Development of equation of state for a double square-well fluid

IF 2.7 3区工程技术 Q3 CHEMISTRY, PHYSICAL Fluid Phase Equilibria Pub Date : 2025-03-31 DOI:10.1016/j.fluid.2025.114437

Mohammad Hossein Hadipanah, Seyed Hossein Mazloumi

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Abstract

A double square-well potential function is proposed to describe the interaction between unbounded particles. This model is constructed based on the Lennard-Jones potential function and has three adjustable parameters. Based on the two-layers local composition model, a coordination number model for this double square-well fluid is developed and then by using the generalized van der Waals partition function a new expression for the attractive part of equation of state is derived. Two new equations of state are presented by sum of the attractive term and repulsive expressions of Carnahan-Starling and van der Waals. These models have three adjustable parameters, which are obtained by simultaneously fitting vapor pressures and liquid densities of pure substances. The capability of these two models in correlation of the vapour pressure and liquid density and in prediction of the vapour molar volume and heat of vaporization of pure compounds is investigated. Good results obtained especially with the new EOS in which Carnahan-Starling repulsive term has been used. The results of this EOS are excellent even for large molecules such as long- chain alkanes from C₁₀ to C₂₀.

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双方井流体状态方程的发展

提出了一个双平方阱势函数来描述无界粒子间的相互作用。该模型基于Lennard-Jones势函数构造，具有三个可调参数。在双层局部组成模型的基础上，建立了双方井流体的配位数模型，并利用广义范德华配分函数导出了状态方程中吸引部分的新表达式。将Carnahan-Starling和van der Waals的吸引项和排斥表达式相加，给出了两个新的状态方程。这些模型有三个可调参数，它们是通过同时拟合纯物质的蒸汽压和液体密度得到的。研究了这两种模型在计算蒸汽压和液体密度的相关性以及预测纯化合物的蒸汽摩尔体积和汽化热方面的能力。特别是使用了Carnahan-Starling斥力项的新EOS得到了很好的结果。即使对于大分子，如从C10到C20的长链烷烃，EOS的结果也很好。

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来源期刊

Fluid Phase Equilibria 工程技术-工程：化工

CiteScore

5.30

自引率

15.40%

发文量

223

审稿时长

53 days

期刊介绍： Fluid Phase Equilibria publishes high-quality papers dealing with experimental, theoretical, and applied research related to equilibrium and transport properties of fluids, solids, and interfaces. Subjects of interest include physical/phase and chemical equilibria; equilibrium and nonequilibrium thermophysical properties; fundamental thermodynamic relations; and stability. The systems central to the journal include pure substances and mixtures of organic and inorganic materials, including polymers, biochemicals, and surfactants with sufficient characterization of composition and purity for the results to be reproduced. Alloys are of interest only when thermodynamic studies are included, purely material studies will not be considered. In all cases, authors are expected to provide physical or chemical interpretations of the results. Experimental research can include measurements under all conditions of temperature, pressure, and composition, including critical and supercritical. Measurements are to be associated with systems and conditions of fundamental or applied interest, and may not be only a collection of routine data, such as physical property or solubility measurements at limited pressures and temperatures close to ambient, or surfactant studies focussed strictly on micellisation or micelle structure. Papers reporting common data must be accompanied by new physical insights and/or contemporary or new theory or techniques.