Suppose the sphere in Problem 2-16 is covered with a 1-cm layer of an insulating material having k = 50 m W/m C and

Suppose the sphere in Problem 2-16 is covered with a 1-cm layer of an insulating material having k = 50 m W/m ∙ ºC and the outside of the insulation is exposed to an environment with h = 20 W/m2 ∙ ºC and T∞ = 10ºC. The inside of the sphere remains at 100ºC. Calculate the heat transfer under these conditions.
Problem 2-16
A spherical tank, 1 m in diameter, is maintained at a temperature of 120ºC and exposed to a convection environment. With h = 25W/m2 ∙ ºC and T∞ = 15ºC, what thickness of urethane foam should be added to ensure that the outer temperature of the insulation does not exceed 40ºC? What percentage reduction in heat loss results from installing this insulation?