Dissertation research involves development of Mobile Order Theory thermodynamic models to mathematically describe and predict the solubility, spectral properties, protonation equilibrium constants and two-phase partitioning behavior of solutes dissolved in binary solvent mixtures of analytical importance. Information gained provide a better understanding of solute-solvent and solvent-solvent interactions at the molecular level, which will facilitate the development of better chemical separation methods based upon both gas-liquid and high-performance liquid chromatography, and better analysis methods based upon complexiometric and spectroscopic methods. Dissertation research emphasizes chemical equilibria in systems containing alcohol cosolvents with the understanding that knowledge gained will be transferable to more environmentally friendly aqueous-organic solvent mixtures.

La cristallisation est un procédé majeur de l’industrie pharmaceutique. Dans la mise au point d’un nouveau procédé de cristallisation, l’information essentielle est la solubilité de la molécule produite dans le solvant de cristallisation. Cette donnée n’est généralement pas connue lors de la phase de développement d’un nouveau principe actif. Elle doit donc être déterminée. L’objectif de cette thèse est d’étudier, et d’approfondir, l’utilisation de modèles thermodynamiques pour prédire la solubilité de molécules organiques complexes. Pour cela, six molécules sont prises pour référence : l’ibuprofène, le paracétamol, les acides salicylique, benzoïque et 4-aminobenzoïque et l’anthracène. Les modèles étudiés sont UNIFAC et ses modifications, COSMO-SAC, NRTL-SAC et PC-SAFT. Dans un premier temps, les potentialités de chaque modèle pour prédire la solubilité dans des solvants purs et des mélanges de solvants sont analysées. Dans un second temps, le modèle COSMO-SAC est approfondi et amélioré pour la prédiction des équilibres liquide-solide mettant en jeu des molécules complexes. Enfin, une nouvelle voie de mesure expérimentale de la solubilité dans de très faibles volumes est ouverte par l’intermédiaire de l’outil microfluidique. / Crystallization is a key process of the pharmaceutical industry. When developing a new crystallization process, the most important thing to discover is the final product solubility in a given solvent. However, it is generally unknown at this early step of drug development. The solubility has to be determined. The objective of this work is to study, and deepen, the use of thermodynamic models for solubility predictions of molecules of pharmaceutical interest. To do so, six complex organic molecules have been chosen : ibuprofen, paracetamol, salicylic acid, benzoic acid, 4-aminobenzoic acid and anthracene. The studied models are UNIFAC and its modifications, COSMO-SAC, NRTL-SAC and PC-SAFT. Initially, these models are analysed and used for predicting solubility in pure and mixed solvents. Subsequent work concerns the COSMO-SAC model in more details. It is more particularly improved for solubility predictions. Finally, a road is opened for solubility measurements in low volumes with the use of microfluidics.

Globally, there are vast amounts of low-grade heat sources from industrial waste and renewables that can be converted into electricity through advanced thermodynamic power cycles and appropriate working fluids. In this thesis, experimental research was conducted to investigate the performance of a small-scale Organic Rankine Cycle (ORC) system under different operating conditions. The experimental setup consisted of typical ORC system components, such as a turboexpander with a high speed generator, a scroll expander, a finned-tube condenser, an ORC pump, a plate evaporator and a shell and tube evaporator. R245fa was selected as the working fluid, on account of its appropriate thermophysical properties for the ORC system and its low ozone depletion potential (ODP). The test rig was fully instrumented and extensive experiments carried out to examine the influences of several important parameters, including heat source temperature, ORC pump speed, heat sink flow velocity, different evaporators and with or without a recuperator on overall R245fa ORC performances. In addition, in terms of the working fluid’s environmental impact, temperature match of the cycle heat processes and system compactness, CO2 transcritical power cycles (T-CO2) were deemed more applicable for converting low-grade heat to power. However, the system thermal efficiency of T-CO2 requires further improvement. Subsequently, a test rig of a small-scale power generation system with T-CO2 power cycles was developed with essential components connected; these included a plate CO2 supercritical heater, a CO2 transcritical turbine, a plate recuperator, an air-cooled finned-tube CO2 condenser and a CO2 liquid pump. Various preliminary test results from the system measurements are demonstrated in this thesis. At the end, a theoretical study was conducted to investigate and compare the performance of T-CO2 and R245fa ORCs using low-grade thermal energy to produce useful shaft or electrical power. The thermodynamic models of both cycles were developed and applied to calculate and compare the