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Theoretical Investigation of Thermodiffusion (Soret Effect) in Multicomponent MixturesAlireza, Abbasi 23 February 2011 (has links)
Thermodiffusion is one of the mechanisms in transport phenomena in which molecules are transported in a multicomponent mixture driven by temperature gradients. Thermodiffusion in associating mixtures presents a larger degree of complexity than non-associating mixtures, since the direction of flow in associating mixtures may change with variations in composition and temperature. In this study a new activation energy model is proposed for predicting the ratio of evaporation energy to activation energy. The new model has been implemented for prediction of thermodiffusion for acetone-water, ethanol-water and isopropanol-water mixtures. In particular, a sign change in the thermodiffusion factor for associating mixtures has been predicted, which is a major step forward in modeling of thermodiffusion for associating mixtures.
In addition, a new model for the prediction of thermodiffusion coefficients for linear chain hydrocarbon binary mixtures is proposed using the theory of irreversible thermodynamics and a kinetics approach. The model predicts the net amount of heat transported based on an available volume for each molecule. This model has been found to be the most reliable and represents a significant improvement over the earlier models. Also a new approach to predicting the Soret coefficient in binary mixtures of linear chain and aromatic hydrocarbons using the thermodynamics of irreversible processes is presented. This approach is based on a free volume theory which explains the diffusivity in diffusion-limited systems. The proposed model combined with the Shukla and Firoozabadi model has been applied to predict the Soret coefficient for binary mixtures of toluene and n-hexane, and benzene and n-heptane. Comparisons of theoretical results with experimental data show a good agreement. The proposed model has also been applied to estimate thermodiffusion coefficients of binary mixtures of n-butane & carbon dioxide and n-dodecane & carbon dioxide at different temperature. The results have also been incorporated into CFD software FLUENT for 3-dimensional simulations of thermodiffusion and convection in porous media. The predictions show the thermodiffuison phenomenon is dominant at low permeabilities (0.0001 to 0.01), but as the permeability increases convection plays an important role in establishing a concentration distribution.
Finally, the activation energy in Eyring’s viscosity theory is examined for associating mixtures. Several methods are used to estimate the activation energy of pure components and then extended to mixtures of linear hydrocarbon chains. The activation energy model based on alternative forms of Eyring’s viscosity theory is implemented to estimate the thermodiffusion coefficient for hydrocarbon binary mixtures. Comparisons of theoretical results with the available thermodiffusion coefficient data have shown a good performance of the activation energy model.
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3D Synthetic Aperture Imaging Using LaserUltrasonicsZalamans, Louise January 2021 (has links)
Synthetic Aperture Focusing Technique (SAFT) is a powerful method to createfocused images of the inside of opaque samples by using delay-and-sum of acquireddata. It gives a high resolution and when using a generation laser and a detectionlaser it is also non-contact. This thesis was made at Swerim, and the aim wasto create an 3D-SAFT algorithm and to visualise the reconstructed image. Twosamples were used, both were 3D-printed with known defects that varied in sizefrom 0.05 mm to 1 mm. The defects were lined up in rows, with 10 in each row.After the algorithm was used on the acquired data from the two samples, six toeight defects were found in each row. Both samples had three rows of defects. Themeasured sizes of the defects were not exactly as the actual size but ranged a fewmillimetre too small or big compared to the real size. Overall the algorithm workswell. The resolution of the 3D images are the same as for the 2D-SAFT algorithmalready made by Swerim. As of now the 3D images may not be worth the time ittakes to process, but if a better way to visualise the data is made in the future, itwill be good to be able to see the defects in 3D.
