A cylindrical container with do = 0.5 m and L = 7.5 mis used for chemical processing with insulated ends. The inside ofthe cylinder is kept at 400o C with 5 kW of power comingfrom a heater. The outer surface temperature is known to be 78oC and ambient air in the factory is 20C.
a.) Estimate the heat transfer coefficient between the surfaceof the cylinder and the ambient air and find the thermal resistancebetween the surface of the cylinder and the chemicals.
A large fan is used to cool the surface of the cylinder with avelocity of 25 m/s. As a result, the heater had to compensate forthe cooling in order to maintain the chemicals inside the cylinderat 400C. Assume the air properties are: ? = 0.96 kg/m3, k = 0.032W/m-K, ? = 215x10-7 Pa-s, and Pr = 0.70.
b.) Estimate the heat transfer coefficient between the air andthe cylinder surface.
c.) Estimate the surface temperature of the cylinder after thefan is turned on and determine the increase in the heater power(W).