cycle thermal and exergy efficiencies at different operating conditions and control strategies. In this thesis, the main results showed that the thermal efficiency of the tested ORC system could be improved with an increased heat source temperature in the system with or without recuperator. When the heat source temperature increased from 145 oC to 155 oC for the system without recuperator, the percentage increase rates of turbine power output and system thermal efficiency were 13.6% and 14% respectively while when the temperature increased from 154 oC to 166 oC for the system with recuperator, the percentage increase rates were 31.2% and 61.97% respectively. In addition, the ORC with recuperator required a relative higher heat source temperature, which is comparable to a system without recuperator. On the other hand, at constant heat source temperatures, the working fluid pump speed could be optimised to maximise system thermal efficiency for ORC both with and without recuperator. The pressure ratio is a key factor impacting the efficiencies and power generation of the turbine and scroll expander. Maximum electrical power outputs of 1556.24W and 750W of the scroll expander and turbine were observed at pressure ratio points of 3.3 and 2.57 respectively. For the T-CO2 system, the main results showing that the CO2 mass flow rate could be directly controlled by varying the CO2 liquid pump speeds. The CO2 pressures at the turbine inlet and outlet and turbine power generation all increased with higher CO2 mass flow rates. When CO2 mass flow rate increased from 0.2 kg/s to 0.26kg/s, the maximum percentage increase rates of measured turbine power generation was 116.9%. However, the heat source flow rate was found to have almost negligible impact on system performance. When the thermal oil flow rate increased from 0.364kg/s to 0.463kg/s, the maximum percentage increase rate of measured turbine power generation was only 14.8%. For the thermodynamic analysis, with the same operating conditions and heat transfer assumptions, the thermal and exergy efficiencies of R245fa ORCs are both slightly higher than those of T-CO2. However, the efficiencies of both cycles can be enhanced by installing a recuperator at under specific operating conditions. The experiment and simulation results can thus inform further design and operation optimisations of both the systems and their components.

abstract: Limited access to clean water due to natural or municipal disasters, drought, or contaminated wells is driving demand for point-of-use and humanitarian drinking water technologies. Atmospheric water capture (AWC) can provide water off the centralized grid by capturing water vapor in ambient air and condensing it to a liquid. The overarching goal of this dissertation was to define geographic and thermodynamic design boundary conditions for AWC and develop nanotechnology-enabled AWC technologies to produce clean drinking water. Widespread application of AWC is currently limited because water production, energy requirement, best technology, and water quality are not parameterized. I developed a geospatial climatic model for classical passive solar desiccant-driven AWC, where water vapor is adsorbed onto a desiccant bed at night, desorbed by solar heat during the day, and condensed. I concluded passive systems can capture 0.25–8 L/m2/day as a function of material properties and climate, and are limited because they only operate one adsorption-desorption-condensation cycle per day. I developed a thermodynamic model for large-scale AWC systems and concluded that the thermodynamic limit for energy to saturate and condense water vapor can vary up to 2-fold as a function of climate and mode of saturation. Thermodynamic and geospatial models indicate opportunity space to develop AWC technologies for arid regions where solar radiation is abundant. I synthesized photothermal desiccants by optimizing surface loading of carbon black nanoparticles on micron-sized silica gel desiccants (CB-SiO2). Surface temperature of CB-SiO2 increased to 60oC under solar radiation and water vapor desorption rate was 4-fold faster than bare silica. CB-SiO2 could operate >10 AWC cycles per day to produce 2.5 L/m2/day at 40% relative humidity, 3-fold more water than a conventional passive system. Models and bench-scale experiments were paired with pilot-scale experiments operating electrical desiccant and compressor dehumidifiers outdoors in a semi-arid climate to benchmark temporal water production, water quality and energy efficiency. Water quality varied temporally, e.g, dissolved organic carbon concentration was 3 – 12 mg/L in the summer and <1 mg/L in the winter. Collected water from desiccant systems met all Environmental Protection Agency standards, while compressor systems may require further purification for metals and turbidity. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2020

Some aspects of grain boundary segregation (GBS) are discussed. This paper adds two new sprouts. The first is connected with formation of the atomic complexes in boundary region and their effect on grain boundary diffusion (GBD). The second – with a nonhomogeneity of energy distribution between boundary sites.

