Stainless steel ball bearings ( = 8085 kg/m3 and cp = 0.480 kJ/kg C) having a

Question:

Stainless steel ball bearings (ρ = 8085 kg/m3 and cp = 0.480 kJ/kg ∙ °C) having a diameter of 1.2 cm are to be quenched in water at a rate of 1400 per minute. The balls leave the oven at a uniform temperature of 900°C and are exposed to air at 30°C for a while before they are dropped into the water. If the temperature of the balls drops to 850°C prior to quenching, determine
(a) The rate of heat transfer from the balls to the air and
(b) The rate of exergy destruction due to heat loss from the balls to the air.