PrincipleofTemperatureMeasurementbyThermocouple熱電偶測(cè)溫原理落版在此謝聰XieCong主講教師Teacher生產(chǎn)的安全、效率與產(chǎn)品質(zhì)量Productionsafety,efficiencyandproductquality溫度的精準(zhǔn)測(cè)量如同“定海神針”Accuratetemperaturemeasurementactslikea"pillarofstability,"工業(yè)生產(chǎn)Industrialproduction熱電偶測(cè)溫原理PrincipleofTemperatureMeasurementbyThermocouple熱電偶Thermocouple測(cè)量范圍Measurementrange可靠性能Reliability便捷使用Easeofuse“中流砥柱”"Backbone"熱電偶測(cè)溫原理PrincipleofTemperatureMeasurementbyThermocouple高溫熔爐High-temperaturefurnace低溫冷藏Low-temperaturestorage化工反應(yīng)釜Chemicalreactor電力鍋爐Electricboiler熱電偶測(cè)溫原理PrincipleofTemperatureMeasurementbyThermocouple如何感知溫度的變化?Howisthetemperaturechangesensed?為何能在復(fù)雜的工業(yè)環(huán)境中穩(wěn)定發(fā)揮作用？Whycanitfunctionstablyincomplexindustrialenvironments?熱電偶測(cè)溫原理PrincipleofTemperatureMeasurementbyThermocouple熱電偶測(cè)溫Thermocoupletemperaturemeasurement熱電偶測(cè)溫原理PrincipleofTemperatureMeasurementbyThermocoupleCaseimport案例導(dǎo)入在某鋼鐵廠的煉鋼車間，一場(chǎng)緊張的生產(chǎn)正在進(jìn)行。高溫熔爐內(nèi)，鋼水翻滾，溫度高達(dá)1600℃，而此刻，精準(zhǔn)把控溫度成為確保鋼材質(zhì)量的關(guān)鍵。工人依靠安裝在熔爐內(nèi)的熱電偶，時(shí)刻監(jiān)測(cè)著溫度變化。Inthesteelmakingworkshopofasteelplant,anintenseproductionisgoingon.Insidethehigh-temperaturefurnace,themoltensteelchurnsattemperaturesreachingupto1,600°C.

Atthismoment,accuratetemperaturecontrolhasbecomethekeytoensuringsteelquality.Workersrelyonthermocouplesinstalledinthefurnacetomonitortemperaturechangesallthetime.Caseimport案例導(dǎo)入但在一次生產(chǎn)過(guò)程中，熱電偶出現(xiàn)故障，溫度反饋延遲，致使?fàn)t溫失控。原本應(yīng)保持在合適區(qū)間的溫度急劇攀升，超出了正常范圍。這直接導(dǎo)致煉出的鋼材內(nèi)部結(jié)構(gòu)產(chǎn)生缺陷，大量鋼材報(bào)廢，企業(yè)損失慘重。However,inaproductionprocess,thethermocouplefailedandthetemperaturefeedbackwasdelayed,resultinginthefurnacetemperaturegettingoutofcontrol.Thetemperaturethatshouldhavebeenkeptintherightrosesharply,beyondthenormalrange.Thisdirectlyledtodefectsintheinternalstructureoftherefinedsteel,alargeamountofsteelwasscrapped,andtheenterprisesufferedheavylosses,PrincipleofTemperatureMeasurementbyThermocouple熱電偶測(cè)溫原理PrincipleofTemperatureMeasurementbyThermocouple熱電偶測(cè)溫原理熱電偶是基于熱電效應(yīng)的測(cè)溫元件，能將溫度信號(hào)轉(zhuǎn)換成毫伏（mV）級(jí)電勢(shì)信號(hào)。一般用于測(cè)量500～1600℃之間的溫度。Thermocoupleisatemperaturemeasuringelementbasedonthethermoelectriceffect,whichcanconvertthetemperaturesignalintoamillivolt(mV)potentialsignal.Itisgenerallyusedtomeasuretemperaturesbetween500and1,600°C.熱電偶Thermocouple兩種不同材料的導(dǎo)體或半導(dǎo)體材料A和B連接成閉合回路時(shí)，若兩個(gè)接點(diǎn)溫度不同，回路中會(huì)產(chǎn)生熱電勢(shì)，熱電勢(shì)由接觸電勢(shì)和溫差電勢(shì)兩部分組成。IfthetemperaturesofthetwocontactsaredifferentwhentwoconductorsorsemiconductormaterialsAandBofdifferentmaterialsareconnectedtoformaclosedloop,athermoelectricpotentialwillbegeneratedintheloop.Thethermoelectricpotentialconsistsoftwoparts:contactpotentialandtemperaturedifferencepotential.熱電偶測(cè)溫原理PrincipleoftemperaturemeasurementbythermocouplePrincipleofTemperatureMeasurementbyThermocouple熱電偶測(cè)溫原理接觸電勢(shì)Contactpotential當(dāng)兩種不同材料的導(dǎo)體A

