steam pipe 75 mm inside and 90 mm outside diameter is lagged with two successive layers of insulation. The layer in contact with the pipe is 38 mm asbestos and the asbestos layer is covered with 25 mm thick magnesia insulation. The convective film coefficients for the inside and outside surfaces are 227 W/m2-K and 6.8 W/m2-K, respectively. The steam temperature is 375oC and the ambient temperature is 35oC. Thermal conductivities in W/m-oC area as follows: pipe material=45, asbestos= 0.14, and magnesia insulation=0.07. Illustrate and label the schematic layout and the equivalent thermal network and calculate (a) the steady state loss of heat transfer for 60 m length of pipe length, (b) the overall heat transfer coefficient based on the outside and inside surface areas of the lagged
A steam pipe 75 mm inside and 90 mm outside diameter is lagged with two successive layers of insulation. The layer in contact with the pipe is 38 mm asbestos and the asbestos layer is covered with 25 mm thick magnesia insulation. The convective film coefficients for the inside and outside surfaces are 227 W/m2-K and 6.8 W/m2-K, respectively. The steam temperature is 375oC and the ambient temperature is 35oC. Thermal conductivities in W/m-oC area as follows: pipe material=45, asbestos= 0.14, and magnesia insulation=0.07. Illustrate and label the schematic layout and the equivalent thermal network and calculate (a) the steady state loss of heat transfer for 60 m length of pipe length, (b) the overall heat transfer coefficient based on the outside and inside surface areas of the lagged steam pipe, and (c) the interface temperature between the two layers of insulations.
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