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Etudes expérimentales et modélisation du comportement de phase et des propriétés de transport des mélanges liés à la capture et au stockage du carbone / Experimental and modelling studies of the phase behaviour and transport properties of mixtures related to carbon capture and storageGonzalez Perez, Alfonso 30 November 2016 (has links)
L'objectif principal de ce travail est le développement d'une équation d’état précise pour la détermination des propriétés thermodynamique de mélange de gaz riche en gaz acides (CO2, H2S) contenant des hydrocarbures et autres gaz (impuretés) comme N2, O2, Ar, etc présente lors du stockage du CO2 (CCS). Après comparaisons avec des données expérimentales, nous avons retenu le modèle SAFT-VR Mie qui prédit de manière satisfaisante les masses volumiques pour les composés purs et les équilibres entre phases. Trois types de propriétés de transport ont également été prédites avec le modèle thermodynamique SAFT-VR Mie associé avec deux autres modèles de prédiction des propriétés de transport (TRAPP et DGT). La prédiction de ces propriétés de transport (viscosité et tension superficielle) repose sur une estimation la plus précise possible des masses volumiques. Pour compléter les banques données expérimentales, les équilibres liquide-vapeur concernant le système binaire H2S-Ar ont été déterminés à l'aide d'un dispositif de mesure dont la méthode technique repose sur la méthode "statique analytique" avec échantillonnage des phases (échantillonneur capillaire ROLI). Déplus, à l'aide d'un densimètre à tube vibrant, les masses volumiques de cinq systèmes binaires (H2S - hydrocarbures (méthane, éthane et propane) ont été mesurées. Les masses volumiques d'un système ternaire (CO2/CH4/H2S) et les masses volumiques et les viscosités d'un mélange multi-constituant riche en CO2 ont aussi été mesurées. Les données sont parfaitement représentées par les modèles développés au cours de cette thèse. / The main aim of this research is to develop a thermodynamic model from an accurate equation of state (EoS) for CO2, hydrocarbons and other gases as N2, O2, Ar, etc. The SAFT-VR Mie EoS was selected to study the phase behaviour and transport properties of mixtures related to carbon capture and storage (CCS). In order to asses this new version of SAFT, several equations of state have been compared (PR, SRK and PC-SAFT). SAFT-VR Mie EoS provides very good density predictions for pure component and binary systems according to the comparative study carried out. Therefore, three transport properties were modelled with SAFT-VR Mie and two models based on density predictions from the EoS. Thus, density, viscosity and interfacial tension (IFT) of CO2-rich systems were calculated by this SAFT-EoS (density), TraPP model (viscosity) and DGT (IFT), in the framework of CCS. Some experimental work was done, in order to extend the available literature data. Isothermal vapor-liquid equilibrium of H2S-Ar binary system was determined at three temperatures from 258 to 288 K. Densities of five binary systems of H2S with methane, ethane and propane were measured continuously at 3 temperatures (253, 273 and 293K) and at pressures up to 30MPa. Following the same technique, the density of the ternary system 42%CO2, 40%CH4 and 18%H2S was measured at pressures ranging from 0.2 to 31.5MPa and at 6 temperatures between 253 and 353K. Densities and viscosities of a multicomponent CO2-rich with 50% of impurities were measured at 5 temperatures between 283 and 423 K and at pressures up to 150 MPa.
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Prediction of Thermodynamic Properties by Structure-Based Group Contribution ApproachesEmami, Fatemesadat 02 September 2008 (has links)
No description available.
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FTIR measurement of monomer fractions in dilute alcohol-acetone systems for the evaluation of the sPC-SAFT EoSKruger, Francois Johan 12 1900 (has links)
Thesis (MScEng)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: The simplified Perturbed-Chain Statistical Associating Fluid Theory (sPC-SAFT) is characterised by the
dual advantages of decreased computational intensity, while remaining accurate for a variety of
systems. Vapour-liquid equilibrium data are used to generate equation of state parameters.
However, incorporating monomer fraction data into the parameter regression has long been
advocated as a good, or even preferred, practice. Therefore, the monomer fraction data of dilute
alcohol-acetone systems were analysed in this study. A small stainless steel sample vessel was
constructed with temperature control, manual pressure control and a mechanism for liquid phase
analysis via infrared spectroscopy.
The performance of the spectrometer was verified by comparison with the ethanol – n-hexane data
of von Solms et al. (2007), after which new monomer fraction data were obtained for dilute
solutions (between 0.01 and 1.5 mol%) of methanol, ethanol, 1-propanol and 2-propanol in acetone
near 23 °C.
For dilute alcohol-acetone systems it was found that the propanols had the highest monomer
fractions, and methanol the lowest. With increasing alcohol concentration, the monomer fractions
decreased exponentially to values of 0.4 and 0.1 for methanol and the other alcohols respectively.
The excess availability of hydrogen bond acceptors in the mixtures explains the equivalency
observed for ethanol, 1-propanol and 2-propanol.