和B

接觸時(shí)，由于材料內(nèi)部電子密度不同，會(huì)發(fā)生電子擴(kuò)散，在接觸界面形成電場(chǎng)，產(chǎn)生接觸電勢(shì)，且溫度t

高于t?時(shí)，會(huì)進(jìn)一步影響電子擴(kuò)散和電勢(shì)大小。WhenconductorsAandBoftwodifferentmaterialsareincontact,electrondiffusionwilloccurduetothedifferentelectrondensitiesinsidethematerials,forminganelectricfieldatthecontactinterfaceandgeneratingcontactpotential.Whenthetemperaturetishigherthant?,itwillfurtheraffectelectrondiffusionandpotentialmagnitude.溫差電勢(shì)Temperaturedifferencepotential對(duì)于單一導(dǎo)體，當(dāng)兩端溫度不同（t≠t?）時(shí)，高溫端的電子能量高于低溫端，電子會(huì)從高溫端向低溫端擴(kuò)散，從而在導(dǎo)體兩端形成電勢(shì)差，即溫差電勢(shì)。Forasingleconductor,whenthetemperaturesatbothendsaredifferent(t≠t?),theenergyofelectronsatthehigh-temperatureendishigherthanthatatthelow-temperatureend,andelectronswilldiffusefromthehigh-temperatureendtothelow-temperatureend,thusformingapotentialdifferenceatbothendsoftheconductor,thatis,temperaturedifferencepotential.PrincipleofTemperatureMeasurementbyThermocouple熱電偶測(cè)溫原理對(duì)于材質(zhì)確定的熱電偶，熱電勢(shì)僅與熱端和冷端溫度有關(guān)，當(dāng)冷端溫度固定時(shí)，熱電勢(shì)E(t,t?)是熱端溫度t的單值函數(shù)。Forthermocoupleswithdeterminedmaterial,thethermoelectricpotentialisonlyrelatedtothetemperatureofthehotendandthecoldend.Whenthecoldendtemperatureisfixed,thermoelectricpotentialE(t,t?)isamonodromefunctionofthehotendtemperaturet.通過(guò)實(shí)測(cè)得到熱端不同溫度t

