(thermal conduction)(thermal convection)(thermal radiation)1导热导热)2 0 xt tw2 tw1 2.w1w 2ttA3w1w 2ttqA热流密度热流密度 qw1w 2ttAw1w 2ttAw1w 2ttRRAtw1 tw2 R热阻网络热阻网络4热对流热对流对流换热对流换热:=Ah(tw tf)q=h(tw tf)5wf1ttAh1hRAhtw tfhR =Ah(tw tf)wfhttR =Ah(tw tf)6 7 h/W/(m2K)110 1001 000 10100 10015 000 250035 000 500025 0008 c0ccn803.0 10c 9 10 11,12辐射换热的主要影响因素辐射换热的主要影响因素:13141f1w1Ah ttf1w111ttAhf1w11httRw1w2ttAw1w2ttAw1w2ttR tw2 tw1 0 xt h1 tf1 h2 tf2 152w2f2Ah ttw2f221ttAhw2f22httRf1f 21211ttAhAAhf1f 2kttRf1f 212hhttRRR12khhRRRRtw1 R1hR2hRtw2 tf1 tf2 16f1f 2Ak ttAk t12111khhf1f2qk ttf1f21211tthh1718