O uso de agrotóxicos e a consequente contaminação têm sido motivo de constante preocupação, sendo necessário monitorar esses compostos por metodologias que as quantifiquem em água e alimentos. As técnicas cromatográficas são as mais utilizadas para a este tipo de análise, mas apresentam desvantagens para aplicações \"in situ\" ou em tempo real. As técnicas eletroquímicas, como os biossensores enzimáticos que utilizam a acetilcolinesterase, têm sido estudadas para a determinação quantitativa de pesticidas em diferentes amostras. No entanto, as enzimas apresentam algumas desvantagens relacionadas com sua capacidade de desnaturação e com a inibição por outras espécies. Diante disso, foi proposta neste projeto a síntese de uma molécula mimética [ácido (4-(1E)-etanohidrazonoil) benzóico] para a acetilcolinesterase para catalisar a hidrólise do substrato (acetiltiocolina). A molécula mimética foi caracterizada por RMN e FTIR. Os produtos da reação, acetato e tiocolina, foram identificados pelo método de Ellman e FTIR. A cinética química do processo catalítico foi estudada, verificando-se que a reação era de primeira ordem em relação à concentração de acetiltiocolina e a constante de velocidade foi 0,623 s-1. Os dados experimentais obtidos com a molécula artificial foram aplicados ao modelo cinético de Michaelis-Menten e os parâmetros cinéticos foram determinados, constatando que a constante de velocidade calculada foi 13000 vezes menor que aquela calculada pelo método diferencial, o que mostrou a inconveniência de aplicar tal modelo enzimático aos catalisadores sintéticos. Além disso, verificou-se que o KM é uma constante que não possui significado quando aplicada às moléculas miméticas. / The application of pesticides and the resulting contamination have been a matter of constant concern, being necessary to monitor these compounds by methods that are able to quantify these compounds in water and food. The chromatographic techniques are most often used for this kind of analysis, but present some drawbacks for \"in situ\" or in real time applications. Electrochemical techniques, like biosensors based on the inhibition of acetylcholinesterase, have been studied for the quantitative determination of pesticides in different samples. However, the use of enzymes is complicated due to their ability to denaturation and the possible inhibition by other species. Therefore, in this project the synthesis of [4-(1E)etanehydrazonoylbenzoic acid], a mimetic molecule for acetylcholinesterase, was carried out, aiming the catalysis of acetylcholine hydrolysis. The mimetic molecule was characterized by NMR and FTIR. The products of reaction, such as acetate and thiocholine, were identified by Ellman\'s method and FTIR. The chemical kinetic of the catalytic process was characterized as of first order with respect to the acetylthiocholine concentration with a rate constant of 0.623 s-1. The experimental data obtained with the artificial molecule were applied to the Michaelis-Menten\'s model and the kinetic parameters were determined, noting that the rate constant was calculated as 13000 times smaller than that obtained by the differential method, which indicates the inconvenience of using the enzymatic model to the mimetic catalysts. Moreover, it was found that KM has no meaning when applied to mimetic molecules.