時(shí)的熱電偶電勢(shì)，制成熱電偶分度表，方便實(shí)際應(yīng)用中查閱使用。Thethermocouplepotentialofthehotendatdifferenttemperaturestcanbeobtainedbyactualmeasurement,andathermocouplegraduationtablecanbemade,whichisconvenientforreferenceanduseinpracticalapplication.在冷端溫度t?=0℃的條件下Theconditionthatthecoldendtemperaturet?=0°CThermocouplegraduationtable熱電偶的分度表Thermocouplegraduationtable熱電偶的分度表t/℃0010203040506070809000.0000.3970.7981.2031.6112.0222.4362.8503.2663.6811004.0954.5084.9195.3275.7336.1376.5396.9397.3387.7372008.1378.5378.9389.3419.74510.15110.56010.96911.38111.79330012.20712.63213.03913.45613.87414.29214.71215.13215.55215.97440016.39516.81817.24117.66418.08818.51318.93819.36319.78820.21450020.64021.06621.49321.91922.34622.77223.19823.62424.05024.47660024.90225.32725.75126.17626.59927.02227.44527.86728.28828.70970029.12829.54729.96530.38330.79931.21431.62932.04232.45532.86680033.27733.68634.09534.50234.90935.31435.71836.12136.52436.92590037.32537.72438.12238.51938.91539.31039.70340.09640.48840.897100041.26941.65742.04542.43242.81743.20243.58543.96844.34944.729110045.10845.48645.86346.23846.61246.98547.35647.72648.05948.462120048.82849.19249.55549.91650.27650.63350.99051.34451.69752.049130052.398鎳鉻—鎳硅熱電偶分度表（簡(jiǎn)表）GraduationTableofNickel-Chromium-Nickel-SiliconThermocouples(AbridgedTable)分度號(hào)為KThegraduationnumberisK冷端溫度t?=0℃Thecoldendtemperaturet?=0℃確定熱端溫度t：假設(shè)熱端溫度為t=250℃。Determinethehotendtemperaturet:Assumethatthehotendtemperatureist=250°C.查找行和列：在表格的第一列（t/℃）中找到最小于并接近250℃的行，即200℃。Findtherowandcolumn:Locatetherowinthefirstcolumn(t/℃)thatisthelargestvaluelessthanorequalto250°C,whichis200°C.確定熱電勢(shì)E：在200℃行和50

列的交叉處，找到對(duì)應(yīng)的數(shù)值為10.151mV。DeterminethethermoelectricpotentialE:Attheintersectionofthe200°Crowandthe50column,thecorrespondingvalueis10.151mV.Thermocouplegraduationtable熱電偶的分度表熱電偶兩個(gè)接點(diǎn)溫度為t

和t?時(shí)，回路產(chǎn)生的熱電勢(shì)等于接點(diǎn)溫度為t、t?和t?、t?時(shí)，兩支同性質(zhì)熱電偶產(chǎn)生的熱電勢(shì)代數(shù)和。Thetemperaturesofthetwocontactsofthethermocouplearetandt?.Atthistime,thethermoelectricpotentialgeneratedbytheloopisequaltothealgebraicsumofthethermoelectricpotentialsgeneratedbythetwothermocouplesofthesamenaturewhenthecontacttemperaturesaret,t?andt?,t?,中間溫度定律IntermediatetemperaturelawEAB(t,t0)=EAB(t,

t1)+EAB(t1,t0)Thermocouplegraduationtable熱電偶的分度表t/℃0010203040506070809000.0000.3970.7981.2031.6112.0222.4362.8503.2663.6811004.0954.5084.9195.3275.7336.1376.5396.9397.3387.7372008.1378.5378.9389.3419.74510.15110.56010.96911.38111.79330012.20712.63213.03913.45613.87414.29214.71215.13215.55215.97440016.39516.81817.24117.66418.08818.51318.93819.36319.78820.21450020.64021.06621.49321.91922.34622.77223.19823.62424.05024.47660024.90225.32725.75126.17626.59927.02227.44527.86728.28828.70970029.12829.54729.96530.38330.79931.21431.62932.04232.45532.86680033.27733.68634.09534.50234.90935.31435.71836.12136.52436.92590037.32537.72438.12238.51938.91539.31039.70340.09640.48840.897100041.26941.65742.04542.43242.81743.20243.58543.96844.34944.729110045.10845.48645.86346.23846.61246.98547.35647.72648.05948.462120048.82849.19249.55549.91650.27650.63350.99051.34451.69752.049130052.398可利用冷端為0℃時(shí)的熱電勢(shì)關(guān)系（查分度表），求出冷端為任意溫度時(shí)的熱電勢(shì)。Youcanusethethermoelectricpotentialrelationshipwhenthecoldendis0°C(checkthegraduationtable)tocalculatethethermoelectricpotentialwhenthecoldendisatanytemperature.EAB(t,t0)＝EAB(t,0)-EAB(t0,0)=符合分度表要求