For dilute acetone-alcohol systems it was found that, especially for methanol and ethanol, there was
a pronounced trend towards acetone monomer fractions of 1 at infinite dilution. For the acetone –
2-propanol system, a previously unrecorded monomer peak was observed and quantified. Acetone
monomer fractions tended to decrease as alcohol chain-length increased, showing that acetone
could more easily penetrate the hydrogen bond network of the solvent when the solvent-solvent
bonds were weaker. Monomer fraction data were compared to predictions for the sPC-SAFT scheme and parameters
combinations published in the literature. The experimental data were accurately modelled using
modified association parameters such that the solute associates strongly (εAB≈103 κ≈1), while the
solvent parameters were decreased (εAB≈102 κ≈10˗3) to give a weakened solvent association effect.
The difficulty for the dilute solute in penetrating the solvent bonding network appeared to be similar
to the hydrophobic effect. Two new association schemes were proposed for acetone, assigning a single (N) or two (2N)
negative association sites to represent the oxygen valence electron pairs. These schemes showed
relative success in modelling acetone as the solvent in the mixture, while not being able to predict
acetone monomer fractions when acetone was the solute. For dilute acetone-alcohol systems, the
data were best described using the 2B model for acetone, while the best choice of scheme for the
alcohol varied from system to system.
For dilute alcohol-acetone mixtures it was generally found that a 2B-N model (with modified
association parameters) provided the best fit to those experimental data. Accurate modelling below
0.1 mol% was difficult to attain with average errors decreasing to the order of 10% when this area
was excluded. In this highly dilute region, not one of the models could describe the rapid change in
(monomer fraction) gradient sufficiently while simultaneously offering accurate predictions over the
entire experimental range. / AFRIKAANSE OPSOMMING: Die sPC-SAFT of simplified Perturbed-Chain Statistical Associating Fluid Theory toestandsvergelykings
word wyd gebruik as gevolg van sy goeie akkuraatheid vir ‘n wye reeks sisteme, ten spyte van
verminderde berekeningsintensiteit. Die parameters vir dié toestandsvergelyk word afgelei van faseewewig
data, maar monomeer fraksie data word voorgestel vir die verbetering van (veral) die
assosiasie parameters. Ten opsigte hiervan, was alkohol-asetoon sisteme bestudeer en hul
monomeer fraksies gemeet. ‘n Staal reaktor was ontwerp (met ‘n temperatuurbeheerstelsel sowel
as drukbeheer) om vloeistof monsters voor te berei vir analise d.m.v. infrarooi-spektroskopie.
Die akkuraatheid van die eksperimentele apparaat is bewys deur nabootsing van etanol – n-heksaan
data van von Solms et al. (2007), waarna nuwe monomeer fraksie data gegenereer is vir verdunde
mengsels (0.01 tot 1.5 mol%) van metanol, etanol, 1- en 2-propanol met asetoon by 23 °C.
Metanol monomeer fraksies het eksponensieël afgeneem na 0.4, terwyl etanol en propanol fraksies
afgeneem het na ‘n gemene waarde van ongeveer 0.1. Hierdie tendens word toegeskryf aan ‘n
oormaat van toeganklike waterstofbindingontvangers in hierdie mengsels.
Vir verdunde asetoon-alkohol sisteme is daar ‘n tendens, (veral vir verdunnings met metanol en
etanol) vir die monomer fraksies om te neig na 1 by oneindige verdunning. ‘n Monomeer piek is ook
waargeneem vir die asetoon – 2-propanol sisteem. Hierdie piek is nie voorheen gesien in ander
studies nie en dit is ook die eerste keer wat sulke data gekwantifiseer is. Daar is bevind dat asetoon
monomeer fraksies afneem soos alkohol kettinglengte toeneem.
Die gegenereerde monomeer fraksie data word vergelyk met verskeie sPC-SAFT parameterstelle
vanuit die literatuur. Oor die algemeen, is die beraamde fraksie veel hoër as die eksperimentele data
wanneer die 2B/3B/2C skemas met ‘n nie-assosiërende asetoon molekuul gemodelleer word.
