傳熱學(xué)第四版習(xí)題答案

本文格式為Word版，下載可任意編輯——傳熱學(xué)第四版習(xí)題答案習(xí)題答案1-1q??kA?T???T?xqkA?3?10??2.5?10???625?x??3?2

??0.2??0.6?C1-7

r1?0.25m,r2?0.3m,k?7?10?3w/m?C,h?9w/m?C,T1?30C,T???20C????2????q??T?R?T1?T?R1?R2ln0.34.145?0.25R1???C/w?32?kLL2?7?10?L?110.0589?R2???C/w?9??2???0.3??L?hA2Lln?r2r1?????qL?T1?T??4.145???0.0589??11.89w/m1-12

T1?1100?273?1373KT2?425?273?698KqA??T1?T2

?84?44???5.669?10??1373?6984??1.88?105w/m21-31qAqAqA?h1?T1?Tw1??100??353?Tw1???Tw1?Tw2?5.669?10?44???8??T4w1?Tw2

4??h2?Tw2?T2??15??Tw2?293?qA?300w/m2Tw1?350K,Tw2?312.9K,

2-1

T1?1300C,T2?30C,k1?1.3w/m?C,k2?0.35w/m?C,?x1?0.02m,????????qA?1830w/m2qA?T1?T2?RqA?18301300?301830?x2k2?R?T1?T2??0.6940m?C/w?2??

?0.021.3??x20.35?0.6940R?R1?R2??x1k1??x2?0.2375m2-9

ro?0.017m,ri?0.015m,ho?197w/m?C,hi?1500w/m?C,Tfo?57C,Tfi?223C,k?46w/m?C???2???2?????2??223?57?11

qL??T?R?12?hiri?T?ro??ln??r??i?2?k??12?horo??1500??0.015??197??0.017????0.017?ln???0.015?46?3016.6w/m2-10

k?0.04w/m?C,T?150x?30x

???2q??kAx?0dTdx??kA?300x?30???kA??30??1.2A??kA?300?0.3?30???60kA??2.4A

x?0.3Thissolidisheatingup.2-16

ri?0.02m,ro?0.04m,Ti?100C,To?50C,k?202w/m?Cq?4?k?Ti?To?1ri?1ro?4??202??100?50?10.02?10.04?5076.8w?????

2-36

??35.3?10w/m,T??20C,h?4000w/m?CA?0.025?0.025?0.000625m,q263??2???V?35.3?106?0.000625q??h?4??0.025Tw?75.16C?????L??Tw??L?22062.5L?T???4000?4??0.025??L??Tw?20?

2-43

??200?106w/m3,k?25w/m??C,Tw?100?C,x?0.004mq??dTdx22??qk?062

T??4?10x?c1x?c2dTBoundarycondition:dx?0x?0

x?0.004,T?Tw?100c1?0,c2?164T??4?10x?164Tmax?Tx?062??164C2-68Forcase1:Tx?L?T??20C,k?380w/m?C20??0.005??380????q?hPkA?0???0.005?2?1204??20??4.8415w

2-72

d1?0.03m,L?0.03m,T??20C,Tw?100C,k?55w/m?C,h?68w/m?C,t?0.002m??????2??FromFig2-12

r1?0.015m,r2?r1?L?0.045m,t?0.002mLc?L?t2?0.031mr2c?r1?Lc?0.046mAm?t?r2c?r1???0.002r2cr1Lc3/2??0.031??6.2?10?5m2

?0.0460.015kAm?3.07?68??5??556.2?10????1/2?h?1/2??0.031?3/2???0.7708Fromthefigure??0.58q??hA?0??0.58??68??2??100?20??0.046?2?0.0152??37.49w?

2-108

k?202w/m?C,?x?0.005m,100uin20atm,ΔToverall?80C

???R1?R2?Rcontact?q??xkA1??0.005202AA??2.475?10A?4?50.88?10hcA?T80R1?R2?Rc?2?2.475?10A?5?0.88?10A?4?581818Aw

?Tcontact?qRc?0.88?10?4??581818A???A????51.2?C??2-117

1??2A?x??2?r??2??0.01?x??0.0005?m4??qk??A4q0.001?k4000qdT1?dT???0.001??0.01?x?dx4?dx????0.04?x?dTdx?k4000qdx???????dT?0.04?x?2?k4000qln?0.04?x?1??T21?kq?ln2?T1?T2T1?T24000ln2?kR?q?4000ln2?k3002.32?4000ln2??380??2.32C/w?

?129w3-3

d?0.25m,D?1.2m,Tw?67C,Tfar?15C,k?1.8w/?m?C????s?2?L?D?ln???r??2?L?1.2?ln??0.125???2.778L

q?ks?T?k?2.778L??TqL??2.778?k?T??2.778??1.8??52??260w/m3-33

dTdx222??hPkA?T?T???0dTdx2Tm?1?Tm?1?2Tm??x?22Tm?1?Tm?1?2Tm??x??hPkA

?Tm?T???0?hP??x?2?hP??x?2Tm??2??T???Tm?1?Tm?1??0kAkA??3-34

k?yTm?1,n?Tm,n?x?k?xTm,n?1?Tm,n2?y?k?xTm,n?1?Tm,n2?y?0?x??yTm,n?1?Tm,n?1?2Tm?1,n?4Tm,n?0

3-35

k?yTm?1,n?Tm,n2?x?k?xTm,n?1?Tm,n2?y?0?x??yTm?1,n?Tm,n?1?2Tm,n?0

3-47?100??700??100?400??700?T1?T2?4T4?400?T4?T3?4T1?500?T4?T3?4T2?500?T1?T2?4T3

T1?487.5,T2?362.5,T3?437.5,T4?412.53-58

??90?106w/m3,k?20w/m??C?x??y?0.01m,q?V?90?10q?