The condenser of a large steam power plant is a heat exchanger in which steam is condensed to liquid water. Assume the condenser to be a shell-and-tube heat exchanger consisting of a single shell and 30,000 tubes, each executing two passes. The tubes are of thin wall construction with D 25 mm, and steam condenses on their outer surface with an associated convection coefficient of ho 11,000 W/m2 · K. The heat transfer rate that must be effected by the exchanger is q 2 X 109 W, and this is accomplished by passing cooling water through the tubes at a rate of 3 X 104 kg/s (the flow rate per tube is therefore 1 kg/s). The water enters at 20°C, while the steam condenses at 50°C. What is the temperature of the cooling water emerging from the condenser? What is the required tube length L per pass?