶增加額沒有這么穩(wěn)定的任何類型的R型或E型南，強，鉀，T和N是基本金屬可用于檢測用熱電偶溫度較低。它們不能用于檢測由于其相對較低的熔點和慢衰竭的高溫氧化。B型熱電偶具有不同的Pt/S型和R比它