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1
Pugh, Daniel. "Combustion characterisation of compositionally dynamic steelworks gases." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/58006/.
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This thesis investigates the combustion of fuel compositions representative of those produced by the integrated steelmaking process. As organisations strive for improvements in utilisation efficiency with increasingly complex technologies, more detailed understanding is required to accurately simulate combustion of the potentially weak and dilute fuels, and thereby aid design processes. Dynamic fuel properties have been characterised through experimentation, in addition to a comparison of numerically simulated results obtained from chemical kinetics. The parameters identified to investigate fuel behaviour were laminar burning velocity and Markstein Length, and characterised with regard to operational instability in practical combustion systems. The design and construction of a suitable experimental rig is detailed, as required to facilitate the accurate determination of burning velocities by quantifying the outward propagation of spherical flames. A regressive analytical technique was developed based on previous studies, nonlinearly relating propagation to change in stretch rate. The developed solution was benchmarked against analogous studies in literature, and ensured experimental performance was accurate and repeatable for the well documented combustion of methane. Steelworks gases were tested to attain representative burning velocities, with significant attention paid to the change resulting from fluctuation in blast furnace gas H2 fraction. The study characterised the observed sensitivity to change in flame speed and discussed the implications with regard to practical combustion systems. Several methods of reducing the measured fluctuation are subsequently quantified, including change in ambient condition, and relative humidity. Non-monotonic behaviour was observed for the latter effect, with a suggested trade-off between a chemically catalytic influence on intermediate species, and lowering of flame temperature. Consequently this suggested water addition could be an effective mechanism for the reduction of H2 induced flame speed variation for blast furnace gas, and influence other synthesised fuels comprising large quantities of CO, including BOS gas. Additional steelworks gases were blended in different ratios to assess dynamic combustive properties relating to fuel flexibility, and the effectiveness of minimising fluctuation in combustion behaviour.
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Chen, Nini. "Premixed combustion of high calorific value gases." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/13385/.
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Gal-Ed, Reuven. "Pulsating catalytic combustion of gaseous fuels." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/15649.
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Parker, S. J. "Electric spark ignition of gases and dusts." Thesis, City University London, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355585.
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Phuoc, Tran Xuan. "Ignition of polymeric material under radiative and convective exposure." Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/18399.
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Anderson, Desmond Carl. "Chemical reactions involved in the desulphurisation of flue gases." Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286829.
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Jimenez, Erick G. "Experimental apparatus for characterizing the methane-air combustion process." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/16775.
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Kan, Tie. "Combustion of solid waste in a pulse incinerator." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/12975.
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Pereira, Luís Manuel Cravo. "Capture of pollutants from post-combustion streams with ionic liquids." Master's thesis, Universidade de Aveiro, 2012. http://hdl.handle.net/10773/9533.
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Mestrado em Engenharia QuímicaO aumento da emissão de poluentes nitrogenados, bem como as limitações presentes nos atuais métodos de controlo e o aparecimento de novas legislações e limites máximos de emissão, requerem o desenvolvimento de novos métodos para a redução destes poluentes. Os Líquidos Iónicos (LIs), pelas suas características únicas e baixa pressão de vapor, têm despertado uma grande atenção durante a última década e estão a tornar-se numa nova classe de solventes muito promissores para a captura de poluentes e separação de gases, quer como fase estacionária num processo de membranas quer como absorvente num processo de extração. Não obstante, o desenvolvimento de novos processos de controlo, ou melhoria dos já existentes, requerem o conhecimento do equilíbrio gás-líquido (EGL) que é, até ao momento, ainda insuficiente. Neste trabalho, a solubilidade de gases presentes em processos de combustão como o azoto (N2), o metano (CH4), óxido nitroso (N2O) e dióxido de carbono (CO2) num líquido iónico muito polar foram estudados através de medições do EGL. Os resultados demostram a já reconhecida elevada solubilidade de N2O e CO2 em LIs bem como a elevada seletividade em relação ao ar devido à baixa solubilidade do N2 nos LIs. Foi ainda observado que, contrariamente aos outros gases, para os sistemas N2 + LIs o aumento da temperatura provoca uma aumento da solubilidade do gás. A descrição dos sistemas anteriores por modelos teóricos é fundamental para o projeto de potenciais técnicas de redução de poluentes. Neste sentido, a soft-SAFT EoS, que tem demonstrado ser capaz de descrever sistemas com LIs com enorme sucesso, foi usada para descrever os diferentes sistemas publicados na literatura e medidos aqui em função da temperatura, composição e pressão, permitindo deste modo estender a aplicabilidade do modelo a novos sistemas. Novos parâmetros moleculares, necessários para a descrição de cada componente, são propostos neste trabalho para o N2O e para três dos cinco LIs estudados. Os resultados demonstraram uma boa descrição dos dados experimentais, tanto no que diz respeito ao comportamento inverso observado para o N2 como a baixa dependência do CH4 com a temperatura. Finalmente, a capacidade de extração dos LIs bem como a sua seletividade é comparada com a dos solventes utilizados nos métodos de controlo atuais, como monoetanolamina (MEA) e éter monometílico de trietilenoglicol (TEGMME). Os resultados demonstram uma capacidade de extração dos LIs igual ou superior à dos solventes convencionais, aliada a uma elevada seletividade em relação ao N2O e CO2. Com base neste trabalho, pode-se afirmar que os LIs, devido às suas características únicas e elevada seletividade, apresentam um grande potencial para serem utilizados na captura de poluentes.
