Chapter 7 External Forced Convection7-83A steam pipe is to be covered with enough insulation to reduce the exposed surface temperature to 30°C . The thickness of insulation that needs to be installed is to be determined. Assumptions1Heat transfer is steady since there is no indication of any change with time. 2 Heat transfer is one-dimensional since there is thermal symmetry about the centerline and no variation in the axial direction. 3 Thermal properties are constant. 4 The thermal contact resistance at the interface is negligible. PropertiesThe thermal conductivities are given to be k= 52 W/m⋅°C for cast iron pipe and k= 0.038 W/m⋅°C for fiberglass insulation. AnalysisThe thermal resistance network for this problem involves 4 resistances in series. The inner radius of the pipe is r1= 2.0 cm and the outer radius of the pipe and thus the inner radius of insulation is r2= 2.3 cm. Letting r3represent the outer radius of insulation, the areas of the surfaces exposed to convection for a L
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This note was uploaded on 01/22/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.