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Asphaltene Precipitation Modeling
Published in Francisco M. Vargas, Mohammad Tavakkoli, Asphaltene Deposition, 2018
C. Sisco, M. I. L. Abutaqiya, F. Wang, J. Zhang, M. Tavakkoli, F. M. Vargas
The EOS that has perhaps gained most popularity for oil applications because of the shortcomings of SRK and PR is PC-SAFT. PC-SAFT is arguably the most widely used EOS model from the SAFT family, which have become the standard EOS models for describing the phase behavior of large, complex molecules like polymers and heavy constituents of crude oil like resins and asphaltenes. The SAFT EOS was originally developed by Chapman et al. (1988, 1990) and a variety of researchers have since proposed modifications to better describe certain classes of fluids. PC-SAFT is one such modification (Gross and Sadowski 2001), and it has shown particular promise in describing the phase behavior of crude oils. The SAFT EOS and its successors are derived from thermodynamic perturbation theory, which describes real fluids as perturbations from idealized and well-described reference systems. In a sense, the cubic equations of state are perturbations from the ideal gas law, in which the ideal gas reference fluid is a system of infinitesimally small noninteracting molecules and the “a” and “b” parameters quantify deviations, or perturbations, from ideal gas behavior. For SAFT, the reference fluid consists of nondeformable nonattractive spheres bonded covalently to form chains and the perturbation terms account for attractive and repulsive forces excluded from the reference terms (Figure 4.4).
Energy Metrics
Published in John Andraos, Synthesis Green Metrics, 2018
The van der Waals, Redlich–Kwong, and Peng–Robinson equations of state are classified as cubic equations of state because if they are expanded algebraically they can be written as cubic functions with respect to the molar volume, V, variable. Example 5.19Show that the van der Waals equation is a cubic function in V.
The Thermodynamics of Equilibrium-Based Separation Processes
Published in Juan H. Vera, Grazyna Wilczek-Vera, Classical Thermodynamics of Fluid Systems, 2016
Juan H. Vera, Grazyna Wilczek-Vera
For high-pressure calculations, and even for low-pressure calculations, the use of cubic equations of state has become popular in the last decades. They are discussed in Chapter 25, and the details for application of the Peng-Robinson-Stryjek-Vera (PRSV) EOS [8,9] are given in Appendix C. Other more complex equations of state have also been used.
New models for the binary interaction parameters of nitrogen–alkanes mixtures based on the cubic equations of state
Published in Chemical Engineering Communications, 2018
Reza Haghbakhsh, Khalil Parvaneh, Feridun Esmaeilzadeh
Binary interaction parameters are generally empirically determined values which appear in the mixing and combining rules, with the purpose to accurately describe vapor–liquid equilibria. Often, the equilibrium calculations in mixtures are not accurate, and binary interaction parameters actually attempt to correct the inaccuracies of calculations. Indeed, binary interaction parameters reduce deviations from experimental values through simple mixing rules (Abudour et al., 2014), conventionally by regression of experimental vapor–liquid equilibrium data. In this way, the accuracy of phase equilibrium predictions by cubic equations of state is generally sensitive not only to the mixing rules, but also the binary interaction parameters (Chou and Prausnitz, 1989). However, obtaining these parameters by regression of experimental data is not always an easy task. It requires experimental data, but experimentation may be an expensive, difficult, and time-consuming process (Chou and Prausnitz, 1989). Therefore, it is an essential research objective to establish thermodynamic models for binary interaction parameters within wide ranges of pressure and temperature, which are independent of experimental data.