The increase in nitrogenated pollutants emissions, along with the limitations of the existing control methods and future stricter legislation, demands the development of new methods to reduce such pollutants. Ionic liquids (ILs), due to their unique characteristics and low vapour pressure, have attracted a large attention during the last decade and are becoming a promising class of solvents to capture pollutants and for gas separation, either as a stationary phase in a membrane process or as an absorption solvent in an extraction process. Nonetheless, the development and/or improvement of new/existing control processes requires the knowledge of gas-liquid equilibrium (GLE) data for ILs + gas systems that are, at the moment, still scarce. The solubilities of some common gases present in combustion processes, such as nitrogen (N2), methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2), were studied through the experimental measurement of the GLE. The results showed a high solubility of N2O and CO2 compared to N2. Furthermore, a surprisingly increase of the solubility of N2 with temperature was observed. The description of previous systems by theoretical models stands also as a vital task for the development of techniques to reduce pollutants. In this sense, the soft-SAFT EoS has proven to be able to describe systems with ILs with a huge success and in a predictive manner. Thus, this model was used to describe the GLE data available in the literature and measured here, for different temperatures and for all concentrations and pressures ranges studied, in order to extend the applicability of the soft-SAFT EoS to describe/predict the gas + ILs systems. The molecular parameters necessary for the description of each compound were determined for the first time in this work for N2O and three of the five ILs involved. The results showed a good description of the experimental data. In addition to that, soft-SAFT EoS successfully predicts the peculiar behaviour observed for N2 as well as the low temperature dependence observed for the CH4 systems. Finally, the extraction capacity and gases selectivity in the ILs was compared with other solvents used in the reduction of pollutants, such as monoethanolamine (MEA) and triethylene glycol monomethyl ether (TEGMME). The results showed a similar or higher extraction capacity of the ILs compared to conventional solvents, combined with a high selectivity towards N2O and CO2. Based on the results showed on this work, it is suggested that ILs due to their unique characteristics and high selectivity are promising agents to capture pollutants.
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Gopalakrishnan, Priya. "Effects of the reacting flowfield on combustion processes in a stagnation point reverse flow combustor." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22682.
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Thesis (Ph. D.)--Aerospace Engineering, Georgia Institute of Technology, 2008.Committee Chair: Seitzman, Jerry; Committee Member: Gaeta, Richard; Committee Member: Jagoda, Jeff; Committee Member: Neumeier, Yedidia; Committee Member: Yoda, Minami; Committee Member: Zinn, Ben.
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Morita, Eugenio de Souza. "Estudo experimental das emissões de NOx na combustão de carvão mineral brasileiro em leito fluidizado rapido." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263553.
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Orientador: Arai Augusta Bernardez PecoraDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-13T23:51:53Z (GMT). No. of bitstreams: 1 Morita_EugeniodeSouza_M.pdf: 4021816 bytes, checksum: da9670c797e58d9f79ea109135e7df7d (MD5) Previous issue date: 2009
Resumo: O objetivo deste trabalho é avaliar as emissões de óxidos de nitrogênio (NO + NO2) durante a combustão de carvão mineral com adição de calcário dolomítico como adsorvente em leito fluidizado circulante (LFC). As variáveis de influência estudadas foram o excesso de ar, que variou entre 18 e 32 %, e a relação molar cálcio enxofre (Ca/S) que variou entre 0 e 2. A quantificação das emissões de NOx foi realizada em condições de regime estacionário através da técnica de detecção por infravermelho não dispersivo (NDIR). Perfis de temperatura e pressão foram medidos durante a realização dos experimentos. A combustão foi mantida a uma temperatura média do riser de 840 ºC e velocidade superficial do gás próxima de 9 m.s-1. Utilizou-se um Delineamento Composto Central Rotacional (DCCR) para o planejamento dos experimentos mediante determinação das variáveis de influência e seus limites de operação. Um total de treze experimentos foram realizados, sendo onze deles relativos ao planejamento experimental. A influência do parâmetro relação molar Ca/S foi mais significativa quando comparada à influência do excesso de ar. O aumento da razão Ca/S provocou acréscimo nas emissões de NOx, enquanto a redução do excesso de ar provocou a diminuição das emissões. Os resultados obtidos nesta pesquisa apontam para uma região de otimização, buscando-se a minimização das emissões de NOx que pode ser alcançada pela utilização de valores baixos de excesso de ar (18 %) e relação Ca/S de 0,6, uma vez que para relações maiores, a emissão de SO2 foi praticamente nula, destacando o elevado poder de remoção do enxofre por este calcário.
