A rectangular ceramic kiln wall of area 0.75 m2 maintains a nearly constant surface temperature of 1100 K while a batch of pottery is fired for 8.0 h. Assume all energy leaves the hot surface by electromagnetic emission and that the reverse flow of energy from the 300 K room to the kiln is negligible.
For numerical work, use σ=5.67×10−8Wm−2K−4.
(a) Calculate the radiant power leaving the kiln wall during the firing period. Express your answer with appropriate units.
(b) Determine the total thermal energy emitted through that wall during the entire 8.0 h firing period. Give your answer in joules.
(c) Convert your result from part (b) to kilowatt-hours, a common billing unit for electrical energy.
(d) The kiln’s electrical heaters are only 60 % efficient at converting input electrical energy into thermal energy delivered to the inner surface of the wall. Using your previous answers, compute the total electrical energy that must be supplied to the kiln heaters during the 8.0 h period.