A piston-cylinder device contains 5 kg of refrigerant-134a at 0.7 MPa and 60 degrees C. The refrigerant is now cooled at constant pressure until it exists as a liquid at 24 degrees C. If the surroundings are at 100kPa and 24 degrees C, determine (a) the exergy of the refrigerant at the initial and final states and (b) the exergy destroyed during the process.