Chapter 12 Radiation Heat Transfer12-31A long cylindrical rod coated with a new material is placed in an evacuated long cylindrical enclosure which is maintained at a uniform temperature. The emissivity of the coating on the rod is to be determined. Assumptions1Steady operating conditions exist 2The surfaces are opaque, diffuse, and gray. PropertiesThe emissivity of the enclosure is given to be ε2= 0.95. AnalysisThe emissivity of the coating on the rod is determined from ()⎟⎠⎞⎜⎝⎛−+−⋅×=⎟⎟⎠⎞⎜⎜⎝⎛−+−=−10195.095.011]K200K500)[KW/m1067.5](m)m)(101.0([W811)(144428212214241112επσrrTTAQ&D2= 0.1 m T2= 200 K ε2= 0.95 D1= 0.01 m T1= 500 K ε1= ? Vacuum which gives ε1= 0.07412-32E The base and the dome of a long semicylindrical duct are maintained at uniform temperatures. The net rate of radiation heat transfer from the dome to the base surface is to be determined.
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This note was uploaded on 01/24/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.