A short brass cylinder (ρ = 8530 kg/m3, cp = 0.389 kJ/kg · °C. k = 110 W/m · °C, and α = 3...

A short brass cylinder (ρ = 8530 kg/m3, cp = 0.389 kJ/kg · °C. k = 110 W/m · °C, and α = 3.39 × 10-5 nr/s) of diameter D = 8 cm and height H = 15 cm is initially at a uniform temperature of Ti = 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 h = 40 W/m2 · °C. Calculate (a) the center temperature of the cylinder; (b) the center temperature of the top surface of the cylinder; and (c) the total heat transfer from the cylinder 15 min after the start of the cooling.

FIGURE P18-78