O uso de agrotóxicos e a consequente contaminação têm sido motivo de constante preocupação, sendo necessário monitorar esses compostos por metodologias que as quantifiquem em água e alimentos. As técnicas cromatográficas são as mais utilizadas para a este tipo de análise, mas apresentam desvantagens para aplicações \"in situ\" ou em tempo real. As técnicas eletroquímicas, como os biossensores enzimáticos que utilizam a acetilcolinesterase, têm sido estudadas para a determinação quantitativa de pesticidas em diferentes amostras. No entanto, as enzimas apresentam algumas desvantagens relacionadas com sua capacidade de desnaturação e com a inibição por outras espécies. Diante disso, foi proposta neste projeto a síntese de uma molécula mimética [ácido (4-(1E)-etanohidrazonoil) benzóico] para a acetilcolinesterase para catalisar a hidrólise do substrato (acetiltiocolina). A molécula mimética foi caracterizada por RMN e FTIR. Os produtos da reação, acetato e tiocolina, foram identificados pelo método de Ellman e FTIR. A cinética química do processo catalítico foi estudada, verificando-se que a reação era de primeira ordem em relação à concentração de acetiltiocolina e a constante de velocidade foi 0,623 s-1. Os dados experimentais obtidos com a molécula artificial foram aplicados ao modelo cinético de Michaelis-Menten e os parâmetros cinéticos foram determinados, constatando que a constante de velocidade calculada foi 13000 vezes menor que aquela calculada pelo método diferencial, o que mostrou a inconveniência de aplicar tal modelo enzimático aos catalisadores sintéticos. Além disso, verificou-se que o KM é uma constante que não possui significado quando aplicada às moléculas miméticas. / The application of pesticides and the resulting contamination have been a matter of constant concern, being necessary to monitor these compounds by methods that are able to quantify these compounds in water and food. The chromatographic techniques are most often used for this kind of analysis, but present some drawbacks for \"in situ\" or in real time applications. Electrochemical techniques, like biosensors based on the inhibition of acetylcholinesterase, have been studied for the quantitative determination of pesticides in different samples. However, the use of enzymes is complicated due to their ability to denaturation and the possible inhibition by other species. Therefore, in this project the synthesis of [4-(1E)etanehydrazonoylbenzoic acid], a mimetic molecule for acetylcholinesterase, was carried out, aiming the catalysis of acetylcholine hydrolysis. The mimetic molecule was characterized by NMR and FTIR. The products of reaction, such as acetate and thiocholine, were identified by Ellman\'s method and FTIR. The chemical kinetic of the catalytic process was characterized as of first order with respect to the acetylthiocholine concentration with a rate constant of 0.623 s-1. The experimental data obtained with the artificial molecule were applied to the Michaelis-Menten\'s model and the kinetic parameters were determined, noting that the rate constant was calculated as 13000 times smaller than that obtained by the differential method, which indicates the inconvenience of using the enzymatic model to the mimetic catalysts. Moreover, it was found that KM has no meaning when applied to mimetic molecules.

Foi realizado um estudo de desenvolvimento de projeto conceitual de uma unidade produtora de triacetina a partir de glicerol, como forma de aumentar a viabilidade de produção de biodiesel. A esterificação de glicerol com ácido acético envolve três reações de acetilação reversíveis consecutivas. Em cada etapa, água é produzida, resultando em conversão limitada e baixa seletividade. Uma forma de aumentar a seletividade da triacetina consiste em remover continuamente a água do meio reacional, de modo a alterar o equilíbrio. Foram considerados dois processos baseados em cinéticas diferentes. O processo A proposto baseia-se no sistema reacional descrito por Mufrodi et al. (2012), que emprega ácido sulfúrico como catalisador e o processo B baseia-se no sistema descrito por Galan et al. (2009), que consiste na esterificação de glicerol utilizando ácido acético em excesso como catalisador. Os dois processos foram simulados usando uma coluna de destilação reativa com hexano como potencializador do arraste de água, e diferentes configurações foram estudadas usando o simulador Aspen Plus®. As especificações do processo conceitual de uma unidade industrial otimizada, capaz de processar o glicerol produzido em uma unidade típica produtora de biodiesel, foram estimadas para os dois processos em termos de mínimo consumo específico de energia e produção de triacetina de pureza molar de 99,9%, com conversão completa de glicerol. O processo A se mostrou mais eficiente em termos energéticos, requerendo cerca de 20% da carga térmica requerida no processo B, além de ser mais compacto na quantidade de operações unitárias necessárias. / A conceptual process design study was carried out, aimed at the design of a triacetin production unit from glycerol, as a way to increase the feasibility of biodiesel production. Glycerol esterification with acetic acid involves three consecutive reversible acetylation reactions. In each step, water is produced, resulting in limited conversion and low selectivity. One way to increase the selectivity of triacetin is to continuously remove water from the reaction medium in order to shift the equilibrium. Two processes were considered, based on different kinetics. Process A is based on the reaction system described by Mufrodi et al. (2012), which employs sulfuric acid as catalyst, and process B is based on the system described by Galan et al. (2009), which consists of the esterification of glycerol using acetic acid in excess as catalyst. Both processes were simulated using a reactive distillation column and hexane as a water entrainment booster, and different configurations were studied by using the Aspen Plus® simulator. The conceptual process specifications of an optimized industrial plant capable of processing glycerol produced in a typical Brazilian biodiesel producer facility were estimated, for both processes, in order to minimize the specific energy consumption and produce triacetin with a molar purity of 99.9%, with complete conversion of glycerol. Process A showed to be more energy efficient, requiring about 20% of the heat duty required in process B, and being more compact in the necessary quantity of unit operations.