Yes / Prediction of engine-out emissions with high fidelity from in-cylinder combustion simulations is still a significant challenge early in the engine development process. This paper contributes to this fast evolving body of knowledge by focusing on the evaluation of NOx emissions predictions capability of a Probability Density Function (PDF) based Stochastic Reactor Engine Models (SRM), for a Diesel engine. The research implements a systematic approach to the study of the SRM engine model performance, based on a detailed space-filling design of experiments based sensitivity analysis of both external and internal parameters, evaluating their effects on the accuracy in matching physical measurements of in-cylinder conditions, and NOx emissions output. The approach proposed in this paper introduces an automatic SRM model calibration methodology across the engine operating envelope, based on a multi-objective optimization approach. This aims to exploit opportunities for internal SRM parameters tuning to achieve good overall modelling performance as a trade-off between physical in-cylinder measurements accuracy and the output NOx emissions predictions error. The results from the case study provide a valuable insight into the effectiveness of the SRM model, showing good capability for NOx emissions prediction and trends, while pointing out the critical sensitivity to the external input parameters and modelling conditions. / 41043/R00836 Jaguar Land Rover funded research “MULTI-PHYSICS ENGINE SIMULATION FRAMEWORK: RESEARCH INTO ADVANCED CAE CAPABILITY FOR MULTI-PHYSICS SIMULATION FRAMEWORK TO GENERATE HIGH FIDELITY PREDICTION OF ENGINE-OUT EMISSIONS”, 2016 – 2019. / Research Development Fund Publication Prize Award winner, March 2019.

The full text will be available at the end of the embargo period: 4th Aug 2025

O estudo e a compreensão da termodinâmica é extremamente importante para todos os processos que envolvam equilíbrio de fases. A determinação das propriedades termodinâmicas de uma mistura pode ser obtida por diferentes formas de cálculo, que podem consumir um grande tempo computacional e apresentar difícil solução. Para casos que envolvam controle e simulações online, otimizações em tempo real e até simuladores de treinamento de operadores (OTS) isso pode ser um fator decisivo no emprego da aplicação. Esta dissertação propõe uma nova formulação denominada de Método dos Modelos Termodinâmico Simplificado (MTS) em lugar da utilização dos modelos termodinâmicos locais (MTL), os quais são destinados à redução do tempo computacional de simulações de processos, através da aproximação de modelos rigorosos e da simplificação das rotinas de cálculos termodinâmicos de equilíbrio líquido-vapor. O MTS proposto neste trabalho é constituído por parâmetros que são estimados utilizando dados calculados de forma rigorosa e que permitem a sua utilização em uma região significativamente mais ampla. Inicialmente, avaliaram-se alguns MTLs empregados na literatura e a partir destes foi proposto um novo modelo com adição de um parâmetro capaz de melhorar a dependência da temperatura de ponto de bolha. Para se determinar os parâmetros do MTS, foi formulado um problema de otimização em que a função objetivo envolve os erros nos ajustes das constantes de equilíbrio e o erro na predição da temperatura de ponto de bolha da mistura, tendo como restrição de igualdade o somatório da composição da fase vapor. Nessa nova abordagem todos os parâmetros são obtidos simultaneamente. Em trabalhos anteriores, os parâmetros eram determinados através da resolução de um problema de mínimos quadrados formulados para cada constante de equilíbrio separadamente. As propriedades termodinâmicas obtidas com essa nova metodologia foram comparadas às propriedades obtidas com modelos rigorosos, apresentando boa correlação e solução simples. O novo MTS e a metodologia proposta foram também validados para uma mistura de cinco componentes. Finalmente o modelo obtido para a mistura acetona, benzeno e etanol foi implementado em uma simulação dinâmica de uma coluna de destilação. Os resultados obtidos foram muito satisfatórios, reduzindo o tempo de resolução do problema em aproximadamente 50 vezes quando comparado ao tempo necessário para resolver o mesmo problema utilizando o modelo rigoroso. / Thermodynamics is very important for all processes involving phase equilibrium. The determination of the thermodynamic properties of a mixture can be obtained by different ways of calculation, which can spend a large computational time and present difficult solution. For cases involving online control and simulations, real-time