Air flows over a flat plate at a velocity of 3 m/sec and ambient conditions are, the pressure is 761 mm of hg and tempera- ture is 15°c. the plate is maintained at 85°c. if the length of the plate is 100 cm along the flow of the air, find out the heat lost by 50 cm of the plate which is measured from the trailing edge. plate width is 50 cm.

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]