Reconsider Prob. 4–113. Using EES (or other) software, investigate the effect of the cooling time on the center temperature of the cylinder, the center temperature of the top surface of the cylinder, and the total heat transfer. Let the time vary from 5 min to 60 min. Plot the center temperature of the cylinder, the center temperature of the top surface, and the total heat transfer as a function of the time, and discuss the results.

Data from problem 113

A short brass cylinder (ρ = 8530 kg/m³, c_p = 0.389 kJ/kg · K, k = 110 W/m · K, and α = 3.39 × 10^-5 m²/s) of diameter 8 cm and height 15 cm is initially at a uniform temperature of 150°C. The cylinder is now placed in atmospheric air at 20°C, where heat transfer takes place by convection with a heat transfer coefficient of 40 W/m² · K. Calculate

(a) The center temperature of the cylinder;

(b) The center temperature of the top surface of the cylinder;

(c) The total heat transfer from the cylinder 15 min after the start of the cooling.