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?