Select a practical fluid to use in a manometer to measure pressures up to 69 kpa of an inert gas ( 3  = 10.4 n/m ), if water (  = 3 9,800 n/m ), oil (  = 3 0.82 g/cm ), and mercury (  = 3 13.6 g/cm ) are available. discuss the rationale for your choice(s).

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]