Consider a curing kiln whose walls are made of 30-cm-thick concrete whose properties are k...

Consider a curing kiln whose walls are made of 30-cm-thick concrete whose properties are k = 0.9 W/m · °C and a = 0.23 × 10”i nr/s. Initially, the kiln and its walls are in equilibrium with the surroundings at 6°C. Then all the doors are closed and the kiln is heated by steam so that the temperature of the inner surface of the walls is raised to 42°C and is maintained at that level for 2.5 h. The curing kiln is then opened and exposed to the atmospheric air after the stream flow is turned off. If the outer surfaces of the walls of the kiln were insulated, would it save any energy that day during the period the kiln was used for curing for 2.5 h only, or would it make no difference? Base your answer on calculations.

FIGURE P18-92