例题7解答 =20.8=1.74a K'=1.74K Q=qm2Cp2(t2-)=KAAtm KA =2 9m2 KA A K 1 2× A =2 =1.15 K' 1.74例题7解答 0.8       2 1.74 K K  1.74 2 2 2 1 ( ) Q q c t t KA t     m p m 2 2 2 m m q K A q KA      1 2 2 1.15 1.74 A K A K       