Consider an air-water heat exchanger. Air flowing steadily at the rate of 0.5 kg/s enters the heat exchanger at 100 kPa and 47ºC (State 1) and exits at 90 kPa and 37ºC (State 2). Water flowing at the rate of 0.2 kg/s enters at 100 kPa and 27ºC (State 3) and exits with negligible pressure change (State 4). Consider that the average temperature of the surface separating the two fluids is 37ºC. Stray heat transfer from the heat exchanger may be neglected. Consider constant specific heats for both water and air.
(a) Calculate the rate of entropy generation (kW/K) for the air flow.
(b) Calculate the rate of entropy generation (kW/K) for the heat exchanger.