Abstract: This work reports an experimental study concerning NOx emissions from brazilian coal combustion with limestone addition in circulating fluidized bed as a function of operational parameters excess air (18 to 32 %) and Ca/S molar ratio (0 to 2). The NOx concentration was achieved at steady state operation through a non-dispersive infrared (NDIR) detection technique. Profiles of temperature and pressure were measured. Bed temperature around 840 ºC and superficial gas velocity around 9 m.s-1 were conditions maintained at the experiments. Central Composite Rotational Design has been used for planning the experiments according to the knowledge of influence variables on combustion process and its operational limits. A total of thirteen experiments were carried out. The influence of Ca/S molar ratio on NOx emissions was greater than air excess influence. Increasing Ca/S molar ratio it was observed tha NOx emissions also rise, meanwhile decreasing air excess factor leds a reduction on NOx emissions. Results pointed to a optimizing area, seeking to minimize NOx concentrations that can be achieved with low air excess (18 %) and Ca/S molar ratio of 0.6, since for larger ratios, the SOx emissions was insignificant, highlighting the limestone's high efficiency to sulfur capture.
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica
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Pierik, Ronald Jay. "Swirling combustion of premixed gaseous reactants in a short cylindrical chamber." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26729.
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The effects of swirl and spark location on combustion duration were studied in a constant volume cylindrical chamber of length-to-diameter ratio of 0.5. A chemically balanced methane-air mixture was swirled up to 628 radians per second by tangential injection. The chamber was closed by a valve before ignition by a spark gap of variable location and electrode geometry.
The burning duration, indicated by repeated measurements of combustion pressure rise, was found to be a strong function of swirl intensity and spark location. Increased swirl resulted in decreased burning duration; mid-radius ignition location combined with high swirl resulted in the shortest combustion durations.
Spark gap was found to have an important effect on the standard deviation of the burning duration, especially with high swirl.
Various "flame holders" were installed to achieve shorter burning durations and lower cyclic variation. Results indicated that the best ignition source geometry was an unshielded, low-drag probe. This gave the least burning durations and the least cyclic variation at the higher swirl values.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Blevins, Linda G. "Effects of high levels of steam addition on NOx̳ reduction in laminar opposed flow diffusion flames." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-05042010-020128/.
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Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992.On t.p. "x̳" is subscript. Vita. Abstract. Includes bibliographical references (leaves 92-97). Also available via the Internet.
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Sauba, Rooktabir Nandan. "Stability limits and combustion measurements in low calorific value gas flames." Thesis, Middlesex University, 1987. http://eprints.mdx.ac.uk/13380/.
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A Hilton combustor was substantially modified to a suitable symmetrical configuration for research purposes. Provisions for swirl, preheat and injection of LCV gases were incorporated with appropriate burner management systems for safe operation. Instrumentation for temperature, velocity and concentration measurements was developed and fully automated by interfacing to a microprocessor for rapid data acquisition. Flame stability limits were determined over a wide range of operating conditions by varying swirl, secondary air temperature and excess air levels while maintaining the burner momentum constant. Addition of swirl up to a limit of O~ 69 generally improved stability. Preheating secondary air alone was beneficial only if the temperature was raised to at least 250 oC. A combination of intermediate swirl and moderate preheat of the secondary air resulted in satisfactory flame stability over a wide range of calorific values of the fuel. Thus, existing concentric pipe burner systems may be easily modified at low cost to burn LCV gases of variable compositions. With LCV gas flames the excess air factor (EAF) had a major influence on values of temperature, species concentration and velocity. Unburnt hydrocarbon (UHC) and CO not surprisingly increased in concentration close to the blow-off limits under the majority of operating conditions. This indicated incomplete combustion probably resulting from the lowered flame temperatures and partial flame lift-off. On the other hand, burnout efficiencies at the exhaust were reasonably high for most operating conditions involving LCV gases. The combustion data were analysed to extract the characteristic mixing and chemical reaction times the ratio of which gave the parameter epsilon, originally proposed for unconfined flames. Close to the blow-off limit epsilon took the value 4.9 compared with 6.2 for fully stable flames. This finding showed that the criterion was also valid for confined flames, supporting the extinction mechanism proposed by Peters and Williams, and providing an important basis for predicting stability limits and burner design parameters.
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Watt, Alan William. "The movement of gases in longwall coalface wastes liable to spontaneous combustion." Thesis, University of Nottingham, 1987. http://eprints.nottingham.ac.uk/11215/.
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The increasing depth, distance from surface connections and falling quality of coal mined are factors that increase the risk of spontaneous combustion in working areas. The trend towards high capital investment, high output faces significantly raises the economic consequences of spontaneous combustion. Much work has been directed towards methods of identifying the liability of a coal to spontaneously combust under given conditions. The cost of prevention and combat of spontaneous combustion underground is high, however this work is carried out with little knowledge of the likely location of a heating in a coalface waste. This thesis investigates the airflow patterns in a coalface waste, with a view towards improving the use of prevention and combat methods. The factors that affect the liability of a coal to spontaneously combust, and the methods of prevention and combat are discussed to provide a background to the subject area. An investigation into the flow of nitrogen that was injected from one hole into a coalface waste as a combat measure was conducted. The results of this showed how the amount of nitrogen entering the waste depended on the rise and fall of the atmospheric pressure. An attempt was made to develop a method of sampling gas from deep within the coalface waste. It proved impossible to sample further than 15m behind the face line. The results from this exercise are presented. The finite element method was used to model the pressure distribution in the waste under differing boundary pressure and waste permeability conditions. A suggested area at risk from spontaneous combustion is presented.
