A rigid tank contains 5 kg of refrigeratnt-134a initially at 20°C and 140 kPa. The refrigerant is now cooled while being stirred until its pressure drops to 100 kPa.Determine the

entropy change (kJ/K) of the refrigerant during the process. Steam enters an adiabatic turbine at 5 MPa and 450°C and leaves at a pressure of1.4 MPa. Determine the work output of the turbine per unit mass of steam if the process is reversible. The compressor of a refrigerator compresses saturated R-134a vapor at -10°C to800 kPa. How much work (kJ/kg) does this process require when the process is isentropic?