Consider a shell in tube heat exchanger for cooling oil using cold water. Oil flows through the inner tube at the rate of 0.65 kg/s while water flows through the annulus at the rate of 0.55 kg/s. The oil is to be cooled from 75?C to 50?C. The temperature of the entering water is 28?C. Oil and water may be treated as pure substances with constant specific heat capacities of 1.65 kJ/kg-K and 4.2 kJ/kg-K, respectively. Calculate the water temperature (K) at the exit, (a) if there is no heat loss from the heat exchanger to the surroundings, and (b) if heat is lost to the surroundings at a rate of 6 kW.