Estimation of the critical properties of compounds using volume-based thermodynamics |
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Authors: | Javad Hekayati Sona Raeissi |
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Affiliation: | School of Chemical and Petroleum Engineering, Shiraz University, Shiraz, Iran |
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Abstract: | The importance, yet scarcity of the critical constants of thermally unstable fluids warrants the development of reliable methods for the estimation of these essential thermodynamic properties. A thorough investigation undertaken in this study on 1,589 compounds belonging to 83 chemical classes, indicated that the ratio of critical temperature to critical pressure of both low and high molecular weight compounds could be well expressed in terms of their volumetric properties. In addition, two new methodologies are presented for estimating Vc, as well as an indirect approach for prediction of Tc from surface tension data, altogether allowing the calculation of Zc. Moreover, comparative studies are made with five group contribution methods. It is also demonstrated that by employing the Peng-Robinson EOS, and without prior knowledge of the critical properties, it is possible to calculate various thermophysical properties including Psat., Tb, , ∆Hvap. , Cp, and even the Tc and Pc themselves. |
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Keywords: | critical pressure critical temperature critical volume derivative properties PR EOS surface tension VBT volumetric thermodynamics Wegner expansion |
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