polykin.thermo.eos

This module implements equations of state (EOS) for gas and liquid mixtures.

B_pure

B_pure(
    T: float | FloatArray, Tc: float, Pc: float, w: float
) -> Union[float, FloatArray]

Estimate the second virial coefficient of a nonpolar or slightly polar gas.

\[ \frac{B P_c}{R T_c} = B^{(0)}(T_r) + \omega B^{(1)}(T_r) \]

where \(B\) is the second virial coefficient, \(P_c\) is the critical pressure, \(T_c\) is the critical temperature, \(T_r=T/T_c\) is the reduced temperature, and \(\omega\) is the acentric factor.

References

• RC Reid, JM Prausniz, and BE Poling. The properties of gases & liquids 4th edition, 1986, p. 40.

PARAMETER	DESCRIPTION
T	Temperature. Unit = K. TYPE: float | FloatArray
Tc	Critical temperature. Unit = K. TYPE: float
Pc	Critical pressure. Unit = Pa. TYPE: float
w	Acentric factor. TYPE: float

RETURNS	DESCRIPTION
float | FloatArray	Second virial coefficient, \(B\). Unit = m³/mol.

Source code in src/polykin/thermo/eos/virial.py

def B_pure(T: Union[float, FloatArray],
           Tc: float,
           Pc: float,
           w: float
           ) -> Union[float, FloatArray]:
    r"""Estimate the second virial coefficient of a nonpolar or slightly polar
    gas.

    $$ \frac{B P_c}{R T_c} = B^{(0)}(T_r) + \omega B^{(1)}(T_r) $$

    where $B$ is the second virial coefficient, $P_c$ is the critical pressure,
    $T_c$ is the critical temperature, $T_r=T/T_c$ is the reduced temperature,
    and $\omega$ is the acentric factor.

    **References**

    *   RC Reid, JM Prausniz, and BE Poling. The properties of gases & liquids
        4th edition, 1986, p. 40.

    Parameters
    ----------
    T : float | FloatArray
        Temperature. Unit = K.
    Tc : float
        Critical temperature. Unit = K.
    Pc : float
        Critical pressure. Unit = Pa.
    w : float
        Acentric factor.

    Returns
    -------
    float | FloatArray
        Second virial coefficient, $B$. Unit = m³/mol.
    """
    Tr = T/Tc
    B0 = 0.083 - 0.422/Tr**1.6
    B1 = 0.139 - 0.172/Tr**4.2
    return R*Tc/Pc*(B0 + w*B1)