abstract: The heat and mass transfer phenomena in micro-scale for the mass transfer phenomena on drug in cylindrical matrix system, the simulation of oxygen/drug diffusion in a three dimensional capillary network, and a reduced chemical kinetic modeling of gas turbine combustion for Jet propellant-10 have been studied numerically. For the numerical analysis of the mass transfer phenomena on drug in cylindrical matrix system, the governing equations are derived from the cylindrical matrix systems, Krogh cylinder model, which modeling system is comprised of a capillary to a surrounding cylinder tissue along with the arterial distance to veins. ADI (Alternative Direction Implicit) scheme and Thomas algorithm are applied to solve the nonlinear partial differential equations (PDEs). This study shows that the important factors which have an effect on the drug penetration depth to the tissue are the mass diffusivity and the consumption of relevant species during the time allowed for diffusion to the brain tissue. Also, a computational fluid dynamics (CFD) model has been developed to simulate the blood flow and oxygen/drug diffusion in a three dimensional capillary network, which are satisfied in the physiological range of a typical capillary. A three dimensional geometry has been constructed to replicate the one studied by Secomb et al. (2000), and the computational framework features a non-Newtonian viscosity model for blood, the oxygen transport model including in oxygen-hemoglobin dissociation and wall flux due to tissue absorption, as well as an ability to study the diffusion of drugs and other materials in the capillary streams. Finally, a chemical kinetic mechanism of JP-10 has been compiled and validated for a wide range of combustion regimes, covering pressures of 1atm to 40atm with temperature ranges of 1,200 K - 1,700 K, which is being studied as a possible Jet propellant for the Pulse Detonation Engine (PDE) and other high-speed flight applications such as hypersonic missiles. The comprehensive skeletal mechanism consists of 58 species and 315 reactions including in CPD, Benzene formation process by the theory for polycyclic aromatic hydrocarbons (PAH) and soot formation process on the constant volume combustor, premixed flame characteristics. / Dissertation/Thesis / Ph.D. Aerospace Engineering 2012

Foi realizado um estudo de desenvolvimento de projeto conceitual de uma unidade produtora de triacetina a partir de glicerol, como forma de aumentar a viabilidade de produção de biodiesel. A esterificação de glicerol com ácido acético envolve três reações de acetilação reversíveis consecutivas. Em cada etapa, água é produzida, resultando em conversão limitada e baixa seletividade. Uma forma de aumentar a seletividade da triacetina consiste em remover continuamente a água do meio reacional, de modo a alterar o equilíbrio. Foram considerados dois processos baseados em cinéticas diferentes. O processo A proposto baseia-se no sistema reacional descrito por Mufrodi et al. (2012), que emprega ácido sulfúrico como catalisador e o processo B baseia-se no sistema descrito por Galan et al. (2009), que consiste na esterificação de glicerol utilizando ácido acético em excesso como catalisador. Os dois processos foram simulados usando uma coluna de destilação reativa com hexano como potencializador do arraste de água, e diferentes configurações foram estudadas usando o simulador Aspen Plus®. As especificações do processo conceitual de uma unidade industrial otimizada, capaz de processar o glicerol produzido em uma unidade típica produtora de biodiesel, foram estimadas para os dois processos em termos de mínimo consumo específico de energia e produção de triacetina de pureza molar de 99,9%, com conversão completa de glicerol. O processo A se mostrou mais eficiente em termos energéticos, requerendo cerca de 20% da carga térmica requerida no processo B, além de ser mais compacto na quantidade de operações unitárias necessárias. / A conceptual process design study was carried out, aimed at the design of a triacetin production unit from glycerol, as a way to increase the feasibility of biodiesel production. Glycerol esterification with acetic acid involves three consecutive reversible acetylation reactions. In each step, water is produced, resulting in limited conversion and low selectivity. One way to increase the selectivity of triacetin is to continuously remove water from the reaction medium in order to shift the equilibrium. Two processes were considered, based on different kinetics. Process A is based on the reaction system described by Mufrodi et al. (2012), which employs sulfuric acid as catalyst, and process B is based on the system described by Galan et al. (2009), which consists of the esterification of glycerol using acetic acid in excess as catalyst. Both processes were simulated using a reactive distillation column and hexane as a water entrainment booster, and different configurations were studied by using the Aspen Plus® simulator. The conceptual process specifications of an optimized industrial plant capable of processing glycerol produced in a typical Brazilian biodiesel producer facility were estimated, for both processes, in order to minimize the specific energy consumption and produce triacetin with a molar purity of 99.9%, with complete conversion of glycerol. Process A showed to be more energy efficient, requiring about 20% of the heat duty required in process B, and being more compact in the necessary quantity of unit operations.

