Question: In a part of a solar-operated seawater desalting plant, air saturated with water vapor at 1 atm and 55°C passes into a condenser where the fresh water is recovered. The condenser is built up of a bank of circular tubes with cooling seawater flowing inside the tubes and the saturated air flowing normally. The heat-transfer coefficient on the inside of the tubes is estimated to be 1400W/(m2 . K). The tube wall is 0.75 mm thick and has a thermal conductivity of 100W/(m . K). On the outside of the tubes, it is estimated that if there were no mass transfer, the average heat-transfer coefficient would be 70W/(m2 • K). If the cooling-water temperature in the first row of tubes (the tubes over which the 55°C saturated air is flowing) is 46°C, calculate the rate of condensation per unit of surface area and the rate of heat transfer to the coolant. Neglect the resistance of the condensate film on the tubes. (Would it be significant if the film thickness was, say, 0.1 mm?)