[case] PengRobinson

Peng-Robinson equation of state.

This class implements the Peng-Robinson equation of state (PR-EOS), a widely used cubic equation of state for describing the behaviour of real gases, particularly hydrocarbons. It accounts for non-ideal behaviour of fluids over a range of temperatures and pressures.

The equation is given in terms of the molar density $\rho$ as:

$$P = \frac{R T \rho}{1 - b \rho} - \frac{a \rho^2}{1 + 2b \rho - b^2 \rho^2}$$

where $P$ is the pressure, $T$ the temperature, $\rho$ the molar density, $R$ the universal gas constant, and $a$, $b$ are substance-specific parameters.

The parameters $a$ and $b$ are computed from the critical temperature $T_c$ in Kelvin, critical pressure $p_c$ in Pascal, and (dimensionless) acentric factor $\omega$ as follows:

$$a = 0.457235 \frac{R^2 T_c^2}{p_c}$$

$$b = 0.077796 \frac{R T_c}{p_c}$$

The Peng-Robinson equation is applicable for a wide range of substances (gases and liquids), particularly hydrocarbons, at conditions ranging from subcritical to supercritical. The EOS is not suitable for solid phases or very low-temperature applications where real gases behave ideally.

All input parameters (temperature, pressure, density) are assumed to be in SI units:

• Temperature $T$ in Kelvin [K]
• Pressure $P$ in Pascal [Pa]
• Mass density $\rho$ in $[kg/m^3]$
• The resulting properties will also follow SI units.

Original source: D.-Y. Peng and D.B. Robinson, "A New Two-Constant Equation of State," Industrial & Engineering Chemistry Fundamentals, vol. 15, pp. 59-64, 1976.

Child parameters, attributes and cases

• [tag] acentric_factor
• [tag] critical_pressure
• [tag] critical_temperature

Additional info

No additional info.

Used in the following test data files

• [→ ogs/ogs/master | → doc] TH2M/H/pressure_PengRobinson/pressure_preos.prj
• [→ ogs/ogs/master | → doc] TH2M/HM/compression_PengRobinson/compression_preos.prj
• [→ ogs/ogs/master | → doc] TH2M/TH/temperature_PengRobinson/temperature_preos.prj