It is desired to cool the engine oil for a large engine in a double pipe heat exchanger. The oil at a flow rate of 1.8 Kg/s is required to be cooled from 95 C to 90 C using water at a flow rate of 1.2 Kg/s and 25 C. A number of 7 m long carbon steel hairpin with 1(1/4) by 2 nominal, schedule of 40 pipe sizes are available. The inner tube contains the engine oil. How many hairpins are required? Determine the outlet temperatures, the heat transfer rate, and the pressure drops for the exchanger