1 |
Phase equilibria in mixtures containing alkanes and alcoholsEl Nikheli, A. H. D. January 1987 (has links)
Vapor-liquid equilibria (VLE) in alkanes and alcohols was measured and a contribution Patel-Teja (GPT) equation proposed in this work. systems of nmodified Group of state was Isothermal vapor-liquid equilibria at temperatures between 298.7K and 333. 7K have been measured for the binary systems n-pentane + n-hexane. n-pentane + noctane. n-pentane + n-decane. and n-pentane + l-propanol. The data were found to be consistent according to a point-to-point consistency test and were correlated using the Wilson. NRTL. and UNIQUAC activity coefficient models. The parameters of the models were estimated using the maximum likelihood principle. A new version of the Group contribution Patel-Teja equation of state was proposed in which a new temperature dependent group interaction expression was introduced. Group interaction parameters for four constituent groups of the alcohols and n-alkanes (viz. CH 2• CH 3 • CH and OH) were determined. These parameters were then used for the prediction of VLE in mixtures of n-alkane + n-alkane. n-alkane + n-alcohol. and n-alcohol + n-alcohol. VLE predictions with the new GPT equation of state were found to be superior to predictions with the original group contributions with molecular equations. The modified equation can be used in systems of nalkanes and alcohols where data for molecular parameters are lacking. The proposed temperature dependence of the group interaction parameters improved predictions over a wide range of temperature and pressure.
|
2 |
Solid-liquid equilibria in solution of normal alkanes with significant chain length differencesRoberts, Kenneth 12 1900 (has links)
No description available.
|
3 |
Evaluation of entrainers for the dehydration of C2 and C3 alcohols via azeotropic distillationPienaar, Cornelia 03 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Distillation is the most widely used separation technique in the chemical process industry and typically accounts
for approximately one-third of the total capital cost and more than half of the total energy consumption of a
typical petrochemical-chemical plant. Therefore, the design and optimization of the distillation sequence are of
critical importance to the economics of the entire process. Azeotropic mixtures cannot be separated into their
pure components via normal distillation. Enhanced distillation techniques such as heterogeneous azeotropic
distillation should be considered for these mixtures. Isobaric vapour-liquid-liquid equilibrium (VLLE) data are
highly important for the design and analysis of heterogeneous distillation columns. However, limited VLLE
data are available in literature due to the difficulties involved with measuring such data.
The objective of this work was to systematically evaluate and compare the performance of selected entrainers
(including benzene, DIPE and cyclohexane) for the dehydration of C2 and C3 alcohols. To meet this objective,
phase equilibrium data had to be measured. Isobaric VLLE at standard atmospheric conditions were measured
with a dynamic Guillespie unit equipped with an ultrasonic homogenizer, which prevented liquid-liquid
separation.
Vapour-liquid equilibrium (VLE) and VLLE data were measured for ethanol/water/di-isopropyl ether (DIPE),
n-propanol/water/DIPE and n-propanol/water/isooctane. The VLE data were found to be thermodynamically
consistent according to the L-W (Wisniak 1993) and McDermott-Ellis consistency tests. No thermodynamic
consistency test, specifically for VLLE data, could be found in literature, but the LLE part of the data followed a
regular profile according to the Othmer-Tobias correlation. The binary DIPE/water and isooctane/water
azeotropes, as well as ternary ethanol/DIPE/water and n-propanol/isooctane/water azeotropes, as measured in
this work, agree well with those found in literature.
Regressed parameters for the NRTL, UNIQUAC, and UNIFAC models, generally improved the model
predictions compared with built-in Aspen parameters. This confirmed the importance of having actual measured
VLLE data available for evaluation and improvement of estimations by thermodynamic models. NRTL
predicted the ethanol/DIPE/water and n-propanol/DIPE/water VLLE most accurately. Despite the improved
regressed parameters for n-propanol/isooctane/water predictions, the models are still considered unsuitable for
accurate prediction of the VLLE behaviour of this system. Separation sequences were simulated in Aspen with
built-in and regressed parameters, respectively, to illustrate the significant effect such inaccurate parameters
have on these simulations.
Phase diagram (VLLE data) evaluation of ethanol and isopropanol (IPA) with various entrainers, as found in
literature, indicated that DIPE might be a good entrainer for the dehydration of these alcohols. Benzene and
cyclohexane are generally used as entrainers in industry for these processes. Benzene is however carcinogenic
and therefore an alternative has to be found (United States Department of Labour - Occupational Safety &
Health Administration 2011). Separation sequences were simulated for ethanol dehydration with benzene and
DIPE as entrainers, respectively. Taking cost and safety into account, DIPE can be considered an acceptable
replacement for benzene as entrainer for ethanol dehydration. A separation sequence was also simulated for the dehydration of IPA with DIPE as entrainer and compared to a
simulation with cyclohexane (Arifin, Chien 2007) as entrainer. DIPE was found to be a reasonable alternative
to cyclohexane as entrainer for IPA dehydration. Two other separation sequences were simulated as practical examples where DIPE could be used as entrainer for the recovery of ethanol or n-propanol from aqueous Fischer
Tropsch waste streams.
