The new Canadian laws on CO2 emissions aim to lower the emissions of coal-fired power plants down to those of natural gas combined cycle units: 420 kg CO2/MWeh. In order to meet these requirements, calcium looping and two process variants are investigated through process simulations using Aspen Plus V8.2. The combination of calcium looping and chemical looping combustion, replacing the required air separation unit, is a way to reduce the energy penalty of the capture process. The addition of copper as an oxygen carrier in two different process configurations is compared to calcium looping and shown to reduce the efficiency penalty from 7.8% to 4.5% points but at the price of circulations rates up to about 3800 kg/s. The other improvement path studied is the implementation of calcium looping to a pressurized fluidized bed combustion unit. The pressurized carbonator acts as a reheater for the gas turbine and operating the carbonator at temperatures up to 798°C results in a reduction of the energy penalty from 5.1% to 3.1% points.

Orientador: Maria Angela de Almeida Meireles / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-22T03:30:32Z (GMT). No. of bitstreams: 1 Cavalcanti_RodrigoNunes_D.pdf: 5256950 bytes, checksum: 08795bef1266bd8fc10cd8e88b7a19ca (MD5) Previous issue date: 2013 / Resumo: Atualmente, o conhecimento científico sobre a utilização de produtos naturais com propriedades funcionais, a exigência do consumidor quanto à qualidade dos alimentos, bem como ações legislativas para redução do uso de corantes sintetizados quimicamente têm propiciado o aumento da utilização de corantes naturais. Dentre estes, as antocianinas constituem pigmentos aquosolúveis responsáveis pelas principais cores encontradas na natureza, podendo variar desde o laranja, vermelho, violeta até o azul. Antocianinas são moléculas polares derivadas do cátion flavilion (C6-C3-C6) constituindo um importante subgrupo dos flavonóides. As principais propriedades biológicas atribuídas às antocianinas são atividade: antiinflamatória, anticarcinogênica e antioxidante. Diversos métodos de extração têm sido utilizados na obtenção de antocianinas. A extração supercrítica apresenta vantagens consideráveis sobre os métodos convencionais: o solvente é facilmente removido do soluto; utiliza pouco ou nenhum solvente orgânico; possibilita uma rápida extração; e, por fim, opera a baixas temperaturas favorecendo a extração de produtos voláteis e termolábeis. Este trabalho visou estudar o processo de extração supercrítica de antocianinas otimizando as diversas etapas do processo através de ensaios experimentais, simulação e comparação com outro(s) método(s) de extração. Inicialmente fez-se a caracterização da matéria-prima a qual apresentou altos teores de proteínas, carboidratos e fibras. As extrações via extração com fluido supercrítico (SFE ¿ supercritical fluid extraction) e extração com líquido pressurizado (PLE ¿ pressurized liquid extraction) utilizaram etanol, isopropanol e água como co-solvente e solvente, respectivamente. A composição dos extratos foi avaliada por espectrofotometria apresentando altos teores de fenólicos, flavonóides, antocianinas e atividade antioxidante em relação aos dados da literatura. Os melhores rendimentos de compostos fenólicos, flavonóides e atividade antioxidante foram obtidos por SFE utilizando co-solventes alcoóis. Já com relação ao teor de antocianinas houve pouca diferença entre os métodos PLE e SFE os quais atingiram melhores resultados utilizando água e alcoóis como solvente e co-solventes, respectivamente. De acordo com os resultados de tempo de retorno e custo de manufatura ambos os métodos de extração foram economicamente viáveis para a produção de extrato bruto de subproduto de jabuticaba. Os menores custos foram obtidos nas condições que apresentaram maior rendimento de extração e nas células extratoras de maior capacidade volumétrica. O estudo dos parâmetros cinéticos indicam que os melhores resultados foram obtidos utilizando alta vazão de solvente para ambos os processos SFE e PLE / Abstract: Currently, scientific knowledge about the use of natural products with functional properties, the consumer demand for quality food, as well as legislative action to reduce the use of chemically synthesized colorants have prompted an increasing use of natural colorants. Among these, anthocyanin are water-soluble pigments responsible for main colors found in nature ranging from orange, through red and violet to blue. Anthocyanins are polar molecules derived from the flavilium cation (C6-C3-C6) constituting an important subgroup of flavonoids. The main biological properties of anthocyanins are activity: anti-inflammatory, anticarcinogenic and antioxidant. Several extraction methods have been used to obtain anthocyanins. Supercritical fluid extraction has considerable advantages over conventional methods: the solvent is easily removed from the solute; uses little or no organic solvent, enables a rapid extraction and, finally, operates at low temperatures favoring the extraction of volatile and thermolabile compounds. This work aims to study the process of supercritical extraction of anthocyanins optimizing the various steps of the process through experimental testing, simulation and comparison with other(s) extraction method(s). Initially it was made the characterization of raw material which showed high levels of protein, carbohydrates and fiber. The extractions were carried out via SFE and PLE using ethanol, isopropanol and water as co-solvent and solvent, respectively. The extracts composition was evaluated by spectrophotometry showing high levels of phenolics, flavonoids, anthocyanins and antioxidant activity (%AA) with respect to the literature data. The highest phenolics and flavonoids content and %AA were obtained by SFE using alcohols as co-solvent. On the other hand, anthocyanins content achieve the best results using water and alcohols as a solvent and co-solvents, respectively. According to payback time and cost of manufacturing results both extraction methods were economic feasible to the production of crude extract from jabuticaba byproduct. The higher the extraction yield and extraction vessel capacity the lower the cost of manufacturing. The study of the kinetic parameters shows the best results were achieved at higher solvent mass flow for both extraction methods / Doutorado / Doutor em Engenharia de Alimentos

