8-34 A piston-cylinder device contains 8 kg of refrigerant-

134a at 0:7 MPa and 60°C. The refrigerant is now cooled at

constant pressure until it exists as a liquid at 20°C. If the sur-

roundings are at 100 kPa and 20°C, determine (a) the exergy

of the refrigerant at the initial and the final states and (b) the

exergy destroyed during this process.