where G(x) is the total Gibbs energy of the system (in moles); gj is the partial molal Gibbs energy function of j-th aqueous species at T,P of interest in the molal scale; xj is the mole quantity of j-th species and w j x that of the water-solvent. Xw is the total mole quantity of the aqueous phase (including water-solvent), γj is the internal asymmetric activity coefficient (in practical scale), and Mw = 18.0153 g mol is the gram-formula mass of H2O. The two terms

a b s t r a c t Recovery of bioethanol from the fermentation broth is classically achieved by distillation. The design and optimization of the distillation requires a reliable thermodynamic model that describes sufficiently the properties of the ethanol/water mixture, and, especially, the vapor–liquid equilibrium (VLE) near the azeotropic point. The purpose of this study is twofold: first, to provide new reliable low-pressure VLE data for the ethanol/water mixture with emphasis given near the azeotropic region, and second, to develop new temperature-dependent binary interaction parameters for three excess Gibbs energy models (UNIQUAC, Wilson and NRTL), by fitting simultaneously VLE data, azeotropic points and excess enthalpies for this mixture.

We show how thermodynamic properties of molecular models can be computed over a large, multidimensional parameter space by combining multistate reweighting analysis with a linear basis function approach. This approach reduces the computational cost to estimate thermodynamic properties from molecular simulations for over 130,000 tested parameter combinations from over 1000 CPU years to tens of CPU days. This speed increase is achieved primarily by computing the potential energy as a linear combination of basis functions, computed from either modified simulation code or as the difference of energy between two reference states, which can be done without any simulation code modification. The thermodynamic properties are then estimated with the Multistate Bennett Acceptance Ratio (MBAR) as a function of multiple model parameters without the need to define a priori how the states are connected by a pathway. Instead, we adaptively sample a set of points in parameter space to create mutual configuration space overlap. The existence of regions of poor configuration space overlap are detected by analyzing the eigenvalues of the sampled states' overlap matrix. The configuration space overlap to sampled states is monitored alongside the mean and maximum uncertainty to determine convergence, as neither the uncertainty or the configuration space overlap alone is a sufficient metric of convergence. This adaptive sampling scheme is demonstrated by estimating with high precision the solvation free energies of charged particles of Lennard-Jones plus Coulomb functional form with charges between -2 and +2 and generally physical values of σij and ϵij in TIP3P water. We also compute entropy, enthalpy, and radial distribution functions of arbitrary unsampled parameter combinations using only the data from these sampled states and use the estimates of free energies over the entire space to examine the deviation of atomistic simulations from the Born approximation to the solvation free energy.

We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H^+, Li^+, Na^+, K^+, NH_(4)^+, Mg^(2+), Ca^(2+), Cl^−, Br^−, NO_(3)^−, HSO_(4)^−, and SO_(4)^(2−). Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with dicarboxylic acids and with levoglucosan. Overall, the new parameterization of AIOMFAC agrees well with a large number of experimental datasets. However, due to various reasons, for certain mixtures important deviations can occur. The new parameterization makes AIOMFAC a versatile thermodynamic tool. It enables the calculation of activity coefficients of thousands of different organic compounds in organic-inorganic mixtures of numerous components. Models based on AIOMFAC can be used to compute deliquescence relative humidities, liquid-liquid phase separations, and gas-particle partitioning of multicomponent mixtures of relevance for atmospheric chemistry or in other scientific fields.

