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All Textbook Solutions for Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

10.39P 10.40P 10.41P 10.42P 10.43P 10.44P 10.45P 10.46P 10.47P 10.48P 10.49P 10.50P 10.51P 10.52P 10.53P 10.54P 10.1DP 10.2DP 10.3DP 11.1P A tungsten filament is heated to 2700 K. At what wavelength is the maximum amount of radiation emitted? What fraction of the total energy is in the visible range (0.4to0.75m)? Assume that the filament radiates as a graybody.Determine the total average hemispherical emissivity and the emissive power of a surface that has a spectral hemispherical emissivity of 0.8 at wavelengths less than 1.5m, 0.6 at wavelengths from 1.5to2.5m, and 0.4 at wavelengths longer than 2.5m. The surface temperature is 1111 K.11.4P 11.5P 11.6P 11.7P 11.8P 11.9P 11.10P 11.11P 11.12P 11.13P 11.14P 11.15P 11.16P 11.17P 11.18P 11.19P 11.20P 11.21P 11.22P 11.23P 11.24P 11.25P 11.26P 11.27P 11.28P 11.29P 11.30P 11.31 A large slab of steel 0.1 m thick contains a 0.1 -m-di- ameter circular hole whose axis is normal to the surface. Considering the sides of the hole to be black, specify the rate of radiative heat loss from the hole. The plate is at 811 K, and the surroundings are at 300 K. 11.32P 11.33P 11.34P 11.35P 11.36P 11.37P 11.38P 11.39P 11.40P 11.41 Determine the steady-state temperatures of two radiation shields placed in the evacuated space between two infinite planes at temperatures of 555 K and 278 K. The emissivity of all surfaces is 0.8. Three thin sheets of polished aluminum are placed parallel to each other so that the distance between them is very small compared to the size of the sheets. If one of the outer sheets is at 280C and the other outer sheet is at 60C, calculate the temperature of the intermediate sheet and the net rate of heat flow by radiation. Convection can be ignored.11.43P 11.44P 11.45P 11.46P 11.47P 11.48P 11.49P 11.50P 11.51P 11.52P 11.53P 11.54P 11.55P 11.56P 11.57P 11.58P 11.59P 11.60P 11.61P 11.62P 11.63P 11.64P 11.65P 11.66P 11.67P 11.68 Two infinitely large, black, plane surfaces are 0.3 m apart, and the space between them is filled by an isothermal gas mixture at 811 K and atmospheric pressure. The gas mixture consists of by volume. If one of the surfaces is maintained at 278 K and the other at 1390 K, calculate (a) the effective emissivity of the gas at its temperature, (b) the effective absorptivity of the gas to radiation from the 1390 K surface, (c) the effective absorptivity of the gas to radiation from the 278 K surface, and (d) the net rate of heat transfer to the gas per square meter of surface area. 11.1DP 11.2DP 11.3DP 11.4DP

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