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Hilton, Moira. "Passive emission monitoring of remote combustion gases using Fourier transform infrared spectroscopy." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262592.
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Sonwane, Pavankumar Bajrang. "Speciation of alkali metals in biomass combustion and gasification." Birmingham, Ala. : University of Alabama at Birmingham, 2006. http://www.mhsl.uab.edu/dt/2006m/sonwane.pdf.
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Cooper, Malcolm. "The formation and monitoring of gases associated with the spontaneous combustion of coal." Thesis, Nottingham Trent University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280630.
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Hegarty, Kieran Thomas. "Investigation of UEGO sensors and their application to novel engine measurements." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708615.
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Pau, Felipe Soto. "Análise experimental dos fenômenos da combustão e da emissão de gases em motores de combustão interna utilizando misturas de etanol e gasolina como combustível." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-27032017-121239/.
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A utilização de combustíveis alternativos em MCI, visa a substituição ou a redução do consumo de combustíveis fósseis. Qualquer estudo do desenvolvimento de métodos e técnicas que melhore o desempenho dos motores usando combustíveis alternativos é de grande importância tecnológica, econômica e social. Com este fim, foi feito este trabalho de pesquisa, o qual consiste em ensaiar um motor usando misturas de 37% e 50% de etanol na gasolina. O etanol utilizado neste trabalho apresentou um grau alcoólico de 92 INPM aproximadamente. Os ensaios foram feitos em taxas de compressão 8:1, 9.5:1 e 11:1. Foi avaliada a influência dos diferentes parâmetros para um máximo de eficiência e um mínimo de poluição, aproveitando as vantagens de ambos combustíveis, já que, a gasolina tem alto poder calorífico e baixo índice octano, e o etanol tem baixo poder calorífico e elevado índice de octana. O combustível ideal deveria ter ambos os fatores elevados. Para verificar os resultados esperados, foram feitos neste trabalho, estudos cinéticos químicos da combustão a partir do desempenho do motor e geração de gases. Para cumprir este fim foram necessários estudos que incluem o diagnóstico do processo de combustão, já que, o diagnóstico do processo de combustão fornece toda a informação necessária, às análises de aspectos críticos do funcionamento do motor e de emissões. Comprovou-se que a velocidade da reação de oxidação do etanol é maior que da gasolina e que, o motor aproveita mais a energia química do etanol que da gasolina.The use of alternative fuels in Internal Combustion engine, seeks the substitution or the reduction of the consumption of fossil fuels. Any study of the development of methods and techniques that it improves the acting of the motors using alternative fuels are of great technological, economic and social importance. With this goal, it was made this research work, which consists of tests in an engine using blends of 37% and 50% of ethanol in the gasoline. The ethanol used in this work presented an alcoholic degree of 92 INPM approximately. The tests were made in compression ratio 8:1, 9.5:1 and 11:1. The influence of the different parameters was evaluated for a maximum of efficiency and a minimum of pollution, taking advantage of the advantages of both fuels, since, the gasoline has high PCI and low octane index, and the ethanol low PCI and high octane index. The ideal fuel should have high both factors. To verify the expected results, they were done in this work, studies kinetic chemists of the combustion starting from engine performance and generation of gases. To execute this goal they were necessary studies that include the diagnostics of the combustion process, since, the diagnostics of the combustion process supplies all the necessary information, to the analyses of engine critical aspects operation and emissions. Was proven that the speed of the ethanol reaction of oxidation is larger than gasoline and that the engine takes advantage of more the ethanol chemical energy that of the gasoline.
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Archer, Egan Douglas. "The removal of volatile organic compounds from combustion flue gases by activated carbon adsorbents." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323699.
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Coussement, Axel. "Direct numerical simulation and reduced chemical schemes for combustion of perfect and real gases." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209765.
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La première partie de cette thèse traite du développement du code de simulation numérique directe YWC, principalement du développement des conditions aux limites. En effet, une forte contribution scientifique a été apportée aux conditions aux limites appelées "Three dimensional Navier-Stokes characteristic boundary condtions" (3D-NSCBC). Premièrement, la formulation de ces conditions aux arêtes et coins a été complétée, ensuite une extension de la formulation a été proposée pour supprimer les déformations observées en sortie dans le cas d'écoulements non-perpendiculaires à la frontière. De plus, ces conditions ont été étendues au cas des gaz réels et une nouvelle définition du facteur de relaxation pour la pression a été proposée. Ce nouveau facteur de relaxation permet de supprimer les déformations observées en sortie pour des écoulements transcritiques.
Les résultats obtenus avec le code YWC ont ensuite été utilisés dans la seconde partie de la thèse pour développer une nouvelle méthode de tabulation basée sur l'analyse en composantes principales. Par rapport aux méthodes existante telles que FPI ou SLFM, la technique proposée, permet une identification automatique des variables à transporter et n'est, de plus, pas lié à un régime de combustion spécifique. Cette technique a permis d'effectuer des calculs d'interaction flamme-vortex en ne transportant que 5 espèces à la place des 9 requises pour le calcul en chimie détaillée complète, sans pour autant perdre en précision.
