Water at 60F enters a 1-in.-ID tube that is used to cool a nuclear reactor. The water flow rate is 30 gal/min.

Determine the total heat transfer, the exiting water temperature, and the wall temperature at the exit of a 15-ft long

tube if the tube wall condition is one of uniform heat flux of

500 Btu/hr ft2

requiero la solucion paso a paso

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 the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct.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.