The air-conditioning system shown utilizes a 16-in diameter galvanized drainage pipe buried at a depth where the soil maintains the pipe surface at 60°f. air is forced through the pipe at a volumetric flow rate of 1200 cfm. the indoor air is maintained at a steady temperature of 72°f. if 63°f cooling air is desired, what length of pipe is required? what is the heat transfer? assume that the pipe has a roughness of 0.10 inch. how can the length of pipe be reduced and still achieve the same heat transfer?

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.