Wanneer die 2B parameters van von Solms et al. (2004) gebruik word, toon die beraming ‘n
drastiese onderskatting van die data. Om ‘n akkurate beraming van die monomeer fraksie data te kry, moet die assosiasie parameters van
die opgeloste stof vermeerder word (met εAB≈103 κ≈1) terwyl die oplosmiddel s’n drasties verswak
moet word (met εAB≈102 κ≈10-3). Hierdie patroon kan vergelyk word met die hidrofobiese effek waar
die kragte binne die oplosmiddel ‘n netwerk vorm wat die opgeloste stof uitstoot. Twee nuwe assosiasie skemas word ook voorgestel vir asetoon waar onderskeidelik een (N) en twee
(2N) negatiewe sones, wat die valenselektroonpare op die suurstofatoom voorstel, aan asetoon
geheg word. Hierdie twee skemas het relatiewe sukses getoon in die modellering van verdunde
alkohol-asetoon sisteme terwyl dit ‘n swak beskrywing van die verdunde asetoon-alkohol mengsels
voorspel het. ‘n Gewysigde 2B asetoon skema gee ‘n goeie beskrywing van die eksperimentele data.
In hierdie geval, is die keuse van alkohol skema minder belangrik, terwyl die waardes van die
assosiasie parameters verminder moet word.
Vir verdunde alkohol-asetoon mengels word daar bevind dat ‘n 2B-N model met nuwe assosiasie
parameters die beste passing van die eksperimentele data gee. Daar was ook bevind dat die modelle
se akkuraatheid drasties afneem (met fout vermeerdering in die orde van 10%) wanneer die
konsentrasie van die opgeloste stof minder as 0.1 mol% is.
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Développement d’un dispositif expérimental original et d’un modèle prédictif pour l’étude thermodynamique des composés soufrés / Development of an original experimental apparatus and a predictive model for the thermodynamic study of sulfur compoundsZhang, Fan 17 November 2015 (has links)
Les composés soufrés sont répandus dans divers secteurs industriels comme la chimie. La conception et/ou l'optimisation des procédés impliquant ces composés nécessite de connaître leurs propriétés thermodynamiques (corps purs et mélanges). Etant donnée la complexité des mélanges et pour des raisons économiques, des modèles thermodynamiques « prédictifs » sont souvent privilégiés. Le développement et la validation de ces modèles nécessitent des données expérimentales. Notre étude bibliographique ciblant les sulfures (R-S-R'), les 1-mercaptans (R-SH) et leurs éventuels solvants (les n-alcanes et les 1-alcools) nous a permis de mettre en évidence un manque de données concernant ces composés. De plus nous avons également observé un manque de techniques expérimentales adaptés, et de ce fait le besoin de développer un nouveau dispositif expérimental.Au cours de cette thèse, nous avons conçu un dispositif expérimental innovant permettant la mesure des équilibres liquide-vapeur à des pressions comprises entre 0,1 et 10 bar. Ce dispositif est basé sur la méthode « statique-analytique ». Nous avons mis en place deux adaptations spécifiques aux échantillonneurs capillaires ROLSITM pour permettre l'échantillonnage à ces pressions. De nouvelles données des mélanges binaires et ternaires d'intérêt ont été ainsi mesurées.Le modèle thermodynamique prédictif choisi est PC-SAFT couplé avec une méthode de Contribution de Groupes (GC-PC-SAFT). Un terme polaire a été introduit. Le travail s'est focalisé sur l'étude de deux familles représentatives de composés soufrés : les sulfures et les 1-mercaptans. Le modèle GC-PC-SAFT a montré sa capacité de bien corréler et prédire les propriétés thermodynamiques des corps purs. L'ajustement des paramètres s'est appuyé sur les données de la littérature et celles obtenues par le nouvel équipement. Les diagrammes de phases des mélanges binaires (sulfure + n-alcane, sulfure + 1-alcool, 1-mercaptan + n-alcane et 1-mercaptan + 1-alcool) et ternaires (1-mercaptan + n-alcane + 1-alcool) ont été prédits. / Sulfur compounds are widespread in various industrial fields. Design and/or optimization of the processes involving these compounds require accurate knowledge of thermodynamic properties of the concerned mixtures. Considering the complexity of industrial mixtures and for economical reasons, one may look to thermodynamic models with predictive features. To develop and validate these models, a minimum number of experimental data are required. Our literature review on sulfides (R-S-R'), 1-thiols (R-SH) and their possible solvents (n-alkanes and 1-alkanols) has shown a lack of data and of adapted experimental method. This observation leads to the need of developing a new experimental apparatus.In this work, we designed an innovative experimental apparatus for vapor-liquid-equilibrium measurements in the pressure range of [0.1 – 10] bar. The new apparatus is based on the “static-analytic” method. The key improvements are the two adaptations made for ROLSITM capillary samplers to achieve phase sampling in this pressure range. After validating the newly developed apparatus, new data of binary and ternary mixtures of interest were measured in order to develop a new predictive thermodynamic model focusing on sulfur compounds.The proposed predictive model is the PC-SAFT equation of state combined with a group contribution method (GC-PC-SAFT). We incorporated a polar term into PC-SAFT and investigated two representative families of sulfur compounds: sulfides and 1-thiols. The GC-PC-SAFT model proved reliable in correlating and predicting thermodynamic properties of pure compounds. Model parameters were fitted to the data found in the literature, as well as to those obtained through the new apparatus. Phase diagrams of some binary (sulfide + n-alkane, sulfide + 1-alkanol, 1-thiol + n-alkane and 1-thiol + 1-alkanol) and ternary (1-mercaptan + n-alkane + 1-alcool) mixtures were predicted.
