Modeling high-pressure densities at wide temperature range with volume scaling: Cyclohexane + n-hexadecane mixtures |
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Authors: | Josinira A Amorim Osvaldo Chiavone-Filho Márcio LL Paredes Krishnaswamy Rajagopal |
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Institution: | 1. Departamento de Engenharia Química, PPGEQ, UFRN Campus Universitário 3000, CEP 59072-970, Brazil;2. PPGEQ, Instituto de Química, UERJ, Campus Maracanã, PHLC 411, CEP 20550-900, Brazil;3. DEQ, Escola de Química, UFRJ, Ilha do Fundão, CT I-122, CEP 21949-900, Brazil |
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Abstract: | High-pressure density data for cyclohexane + n-hexadecane mixtures at a wide temperature range was modeled with several classical equations of state (EOS) and correlative models. A modification for softening the co-volume and another for a volume scaling of the Peng–Robinson EOS (VS-PR) were proposed. The VS-PR model is able to correlate the pure component experimental data employing only five adjustable parameters, with root-mean-square deviation (RMSD) between calculated and experimental densities essentially within the experimental error. This result is superior to widely used approaches, i.e., a six parameter Tait model and six parameter volume translations (temperature and pressure dependent) for Peng–Robinson and Patel–Teja EOS. The VS-PR model also represents well the isobaric thermal expansion and the isothermal compressibility coefficients of the pure cyclohexane, a small naphthenic substance as well as a long chain n-alkane hydrocarbon, n-hexadecane. When modeling the mixture data, the use of VS-PR model of pure components along with the Redlich–Kister expansion, truncated at the first term, the density was correlated within a RMSD only 60% greater than the experimental error. The proposed model is able to accurately represent all the tested mixture data with a relatively small number of parameters. |
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Keywords: | High-pressure density Equation of state modeling Thermal expansion coefficient Isothermal compressibility Volume scaling |
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