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?

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.