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Application de l'équation PC-SAFT à la capture du dioxyde de carbone et à la désulfuration des essences / Application of PC-SAFT equation of state in the carbon dioxide capture and the gasoline desulfurizationChen, Yushu 26 September 2013 (has links)
Le remplacement des solvants organiques classiques par une nouvelle génération de solvants moins toxiques, moins inflammables et moins polluants est un défi majeur pour l'industrie chimique. Les liquides ioniques, sels liquides qui satisfont ces critères, sont envisagés comme alternatives. Le but de ce travail est d'évaluer le comportement des liquides ioniques en présence de gaz à effet de serre (CO2, N2O et CH4) ou de composés organiques. Dans un premier temps, une étude théorique présente les performances du modèle thermodynamique PC-SAFT sur la représentation des équilibres liquide-vapeur de systèmes constitués de dioxyde de carbone et de liquide ionique. Ensuite, l'étude de la solubilité du méthane, du dioxyde de carbone et du protoxyde d'azote dans divers liquides ioniques a été effectuée sous basse ou haute pression. Ce travail propose un modèle basé sur le concept de contribution de groupes afin de prédire la constante d'Henry du CO2 dans les liquides ioniques. Enfin, une étude sur les équilibres liquide-vapeur des systèmes binaires rencontrés dans la désulfuration des essences a été effectuée. Les données expérimentales ont permis d'évaluer les performances de l'équation PC-SAFT à représenter les équilibres entre phases de systèmes {composés soufrés / aromatiques + liquide ionique} / The replacement of conventional organic solvents by a new generation of solvents less toxic, less flammable and less polluting is a major challenge for the chemical industry. Ionic liquids have been widely promoted as interesting substitutes for traditional solvents. The purpose of this work is to evaluate the behavior of ionic liquids in the presence of greenhouse gases (CO2, CH4 and N2O) or organic compounds. Firstly, a theoretical study presents the performance of the thermodynamic model PC-SAFT in the representation of vapor-liquid equilibrium of systems containing ionic liquids and carbon dioxide. Then, the solubility study of methane, carbon dioxide and nitrous oxide in various ionic liquids was performed at high or low pressure. The group contribution concept is proposed in this study in order to predict the Henry's law constant of carbon dioxide in ionic liquids. Finally, a study on the vapor-liquid equilibrium of binary systems encountered in gasoline desulfurization was carried out. Experimental data were used to evaluate the performance of PC-SAFT equation of state to represent phase equilibrium of systems {sulfur / aromatic compounds + ionic liquid}
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Delad Opinion : En uppsats om de mest delade opinionstexterna på FacebookWiorek, Daniel, Jonsson, Oskar January 2017 (has links)
C-uppsatsens huvudsakliga syfte är att undersöka vilka egenskaper som utmärker de opinionsartiklar som delas mest på Facebook. Merparten av uppsatsen bygger på en kvalitativ metod där vi har analyserat åtta artiklar med hjälp av retorisk analys, nyhetsvärderingsteori samt modeller för hur en opinionstext bör utformas. Dessutom innehåller uppsatsen en kvantitativ undersökning av de artiklar som delas mest på Facebook. Där har vi bland annat undersökt var artiklarna är publicerade, vilka ämnen de handlar om och vilken genre de tillhör. I den kvalitativa undersökningen kom vi fram till att de mest delade opinionsartiklarna handlade om aktuella frågor som berör många människor. Det fanns också alltid någon aspekt eller egenskap i texten som gjorde att den utmärkte sig, såsom att skribenten var en elitperson eller skrev utifrån egen erfarenhet. I den kvantitativa undersökningen kom vi bland annat fram till att en klar majoritet av alla artiklar som delas på Facebook är publicerade av kvällstidningar. Undersökningen visade också att den vanligaste typen av artikeln var nyhetsartiklar som utgjorde 69 % av urvalet, 23 % av urvalet var opinionsmaterial. Den slutsats vi drar från den kvalitativa undersökningen är att de mest delade artiklarna oftast är skrivna utifrån personlig erfarenhet. Vi tolkar det som att den personliga erfarenheten förstärker skribentens trovärdighet, ethos, och att det bidrar till att läsarna blir mer benägna att dela artikeln. De slutsatser vi drar från den kvantitativa undersökningen är att de ämnen som de mest delade artiklarna handlar om påverkas av vad som händer i omvärlden, och således ändras över tid. Nyckelbegrepp: delningar, retorisk analys, nyhetsvärdering, SPADER-och SAFT-modellen, opinionsartiklar, Facebook.