Finalement, dans le but de réduire encore le nombre d'espèces transportées, les techniques T-BAKED et HT-BAKED PCA ont été introduites. En utilisant une pondération des points sous-représentés, ces deux techniques permettent d'augmenter la précision de l'analyse par composantes principales dans le cadre des phénomènes de combustion.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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Chronopoulos, Theodore. "Microwave Swing Adsorption for post-combustion CO2 capture from flue gases using solid sorbents." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3199.
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In recent years, there has been an increasing global interest in carbon dioxide capture and storage (CCS) as an important technology for climate change mitigation. However, improved technologies for the CO2 capture process that could possibly lead CCS to be highly competitive against the renewable energy market, are necessary. The evaluation of a CO2 capture system is often driven by energy demands and in adsorption technology this energy is particularly required for the desorption step. As a result, efficient regeneration systems ensuring multiple re-use of adsorbent materials, while minimizing energy use, are required, in an attempt to replace the conventional PSA (Pressure Swing Adsorption) and TSA (Temperature Swing Adsorption) technologies. This study presents and analyses a relatively new approach for CO2 sorbent regeneration, namely Microwave Swing Adsorption (MSA). The aim of this research is to intensify the CO2 desorption process from solid materials, focusing on improving the regeneration efficiency and kinetics as well as the energy spent during this step. The hypothesis that the direct absorption of energy during microwave heating by the solid adsorbent may enable a fast process with a low purge gas flow rate low desorption temperature resulting in low energy demands, is examined. However, MSA depends on numerous parameters, divided in two main categories, namely process parameters (flue gas composition, desorption temperature, moisture presence, gas flow rate) and material parameters (adsorbent shape and size, porosity, surface modifications, dielectric properties). To this regard, an extensive investigation of the above criteria and their connection with the performance of the MSA system is studied. In terms of the adsorption step, it was found that a switch to higher total flow rates results in an increase in the CO2 adsorption capacity of the GAC. Moreover, moisture presence also enhances the CO2 adsorption, as a result of an increase in the total flow rate and in the adsorption temperature. With regards to the desorption step, it was shown that MSA technology leads to enhanced performance efficiency of the sorbent by ~10%, while preserving its porous structure. Moreover, the regeneration time and the energy consumption were also considerably reduced (30% and 40%, respectively), for MSA compared to TSA.
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Gonçalves, Cátia Vanessa Maio. "Contribution of biomass combustion to air pollutant emissions." Doctoral thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/8104.
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Doutoramento em Ciências e Engenharia do AmbienteIn Portugal, it was estimated that around 1.95 Mton/year of wood is used in residential wood burning for heating and cooking. Additionally, in the last decades, burnt forest area has also been increasing. These combustions result in high levels of toxic air pollutants and a large perturbation of atmospheric chemistry, interfere with climate and have adverse effects on health. Accurate quantification of the amounts of trace gases and particulate matter emitted from residential wood burning, agriculture and garden waste burning and forest fires on a regional and global basis is essential for various purposes, including: the investigation of several atmospheric processes, the reporting of greenhouse gas emissions, and quantification of the air pollution sources that affect human health at regional scales. In Southern Europe, data on detailed emission factors from biomass burning are rather inexistent. Emission inventories and source apportionment, photochemical and climate change models use default values obtained for US and Northern Europe biofuels. Thus, it is desirable to use more specific locally available data. The objective of this study is to characterise and quantify the contribution of biomass combustion sources to atmospheric trace gases and aerosol concentrations more representative of the national reality. Laboratory (residential wood combustion) and field (agriculture/garden waste burning and experimental wildland fires) sampling experiments were carried out. In the laboratory, after the selection of the most representative wood species and combustion equipment in Portugal, a sampling program to determine gaseous and particulate matter emission rates was set up, including organic and inorganic aerosol composition. In the field, the smoke plumes from agriculture/garden waste and experimental wildland fires were sampled. The results of this study show that the combustion equipment and biofuel type used have an important role in the emission levels and composition. Significant differences between the use of traditional combustion equipment versus modern equipments were also observed. These differences are due to higher combustion efficiency of modern equipment, reflecting the smallest amount of particulate matter, organic carbon and carbon monoxide released. With regard to experimental wildland fires in shrub dominated areas, it was observed that the largest organic fraction in the samples studied was mainly composed by vegetation pyrolysis products. The major organic components in the smoke samples were pyrolysates of vegetation cuticles, mainly comprising steradienes and sterol derivatives, carbohydrates from the breakdown of cellulose, aliphatic lipids from vegetation waxes and methoxyphenols from the lignin thermal degradation. Despite being a banned practice in our country, agriculture/garden waste burning is actually quite common. To assess the particulate matter composition, the smoke from three different agriculture/garden residues have been sampled into 3 different size fractions (PM2.5, PM2.5-10 and PM>10). Despite distribution patterns of organic compounds in particulate matter varied among residues, the amounts of phenolics (polyphenol and guaiacyl derivatives) and organic acids were always predominant over other organic compounds in the organosoluble fraction of smoke. Among biomarkers, levoglucosan, β-sitosterol and phytol were detected in appreciable amounts in the smoke of all agriculture/garden residues. In addition, inositol may be considered as an eventual tracer for the smoke from potato haulm burning. It was shown that the prevailing ambient conditions (such as high humidity in the atmosphere) likely contributed to atmospheric processes (e.g. coagulation and hygroscopic growth), which influenced the particle size characteristics of the smoke tracers, shifting their distribution to larger diameters. An assessment of household biomass consumption was also made through a national scale survey. The information obtained with the survey combined with the databases on emission factors from the laboratory and field tests allowed us to estimate the pollutant amounts emitted in each Portuguese district. In addition to a likely contribution to the improvement of emission inventories, emission factors obtained for tracer compounds in this study can be applied in receptor models to assess the contribution of biomass burning to the levels of atmospheric aerosols and their constituents obtained in monitoring campaigns in Mediterranean Europe.
