During air cooling of steel balls, the convection heat transfer coefficient is determined experimentally as a func- tion of air velocity to be h 17.9v054 for 0.5 < v< 2 m/s, where h and v are in w/m2.k and m/s, respectively. consider a 24-mm-diameter steel ball initially at 300°c with a thermal conductivity of 15 w/m-k. the steel balls are cooled in air at 10°c and a velocity of 1.5 m/s. determine the initial values of the heat flux and the temperature gradient in the steel ball at the surface.

A2-m rigid tank initially contains saturated water vapor at 100 kpa. the tank is connected to a supply line through a valve. steam is flowing in the supply line at 600 kpa and 300 c. the valve is opened, and steam is allowed to enter the tank until the pressure in the tank reaches the line pressure, at which point the valve is closed. a thermometer placed in the tank indicates that the temperature at the final state is 200°c. determine (a) the mass of steam that has entered the tank (b) the amount of heat transfer.