DIPE is therefore found to be a feasible alternative entrainer to benzene and cyclohexane for the
dehydration of ethanol and IPA via heterogeneous azeotropic distillation, based on pre-liminary cost
considerations, separation ability and safety. Better entrainers than DIPE may exist, but from the data
available in literature and the measurements made in this work DIPE appears to be superior to benzene,
cyclohexane and isooctane. / AFRIKAANSE OPSOMMING: Distillasie is die mees algemeen-gebruikte skeidingstegniek in die chemiese proses-industrie. Dit is tipies
verantwoordelik vir ʼn derde van die totale kapitaalkoste en meer as die helfte van die totale energie verbruik op
ʼn tipiese petrochemiese chemiese aanleg. Daarom is die ontwerp en optimering van ʼn distillasie trein van
kardinale belang vir die winsgewendheid van die proses. Azeotropiese mengsels kan nie slegs deur normale
distillasie in suiwer komponente geskei word nie. Gevorderde distillasie tegnieke soos heterogene azeotropiese
distillasie moet dus oorweeg word vir sulke mengsels. Isobariese damp-vloeistof-vloeistof ewewigsdata is een
van die belangrikste fisiese eienskappe vir die ontwerp van heterogene distillasie kolomme. Die hoeveelheid
damp-vloeistof-vloeistof ewewigsdata wat beskikbaar is in die literatuur is egter baie beperk omdat dit moeilik
is om die data te meet.
In hierdie werk is isobariese damp-vloeistof-vloeistof ewewigsdata met ʼn dinamiese Guillespie eenheid, by
standaard atmosferiese druk gemeet. Die eenheid is toegerus met ʼn ultrasoniese homogeniseerder om
vloeistof-vloeistof skeiding te voorkom. Temperatuur is gemeet met ʼn akkuraatheid van 0.03oC by 0oC. Die
sisteem se druk is konstant gehou op 101.3 kPa met ʼn akkuraatheid van 0.35 % VSU (Vol Skaal Uitset). Die
ewewigsamestellings is met ʼn relatiewe akkuraatheid van 2 % gemeet.
Daar is damp-vloeistof en damp-vloeistof-vloeistof ewewigsdata van etanol/water/di-isopropiel eter (DIPE), npropanol/
water/ DIPE en n-propanol/water/iso-oktaan gemeet. Die damp-vloeistof ewewigsdata is deur die LW
(Wisniak 1993) en McDermott-Ellis termodinamiese konsistensie toetse getoets en konsistent bevind. Geen
termodinamiese konsistensie toets spesifiek vir damp-vloeistof-vloeistof ewewigsdata kon gevind word nie. Die
Othmer-Tobias korrelasie dui egter aan dat die vloeistof-vloeistof ewewig gedeelte van die data ʼn reëlmatige
gang volg. Die binêre DIPE/water en iso-oktaan/water azeotrope en ternêre etanol/DIPE/water en
n-propanol/iso-oktaan/water fase-ewewigte wat in hierdie werk gemeet is, stem ooreen met die wat in die
literatuur te vind is.
Die parameters vir die modelle (NRTL, UNIQUAC en UNIFAC) wat in hierdie werk bestudeer is, is in die
algemeen verbeter deur regressie van die eksperimentele data. Dit dui daarop dat dit belangrik is om
eksperimentele damp-vloeistof-vloeistof ewewigsdata te hê om die voorspellings van termodinamiese modelle
mee te evalueer en te verbeter. Die etanol/water/ DIPE en n-propanol/water/DIPE damp-vloeistof-vloeistof
ewewigsdata is die akkuraatste deur NRTL voorspel. Ten spyte van die verbeteringe wat deur regressie behaal
is met die NRTL en UNIQUAC parameters vir n-propanol/water/isooktaan, word hierdie modelle steeds nie as
gepas vir die voorspelling van hierdie datastel beskou nie.
Skeidingsreekse is gesimuleer met die ingeboude Aspen parameters en regressie parameters, onderskeidelik, om
te illustreer dat onakkurate parameters ʼn beduidende effek op sulke simulasies het.