Practical combustion devices such as gas turbines and diesel engines operate at high pressures to increase their efficiency. Pressure significantly increases the overall soot yield. Morphology of these ultra-fine particles determines their airborne lifetime and their interaction with the human respiratory system. Therefore, investigating soot morphology at high pressure is of practical relevance. In this work, a novel experimental setup has been designed and built to study the soot morphology at elevated pressures. The experimental setup consists of a pressure vessel, which can provide optical access from 10° to 165° for multi-angle light scattering, and a counterflow burner which produces laminar flames at elevated pressures. In the first part of the study, N2-diluted ethylene/air and ethane air counterflow flames are stabilized from 2 to 5 atm. Two-angle light scattering and extinction technique have been used to study the effects of pressure on soot parameters. Path averaged soot volume fraction is found to be very sensitive to pressure and increased significantly from 2 to 5 atm. Primary particle size and aggregate size also increased with pressure. Multi-angle light scattering is also performed and flames are investigated from 3 to 5 atm. Scattering to absorption ratio is calculated from multi-angle light scattering and extinction data. Scattering to absorption ratio increased with pressure whereas the number of primary particles in an aggregate decreased with increasing pressure. In the next part of the study, Thermophoretic Sampling of soot is performed, in counterflow flames from 3 to 10 atm, followed by transmission electron microscopy. Mean primary particle size increased with pressure and these trends are consistent withour light scattering measurements. Fractal properties of soot aggregates are found to be insensitive to pressure. 2D diffused light line of sight attenuation (LOSA) and Laser Induced Incandescence (LII) are used to measure local soot volume fraction from 2 to 10 atm. Local soot volume fraction increased with pressure and soot concentration profiles showed good agreements when measured by both techniques. Experimental data obtained in this work is very helpful for the modelers for validating their codes and predicting the soot formation in pressurized flames.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第22672号 / エネ博第404号 / 新制||エネ||77(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー変換科学専攻 / (主査)准教授 森下 和功, 教授 星出 敏彦, 教授 今谷 勝次 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