optimizations and operator training simulators (OTS) this point can be a decisive factor in the use of application. A new concept is proposed for the use of local thermodynamic models (LTM), which are aimed at reducing the computational time of processes simulations, through the approximation of rigorous models and simplifying thermodynamic routines of phase equilibrium calculations, to be used in a new approach, as a simplified thermodynamic models (STM) with global application. The STM presented consists of parameters that are estimated using data rigorous calculated. First of all, some LTM presented in the literature were evaluated and it was proposed a new model with the addition of one parameter that provides better adjustment to the bubble point temperature. This new model was called STM. After define an STM for a ternary mixture, we a new methodology to obtain the model parameters was proposed. In previous papers, the parameters were determined by solving a least squares problem, it is necessary to obtain separately the parameters of each component model. The new methodology is based on an optimization problem that minimizes the error between the K-value obtained by rigorous model and the K-value predicted by STM, adjusting the parameters of all components simultaneously in the same calculation and estimating the bubble point temperature of mixture. The thermodynamic properties obtained with this new method were compared to the properties obtained with rigorous models, presenting good correlation and simple solution. The new STM and the proposed methodology were also validated for a mixture of five components. Finally the model obtained for the mixture was implemented in a dynamic simulation of a distillation column, in which it was obtained very satisfactory results, reducing the time to resolution of the problem in about 50 times when compared to the time required to solve the same problem using the rigorous model.

Made available in DSpace on 2016-06-02T19:55:36Z (GMT). No. of bitstreams: 1 TeseJCTF.pdf: 3670025 bytes, checksum: 32289c02fa0f16236c28137ea6d2a96c (MD5) Previous issue date: 2004-12-13 / Universidade Federal de Sao Carlos / Natural zeolites are the most important inorganic cationic exchangers exhibiting high ion exchange capacity, selectivity and environment compatibility. Heavy metals are well known for toxicity and their disposal is a significant industrial waste problem. The goal of this work was directed to evaluate the selectivity of a purified homo-ionic clinoptilolite mineral for aqueous Pb2+, Zn2+, Cu2+ and Na+ ions at 0,005 eq/L and 303 K, interpreted through the application of empirical thermodynamic models to the zeolite phase (Margules, Van Laar, Wilson) coupled with a well established ion-interaction approach for the electrolyte solution (Pitzer). The present study considered the following stages: (1) adsorbent material: preparation and characterization; (2) aqueous solutions: nitrates of sodium, lead, zinc and copper; (3) equilibration of weighed amounts of homo-ionic clinoptilolite with a series of solutions containing the two competing cations; (4) analysis for aqueous cations by AAE; (5) construction of the equilibrium points; isotherm analysis; (6) test for thermodynamic reversibility; (7) empirical models for the zeolite phase (admitted as a solid solution) jointed to the ion-interaction model chosen for the aqueous solution; (8) equilibrium constant and Gibbs free energy for the ion-exchange reactions; phenomenological interpretation of the thermodynamic parameters obtained by means of the application of empirical models to the zeolite phase. The above procedure was, in the same way, followed for the ternary systems. The results obtained in this work shown that the empirical models adopted for the solid phase coupled to Pitzer s model for the activity coefficients in the electrolyte solution describe successfully the binary ion-exchange equilibria. The calculated equilibrium constant and the corresponding Gibbs free energy for each binary-exchange reaction resulted in a selectivity sequence, at the normality and temperature of this study, easily deduced as: 2 2 2 Pb Na Cu Zn + + + + > > . Besides, the parameters estimated applying the Margules , Van Laar s and Wilson s equations for cations in the solid binary mixture resulted in useful values quantifying adequately the cation zeolite framework interactions, thus, an alternative way to interpret the adsorbent selectivity from the charge and cationic radius effect. The ternary parameters obtained applying multi-component empirical models do not explain properly the