6 truyen nhiet

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<ul><li> 1. TKHOA NNG LM TPT0120 CH N N AN</li></ul> <p> 2. T ) Q A t thngng nh 3. ng- u- ng-ng- n i-n-c-t 4. T- t- t)- 5. T nhau-- i)- ng 6. NH FOURIER ng dQ dT kA dt dx- po:--u- ch-t 7. t)y. nht) t (W/m.K) nh) nh: dTT dxx 8. P QAT1T1 T2 T2 Q kAx 9. PQ 30WT=T1-T2nh bn).A=0.1m2n: TQkAx T1T Q x 30 0.025 37 .5 o CT2 kA 0 . 2 0 .1 i sao T m? 10. T u-i-o nn? 11. i:50-400 J/oC.s.my tinh: 0.51 J/oC.s.mp kim:10-120 J/oC.s.m :0.024 J/oC.s.m c: 0.7 J/oC.s.m :2.3 J/oC.s.m t: 0.026-0.052 J/oC.s.mt 12. M- m cao-i W&gt;60%:k = 0.148 + 0.00493W- i W=60-80%k = 0.08 + 0.0052W-Heldman, Fellows 13. m 75%?ng? 14. cht thng = dQ/A.dtdx: vi phn,ngng Watt (W) ng Joule (J)ng trn giy (W=J/s) 15. -12o 21o t vung? 16. NdQdT T kAdtdx x kA n-n-- c) 17. ELECTRICAL CIRCUIT ch nV V A I RRI 18. TdT T Q x kA Q R=dx/kA 19. P ng:dTT1 T2 k1k2dx1 dx2QR1R2 k1 Ak2 A Q dx1 dx2ng 20. -= R1+R2-:dx1dx21 RTk1 A k2 AUA- t RT T QUA T RT-t 21. I LUi lu.ng nh 22. TQ hA Ts T Ts ngngT 23. I LUm):-- ngringt nhanh hn):-o. 24. NHQ hA Ts T:- t- t- 25. I LUc: Q T1 hAn: V I Ri lu: R = 1/hA 26. T m : nhin 5-25 J/oC.s.m2 c 10-200c: nhin 20-100 c 50-10,000 c si 3,000 100,000 5000 100,000 27. t1m2 120o 10 J/oC.s.m2 Q hA Ts T Q 10 1 120 201000 W 28. ngngtn trong chn khng 29. Tc: h1,A h2,Ak,x,AT1 T2 R1R2R3 30. NH U :11x1 UA h1 A kA h2 A t UA (T T ) Q1 2 31. nh 20cm)i: k = 400W/m.K c) = 0.0105 K/Wt?100oCy: 3 mm250oC 32. N :- u- c:x 0.0034 R1 22.4 10 K/W kA 400 0.1 R2 0.0105 K/Wt: 250 100 QT / R1 R214.0 kW0.0105 0.00024 33. NGi, T2i, Lm, T1r2 r1 34. TdrT2r1 r2 T1 35. CH dT QkA dr Q k 2 rL dT dr dr 2 Lk dTr Q r2 1dr 2 Lk (T1 T2 ) r Q r 1 36. r2 (T T )2 Lkln 1 2 r1 QQ 2 Lk (T1 T2 ) r2ln r1 37. NGRcylln r r R2 1cyl 2 Lkng 38. P i luy tinhT=35oC K trong = 2.1 cm i a = 2.67 cm 150oC i = 3.335 cm k i TT= 0.0351 W/m.K k ng KL= 45 W/m.K 39. N :R ng= ln(1.335/1.05)/(2 45) i) = 0.00085 K/WR i TT= ln(1.667/1.335)/(2 0.0351) = 1.008 K/W t = (150-35)/(1.007+0.00085) = 114.104 W/m 40. T u:h1=6.5 W/m2Kh2, T h2=4.5 W/m2KT1=135oCk h1, T1 T =20oCk1=202 W/mKri ro ri=4.88 cmro=5.08 cmi? 41. Ni lu bn trong 11Ri0.502h1 A1 6.5 (2 0.0488 )i:1 1 Ro 0.696h2 A2 4.5 (2 0.0508 )ng: ro ln ri ln 5.08 4.88 Ro 0.000032 k2 (202) 42. = 0.502+0.696+0=1.20t: q T1 T135 2095 .8 W / m L RT1.20FST42/76 43. Tpt 44. To:-t-i gian)-t-n 45. N ttro ln 1ri RThA 2 kLro nh. 46. C t khTT1 q T2q nng x 47. NGy i.kA T2 T1q hA(T2 T )xT1 T x1qRT x1 kA hAkA hA 48. Tm i:--t)---nhin) 49. P 15oC.y 12.5mm.p10W/m2.K 37o ?o?y bia. k p =15 W/m.K kTT =0.73 W/m.K 50. N pl TT15oC 37oC H=18 mh=10 QD = 13 m 51. 6</p>