Consider a mixing tank initially containing 2000 lbm of liquid water. the tank is fitted with two inlet pipes, one delivering hot water at a mass flow rate of 0.8 lbm/s and the other delivering cold water at a mass flow rate of 1.2 lbm/s. water exits through a single exit pipe at a mass flow rate of 2.5 lbm/s. determine the amount of water [lbm] in the tank after one hour.

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.