![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
The vapour–liquid equilibrium (VLE) properties of polar and non-polar fluids have been modelled by the use of two modified van der Waals (vdW)-type equations of state (EOSs). In this article, a revised method is applied to the above-mentioned EOSs to improve the representation of VLE properties of different class of fluids. In this respect, the repulsion parameter b is considered to be temperature dependent and also a temperature-dependent revision factor α(T) is introduced to the liquid fugacity coefficient expression derived from traditional isothermal integration to reproduce the vapour pressure (Ps) of pure liquids. The present method is also extended to represent the VLE properties of binary mixtures containing noble gases, refrigerants and hydrocarbons. This method outperforms the original vdW-type EOSs in predicting the VLE and pressure-volume-temperature (PVT) properties of 22 pure substances and 7 binary mixtures.
Acknowledgement
We thank Shiraz University and Shiraz University of Technology for supporting this project.
| Nomenclature and units | ||
| a | = | Strengths of attractive forces between spheres, J m–3 |
| b | = | van der Waals co-volume, m3 |
| P | = | Pressure, Pa |
| R | = | Gas constant, J mole–1 K–1 |
| T | = | Absolute temperature, K |
| k | = | Boltzmann constant, J K–1 |
| Z | = | Compression factor |
| V | = | Molar volume |
| a1–a4 | = | Coefficients in temperature function for α(T) |
| b1–b3 | = | Coefficients in temperature function for b(T) |
| x | = | Mole fraction |
| Greek letters | ||
| ρ | = | Molar density |
| η | = | Packing fraction |
| α | = | Temperature-dependent revision factor for fugacity coefficient |
| φ | = | Fugacity coefficient |
| Subscripts | ||
| c | = | Critical |
| m | = | Mixture |
| att | = | Attraction contribution |
| rep | = | Repulsion contribution |
| r | = | Reduced state |
| Superscripts | ||
| l | = | Liquid |
| v | = | Vapour |
| s | = | Saturated state |