WATER ACTIVITY AND SORPTION PROPERTIES OF FOODDefinition:Water ActivityWater Activity Measurement:Colligative Properties MethodsMethod Based on Equilibrium Sorption RateMethod Based on Hygroscopicity of SaltsMethods Using Hygrometric InstrumentsMeasurement Based on Isopiestic TransferMeasurement Based on Suction PotentialSelection of a Suitable MethodWater Activity Prediction:Prediction Model for Ideal SolutionsReasons for Non-Ideal Behavior of SolutionsWater Activity Prediction Models for Non-Ideal SolutionsLimitations of the Water Activity Prediction Models in Case of FoodsSorptions Isotherms:Hysteresis in Sorption IsothermsTheories of Sorption HysteresisIsotherm ModelsTemperature Shift of Isotherms:Shift Above Frozen StateWater Activity Below FreezingEffect of Pressure on Water ActivityWater Activity of Multicomponent Mixture:Equilibrium Water Activity of Multicomponent Mixture from Individual IsothermApplications of Water Activity:Product Stability DeterminationProcess Design and ControlIngredient SelectionPackaging SelectionThermodynamic Properties PredictionStructure InvestigationNomenclaturePHASE TRANSITIONS IN FOODPhysics of the Phase Transition:Cooling and Heating CurvesPhase DiagramState DiagramThermal Behavior by Heat Flow CalorimetryGelatinizationCrystallizationCollapse and Sticky TemperatureState of Water in Foods:NMR Reluxation of Water in FoodsDSC Caloric State of Water in FoodsState of Water from Sorption IsothermDielectric State of Water in FoodsState of Water from Suction PotentialState of Water from Indirect MethodsFreezing Point:Freezing Point Measurement MethodsFreezing Points of FoodsFreezing Point Prediction ModelsGlass Transition Temperature:Glass Transition Measurement MethodsGlass Transition Temperatures of FoodsGlass Transition Temperature PredictionGelatinization in Foods:Measurement Techniques of Gelatinization TemperatureGelatinization Temperature of Food ComponentsGelatinization Temperature PredictionCrystallization in Foods:Crystallization DynamicsCrystallization KineticsCollapse and Sticky Temperature:Measurement of Collapse TemperatureApplications:Importance of Freezing Point in Food ProcessingApplication of Glass Transition TemperatureDecomposition, Fusion, and CrystallizationImportance of GelatinizationCollapse and Sticky PointNomenclaturePHYSICAL PROPERTIES OF FOODDefinition:DensityPorosityShrinkageSurface Area and VolumeMeasurement Techniques:Volume MeasurementPorosity MeasurementSurface Area MeasurementExperimental Data:Density Prediction ModelsPorosity Prediction ModelsShrinkage Prediction ModelsSurface Area Prediction ModelsApplications:Process DesignFood Products Quality DeterminationNomenclatureSPECIFIC HEAT, ENTHALPY, AND LATENT HEAT OF FOODDefinition:EnergyEnthalpySp

Vapor sorption equilibrium data of ten binary polymer/solvent systems were measured using sorption equilibrium cell equipped with a vacuum electromicrobalance. Tested solvents were water, methanol, ethanol and npropanol and polymer solutes were poly(ethylene glycol), poly(propylene glycol), poly(tetramethylene glycol) and poly(ethylene oxide). The measured sorption obtained in the present work, were compared with existing literature data and the degree of reliability of the measured data was discussed. Vapor sorption equilibrium data obtained in the present study were correlated by UNIQUAC model and the multi-fluid non-random lattice fluid hydrogen bonding equation of state (MF-NLF-HB EOS) recently proposed by the present authors.

Unified power flow controller (UPFC) has been the most versatile Flexible AC Transmission System (FACTS) device due to its ability to control real and reactive power on transmission lines while controlling the voltage of the bus to which it is connected. UPFC being a multi-variable power system controller it is necessary to analyze its effect on power system operation. To study the performance of the UPFC in damping power oscillations using MATLAB/Simulink software, a de-coupled control system has been designed for the shunt inverter to control the UPFC bus voltage and the DC link capacitor voltage. The series inverter of a UPFC controls the real power flow in the transmission line. One problem associated with using a high gain PI controller (used to achieve fast control) for the series inverter of a UPFC to control the real power flow in a transmission line is the presence of low damping. This problem is solved in this research by using an adaptive fuzzy PI controller for the series inverter of UPFC. Transient response studies have been conducted using MATLAB/Simulink software to show the improvement in power oscillation damping with UPFC in a single machine infinite bus and then in a multi machine power system in two cases, the first one when the series inverter is equipped with a conventional PI controller, the second one when it is equipped with an adaptive fuzzy PI controller. The simulation results have been conducted in MATLAB/Simulink software show the viability of the proposed control strategy in damping power oscillations. A la memoire de mon pere a ma mere a mon epouse a mes fils et a mes freres et sœurs

Two new composition dependent mixing rules for cubic equations of state are proposed. Both mixing rules contain two adjustable binary parameters and reduce to the conventional one parameter mixing rule when the parameters are equal. Vapor-liquid equilibrium data for mixtures of polar (associated or not) compounds with saturated hydrocarbons and for systems water/alcohol have been used to test the new mixing rules applied to the PRSV cubic equation of state. For these highly nonideal systems, correlation of the data with a new mixing rule of the Van Laar type for the PRSV equation gives better results than those obtained using excess Gibbs energy functions like the Wilson equation, NRTL and UNIQUAC.

