The condenser in Problem 4.118 uses cooling water from a lake at 20◦C and it should not be heated more than 5◦C, as it goes back to the lake. Assume the heat transfer rate inside the condenser is ˙Q = 350 (W/m2 K) × A ΔT . Estimate the flow rate of the cooling water and the needed interface area. Discuss your estimates and the size of the pump for the cooling water.

Data from Problem 4.118

A condenser is maintained at 60◦C by cooling it with atmospheric air coming in at 20◦C and leaving at 35◦C. The condenser must reject 25 MW from the water to the air. Find the flow rate of air and the second-law efficiency of the heat exchanger.