Em Portugal, estima-se que 1.95 Mton/ano de lenha sejam utilizadas na queima doméstica para aquecimento e confecção de alimentos. Em simultâneo, nas últimas décadas, a área de floresta ardida também tem vindo a aumentar. Estes tipos de combustão contribuem para a libertação de quantidades elevadas de poluentes tóxicos que perturbam a química da atmosfera, interferem com o clima e possuem efeitos nefastos na saúde. A quantificação rigorosa, à escala regional e global, das emissões de gases e matéria particulada associada à queima doméstica, queima de resíduos agrícolas e fogos florestais é fundamental para vários fins, nomeadamente na investigação dos diversos processos atmosféricos, na elaboração de relatórios de emissões de gases de estufa, e na quantificação de fontes de poluição atmosférica que afectam a saúde humana. No sul da Europa, as bases de dados com factores de emissão detalhados são praticamente inexistentes. Os modelos climáticos, a modelização fotoquímica, os inventários de emissões e os estudos de identificação de fontes emissoras utilizam valores típicos obtidos para biomassa norte-americana ou do norte da Europa. Assim, é conveniente utilizar valores mais específicos obtidos localmente. Este estudo teve como principal objectivo a caracterização e quantificação dos gases e aerossóis emitidos por fontes de queima de biomassa, englobando as espécies lenhosas mais representativas da realidade nacional. Foram realizadas experiências de amostragem em laboratório (queima doméstica) e no campo (queima de resíduos agrícolas/jardim e fogos florestais controlados). Em laboratório, após selecção das espécies de biomassa e dos equipamentos de queima mais representativos em Portugal, estabeleceu-se um programa de amostragem para determinar os factores de emissão de poluentes gasosos e particulados, incluindo a composição orgânica e inorgânica dos aerossóis. Ao nível do campo, efectuou-se a amostragem das plumas de fumo resultantes da queima de resíduos agrícolas/jardim e de fogos controlados numa área dominada por espécies arbustivas. Os resultados deste estudo mostram que o tipo de equipamento de combustão e o tipo de biomassa utilizados têm um papel importante nos níveis e composição dos poluentes emitidos. Diferenças significativas entre o uso de equipamentos de combustão tradicionais versus equipamentos modernos foram observadas. Estas diferenças devem-se à maior eficiência de combustão dos equipamentos modernos, reflectindo-se na menor quantidade de matéria particulada, carbono orgânico e monóxido de carbono libertados. No que diz respeito ao fogo controlado em áreas dominadas por espécies arbustivas observou-se que a fracção orgânica estudada nas amostras de fumo é composta essencialmente por produtos resultantes da pirólise da vegetação. Estes produtos são constituídos na sua maioria por esteredienos e derivados de esteróis, hidratos de carbono resultantes da quebra das moléculas de celulose, produtos alifáticos provenientes de ceras vegetais e metoxifenóis resultantes da degradação térmica da lenhina. A queima de resíduos agrícolas e de jardim, apesar de ser uma prática proibida no nosso país, é uma realidade bastante frequente. Para avaliar a composição das emissões de alguns tipos de resíduos foram recolhidas amostras de três tamanhos diferentes (PM2.5, PM2.5-10 and PM>10). Apesar de se poder observar uma grande variabilidade em termos de compostos orgânicos dependendo do tipo de resíduo queimado, os compostos fenólicos (derivados do polifenol e guaiacil) e os ácidos orgânicos foram sempre predominantes em relação à restante fracção orgânica. O levoglucosano, o β-sitosterol e o fitol foram os traçadores de queima de biomassa detectados em quantidades mais apreciáveis na generalidade dos resíduos agrícolas e de jardim. O inositol pode ser considerado um bom traçador para as emissões resultantes da queima de rama de batata. Observou-se que as condições ambientais (tais como valores elevados de humidade relativa na atmosfera) provavelmente contribuíram para processos de coagulação e de crescimento higroscópico que influenciaram as características dos traçadores de biomassa, mudando sua distribuição para diâmetros maiores. Foi também feita a avaliação do consumo doméstico de biomassa na forma de um inquérito aplicado à escala nacional. Os resultados obtidos, conjugados com as bases de dados sobre factores de emissão obtidas nos ensaios de queima laboratoriais, permitiram estimar as quantidades emitidas de vários poluentes em cada distrito de Portugal continental. Além de contribuir significativamente para o aperfeiçoamento dos inventários de emissões, os factores de emissão obtidos para vários compostos traçadores poderão ser aplicados em modelos no receptor de forma a avaliar a contribuição da queima de biomassa para os níveis de aerossóis atmosféricas e seus constituintes obtidos em campanhas de monitorização na Europa mediterrânea.