Tropospheric aerosols contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behaviour. By means of activity coefficients, non-ideal behaviour can be taken into account. We present here a thermodynamic model named AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) that is able to calculate activity coefficients covering inorganic, organic, and organic-inorganic interactions in aqueous solutions over a wide concentration range. This model is based on the activity coefficient model LIFAC by Yan et al. (1999) that we modified and reparametrised to better describe atmospherically relevant conditions and mixture compositions. Focusing on atmospheric applications we considered H^+, Li^+, Na^+, K^+, NH^+_4, Mg^(2+), Ca^(2+), Cl^−, Br^−, NO^−_3, HSO^−_4, and SO^(2−)_4 as cations and anions and a wide range of alcohols/polyols composed of the functional groups CH_n and OH as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are well represented up to high ionic strength. Most notably, a semi-empirical middle-range parametrisation of direct organic-inorganic interactions in alcohol+water+salt solutions strongly improves the agreement between experimental and modelled activity coefficients. At room temperature, this novel thermodynamic model offers the possibility to compute equilibrium relative humidities, gas/particle partitioning and liquid-liquid phase separations with high accuracy. In further studies, other organic functional groups will be introduced. The model framework is not restricted to specific ions or organic compounds and is therefore also applicable for other research topics.

This work reviews research activities in the development of phase-change CO2 capture solvents and processes. The focus is on liquid–liquid phase-change solvents in which the CO2-lean phase can be r...

This work evaluates the performance of the group contribution volume translated Peng-Robinson model when predicting the vapor-liquid equilibrium and single phase densities of 28 commercial refrigerant mixtures with low global warming potential and zero ozone depletion potential. Cubic equations of state, and particularly the Peng-Robinson equation of state, are widely used in the refrigeration industry due to their easy applicability for new substances, and their low computational time, although generally lower prediction accuracies must be expected compared to multiparameter equations of state. The group contribution volume translated Peng-Robinson equation of state combines the Peng-Robinson equation of state with a new attraction term, improved mixing rules using a group contribution approach, and volume translation. The results are compared with the estimates obtained using the non translated Peng-Robinson equation of state, and a multiparameter equation of state.

This work deals with CO2 capture plants for an advanced air-blown gasification-based combined cycle where a coal with high sulphur content, which is really relevant for the coal market, is used as feedstock. The sulphur removed as H2S from the coal-derived gas enters a wet sulphuric acid process. Later, the resulting acid is used to control ammonia slip in a post-combustion CO2 capture plant based on ammonia scrubbing and designed for a reduced energy demand. Thus, limiting the energy impact of the CO2 capture technology will improve the power plant efficiency, according to a presumable lower cost of the generated electricity, as a high-sulphur coal is used as fuel input.

This work approaches the study of gas-liquid flow in the expansion chamber of a typical cylindrical cyclonic separator. To understand its operation, first is analyzed the velocity field of the liquid phase inside the equipment. The analysis is based on numerical simulations and experimental measurements. From the results, is developed a model that determines the velocity and the thickness of the liquid film flow along the separator. The model developed produces results with good accuracy for a wide range of operating conditions and dimensions of the separator. In the second step, a formulation for bubble tracking is coupled in the single phase model, in order to evaluate its theoretical separation from a continuous liquid medium. The study of two-phase flow identifies the optimum length of the separator to separate bubbles and also allows understand the influence of operating conditions on the separation process. The results achieved should contribute to the state of the art in the subject and provide engineers working in the area a relatively simple tool for the design of these separators.

This thesis modifies an already existing dynamic Matlab Simulink model to correlate with a Hysys model from a similar research. The models are concerned with the reactive distillation for production of biodiesel from linoleic esters of soybean oil through transesterification reactions. The Matlab model was constructed using molar balances, Francis? weir equation for the liquid dynamics, no vapour dynamics, kinetics according to the rate law and temperature estimations according to the UNIQUAC method. Very similar results were presented for the two models besides the Matlab being of simpler origin, and having no inclusion of energy balances compared to the Hysys model. Both a dynamic Simulink and a DAE-system model were produced, with the DAE system having reduced simulation time and an additional steady-state version. The steady-state version of the DAE-model was used for optimisation according to the Skogestad Economic Plantwide Optimisation principles. The first part of the systematic top-down/bottom-up method was applied, focusing on the economic control. Four distinct active constraint regions were identified; varying with the feed flowrate and molar ratio. The first region could not be solved with regard to quality constraints, while the second had maximum flowrate and maximum impurity of total glycerol in the biodiesel product as the active constraints. The third region had active constraints of maximum temperature in the reboiler and maximum impurity of glycerol. The fourth region would not be solved by the Matlab fmincon interior-point algorithm, and applies very high feed ratios outside of the range normally applied by biodiesel production processes.