Conformtograduation

tablerequirements

ABt0t

AB0t

AB0t0

---Thermocouplegraduationtable熱電偶的分度表練習(xí)：假如用K型熱電偶測(cè)量某加熱爐溫度。測(cè)得熱電勢(shì)為E(t,t0)=36.122mV，而冷端溫度t0=30℃，求被測(cè)點(diǎn)的實(shí)際溫度。Exercise:SupposeaK-typethermocoupleisusedtomeasurethetemperatureofaheatingfurnace.ThemeasuredthermoelectricpotentialisE(t,t0)=36.122mV,andthecoldendtemperaturet0

=30℃.Findtheactualtemperatureofthemeasuredpoint.t/℃0010203040506070809000.0000.3970.7981.2031.6112.0222.4362.8503.2663.6811004.0954.5084.9195.3275.7336.1376.5396.9397.3387.7372008.1378.5378.9389.3419.74510.15110.56010.96911.38111.79330012.20712.63213.03913.45613.87414.29214.71215.13215.55215.97440016.39516.81817.24117.66418.08818.51318.93819.36319.78820.21450020.64021.06621.49321.91922.34622.77223.19823.62424.05024.47660024.90225.32725.75126.17626.59927.02227.44527.86728.28828.70970029.12829.54729.96530.38330.79931.21431.62932.04232.45532.86680033.27733.68634.09534.50234.90935.31435.71836.12136.52436.92590037.32537.72438.12238.51938.91539.31039.70340.09640.48840.897100041.26941.65742.04542.43242.81743.20243.58543.96844.34944.729110045.10845.48645.86346.23846.61246.98547.35647.72648.05948.462120048.82849.19249.55549.91650.27650.63350.99051.34451.69752.049130052.398從分度表查得K

型熱電偶E(30,0)=1.203mV。Fromthegraduationtable,findK-typethermocoupleE(30,0)=1.203mV.查閱分度表，確定被測(cè)點(diǎn)溫度為900℃。Consultthegraduationtableagaintodeterminethatthemeasuredpointtemperatureis900°C.則

E(t,0)=E(t,30)+E(30,0)=36.122+1.203=37.325mV

Then

E(t,0)=

E(t,30)+E(30,0)=36.122+1.203=37.325mV

PrincipleofTemperatureMeasurementbyThermocouple熱電偶測(cè)溫原理溫度信號(hào)Temperaturesignals熱電偶Thermocouples熱電勢(shì)信號(hào)Thermoelectricpotentialsignals熱電效應(yīng)Thermoelectriceffect再通過(guò)與分度表結(jié)合以及中間溫度定律等，實(shí)現(xiàn)對(duì)溫度的準(zhǔn)確測(cè)量，在工業(yè)生產(chǎn)、科學(xué)研究等眾多領(lǐng)域有著廣泛且重要的應(yīng)用。Throughcombinationwithgraduationtablesandlawsliketheintermediatetemperaturelaw,theyachieveaccuratetemperaturemeasurementandarewidelyandcriticallyappliedinindustrialproduction,scientificresearch,andmanyotherfields.PrincipleofTemperatureMeasurementbyThermocouple熱電偶測(cè)溫原理關(guān)乎生產(chǎn)安全Crucialforproductionsafety國(guó)之重器質(zhì)量QualityofthecriticalnationalinfrastructurePrincipleofTemperatureMeasurementbyThermocouple熱電偶測(cè)溫原理錘煉靈敏可靠的專業(yè)本領(lǐng)；Honekeenandreliableprofessionalskills;以毫伏級(jí)的精準(zhǔn)擔(dān)當(dāng)，守護(hù)中國(guó)制造的生命線。To