PengRobinson EOS in FPROPS
Work on this is went on as a part of GSoC 2010 (Project Ankit) and continues as part of GSoC 2011 (Richard Towers). See also FPROPS.
Comments and suggestions are welcome
Overview
The Peng-Robinson EOS is a cubic equation of state in that it contains volume terms to the third power, it is one of several equations of state that can be expressed in the form
- <math>
\begin{align} P=\frac{RT}{V-b}-\frac{a}{V^2+ubV+wb^2} \end{align} </math> or
- <math>
\begin{align} Z^3-(1+B^*-uB^*)Z^2+(A^*+wB^{*2}-uB^*-uB^{*2})Z-A^*B^*-wB^{*2}-wB^{*3}=0 \end{align} </math> Where
- <math>
\begin{align} A^*=\frac{aP}{R^2T^2} \end{align} </math>
- <math>
\begin{align} B^*=\frac{bP}{RT} \end{align} </math> In the Peng-Robinson values for <math>u,</math> <math>w</math>, <math>b</math> and <math>a</math> are set as
- <math>
\begin{align} u=2 \end{align} </math>
- <math>
\begin{align} w=-1 \end{align} </math>
- <math>
\begin{align} b=\frac{0.7780RT_c}{P_c} \end{align} </math>
- <math>
\begin{align} a=\frac{0.45724R^2T_c^2}{P_c}[1+f\omega(1-T_r^{\frac{1}{2}})]^2 \end{align} </math>
- <math>
\begin{align} f\omega=0.37464+1.54226\omega-0.26992\omega^2 \end{align} </math> For any given pair of P,V and T we can solve for the other. Other thermodynamic properties can be obtained from the departure functions.