A piston–cylinder device initially contains 0.8 m3 of nitrogen gas at 534 kPa and 22 °C. An electric heater within the device is turned on and is allowed to pass a current of 2 A for 8 min from a 107 -V source. Nitrogen expands at constant pressure, and a heat loss of 1,876 J occurs during the process. Determine the final temperature of nitrogen. Assume that Cp for nitrogen is equal to 1.039 KJ

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]