Unit Five Homework Solutions


  1. Steam flows steadily through an adiabatic turbine. The inlet conditions of the steam are 10 MPa, 450oC, and 80 m/s. The exit conditions are 10 kPa, 92% quality, and 50 m/s. The mass flow rate of the steam is 12 kg/s. Determine (a) the change in kinetic energy, (b) the power output, and (c) the turbine inlet area.
  2. Argon gas enters an adiabatic turbine steadily at 900 kPa and 450oC with a velocity of 80 m/s and leaves at 150 kPa with a velocity of 150 m/s. The inlet area of the turbine is is 60 cm2. If the power output of the turbine is 250 kW, determine the exit temperature of the argon.
  3. Refrigerant-134a enters an adiabatic compressor as saturated vapor at -24oC and leaves at 0.8 MPa and 60oC. The mass flow rate of the refrigerant is 1.2 kg/s. Determine (a) the power input to the compressor and (b) the volume flow rate of the refrigerant at the compressor inlet.
  4. Refrigerant-134a is throttled from the saturated liquid state at 700 kPa to a pressure of 160 kPa. Determine the temperature drop during this process and the final specific volume of the refrigerant.
  5. Refrigerant-134a at 1 MPa and 90oC is to be cooled to 1 MPa and 30oC in a condenser by air. The air enters at 100 kPa and 27oC with a volume flow rate of 600 m3/min and leaves at 95 kPa and 60oC. Determine the mass flow rate of the refrigerant.
  6. Air enters the evaporator section of a window air conditioner at 14.7 psia and 90 oF with a volume flow rate of 200 ft3/min. Refrigerant-134a at 20 psia with a quality of 30% enters the evaporator at a rate of 4 lbm/min and leaves as a saturated vapor at the same pressure. Determine (a) the exit temperature of the air and (b) the rate of heat transfer from the air.