磁熱效應(yīng)及致冷技術(shù)

13-幾種磁性功能材(二)磁熱效應(yīng)與磁制冷技--韓滿 0.磁致冷技術(shù)的發(fā)展歷程1.磁熱效應(yīng)的發(fā)現(xiàn)與基2.近室溫磁致冷技術(shù)3.從傳統(tǒng)小的磁熱效應(yīng)-→巨磁熱效應(yīng)4.現(xiàn) 的問(wèn)題及今后的發(fā)展5.磁致冷技術(shù)的潛在應(yīng)InternationalConferenceoftheIIR磁致冷技術(shù)的發(fā)展歷1926MagneticrefrigeratorproposedbyDebyeandGiauque1949NobelPrizeawardedtoGiauqueformagneticrefrigeration1978LosAlamosDOELabpatents“AMR”magneticrefrigerator1989Navydemonstrates“AMR”magneticrefrigerator1991Astronauticsdemonstrates40Khighefficiency1997AstronauticsdemonstrateshighpowerNRT2000GiantMagnetocaloricEffectalloysmadebyAmesDOE2001AstronauticsdemonstratespermanentmagnetrotaryInterl

onferenceoftheIIR磁熱效應(yīng)的發(fā)現(xiàn)與基Interl

onferenceoftheIIR磁熱效應(yīng)的發(fā)現(xiàn)與基什么是磁熱效應(yīng)是磁性材料固有的基本性質(zhì)，在外加循環(huán)磁場(chǎng)作用下可以觀察到材料溫度的可逆變化。DiscoveredbyE.Warburg(1881)astheheatingofFeuponmagnetizationandthecoolingofthesameupondemagnetization(mK!!!).Ann.Phys.(Leipzig)13,141磁熱效應(yīng)是指磁性材料在外加磁場(chǎng)作用下內(nèi)能的變兩個(gè)物理量來(lái)表述MCE效應(yīng)絕熱溫變：絕熱條件下，外加磁場(chǎng)導(dǎo)致體系的溫度變化2絕熱溫變B1=S1,

B2>>0.1S2=S1,T2>

磁場(chǎng)作用磁矩取向的改絕熱條件S=

電子Tad=T2–B>0:S=(S+Tad=T2–B>0:S=(S+S+S +(SM等溫熵變Maxwell方P=const,V=

dETdSGibbsfree

GEdGdETdSMTMTHSHGisstatePispressure,Visvolume,Tistemperature,Mismagnetization,Hismagneticfieldstrength,EisSisentropy,GisGibbsfree絕熱溫變P=const,V=const,S=Second

CdQ

dQ

TdSHeat

dT dT

HHM SHMaxwellS(T,H)asstate

H

dSS

dTS

TS

dTTS H

H

TdS

dTTM dT MdT M CHTHHAdiabatic:dS=Pispressure,Visvolume,Tistemperature,Mismagnetization,Hismagneticfieldstrength,SisCisheatcapacity,QisInternationalConferenceoftheIIR金屬Gd磁致冷、氣體壓縮制冷比制冷方制冷工操工熵密外發(fā)生裝操作種磁致磁性物高磁勵(lì)磁、氣體制氣低壓壓縮壓縮、循環(huán)名優(yōu)缺使用場(chǎng)20K1990FeRh(Nikitinet1997Gd5Si2Ge(Percharsky&Gschneidner1998RCo2(Foldeakiet La(Fe,Si)13（zhangetal.,Fukamichietal.)2001MnAs1-xSbx (Wadaetal.)2002 (Teguset2003Co(S1-xSex)2(Yamada&InternationalConferenceoftheIIRGd5Si2Ge2近室溫磁致冷技近室溫磁致冷Whyonly

M dHMCE(arb.MCE(arb.

THMnear

dT

M MM(arb.

CHTHPolycrystallineMagnetocaloriMagnetocalorieffect,T

Pulsed Heat642T=900 Magneticfield近室溫磁致冷:早期努1976BrownTemperaturespanof47oCusingGdplatestoregeneratecolumnofaalcoholmixture;7T,cycletime–severalCoolingloopHotendTB=T

B=0Cold

G.V.Brown,J.Appl.Phys.47,3673tic近室溫磁致冷機(jī):近期進(jìn)Astronautics/AmesLaboratory,USA,superconductingmagnet,reciprocating,announcedFeb.20,1997.MaterialsScienceInstitute,Spain,permanentmagnet,rotary,announcedChubuElectric/Toshiba,Japan,superconductingmagnet,announcedlocallyinsummerofUniversityofVictoria,Canada,superconductingmagnet,announcedinJulyofAstronautics,USA,permanentmagnet,rotary,announcedinSep.ofSichuanInst.Technology/NanjingUniv.,China,permanentmagnet,reciprocating,announcedpriva ytoK.Gschneidner,Jr.Apr.23,2002,publiclyMay4,2003.ChubuElectric/Toshiba,permanentmagnet,reciprocating,October5,ChubuElectric/Toshiba,permanentmagnet,rotary,announcedMarch4,Laboratoired’ElectrontechniquedeGrenoble,France,permanentreciprocating,announcedinAprilofGeorgeWashingtonUniversity,USA,permanentmagnet,announcedinJulyof換熱缺點(diǎn)：大磁超導(dǎo)其它解決方法從傳統(tǒng)小的磁熱效應(yīng)→巨磁熱效主要影響因素:磁熱效應(yīng)的大M

只在相變點(diǎn)溫度T

H

H

傳統(tǒng)的磁熱效應(yīng)ParamagnetorsuperparamagnetatlowPMFM二級(jí)相變PMAFM二級(jí)相變巨磁熱效應(yīng)(GMCE)-源于磁彈性耦合的增強(qiáng)效磁相變-晶體結(jié)構(gòu)相變耦合PMFM一級(jí)相變磁相變-晶體結(jié)構(gòu)相變耦合FMAFM一級(jí)相變磁體積變化(結(jié)構(gòu)相伴IEM一級(jí)相變先進(jìn)的巨磁熱效應(yīng)材–R-Lanthanide,M–Alkali,AlkalineR(Fe1-(FeMn)(P1-B=5B=5GMCEMCE00Transitiontemperature,TCMagnetocaloriceffect,-SM(mJ/cm3 SM數(shù)值比3Magnetocaloric3Magnetocaloriceffect,-SM 0

TC=318K

TC=195KTC=145TC=227K

TC=142TC=270KTC=294 Magneticfieldchange,HTC=270TC=294TC=195TC=142500Magneticfieldchange,HMagnetocaloriceffect,Tad現(xiàn) 的問(wèn)題及今后的發(fā)一級(jí)磁相變材 的問(wèn)相變應(yīng)能在較寬的溫區(qū)內(nèi)(2-10K)和更小的磁場(chǎng)下field(2-10kOe)驅(qū).Onlypartoftheoriginallowmagneticphasemayhave磁滯損耗要盡量(mustbeOriginallowmagneticfieldphasemaynotbe-SMand 的準(zhǔn)確測(cè)Static–heatcapacityQuasi-static–magnetizationanddirectDynamic–direct(pulsed磁制冷機(jī)的動(dòng)態(tài)工作條1to10將來(lái)怎么辦結(jié)構(gòu)相變也為耦合型的，且能被較低的磁場(chǎng)所驅(qū)動(dòng)