Aniline is to be cooled from 200 to 150°f in a double-pipe heat exchanger having a total outside area of 70 ft2. for cooling, a stream of toluene amounting to 8,600 lb/h at a temperature of 100°f is available. the exchanger consists of 1¼-in. schedule 40 pipe in 2-in. schedule 40 pipe. the aniline flow rate is 10,000 lb/h.

(a) if flow is countercurrent, what are the toluene outlet temperature, the lmtd, and the overall heat-transfer coefficient?

(b) what are they if flow is parallel?

(c) how much aniline can be cooled if the over-all heat-transfer coefficient is 70 btu/ft2•h•°f?

To save energy, the air supply to a 2000 ft office has been shut off overnight and the room temperature has dropped to 40°f. in the morning, the thermostat is reset to 70°f and warm air at 120 f begins to flov in at 200ft'/min. the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct. the air pressure is nearly 1 atm everywhere. ignoring heat transfer with the surroundings and kinetic and potential energy effects, estimate how long it takes for the room temperature to reach 70°f. plot the room temperature as a function of time.