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Pritchett, Blair. "Mutagenic and genotoxic potential of nitrated polyaromatic hydrocarbons in combustion byproduct mixtures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0021/MQ55538.pdf.
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Silva, Sam, and A. Arellano. "Characterizing Regional-Scale Combustion Using Satellite Retrievals of CO, NO2 and CO2." MDPI AG, 2017. http://hdl.handle.net/10150/625469.
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We present joint analyses of satellite-observed combustion products to examine bulk characteristics of combustion in megacities and fire regions. We use retrievals of CO, NO2 and CO2 from NASA/Terra Measurement of Pollution In The Troposphere, NASA/Aura Ozone Monitoring Instrument, and JAXA Greenhouse Gases Observing Satellite to estimate atmospheric enhancements of these co-emitted species based on their spatiotemporal variability (spread, sigma) within 14 regions dominated by combustion emissions. We find that patterns in sigma(XCO)/sigma(XCO2) and sigma(XCO)/sigma(XNO2) are able to distinguish between combustion types across the globe. These patterns show distinct groupings for biomass burning and the developing/developed status of a region that are not well represented in global emissions inventories. We show here that such multi-species analyses can provide constraints on emission inventories, and be useful in monitoring trends and understanding regional-scale combustion.
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Seneviratne, Hemantha Revata. "Evaluating sorbents produced from waste to remove mercury in simulated flue gases from coal combustion." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11231.
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Coal-fired utility plants are the largest anthropogenic source of mercury emiSSIOns. Mercury abatement legislation for these plants is in place in Canada and U.S.A. Several facilities are achieving mercury emission reductions by using commercial activated carbons. However, these carbons are expensive. The present project aimed to determine mercury capture efficiencies of some fly ashes and sorbents produced from scrap tyre rubber and sewage sludge, compared to the effectiveness of commercial active carbons. E.U. legislation limits the methods available for disposing of waste materials, using them to manufacture sorbents provides a cost-effective disposal solution. A novel bench scale fixed-bed sorbent test system was designed and built for evaluating mercury capture efficiencies of sorbents by exposing the samples to different gaseous atmospheres. Pre-treating selected sorbents with a gas stream containing either NOx or HCl gave information on the effect of acid gases. Thermal desorption experiments completed on spent sorbents provided indications regarding the adsorption process.
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Lively, Ryan P. "Hollow fiber sorbents for post-combustion CO₂ capture." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43758.
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As concerns mount about the rise in atmospheric CO₂ concentrations, many different routes to reduce CO₂ emissions have been proposed. Of these, post-combustion CO₂ capture from coal-fired power stations is often the most controversial, as the CO₂ capture system will remove generating capacity from the grid whereas many of the other solutions involve increasing the generating capacity of the grid with low CO₂-emission plants. Despite this, coal-fired power stations represent a major point source for CO₂ emissions, and if a consensus is reached on the need to reduce CO₂ emissions, a low-cost method for capturing and storing the CO₂ released by these power plants needs to be developed. The overarching goal of this research is to design and develop a novel hollow fiber sorbent system for post-combustion CO₂ capture.
To achieve this goal, three objectives were developed to guide this research: i) develop a conceptual framework for hollow fiber sorbents that focuses on the energetic requirements of the system, ii) demonstrate that hollow fiber sorbents can be created, and a defect-free lumen layer can be made, iii) perform proof-of-concept CO₂ sorption experiments to confirm the validity of this approach to CO₂ capture. Each of these objectives is addressed in the body of this dissertation.
Work on the first objective showed that fiber sorbents can combine the energetic advantages of a physi-/chemi-sorption process utilizing a solid sorbent while mitigating the process deficiencies associated with using solid sorbents in a typical packed bed. All CO₂ capture technologies--including fiber sorbents--were shown to be highly parasitic to a host power plant in the absence of effective heat integration. Fiber sorbents have the unique advantage that heat integration is enabled most effectively by the hollow fiber morphology: the CO₂-sorbing fibers can behave as "adsorbing heat exchangers."
A dry-jet, wet-quench based hollow fiber spinning process was utilized to spin fibers that were 75wt% solid sorbent (zeolite 13X) and 25wt% support polymer (cellulose acetate). The spinning process was consistent and repeatable, allowing for production of large quantities of fibers. The fibers were successfully post-treated with an emulsion-based polymer (polyvinylidene chloride) to create a defect-free lumen side coating that was an excellent barrier to both water and gas permeation. A film study was conducted to elucidate the dominant factors in the formation of a defect-free film, and these factors were used for the creation of defect-free lumen layers. The work discussed in this thesis shows that the second objective of this work was definitively achieved.
For the third objective, sorption experiments conducted on the fiber sorbents indicated that the fiber sorbents CO₂ uptake is simply a weighted average of the support material CO₂ uptake and the solid sorbent uptake. Furthermore, kinetic experiments indicate that CO₂ access to the sorbents is not occluded noticeably by the polymer matrix. Using the fiber sorbents in a simulated rapid thermal swing adsorption cycle provided evidence for the fiber sorbents ability to capture the sorption enthalpy released by the CO₂-13X interaction. Finally, a slightly more-pure CO₂ product was able to be generated from the fiber sorbents via a thermal swing/inert purge process.