non-ideality of ions in a solid mixture containing more than two components. This is in accordance with the results encountered in a number of publications on crystal structure of heulandite-group zeolites: these aluminosilicates are found to contain crystallographically distinct set of sites throughout the exchanger framework and that normally each set of sites is partially populated by the exchanging ions. As a consequence, activity coefficients for a multi-component exchange reaction cannot be predicted from appropriate binary data for a heterogeneous exchanger, since the phenomenological binary coefficients are complicated functions of each site set, population and composition, and both these properties will change on introducing other species of ion in the exchanger. In this sense, and from what were obtained here, is believed that multi-component solid phase nonideality must, at least, be interpreted through the application of statistical thermodynamic models considering the energetic heterogeneity of a number of site set and the charge density of the specific zeolite framework. / Obs.: Devido a restrições dos caracteres especias, verifcar resumo em texto completo para download. As zeólitas naturais constituem os trocadores iônicos inorgânicos mais importantes, as quais mostram elevada capacidade de troca iônica, seletividade e compatibilidade com o ambiente natural. Os metais pesados são conhecidos pela sua toxicidade e seus depósitos constituem o maior problema quanto a despejos industriais. Os objetivos básicos deste trabalho foram a interpretação do equilíbrio de adsorção e a avaliação da seletividade de um mineral de clinoptilolita purificado e homo-iônico por Pb2+, Zn2+, Cu2+ e Na+ aquosos à normalidade de 0,005 eq/L e temperatura de 303 K. O estudo proposto foi feito obedecendo as seguintes etapas: (1) preparação e caracterização do material adsorvente; (2) preparação e análise de soluções eletrolíticas; (3) equilíbrio termodinâmico de clinoptilolita homo-iônica com soluções contendo os dois cátions competitivos; (4) análises, no equilíbrio, das soluções mediante EAA; (5) construção dos pontos experimentais e análise das isotermas; (6) testes de reversibilidade termodinâmica; (7) uso de modelos empíricos para a fase zeólita, admitida como uma pseudo-solução, e modelos de interação iônica para a solução eletrolítica; (8) análise da constante de equilíbrio e da energia livre de Gibbs das reações de troca binárias e interpretação fenomenológica dos parâmetros termodinâmicos. Os resultados obtidos mostraram que os modelos adotados para a fase zeólita, considerada como uma mistura, junto com o modelo de Pitzer para os coeficientes de atividade na solução eletrolítica descrevem com sucesso o equilíbrio de troca binária dos sistemas estudados. A constante de equilíbrio calculada e a correspondente energia livre de Gibbs, para cada reação de troca binária à normalidade e temperatura estudadas, resultaram numa seqüência de seletividade dada por: 2 2 2 Pb Na Cu Zn + + + + > > . Paralelamente, os parâmetros estimados através do o uso das equações de Margules, Van Laar e Wilson para os cations na mistura binária resultaram em valores úteis na quantificação das interações cátion estrutura. Desta forma, a avaliação destes parâmetros constituiu uma alternativa na interpretação da seletividade do adsorvente pelos diferentes cátions de troca a partir do efeito do raio e da carga dos cátions. Os parâmetros ternários obtidos através da aplicação de modelos clássicos de estrutura multicomponente resultaram não satisfatórios na interpretação fenomenológica da mistura de mais de dois componentes. Este resultado confirma o encontrado em estudos sobre a estrutura cristalina das zeólitas tipo heulandita: estes aluminosilicatos geralmente contêm grupos de sítios cristalográficos distinguíveis e, por outro lado, que os coeficientes de atividade dos íons em cada tipo de sítios é uma função fortemente dependente da composição e população destes. Desta forma, a inclusão de um terceiro componente torna extremamente complicada a predição e interpretação dos coeficientes de atividade fenomenológicos na mistura sólida multicomponente. Neste sentido e, a partir dos resultados deste estudo, acredita-se que a interpretação da não idealidade da mistura sólida multicomponente deve ser feita através do uso de modelos que considerem a heterogeneidade energética dos diferentes grupos de sítios dentro da zeólita, acoplado a considerações da termodinâmica estatística que têm em conta a população e composição em cada grupo de sítios, além da densidade de carga da rede cristalina do adsorvente.

