bd 管壁: 45×0022 041% k 001542 2u R+r K d 102×05×100×0202×00018 0025 200045×0022 =001010m2C/W 9899W/(m2℃ ③W=2W +R:+R K 入dad 00025×0025002 08×200045×0022100×002 +2×000118 =001521m2C/W K0=6574W(m2℃)管壁: bd d K m 0 0 1 0 0025 0 025 45 0 022 0 01542 0 41% = = . . . . . ② Wi Wi = 2 , ui ui = 2 , i i = 2 0.8 ∴ 1 1 0 0 0 0 0 K bd d d d R R m i i i = + + + + = + + + 1 2000 0 0025 0 025 45 0 022 0 025 2 100 0 02 2 0 00118 0 8 . . . . . . . = 0.01010 m2℃/W K0 98 99 = . W/( m2℃) ③ W0 2W0 = , 0 0 8 2 0 = . ∴ 1 1 0 0 0 0 0 K bd d d d R R m i i i = + + + + = + + + 1 2 2000 0 0025 0 025 45 0 022 0 025 100 0 02 2 0 00118 0.8 . . . . . . = 0.01521 m2℃/W K0 6574 = . W/( m2℃)