热量传输 Nuf =0.023 Re Pr 5I5R5A=0.023 Re Pr 对水:n=0.4 0.599 0.023Ree°Pr ×0.023×(13270)08×(702)04 0.05 1194w/m2°C 对空气:n=0.3 2.59×10-2 0.023 Re Pr ×0.023×(13280)×(7.02) 0.3 d 0.05 =21.3w/m2C 出 (#‹#› n f 0.8 l R t f n f 0.8 Nuf = 0.023Ref Pr    = 0.023Re Pr  对水：n=0.4 1194w / m C 0.023 (13270) (7.02) 0.05 0.599 0.023Re Pr d 2 0.4 0.8 0.4 f 0.8 f  = =      = 对空气：n=0.3 21.3w / m C 0.023 (13280) (7.02) 0.05 2.59 10 0.023Re Pr d 2 0.8 0.3 2 0.3 f 0.8 f  − =     =   = 第二章 热 量 传 输