A concrete wall 20 cm thick initially at 100 ° C, is suddenly exposed on one side to a hot gas at 800 ° C. If the convective heat transfer coefficient on the hot side is 5 W / m2 ° K and the cold side...

A concrete wall 20 cm thick initially at 100 ° C, is suddenly exposed on one side to a hot gas at 800 ° C. If the convective heat transfer coefficient on the hot side is 5 W / m2 ° K and the cold side is insulated, calculate, a) the time required for the insulated face to reach a temperature of 200 ° C, b) the temperature distribution at that instant.