(1) A constant-pressure insulated piston-cylinder device contains 1.7 kg of saturated liquid-vapor mixture of water at 150 kPa with an initial quality of 0.2. Energy is then added to the system by an electric heater until all the liquid is vaporized. The environment is at 99 kPa and 2°C. Calculate the change in exergy of the contents in kJ.
(2) Air is cooled from 128°F to 62°F at a rate of 0.8 lbm/s in a heat exchanger. The coolant is water that enters the exchanger at 36°F and 0.6 lbm/s. What is the rate of exergy destruction in this heat exchanger, in units of Btu/s? Assume atmospheric pressure and negligible pressure drop in both fluids, and the environment is 46°F.