Die evaluasie van fase diagramme van etanol en IPA met verskeie skeidingsagente, wat in die literatuur te vind
is, dui aan dat DIPE ʼn goeie skeidingsagent kan wees vir die dehidrasie van hierdie alkohole. Skeidingsreekse
vir die dehidrasie van etanol met benseen en DIPE, onderskeidelik, is gesimuleer. Met koste en veiligheid in ag
geneem, is daar gevind dat DIPE ʼn aanvaarbare plaasvervanger vir benseen as skeidingsagent vir etanol
dehidrasie kan wees. Daar is ook ʼn skeidingsreeks vir die dehidrasie van IPA met DIPE as skeidingsagent gesimuleer en met ʼn
simulasie (Arifin, Chien 2007) wat sikloheksaan as skeidingsagent gebruik, vergelyk. Daar is bevind dat DIPE ʼn
redelike alternatief vir sikloheksaan kan wees as skeidingsagent vir IPA dehidrasie. Nog twee skeidingsreekse is gesimuleer om as praktiese voorbeelde te dien van die gebruik van DIPE as skeidingsagent om etanol of
n-propanol vanaf waterige Fischer-Tropsch afvalstrome te herwin.
Daarom is daar bevind dat DIPE ʼn geldige alternatiewe skeidingsagent vir benseen en sikloheksaan is,
gebaseer op koste, skeidingsvermoë en veiligheid. Daar kan beter skeidingsagente as DIPE bestaan, maar
vanuit die data beskikbaar in literatuur en die metings geneem in hierdie werk, is DIPE die beste.
|
4 |
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.
|
5 |
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.
|
6 |
Simulação computacional de processos de desodorização e desacidificação de oleos vegetais / Computational simulation of deodorization and deacidification of vegetable oilsCeriani, Roberta, 1976- 10 July 2005 (has links)
Orientador: Antonio José de Almeida Meirelles / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-05T02:06:27Z (GMT). No. of bitstreams: 1
Ceriani_Roberta_D.pdf: 4668987 bytes, checksum: 15445f170d90738497cea3add4fb4d66 (MD5)
Previous issue date: 2005 / Doutorado / Doutor em Engenharia de Alimentos
|
7 |
Performance Evaluation Of Vapour Compression System With Environment Friendly Refrigerant MixturesNannaware, Ajay S 08 1900 (has links) (PDF)
No description available.
|
8 |
CROSS-PLATFORM FORCE FIELD DEVELOPMENT BASED ON FORCE-SMOOTHED POTENTIAL MODELSRazavi, Seyed Mostafa 15 July 2020 (has links)
No description available.
|
9 |
Modeling Phase and Sorption Equilibria using First Principles SimulationsGoel, Himanshu 10 August 2018 (has links)
To capture the underlying chemistry and physics of a system on electronic structure platform, it is necessary to accurately describe the intermolecular interactions such as repulsion, polarization, hydrogen bonding, and van der Waals interactions. Among these interactions, van der Waals (dispersion) interactions are weak in nature as compare to covalent bonds and hydrogen bonding, but it is physically and chemically very important in accurately predicting condensed phase properties such as Vapor liquid equilibria. This presents a significant challenge in modeling VLE using a first principles approach. However, recent developments in dispersion corrected (DFT-D3) and nonlocal density functionals can model dispersion interactions with reasonable accuracy. Here, we will present some of results that quantify efficacy of recent density functionals in predicting phase equilibria of molecular systems via first principle Monte Carlo (FPMC) simulations. Our aim is to assess the performance of several density functional by determining VLE, critical properties, dimer potential energy curves, vibrational spectra, and structural properties. The functional used in our study includes PBE-D3, BLYP-D3, rVV10, PBE0- D3, and M062X-D3. In addition, we have used the second order Møller-Plesset perturbation theory (MP2) method for computing density of argon at single temperature. The organic compounds considered for this study involves argon, CO2, SO2, and various hydroflurocarbons (R14, R134a, CF3H, CF2H2, CFH3) molecules. Additionally, the development of new materials, ionic liquids, and modification of industrial processes are an ongoing effort by researchers to efficiently capture acidic gases. Our ability to model these sorption processes using a first principles approach can have significant impact in speeding up the discovery process. In our work, we have predicted CO2 solubility in triethyl(butyl)phosphonium ionic liquid via FPMC simulations. Our results reveal the infrared spectra, structural and transport properties for pure ionic liquid and its mixture with CO2 through ab initio molecular dynamics simulations.
|
10 |
TRANSFERABLE STEP-POTENTIALS FOR HALOGENATED HYDROCARBONS AND MIXTURE PREDICTIONS FROM SPEADMDSans, Amanda Dzintra January 2006 (has links)
No description available.
|
Page generated in 0.0636 seconds