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MEASUREMENTS AND MODELING OF HYDROCARBON MIXTURE FLUID PROPERTIES UNDER EXTREME TEMPERATURE AND PRESSURE CONDITIONSBamgbade, Babatunde A 01 January 2015 (has links)
Knowledge of thermodynamic fluid properties, such as density and phase behavior, is important for the design, operation, and safety of several processes including drilling, extraction, transportation, and separation that are required in the petroleum. The knowledge is even more critical at extreme temperature and pressure conditions as the search for more crude oil reserves lead to harsher conditions. Currently, there is dearth of experimental data at these conditions and as such, the predictive capability of the existing modeling tools are unproven. The objective of this research is to develop a fundamental understanding of the impact of molecular architecture on fluid phase behavior at temperatures to 523 K (250 °C) and pressures to 275 MPa (40,000 psi). These high-temperature and high-pressure (HTHP) conditions are typical of operating conditions often encountered in petroleum exploration and recovery from ultra-deep wells that are encountered in the Gulf of Mexico.
This PhD study focuses on the fluid phase behavior of a low molecular weight compound, two moderately high molecular weight compounds, three asymmetric binary mixtures of a light gas and a heavy hydrocarbon compound with varying molecular size. The compounds are selected to represent the family of saturated compounds found in typical crude oils. Furthermore, this study reports experimental data for two "dead" crude oil samples obtained from the Gulf of Mexico and their mixtures with methane from ambient to HTHP conditions. A variable-volume view cell coupled with a linear variable differential transformer is used to experimentally measure the high-pressure properties of these compounds and mixtures. The reported density data compare well to the limited available data in the literature with deviations that are less than 0.9%, which is the experimental uncertainty of the density data reported in this study.
The phase behavior and density data obtained in this study are modeled using the Peng-Robinson (PR), the volume-translated (VT) PR, and the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equations of state (EoS). The EoS pure component parameters, typically obtained from the open literature, are derived from fitting the particular EoS to, critical point, or to vapor pressure and saturated liquid density data, or to HTHP density data. For the density data reported here, the PREoS provided the worst predictions, while the VT-PREoS gives an improved performance as compared to the PREoS. However, the PC-SAFT EoS provided the best HTHP density predictions especially when using HTHP pure component parameters. The situation is however reversed in the modeling performance for the phase behavior data whereby the PC-SAFT EoS with HTHP parameters provided the worst vapor-liquid equilibria predictions. Better predictions are obtained with the PC-SAFT EoS when using parameters obtained from fit of the vapor pressure data and is comparable to the PREoS predictions. This reversal in performance is not surprising since the phase behavior data occur at moderately low pressures. The performance of the PC-SAFT EoS is extended to the experimental density data reported for the dead crude oil samples and their mixtures with methane. The PC-SAFT EoS with either set of pure component parameters yield similar predictions that are within 3% of the reported crude oil density data. However, when using the HTHP parameters, the PC-SAFT gives a good representation of the slope of experimental data, which is crucial in the calculation of second-derivative properties such has isothermal compressibility.