This thesis investigates the capture of CO2 from the flue gas of coal-fired power plants using an aqueous solution of MEA, and the main aim of this thesis is the development of an optimized amine-based post-combustion CO2 capture (PCC) process that can be integrated optimally with a pulverized coal-fired power plant. The relevance of this thesis cannot be overemphasised because the reduction of solvent regeneration energy is the focus of most of the solvent-based post-combustion CO2 capture (PCC) research currently being performed globally. From the view point of current research and development (R&D) activities worldwide, three main areas are being investigated in order to reduce the regeneration energy requirement of an amine-based PCC process, namely: (i) development of new solvents with better overall performance than 30 wt% monoethanolamine (MEA) aqueous solution, (ii) PCC plant optimization, and (iii) optimal integration of the PCC Plant, including the associated CO2 compression system, to the upstream power plant. In this thesis, PCC plant optimization and the optimal integration of an optimized PCC Plant, including the associated CO2 compression system, with an upstream coal-fired power plant has been investigated. Thus, an integrated process comprising ~550 MWe (net power after CO2 capture and compression) pulverized coal-fired (PC-fired) supercritical power plant, an MEA-based post-combustion capture (PCC) plant and a CO2 compression system has been modelled, simulated and optimized. The scale-up design of the PCC plant was performed using a novel method based on a rate-based calculation and thus the unnecessary over-design of the PCC plant columns was avoided. Furthermore, because of the importance of the operating pressure of the stripper in a PCC plant integrated to a PC-fired power plant, the impact of the operating pressure of the stripper on the net plant efficiency of the integrated system has been quantified. Also, the impacts of coal type on the overall performance of the integrated process have been quantified.

This thesis interprets about the dynamics and control study of distillation columns using Aspen. As all of us are aware, that distillation is one of the most important separation processes in the Chemical Engineering. In the present thesis, simulation studies of the distillation column are presented. Steady state simulations are being performed using Aspen Plus followed by Aspen Dynamic simulation, licensed software of Aspen Tech. In the steady state simulation we have tried to see the effect of changing the flow rate of the extracting solvent etc., which gives criterion about the optimum flow rate in the distillation column. The basic controllers are used for controlling sump level, reflux level and molar feed flow rate. Further two important strategies used for controlling the purity of distillate are: (1) controlling the tray temperature where the maximum change of temperature is observed due to reboiler heat change (2) composition controller. Tyreus iVLuyben method is used to tune the proportional integrator controller (PI) for temperature and composition control. The location of temperature controlled tray is obtained by steady state gain value. The design value of integral time constant, I ƒa of temperature control and composition control configurations are found as 2.54 min. and 68.54 min. respectively. Hence, response of temperature controller is faster than the composition controller, but on account of less purity. Thus results encourage to use cascade controller.

This thesis extends the Cubic Plus Association (CPA) equation of state (EoS) to handle mixtures containing ions from fully dissociated salts. The CPA EoS has during the past 18 years been applied to thermodynamic modeling of a wide range of industrially important chemicals, mainly in relation to the oiland gas sector. One of the strengths of the CPA EoS is that it reduces to the Soave Redlich Kwong (SRK) cubic EoS in the absence of associating compounds and is therefore compatible with existing tools for oil characterization. In a similar fasion, the electrolyte CPA (e-CPA) EoS reduces to the CPA EoS in the absence of electrolytes, making it possible to extend the applicability of the CPA EoS while retaining backwards compatibility and resuing the parameters for non-electrolyte systems . There are many challenges related to thermodynamic modeling of mixtures containing electrolytes, and many different approaches to the development of an electrolyte EoS have been suggested by scientists in the field. However, most of these approaches are focusing on aqueous solutions and cannot easily be extended to handle mixed solvents. Furthermore, the approaches suggested in current literature have rarely been applied to all types of thermodynamic equilibrium calculations relevant to electrolyte solutions. This project has aimed to determine the best recipe to deliver a complete thermodynamic model capable of handling electrolytes in mixed solvents and at a wide range of temperature and pressure. Different terms describing the electrostatic interactions have been compared and it was concluded that the differences between the Debye-Hückel and the "mean spherical approximation" models are negligible. A term accounting for the Gibbs energy of hydration (such as the Born term) must be included in order to provide sufficient driving forces for electrolytes towards the most polar phase. The static permittivity of the mixture was found to be the most important property; yet it was shown that the empirical models suggested by literature could lead to unphysical behavior of the equation of state. A new theoretical model was developed to extend the framework for modeling of the static permittivity to hydrogen-bonding compounds and salts. The model relates the geometrical configuration of hydrogen-bonding dipolar molecules to the Kirkwood g-factor using the Wertheim association model that is included with modern EoS such as CPA or SAFT (Statistical Associating Fluid Theory). This new model was shown to give excellent predictions of the static permittivity of mixtures over wide ranges of temperature, pressure, and composition and thereby generalizes the handling of electrolytes in mixed solvents in an electrolyte EoS. The CPA EoS was extended with a Debye-Hückel and a Born term to account for the electrostatics along with the new model for the static permittivity. This new e-CPA EoS was parameterized against osmotic coefficient, density, and mean ionic activity coefficient data of pure salts and validated against salt mixture data. The model was then applied to predict: • the solubility of light gases, hydrocarbons, and aromatics in aqueous mixtures and mixed solvents • solid-liquid equilibrium in aqueous salt mixtures and mixed solvents • gas hydrate formation pressures of methane with salts in water+methanol • liquid-liquid and liquid-liquid-liquid equilibrium with water-propan-1-ol-NaCl-octane solutions It was demonstrated that the model has a good potential for applications in relation to e.g. flow assurance during the production of natural gas. The parameterization of electrolyte EoS is of high importance and more work is needed in order to obtain good ion-specific parameters that include interaction parameters with gases and relevant chemicals.

