Extension of GMA Equation of State to Long-Chain Alkanes Using Group Contribution Method

Abstract

In this work, the group contribution method has been applied in combination with the Goharshadi−Morsali−Abbaspour (GMA) equation of state (EoS) to calculate the density of n-alkanes and their binary and ternary mixtures. Each normal alkane has been considered as a hypothetical mixture of methyl and methylene groups in which the interaction potential between each pair is assumed to be the average effective pair potential (AEPP). The GMA EoS has been modified for n-alkanes according to the group contribution method (GCM), and the new regularity is called GCM−GMA EoS. Propane, n-butane, and n-hexane have been used as basic compounds to investigate the contribution of each carbonic (methyl and methylene) group in the new EoS parameters. The calculated parameters along with GCM−GMA EoS have been used to calculate the density of n-alkanes and their binary and ternary mixtures at different temperatures, pressures, and compositions. The results in the prediction of density show good agreement with experimental data. To show the ability of this equation of state in the prediction of density, the calculated densities of some liquid mixtures have been compared with those computed from original GMA EoS according to mixing and combining rules and also with the COSTALD method. The GCM-GMA EoS have been also compared with four cubic equations of state, namely, RM (Riazi-Mansoori), RK (Redlich-Kwong), SRK (Soave-Redlich-Kwong), and PR (Peng-Rabinson). The results show that the group contribution method gives better results than other methods.

Further development of the predictive models for physical properties of pure ionic liquids: Thermal conductivity and heat capacity

“…Many of these models have been based on those originally applied to molecular solvents using group contribution methods or equation of state relationships [26][27][28][29][30].…”

A new equation of state for molten alkali metal alloys

“…Using the values of C and D parameters along with the Eqs. (27)(28)(29)(30)(31)(32), these derived properties of liquid alkali metal alloys can be calculated at any thermodynamic state point. Isobaric expansion coefficient may be calculated from the following expression:…”

“…(1) instead of the Lennard-Jones (LJ; 12-9) as the pair potential function in the derivation of the GMA EoS [20], which is valid for most of normal fluids [21][22][23][24][25][26][27][28][29][30][31], a new regularity can be obtained for liquid alkali metals over the whole liquid range (in the range of T b T c and ρ > ρ c ). Using Eqs.…”

A new regularity and an equation of state for alkali metals over the whole liquid range

“…In the final form, it states that for dense normal fluids, isotherms of (2Z − 1)V 3 m are linear versus , where Z, V m , and = 1/V m are compressibility factor, molar volume, and molar density, respectively. This regularity has been found to be valid for different classes of normal fluids in both pure and mixture forms [22][23][24][25][26][27][28][29] and holds very well for these liquids in the range of T < T c and > c .…”