A variety of analytical techniques are showcased for their ability to provide insights into reaction mechanisms as well as active intermediate speciation. Pressurized Sample Infusion-Mass Spectrometry (PSI-ESI-MS), ion mobility-mass spectrometry (IMS-MS), and Nuclear Magnetic Resonance (NMR) spectroscopy are powerful analytical techniques capable of reaction monitoring. Contamination from vulcanized rubber was an issue with the PSI-ESI-MS technique as ions unrelated to the reaction were convoluting the mass spectrum. This was resolved by re-designing the PSI flask such that the septum was positioned above a condenser, preventing heat degradation of the septum and subsequent leaching of contam- inants into the reaction solution. The technique was then used to analyze the Buchwald-Hartwig amination reaction in real-time. The innovative use of Multiple Reaction Monitoring (MRM) scans facilitated observation of all catalytic intermediates, and elucidation of relative reaction rates for each step of the catalytic cycle. PSI-ESI-MS and NMR are complementary methods whereby catalytic intermediates are monitored via PSI-ESI-MS, and the rate of product formation is monitored via NMR spectroscopy. This combination of analytical methods was employed in the investigation of the Barluenga cross-coupling reaction between N-tosylhydrazones and aryl halides. A reaction screen revealed optimized homogeneous conditions, and the turnover limiting step was found to be off-cycle. IMS separates gaseous ions based on their size and shape immediately prior to MS analysis. Upon investigation of [PtCl3(C2H4)], and [PtCl3(CO)], it was found that residual [PtCl3] was forming [PtCl3(N2)] in the source of the instrument. Ion mobility was able to separate these isobaric ions, and DFT calculations and collision-induced dissociation experiments confirmed the existence of the gaseous [PtCl3(N2)] complex. NMR spectroscopy may also be employed as a strong reaction monitoring technique. The mechanism of C–H silylation by trimethyl(trifluoromethyl)silane and tetrabutylammonium difluorotriphenylsilicate was investigated using 19F-NMR. All intermediates and reaction byproducts were quantitatively observed, and the reaction conditions were optimized. A stopped-flow NMR system was used to gather data points in the first 0.2 seconds of the reaction. / Graduate

This diploma thesis deals with application of pressurized liquid extraction (PFE) on grape skins of Vitis vinifera cultivars Alibernet and Svatovavřinecké to gain extraction of anthocyanin pigments in the form of 3-monoglucosides. This thesis deals with comparison efficiency pressurized liquid extraction (PFE) for the range temperatures 40–120 °C and the Soxhlet extraction with four extraction solvents. The identification of the anthocyanin pigments by high-performance liquid chromatography with diode array detection (HPLC/DAD) based on Synergi C12 column separation (Phenomenex) was performed. The anthocyanin pigments were identified at wavelength 520 nm. The complete amount of anthocyanin pigments grape skins was depended on the extraction solvent and temperature in range 0,38–244,06 mg/g for cultivar Alibernet and 0,28–105,01 mg/g for cultivar Svatovavřinecké. The contents of anthocyanin pigments was determined in the samples of wine both cultivars in the range 3,83–2836,84 mg/l too. PFE followed by HPLC/DAD employing Synergi C12 column provides relatively fast, quantitative and reproducible determination of anthocyanins in grape skins and wines.

This master thesis deals with the possibilities of traffic of nuclear power unit at thermal and power effect at the end of the campaign, focusing on VVER reactors. For a better idea of the reader the design of key components of the unit in terms of performance is analysed. Parameters of relevant components for Dukovany NPP are presented briefly. The possibilities of traffic of nuclear power unit on thermal and power effect at the end of the campaign are particularly demonstrated on the example of the Dukovany NPP. Furthermore the program Moby-Dick is introduced and the basic possibilities for its use to calculate the course of the campaign are described. At the end of the thesis, we conducted sample calculations for the duration of the campaign on the fourth block of the nuclear power plant.