This thesis explores mathematical optimization techniques to address the computeraided molecular and mixture design problems (CAMD/CAMxD). In particular, we leverage the power of mixed-integer linear programs (MILPs) to quickly and efficiently design over the massive chemical search space. These MILPs, when coupled with state-ofthe- art derivative-free optimization (DFO) methods, make for an efficient optimization strategy when designing mixtures of molecules or when considering a single molecule design problem that involves difficult thermodynamics or process models. In the first chapter, we provide a very general overview of the field of CAMD as addressed from the perspective of mathematical optimization. We discuss many relevant quantitative structure-property relationships (QSPRs) and provide constraints typically used in CAMD/CAMxD optimization problems. The second chapter introduces our DFO-based molecular/mixture design algorithm and describes how this approach enables a much greater molecular diversity to be considered in the search space as compared to traditional methods. Additionally, this chapter looks at a few case studies relevant to crystallization solvents and provides a detailed comparison of 27 different DFO algorithms for solving these problems. The third chapter introduces COSMO-RS/-SAC as alternatives to UNIFAC as the method used to capture mixture thermodynamics for a variety of CAMD/CAMxD problems. To fully incorporate COSMO-RS/-SAC into CAMD, we introduce group contribution (GC) methods for estimating a few necessary parameters for COSMO-based methods. We demonstrate the utility of COSMO-RS/-SAC in a few case studies for which UNIFAC-like methods are insufficient. In the fourth chapter, we investigate reaction solvent design using COSMO-based methods. COSMO-RS is particularly suitable for these problems as they allow for modeling of many relevant species in chemical reactions (transition states, charges, etc.) directly at the quantum level. This information can be immediately passed to the CAMD problem. We investigate a number of solvent design problems for a few difficult reactions. We summarize the work and provide a few future directions in the final chapter. Overall, this thesis serves to push the field of CAMD forward by introducing new methods to more efficiently explore the massive chemical search space and to enable a few new classes of problems which were previously untenable.

This study has demonstrated the existence of maximum flash-point solutions, where the maximum flash-point value is larger than those of the individual components. The behavior of such a solution has potential application in hazard reduction. The sufficient condition for a binary mixture to form such a maximum flash-point solution, and the equations to determine its composition and maximum flash point are proposed here, as these may be important in terms of hazard reduction. The sufficient condition and associated equations were verified by comparison with the experimental data. Our results reveal that this derived condition is satisfactory to establish that a liquid mixture is a maximum flash-point solution. The proposed equations may be successfully applied to estimate the composition and maximum flash-point value of such a mixture.

This study focuses on the use of an ionic liquid for extracting an aromatic hydrocarbon from a mixture of an aromatic and an aliphatic hydrocarbon. Liquid−liquid equilibrium data were collected for the toluene + heptane + 1-ethyl-3-methylimidazolium triiodide system at 45 °C and for the toluene + heptane + 1-butyl-3-methylimidazolium triiodide system at 35 °C. The nonrandom two-liquid (NRTL) physical thermodynamic model was used to correlate the experimental data. The NRTL model was found to represent the data very well. The selectivity and capacity of the ionic liquids for extracting toluene from toluene + heptane solutions were evaluated. The separation factors were found to be above 50 for low toluene compositions and nearly unity for high toluene compositions.