Air is compressed steadily and adiabatically from 17°C and 90 kPa to 200°C and 400 kPa. Assuming constant specific heats for air at room temperature, the isentropic efficiency of the compressor is (a) 0.76 (b) 0.94 (c) 0.86 (d) 0.84 (e) 1

Water steam flows steadily through an adiabatic turbine. The inlet conditions of steam are 1.0 x 106 Pa and 600°C, one of the exit conditions is 7.5 x 10³ Pa. Assuming the process is isentropic, determine (with the help of the steam table): (a) the temperature of the steam at the exit (K). (b) the quality of the steam at the exit (%). (c) the specific enthalpy of the steam at the exit (kJ/kg). (d) the work done per unit mass by the turbine (kJ/kg).

A steady-flow compressor has R-134a entering at 120 kPa as a saturated vapor and exits at 800 kPa and 50°C, requiring 55 kJ/kg of work. Assume that the boundary of the compressor is at 30°C. What is the specific enthalpy of the R-134a at the inlet, in kJ/kg? What is the specific enthalpy of the R-134a at the outlet, in kJ/kg? How much heat transfer, in kJ/kg, exits the system?