An adiabatic heat exchanger receives 3 kg/s of R12 as a saturated vapor at 960 kPa and condenses it to a saturated liquid at this pressure. The cooling water at 100 kPa enters the heat exchanger at 20 C and leaves at 35 C. Determine the heat transfer to the water in kW and the water flowrate in kg/s.

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.