Acounter-flow double-pipe heat exchanger serves as an oil cooler with oil flowing in one direction through the inner tube and cooling water in the opposite direction through the annulus. the oil flow rate is 0.63 kg/s, the oil has a specific heat of 1.68 kj/(kg. k), the water flow rate is 0.5 kg/s and its specific heat is 4.19 kj/(kg. k). in a test of a prototype, oil entering at 78 oc was cooled to 54oc when the entering water temperature was 30oc. the possibility of increasing the area of the heat exchanger by increasing the length of the double pipe is to be considered. if the flow rates, fluid properties, and entering temperatures remain unchanged, what will the expected outlet temperature of the oil be if the area is increased by 20%?