19 million joules of chemical energy are supplied to a boiler in a power plant. 5 x 106 joules of energy are lost through unburnt fuel. the boiler radiates 1.1 million joules to the atmosphere. what is the efficiency of the boiler?

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]