A heated spherical ceramic object (diameter= 10cm), initially at 1200k, is held in a large enclosure whose walls are maintained at a temperature of 300k. The sphere has an emissivity of 0.7. Properties of Sphere: Density =4500 kg/m^3, heat capacity= 400 J/(kg.K); thermal conductivity= 22 W/ (m.K). Assume properties of the sphere do not vary with temperature. The rest of the enclosure is filled with stagnant nitrogen at a bulk temperature of 300 K.
a) What is the initial rate of heat transfer from sphere?
b) What are the relative contributions of radiation and convection to the rate of heat loss when the sphere is at 1200K
c) What are the relative contributions of radiation and convection to the rate of heat loss when the sphere is at 600K
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Nice try!
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