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Air enters a 25cm-diameter 12 -m-long underwater duct at 50C and 1 atm at a mean velocity of 7m/s, and is cooled by the water outside. If the average heat transfer coefficient is 85W/m2.K and the tube temperature is nearly equal to the water temperature of 10C, determine the exit temperature of the air and the rate of heat transfer. Evaluate air properties at a bulk mean temperature of 30C. Is this a good assumption? (6 Marks)