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Heat capacity

For all phases, the consistent way to calculate heat capacity (including mixing enthalpy terms) is to calculate it from enthalpy. This is the default calculation routine for heat capacity. Other methods are described below.

Liquid heat capacity

The mixture liquid heat capacity is the molar average of the compound liquid heat capacities.

Temperature Correlation

The parameters for the temperature correlation for liquid heat capacity are available through TEA's PCD data files.

Corresponding states

Liquid heat capacity can be computed from a corresponding states method and the ideal gas capacity. Rowlinson (1969, see A140) proposed a Lee-Kesler heat capacity departure function which was later modified to:

\begin{displaymath}C^L_{p,i} - C^{ig}_p = 1.45 + 0.45 (1-T_r)^{-1} + 0.25 \om...... + 25.2 (1-T_r)^{1/3} T_r^{-1} +1.742 (1-T_r)^{-1} \right]\end{displaymath}

If the reduced temperature exceeds 0.98, a value of 0.98 is used instead.

Temperature derivatives are determined by perturbation.

Vapor heat capacity

The mixture vapor heat capacity is the molar average of the compound vapor heat capacities.

Temperature Correlation

The parameters for the temperature correlation for vapor heat capacity are available through TEA's PCD data files.

Solid heat capacity

The mixture solid heat capacity is the molar average of the compound solid heat capacities. The solid heat capacities are configured per compound.

Temperature Correlation

The parameters for the temperature correlation for solid heat capacity are available through TEA's PCD data files.

Temperature Correlation for liquid phase

If solid phase heat capacity data is not available, the liquid heat capacity temperature correlation can be selected for the solid phase. The parameters for the temperature correlation for liquid heat capacity are available through TEA's PCD data files.

Ideal gas contribution

If solid and liquid phase heat capacity data are not available, the ideal vapor heat capacity temperature correlation can be selected for the solid phase. The parameters for the temperature correlation for vapor heat capacity are available through TEA's PCD data files.

Zero contribution

For compounds that do not appear in the solid phase, zero contribution is a safe selection for solid heat capacity.

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