The PC-SAFT EoS is also employed to model the crude oil HTHP density data for both the dead crude oils and their mixtures with methane using correlations for both the Low-P parameters and the HTHP parameters. The Low-P parameters are derived from fitting the PC-SAFT EoS to pure compound vapor pressure and saturated liquid density data, while the HTHP parameters are obtained from fitting the PC-SAFT EoS to pure compound HTHP liquid density data. Interestingly, the PC-SAFT EoS with the Low-P parameters provided better HTHP density predictions that are within 1.5% of the experimental data for the dead oils than the HTHP parameters that are within 2 to 4% of the data. Density predictions for the dead oil mixtures with methane are however comparable for both sets of parameters and are within 1% on average. However, the PC-SAFT EoS with HTHP parameters clearly provided better representation of the isothermal property, a derivative property obtained from density data, within 10% while predictions with the Low-P parameters can be as high as 37%.
The successful completion of the thesis work expands the current knowledge base of fluid phase behavior at the extreme operating conditions encountered by engineers in the petroleum industries. Furthermore, the reported HTHP experimental data also provide a means to scientists and researchers for the development, improvement, and validation of equations with improved modeling performance.
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Estimação dos parâmetros do modelo GC-PC-SAFT utilizando dados de mistura como forma de evitar o uso de parâmetros de interação bináriaBender, Neumara January 2018 (has links)
Nesse trabalho, a equação de estado PC-SAFT é combinada com um método de contribuição de grupos (GC) para estimação dos seus parâmetros. Para tanto, foram utilizados dados experimentais dos componentes puros (pressão de vapor e volume específico do líquido) e em mistura (equilíbrio líquido-vapor - VLE e coeficiente de atividade em diluição infinita - IDAC). Através de uma análise de sensibilidade, verificou-se que o parâmetro volume de associação poderia ser mantido constante, reduzindo o número de parâmetros a serem estimados. O objetivo principal foi estudar misturas que apresentassem associação cruzada ou forte interação entre os compostos. Com os parâmetros estimados, avaliou-se o desempenho do modelo GC-PC-SAFT no cálculo de propriedades de n-alcanos, 1-álcoois, aminas, clorofórmio e acetona. Os desvios médios obtidos no cálculo do equilíbrio líquido-vapor (VLE), entre as diferentes misturas estudadas, mostraram que a estratégia adotada para a estimação do parâmetro energia de associação apresentou bons resultados, com desvios relativamente baixos para a maioria dos casos estudados. Para IDAC, as predições foram muito semelhantes àquelas obtidas por outros modelos. Os resultados de VLE são importantes, pois fornecem informações sobre as concentrações intermediárias de uma mistura, enquanto que o IDAC fornece uma medida eficiente do grau de não-idealidade da mistura. Essas propriedades foram escolhidas com o objetivo de conseguir uma melhor representação das misturas, buscando eliminar a necessidade de parâmetros de interação binária. Os resultados obtidos revelam que o modelo GC-PC-SAFT proposto pode ser utilizado para predizer o equilíbrio líquido-vapor com uma precisão satisfatória para sistemas binários entre os diferentes compostos estudados, sem nenhum parâmetro de interação binária. / In this work, the PC-SAFT EoS is combined with a group contribution method (GC) for parameter estimation. To achieve this, experimental data for pure components (vapor pressure and liquid volume) and mixtures (vapor-liquid equilibria - VLE and infinite dilution activity coefficient -IDAC) has been used. Through sensitivity analysis, it has been found that the association volume parameter could be set constant, thus reducing the amount of parameters that needed to be estimated. The aim of this work was to study mixtures that presented cross association or strong component interaction. With the estimated parameters, GC-PC-SAFT performance in properties calculation of n-alkanes, 1-alcohols, amines, chloroform and ketone has been evaluated. The average deviations obtained in the calculation of vapor-liquid equilibria (VLE), in the different mixtures considered, have shown that the strategy for association energy parameter estimation has presented good results, with relatively low deviations for most of the cases. For IDAC, the predictions presented very similar results to those obtained by other models. VLE results are important because they provide information about mixtures’ intermediary concentrations, whereas IDAC offers an efficient measure of mixtures’ degree of non-ideality. These properties have been chosen with the aim of getting a better representation of the mixtures, seeking to eliminate the need for binary interaction parameters. The obtained results show that GC-PC-SAFT can be used to predict vapor-liquid equilibria for binary systems among the different studied components with satisfactory accuracy with no binary interaction parameter.
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