A Rankine steam power plant should operate with a high pressure of 3 MPa, a low pressure of 10 kPa, and the boiler exit temperature should be 500C. The available high-temperature source is the exhaust of 175 kg/s air at 600C from a gas turbine. If the boiler operates as a counter flowing heat exchanger where the temperature difference at the pinch point is 20C, find the maximum water mass flow rate possible and the air exit temperature.