1. Air is compressed by a 30 kW compressor from P1 to P2. The air temperature is maintained constant at 25 oC during this process as a result of heat transfer to the surroundings at 17 oC. Determine the entropy change of the air.
2. Heat in the amount of 100 kJ is transferred directly from a hot reservoir at 1200 K to a cold reservoir at 600 K. Calculate the entropy change of the two reservoirs and determine if the increase of entropy principle is satisfied.
3. Is a process that is internally reversible and adiabatic necessarily isentropic? Explain using an equation.
4. A well- insulated rigid tank contains 5 kg of a saturated liquid-vapor mixture of water at 150 kPa. Initially three-quarters of the mass is in the liquid phase. An electric resistance heater placed in the tank is now turned on and kept on until all the liquid in the tank is vaporized. Determine the entropy change of the steam during this process.
5. Steam enters a turbine at a pressure of P1 = 6 MPa and a temperature of T1 = 400 oC and leaves at a pressure of P2 = 100 kPa. Find the change in Specific Enthalpy of the steam if the expansion process is isentropic.
6. A piston-cylinder contains 1.2 kg of saturated water vapor at an initial temperature of T1 = 200 oC. Heat is transferred to the steam, so that the steam expands reversibly and isothermally to a final pressure of P2 = 800 kPa. Determine the heat transferred and the work done during this process.