T=T2+ lx podp s dM RT dⅣ=Sx,S—管横截面积 dM Mmpl posix Mmpl Pos dx RT R(T2+ T1-72 L M d M ml R T1 L Mmps l M In 5 R(T1-T2) 图8-110 . . . . . . . 图8-1 x dx x x L T T T T 1 2 2 − = + RT M dM p dV mol o = dV = Sdx ,S ⎯管横截面积 RT M p Sdx dM mol o = d x x ) L T T R(T Mmol po S 1 2 2 − + = x ) L T T (T d x R M p S M L mol o 1 2 2 0 − + =  5 1 2 ln (T T ) L R M p S M mol o −  =