An airplane is consuming fuel at a rate of 8 gal/min when cruising at a constant altitude of 10,000 ft at constant speed. assuming the drag coefficient and the engine efficiency to remain the same, determine the rate of fuel consumption at an altitude of 30,000 ft at the same speed. take the density of standard air as rho1 = 0.05648 lbm/ft3 at 10,000 ft and rho2 = 0.02866 lbm/ft3 at 30,000 ft.

Athin walled concentric tube exchanger is used to cool engine oil from 160°c to 60°c with water that is available at 25°c acting as a coolant. the oil and water flow rates are each at 2 kg/s, and the diameter of the inner tube is 0.5 m and the corresponding value of the overall heat transfer coefficient is 250 w/m2. oc. how long must the heat exchanger be to accomplish the desired cooling? cpwater=4.187 kj/kg-candcpengine el=2.035 kj/kg·°c, oil . 120]