Problem # p015

Conservation of energy, isentropic expansion

Steam at 3.0 MPa and 500°C enters a well-insulated turbine at a velocity of 70 m/s and exits at 0.3 MPa with a velocity of 140 m/s. The manufacturer claims that his/her turbine produces a work of 667 kJ per kg of steam flowing through the turbine. Let's run a check on this claim.

  1. Based on the claimed work output, the other data provided by the manufacturer, and the property data given in the table below, determine the enthalpy of the steam leaving the turbine.

  2. Based on the results from part 1), the given exit pressure and the table given below, determine the entropy of the water leaving the turbine using linear interpolation.

  3. Clearly state whether your results from part 2) support or disprove the manufacturer's claim and what the reason for your statement is.

p [MPa]T [°C]v [m³/kg]u [kJ/kg] h [kJ/kg]s [kJ/(kg K)]
3.05000.116193108.0 3456.57.2338
0.31500.63392570.8 2761.07.0778
0.32000.71632650.7 2865.67.3115