O estudo e a compreensão da termodinâmica é extremamente importante para todos os processos que envolvam equilíbrio de fases. A determinação das propriedades termodinâmicas de uma mistura pode ser obtida por diferentes formas de cálculo, que podem consumir um grande tempo computacional e apresentar difícil solução. Para casos que envolvam controle e simulações online, otimizações em tempo real e até simuladores de treinamento de operadores (OTS) isso pode ser um fator decisivo no emprego da aplicação. Esta dissertação propõe uma nova formulação denominada de Método dos Modelos Termodinâmico Simplificado (MTS) em lugar da utilização dos modelos termodinâmicos locais (MTL), os quais são destinados à redução do tempo computacional de simulações de processos, através da aproximação de modelos rigorosos e da simplificação das rotinas de cálculos termodinâmicos de equilíbrio líquido-vapor. O MTS proposto neste trabalho é constituído por parâmetros que são estimados utilizando dados calculados de forma rigorosa e que permitem a sua utilização em uma região significativamente mais ampla. Inicialmente, avaliaram-se alguns MTLs empregados na literatura e a partir destes foi proposto um novo modelo com adição de um parâmetro capaz de melhorar a dependência da temperatura de ponto de bolha. Para se determinar os parâmetros do MTS, foi formulado um problema de otimização em que a função objetivo envolve os erros nos ajustes das constantes de equilíbrio e o erro na predição da temperatura de ponto de bolha da mistura, tendo como restrição de igualdade o somatório da composição da fase vapor. Nessa nova abordagem todos os parâmetros são obtidos simultaneamente. Em trabalhos anteriores, os parâmetros eram determinados através da resolução de um problema de mínimos quadrados formulados para cada constante de equilíbrio separadamente. As propriedades termodinâmicas obtidas com essa nova metodologia foram comparadas às propriedades obtidas com modelos rigorosos, apresentando boa correlação e solução simples. O novo MTS e a metodologia proposta foram também validados para uma mistura de cinco componentes. Finalmente o modelo obtido para a mistura acetona, benzeno e etanol foi implementado em uma simulação dinâmica de uma coluna de destilação. Os resultados obtidos foram muito satisfatórios, reduzindo o tempo de resolução do problema em aproximadamente 50 vezes quando comparado ao tempo necessário para resolver o mesmo problema utilizando o modelo rigoroso. / Thermodynamics is very important for all processes involving phase equilibrium. The determination of the thermodynamic properties of a mixture can be obtained by different ways of calculation, which can spend a large computational time and present difficult solution. For cases involving online control and simulations, real-time optimizations and operator training simulators (OTS) this point can be a decisive factor in the use of application. A new concept is proposed for the use of local thermodynamic models (LTM), which are aimed at reducing the computational time of processes simulations, through the approximation of rigorous models and simplifying thermodynamic routines of phase equilibrium calculations, to be used in a new approach, as a simplified thermodynamic models (STM) with global application. The STM presented consists of parameters that are estimated using data rigorous calculated. First of all, some LTM presented in the literature were evaluated and it was proposed a new model with the addition of one parameter that provides better adjustment to the bubble point temperature. This new model was called STM. After define an STM for a ternary mixture, we a new methodology to obtain the model parameters was proposed. In previous papers, the parameters were determined by solving a least squares problem, it is necessary to obtain separately the parameters of each component model. The new methodology is based on an optimization problem that minimizes the error between the K-value obtained by rigorous model and the K-value predicted by STM, adjusting the parameters of all components simultaneously in the same calculation and estimating the bubble point temperature of mixture. The thermodynamic properties obtained with this new method were compared to the properties obtained with rigorous models, presenting good correlation and simple solution. The new STM and the proposed methodology were also validated for a mixture of five components. Finally the model obtained for the mixture was implemented in a dynamic simulation of a distillation column, in which it was obtained very satisfactory results, reducing the time to resolution of the problem in about 50 times when compared to the time required to solve the same problem using the rigorous model.