The thesis examines the adhesive interaction between graphite layers and atomically thin MoS2 crystals. Vertical van der Waals(vdW) heterostructures are fabricated by stacking different two-dimensional (2D) materials on top of each other. Blister test is used to measure the adhesive interactions between 2D heterostructures and their transferred substrates and between the layers themselves. This adhesive interaction is important in maintaining the mechanical integrity of the device during mechanical loadings and its understanding will help pave the way to the design and fabrication of micromechanical device from 2D heterostructures. Furthermore, applying controlled strains can be used to alter the electrical and optical properties thereby improving efficiency and performance. At first, we grew MoS2 and graphene by CVD and stacked the layers on top of each other using a dry transfer method. The MoS2/graphene heterostructure was then transferred onto pre-etched cavities on a silicon wafer. The blister test was used for controllably introducing strain into the heterostructure. Atomic Force Microscopy was used for measuring the shape of the deformed blister and Raman and Photoluminescence(PL) measured the optical response. The strain mismatch between the biaxial strain and a PL-converted strain suggests crumpling of the graphene layer and a substantial softening of the mechanical response. Lastly, we created graphite holes with photolithography to measure the work of separation between an atomically smooth graphite surface and MoS2. We found this value to be at least 320mJ/m2 which is higher than the MoS2/SiOx areas that was previously studied. / 2023-07-02T00:00:00Z

Pressurized chemical looping combustion (PCLC) is a promising next generation carbon capture technology which operates on the fundamentals of oxyfuel combustion to concentrate carbon dioxide in the flue gas stream. Oxygen is supplied through cyclic oxidation and reduction of a solid metal oxide between an air reactor and fuel reactor to prevent the direct contact of fuel and air. CanmetENERGY-Ottawa, in collaboration with Hatch Ltd., is designing a pilot scale PCLC system which uses ilmenite as the oxygen carrier and a novel fluidized bed design called the Plug Flow Internally-recirculating Reactor (PFIR). The PFIR consists of an annular bubbling fluidized region in which particles are circulated by angle jets through two reactive zones separated by baffles. The overall objective of this thesis was to provide key design parameters and insight for the construction of the pilot facility. Experimental work was first conducted investigating the minimum fluidization velocity (Umf), gas bubble size, and tube-to-bed heat transfer coefficients of different ilmenite particle size distributions (PSDs) at varying pressures up to 2000 kPa. The data was compared to a variety of literature correlations. The Saxena & Vogel (1977) constants for the Wen-Yu type correlations (Remf=√C12+C2Ar-C1) resulted in the best fit for predicting the Umf of the PSDs with Sauter mean diameters (SMD) less than 109 μm, while the Chitester et al. (1984) constants resulted in better predictions for the larger particle size distributions (SMD greater than 236 μm). Gas bubble size was found to be marginally impacted by pressure, with the Mori & Wen (1975) correlation best fitting the data. The heat transfer coefficient was found to also be marginally increased by pressure with the the Molerus et al. (1995) correlation matching the atmospheric data. A computational particle fluid dynamic (CPFD) model of the experimental unit was then created and validated using the obtained data for minimum fluidization velocity and bubble size. The accuracy of the model was found to be dependent on the particle close packing factor input variable, with a value of 0.58 resulting in the best results for each of the ilmenite PSDs modeled. Finally, a CPFD model was created for a cold flow design of the PFIR to investigate the impacts of different operating parameters on the solids circulation rate and gas infiltration rate between the two reactor zones. This model used the validated parameters of the previous CPFD model to add confidence to the results. The impacts of increasing superficial gas velocity, fluidizing gas jet velocity, bed height, and pressure were all found to increase the solids circulation rate through their respective impacts on the momentum rate of the fluidizing gas. A polynomial function was fit between these two variables resulting in a method to predict the solids circulation rate. Similarly, the rate of gas infiltration between sections was found to be dependent on the solids circulation rate, allowing for a function to be made to predict the gas infiltration at different operating conditions.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Donald Kent Parsons. / M.S.