Le travail de cette thèse porte sur la modélisation de la combustion du méthane et de l’oxygène dans des conditions de pression et température typiques de celles rencontrées au sein des moteur-fusées. Pour cette application, des modèles de transports, de thermodynamiques et des équations d’état de type gaz réel ont été implémentés au sein du code de calcul compressible utilisé. Le formalisme des conditions aux limites a été étendu aux gaz réels. La validation de l’ensemble de cette modélisation a été effectuée. Pour la modélisation de la combustion, une méthode de chimie tabulée a été considérée. La méthode de calcul de la température TTC a été choisie et étendue au formalisme des gaz réels. Deux formes pour la tabulation de l’équation d’état gaz réel ont été proposées. Le formalisme du couplage entre la thermodynamique tabulée et les conditions aux limites caractéristiques est établi puis validé. L’étude de l’interaction chimie-turbulence au sein de la combustion LOx/CH4 à haute pression a ensuite été menée au travers de simulations basées sur des essais expérimentaux effectués sur le banc MASCOTTE de l’ONERA. / This work focuses on the methane and oxygene combustion modelisation under conditions typically uncountered in rocket engines. Modelisation under such conditions requires high pressure models for equation of state and transport and thermodynamic properties evaluation. Those models are implemented in the compressible CFD code used during this thesis and validated. Characteristic boundary conditions are also extended to high pressure formulation. The PCM-FPI method coupled with the TTC method for the temperature computation are chosen to model the combustion. Coupling between this evolved model and characteristic boundary conditions formulation is extended to the high pressure framework. Then the study of interaction between chemical kinetic and turbulence in a oxygen/methane high pressure flame is realised through simulations based on ONERA MASCOTTE test bench cases.

Population growth and increasing standards of living have resulted in a rapid demand for energy. Our primary energy production is still dominated by fossil fuels. This extensive usage of fossil fuels has led to global warming, environmental pollution, as well as the depletion of hydrocarbon resources. The prevailing difficult situation offers not only a challenge but also an opportunity to search for alternatives to fossil fuels. Hence, there is an urgent need to explore environmentally friendly and cost-effective renewable energy sources. Oxygenates (alcohols, ethers) and ammonia are among the potential renewable alternative fuels of the future. This thesis investigates the combustion characteristics of promising alternative fuels and their blends using a combination of experimental and modelling methodologies. The studied fuels include ethanol, diethyl ether, dimethyl ether, dimethoxy methane, γ-valerolactone, cyclopentanone, and ammonia. For the results presented in this thesis, the studies may be classified into three main categories: 1. Ignition delay time measurements of ethanol and its blends by using a rapid compression machine and a shock tube. The blends studied include binary mixtures of ethanol/diethyl ether and ternary mixtures of ethanol/diethyl ether/ethyl levulinate. A chemical kinetic model has been constructed and validated over a wide range of experimental conditions. The results showed that a high-reactivity fuel, diethyl ether, may be blended with a low-reactivity fuel, ethanol, in varying concentrations to achieve the desired combustion characteristics. A ternary blend of ethanol/diethyl ether/ethyl levulinate may be formulated from a single production stream, and this blend is shown to behave similarly to a conventional gasoline. 2. Ignition delay time and flame speed measurements of ammonia blended with combustion promoters by utilizing a rapid compression machine and a constant volume spherical reactor. The extremely low reactivity of ammonia makes it unsuitable for direct use in many combustion systems. One of the potential strategies to utilize ammonia is to blend it with a combustion promoter. In this work, dimethyl ether, diethyl ether, and dimethoxy methane are explored as potential promoters of ammonia combustion. Chemical kinetic models were developed and validated in the high temperature regime by using flame speed data and in the low-to-intermediate temperature regime by using ignition delay time data. The results showed that even a small addition (~ 5 – 10%) of combustion promoters can significantly alter ammonia combustion, and diethyl ether was found to have the highest propensity to enhance ammonia ignition and flame propagation. Blends of combustion promoters with ammonia can thus be utilized in modern downsized turbo-charged engines. 3. Octane boosting and emissions minimization effects of next generation oxygenated biofuels. These studies were carried out using a cooperative fuel research engine operating in a homogenous charge compression ignition (HCCI) mode. The oxygenated fuels considered here include γ-valerolactone and cyclopentanone. The results showed that γ-valerolactone and cyclopentanone can be effective additives for octane boosting and emission reduction of conventional fuels. Overall, the results and outcomes of this thesis will be highly useful in choosing and optimizing alternative fuels for future transportation systems.

