This problem considers an adiabatic turbine/expander using the Peng/Robinson equation of state.

(a)Using the Peng-Robinson equation of state, calculate the change in enthalpy (J/mol) for a reversible adiabatic turbine/expander when steam is expanded from a pressure of 8 MPa and temperature of 700 K to a pressure of 1 MPa. Remember to use the correct sign. Use a reference state H_R = 0 for a real fluid in the most stable state of aggregation at 298.15K and 0.1 MPa. (Note that the Peng-Robinson is only semi-quantitative for water, so the results will differ slightly from steam table calculations.)

b) What is the change in enthalpy in (J/mol) if the turbine/expander efficiency is _E = 0.82? Remember to use the correct sign.

NOTE: This is second time that I submit this question. First time, the answer was wrong.