Evaluation of structural (s)-SAFT-γ Mie using newly measured binary VLE data of alkanes mixed with branched alcohols

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dc.contributor.advisorBurger, Andries Jacobusen_ZA
dc.contributor.authorSlabbert, Robert Malcolmen_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Process Engineering.en_ZA
dc.date.accessioned2024-03-05T08:17:00Zen_ZA
dc.date.accessioned2024-04-26T20:31:43Zen_ZA
dc.date.available2024-03-05T08:17:00Zen_ZA
dc.date.available2024-04-26T20:31:43Zen_ZA
dc.date.issued2024-03en_ZA
dc.descriptionThesis (MEng)--Stellenbosch University, 2024.en_ZA
dc.description.abstractENGLISH ABSTRACT: The application of group contribution (GC) methods to an equation of state (EoS) increases the flexibility of the EoS and has shown improvement in the predictive capabilities of EoSs. The application of GC methods to EoSs requires parameterisation of several functional groups, and it then allows for the prediction of physical properties of mixtures (for which no experimental data exist) constructed out of such pre-parameterised functional groups. The application of GC methods to statistical associating fluid theory (SAFT) EoSs has been more naturally adopted due to the spherical chain segments present in the reference fluid, with one such EoS being SAFT-γ Mie. Although its predictive capabilities are well-established, SAFT-γ Mie cannot distinguish between structural isomers. A recent modification to the chain term, structural (s)-SAFT-γ Mie, seeks to rectify this flaw by allowing SAFT-γ Mie to consider both the inter- and intragroup bonds without new fitting parameters. Assessing the accuracy of thermodynamic models is primarily done using reliable experimental data; however, gaps in the available literature data hinder the improvement of these models. To evaluate (s)-SAFT-γ Mie, novel isobaric vapour-liquid equilibrium (VLE) data for methyl butanol isomers/alkanes (C6 – C8) were measured. The verification of the experimental methodology was achieved using vapour pressure curves correlated to DIPPR correlations and the replication of binary VLE data for the system hexane/1-butanol at 101.3 kPa. New isobaric VLE data for twelve binary systems were then produced at 101.32 kPa. The maximum uncertainties calculated were determined to be 0.531 kPa, 0.431 K, 0.0135 mole/mole and 0.0126 mole/mole for the pressure, temperature, and liquid and vapour composition, respectively. With the exception of systems containing 2-methyl-1-butanol, all systems were found thermodynamically consistent according to the L-W area test and McDermott-Ellis test. It is quite possible that the heat of vaporisation correlation used for 2-methyl-1-butanol mixtures caused these systems to fail the L-W test. Both OH and first order hydroxyl groups (CHnOH) were used for modelling of branched alcohols. Pure component property predictions (vapour pressure, liquid density and heat of vaporisation) of the methyl butanol isomers were generated using SAFT-γ Mie and s-SAFT-γ Mie. SAFT-γ Mie matched the predictions of (s)-SAFT-γ Mie for pure component properties. For binary phase predictions, UNIFAC, acting as a reference for activity coefficient models (ACMs), matched those of SAFT EoSs. SAFT-γ Mie matched or outperformed the predictions of (s)-SAFT-γ Mie for binary phase predictions. This was deemed to be a result of the imported parameters used for s-SAFT-γ Mie, as these parameters were previously regressed using linear alcohol data. The modification to the chain term of s-SAFT-γ Mie allows for the distinction between the structural isomers, but often resulted in larger deviation from experimental data. This is most likely due to the inherent limitations of SAFT, with non-neighbouring interactions not considered and only limited steric hinderance effects being accounted for. Therefore, it is recommended that, while s-SAFT-γ Mie has notable advantagesfor certain applications, its use should be limited to primary branched chain alcohols, branched chain molecules using first order functional groups, branched chain molecules that are non-associating, and branched molecules with short chain branches.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Geen opsomming beskikbaar.af_ZA
dc.description.versionMastersen_ZA
dc.format.extentxvi, 261 pages : illustrationsen_ZA
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/130518en_ZA
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshEquations of stateen_ZA
dc.subject.lcshThermodynamicsen_ZA
dc.subject.lcshGroup contributionen_ZA
dc.subject.lcshChemical equilibriumen_ZA
dc.titleEvaluation of structural (s)-SAFT-γ Mie using newly measured binary VLE data of alkanes mixed with branched alcoholsen_ZA
dc.typeThesisen_ZA
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