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Question: 1 a pipe in a power plant carries superheated steam...

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1. A pipe in a power plant carries superheated steam at 540 °C. The pipe has an inside diameter of 0.290 m, a wall thickness of 0.017 m, an outside diameter of 0.324, and is covered with a 0.075-m-thick layer of calcium silicate insulation. The thermal conductivity of the insulation is 0.07 W(m K) at its average temperature (p. 848) and the thermal conductivity of the low chromium alloy steel pipe is 40 WI(m k) (p. 841). The steam is moving at high velocity, with a convective heat transfer coefficient inside the pipe, between the steam and the pipe wall, of 250 W/(m2.K). On the outside of the insulation, exposed to ambient air on a windy day, the convective heat transfer coefficient is 60 WI(m2.K) and the temperature of the air is 15 °C. The outer surface of the insulation is covered with a thin sheet of aluminum (not shown) to protect it and lower its emissivity, so radiative transfer from the surface to the surroundings may be neglected, and the aluminum also makes no significant contribution to conduction heat transfer resistance. a. What fraction (%) of the total of the convection plus conduction resistances to heat transfer is contributed by the alloy steel pipe wall? b. Calculate the rate of heat loss from the steam per meter length of the pipe, q(W/m). c. Estimate the temperature on the outer surface of the insulation (same as the temperature of the protective aluminum sheet). る:50 insulation 石丶:/5 ℃ =2 metal Σ尺
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