The walls of a furnace are made of 1.3-ft-thick concrete (k = 0.64 Btu/h⋅ft⋅°F and α = 0.023 ft2/h). Initially, the furnace and the surrounding air are in thermal equilibrium at 70°F. The furnace is then fired, and the inner surfaces of the furnace are subjected to hot gases at 1800°F with a very large heat transfer coefficient. Determine how long it will take for the temperature of the outer surface of the furnace walls to rise to 70.1°F.
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The walls of a furnace are made of 1.3-ft-thick concrete (k = 0.64 Btu/h⋅ft⋅°F and α = 0.023 ft2/h)....
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