Laser absorption based sensors are extensively used in a variety of gas sensing areas such as combustion, atmospheric research, human breath analysis, and high resolution infrared spectroscopy. Quantum cascade lasers have recently emerged as high resolution, high power laser sources operating in mid infrared region and can have wide tunability range. These devices provide an opportunity to access stronger fundamental and combination vibrational bands located in mid infrared region than previously accessible weaker overtone vibrational bands located in near infrared region. Spectroscopic region near 8 µm contains strong vibrational bands of methane, acetylene, hydrogen peroxide, water vapor and nitrous oxide. These molecules have important applications in a wide range of applications. This thesis presents studies pertaining to spectroscopy and combustion applications. Advancements in combustion research are imperative to achieve lower emissions and higher efficiency in practical combustion devices such as gas turbines and engines. Accurate chemical kinetic models are critical to achieve predictive models which contain several thousand reactions and hundreds of species. These models need highly reliable experimental data for validation and improvements. Shock tubes are ideal devices to obtain such information. A shock tube is a homogenous, nearly constant volume, constant pressure, adiabatic and 0-D reactor. In combination with laser absorption sensors, shock tubes can be used to measure reaction rates and species time histories of several intermediates and products formed during pyrolysis and oxidation of fuels. This work describes measurement of the decomposition rate of hydrogen peroxide which is an important intermediate species controlling reactivity of combustion system in the intermediate temperature range. Spectroscopic parameters (linestrengths, broadening coefficients and temperature dependent coefficients) are determined for various transitions of acetylene. Furthermore, methane and acetylene sensors are developed for shock tube applications. The application of these sensors (along with an ethylene sensor) has been demonstrated to measure these species during the pyrolysis of n-pentane and iso-pentane.

The need for sustainability has been on the rise. Municipalities are finding ways of reducing waste, but also finding ways to reduce energy costs. Waste-to-energy is a sustainable method that may reduce bio-solids volume while also producing energy. In this research study bio-solids enters a bubbling bed gasifier and within the gasifier a synthesis gas is produced. This synthesis gas exits through the top of the gasifier and enters a thermal oxidizer for combustion. The thermal oxidizer has an innovative method of oxidizing the synthesis gas. The thermal oxidizer has two air injection sites and the possibility for aqueous ammonia injection for further NOx reduction. Most thermal oxidizers already include an oxidizer such as air in the fuel before it enters the thermal oxidizer; thus making this research and operation different from many other thermal oxidizers and waste-to-energy plants. The reduction in waste means less volume loads to a landfill. This process significantly reduces the amount of bio-solids to a landfill. The energy produced from the synthesis is beneficial for any municipality, as it may be used to run the waste-to-energy facility. The purpose of this study is to determine methods in which operators may configure future plants to reduce NOx emissions. NOx mixed with volatile organic compounds (VOC) and sunlight, produce ozone (O3) a deadly gas at high concentrations. This study developed a model to determine the best methods to reduce NOx emissions. Results indicate that a fuel-rich then fuel-lean injection scheme results in lower NOx emissions. This is because at fuel-rich conditions not all of the ammonia in the first air ring is converted to NOx, but rather a partial of the ammonia is converted to NOx and N2 and then the second air ring operates at fuel-lean which further oxidizes the remaining ammonia which converts to NOx, but also a fraction to N2. If NOx standards reach more stringency then aqueous ammonia injection is a recommended method for NOx reduction; this method is also known as selective non-catalytic reduction (SNCR). The findings in this study will allow operators to make better judgment in the way that they operate a two air injection scheme thermal oxidizer. The goal of the operator and the organization is to meet air quality standards and this study aims at finding ways to reduce emissions, specifically NOx.

To improve the performance of the three-way catalytic (TWC) converter, advanced control strategies and on-board diagnostics (OBD) systems are needed. Both rely on a relatively accurate but computationally efficient TWC converter model. This thesis aims to develop a control-oriented model that can be employed to develop the control strategies and OBD systems of the TWC converter. The thesis consists of two parts, i.e., the high-fidelity model development and the model reduction. Firstly, a high-fidelity model is built using the energy and mass conservation principles. In this model, a constant inlet simulation is used to validate the warming-up characteristics, and a driving cycle simulation is used to calibrate the reaction rate parameters. The results of the simulation show that the high-fidelity model has adequate accuracy. Secondly, a reduced-order model is developed based on phase and reaction simplifications of the high-fidelity model. The aim of the development of the reduced-order model is to propose a computationally efficient model for further development of control strategies and state estimators for OBD systems. The accuracy of the reduced-order model is then validated by means of simulations. / Thesis / Master of Applied Science (MASc)