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Page 1 PROBLEM 3.1 KNOWN: One-dimensional, plane wall ...

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<strong>PROBLEM</strong> 3.20<strong>KNOWN</strong>: Materials and dimensions of a composite <strong>wall</strong> separating a combustion gas from aliquid coolant.FIND: (a) Heat loss per unit area, and (b) Temperature distribution.SCHEMATIC:ASSUMPTIONS: (1) <strong>One</strong>-<strong>dimensional</strong> heat transfer, (2) Steady-state conditions, (3)Constant properties, (4) Negligible radiation effects.PROPERTIES: Table A-1, St. St. (304) ( T ≈ 1000K ):k = 25.4 W/m⋅K; Table A-2,Beryllium Oxide (T ≈ 1500K): k = 21.5 W/m⋅K.ANALYSIS: (a) The desired heat flux may be expressed as( − )T∞,1 − T∞,22600 100 Cq= ′′ =1 L A L B 1 1 0.01 0.02 1 m2+ + R .Kt,c + + ⎡⎤h 0.051 kA kB h2⎢+ + + +⎣50 21.5 25.4 1000 ⎥⎦ Wq ′′ =34,600 W/m2.

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