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Ferreira, PlÃcido GonÃalves. "Effects of carbon dioxide from biogas in filtration combustion." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=15117.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorThe use of biogas, with high concentrations of carbon dioxide (CO2) in its composition, in thermal systems of conventional combustion can result in combustion instabilities, leading to a decrease of the flame front propagation velocity, resulting even to the flame extinction. In addition, this contaminant can increase greenhouse gas levels in the exhaust, such as carbon monoxide (CO), unburned hydrocarbons (UHC), nitrogen oxides (NOx) among others. Thus, this research aims to demonstrate the effectiveness of "Filtration Combustion" (FC) to deal with fuels of low heat content, such as biogas. CF is a non-conventional technology capable of producing ultra-low emissions of CO, HC and NOx. The experimental apparatus used in this research consists of a porous burner constituted of ceramic spheres (alumina) that fill the combustion chamber, where heat exchangers are inserted at the porous matrix ends. The FC allows even the application of a reciprocating gas flow system, which periodically switches the direction of the gas flow in the chamber. The reciprocal filtration combustion allows the operation with several fuels and providing a stable combustion process with temperature distribution on trapezoidal profile, with temperature peaks between 1300 and 1600 K. In this context, the present experimental study tries to identify and to analyze the effects of carbon dioxide in FC, which covers energy extraction efficiency, emissions, reaction stability, and flammability limits using several air-fuel mixtures, altering both the CO2 concentration in the biogas composition as the equivalence ratio (ER), in which the technical methane is taken as the reference gas. The results have pointed out significant benefits of the reversal on the combustion process, allowing operation in a wide equivalence ratio range (0.1 <Ф <1.0), and achieving energy extraction efficiencies above 90%, with ultra-low CO and NOx emissions (below 1 ppm). However, when the burner operates on only flow direction, it is possible to realize a drastic reduction of the flammability limit, as the CO2 content in the biogas composition is increased.
A utilizaÃÃo do biogÃs, com elevadas concentraÃÃes de diÃxido de carbono (CO2) em sua composiÃÃo, em sistemas tÃrmicos de combustÃo convencionais pode resultar em instabilidades na reaÃÃo, levando a uma diminuiÃÃo da velocidade de propagaÃÃo da frente de chama (onda de combustÃo), ocasionando inclusive a sua extinÃÃo. AlÃm disso, este contaminante pode aumentar os Ãndices de gases poluentes na exaustÃo, tais como: monÃxido de carbono (CO), hidrocarbonetos nÃo queimados (HC), Ãxidos de nitrogÃnio (NOx), dentre outros. Por esta razÃo, esta pesquisa tem como objetivo demonstrar a eficÃcia da "CombustÃo de FiltraÃÃo" (CF) em lidar com os combustÃveis de baixo poder calorÃfico, como o biogÃs. CF à uma tecnologia nÃo-convencional capaz de produzir emissÃes ultrabaixas de CO, HC e NOx. O aparato experimental empregado nessa pesquisa consistiu de um queimador poroso, constituÃdo de esferas cerÃmicas (alumina) que preenchem a cÃmara de combustÃo, onde trocadores de calor estÃo inseridos nas extremidades dessa matriz porosa. A CF possibilitou, inclusive, a aplicaÃÃo de um sistema de escoamento recÃproco, que alternou periodicamente a direÃÃo do escoamento dos gases na cÃmara. A combustÃo de filtraÃÃo recÃproca permitiu a operaÃÃo com diversos combustÃveis e proporciona um processo de combustÃo estÃvel com a distribuiÃÃo de temperatura em perfil trapezoidal, com picos de temperatura entre 1300 e 1600 K. Neste contexto, o presente estudo experimental buscou identificar e analisar os efeitos do diÃxido de carbono na CF, o que engloba eficiÃncia de extraÃÃo de energia, emissÃes, estabilidade da reaÃÃo, e limites de inflamabilidade, utilizando vÃrias misturas ar-combustÃvel, alterando tanto a concentraÃÃo de CO2 na composiÃÃo do biogÃs como a razÃo de equivalÃncia (RE), tendo como gÃs de referÃncia o metano tÃcnico. Os resultados apontaram benefÃcios significativos da reversÃo sobre o processo de combustÃo, permitindo a operaÃÃo em uma ampla faixa de razÃo de equivalÃncia (0,1<Ф<1,0), e alcanÃando uma eficiÃncia de extraÃÃo de energia acima de 90%, com emissÃes ultrabaixas de CO e NOx (abaixo de 1 ppm). Em contrapartida, quando o queimador operou em apenas um sentido do escoamento, foi possÃvel perceber uma reduÃÃo no limite de inflamabilidade à medida que foi incrementado o teor de CO2 na composiÃÃo do biogÃs.
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Cha, Chong M. "Modeling turbulent mixing effects in natural gas reburning /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/7091.
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Ambhore, Atul Vitthalrao. "Effect of air addition on the plasma-based reforming of methane and propane." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Vierboom, Peter. "The optimisation of plasma torch design for the direct ignition of pulverised coal." Thesis, The University of Sydney, 1991. https://hdl.handle.net/2123/26481.
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This thesis describes several aspects of the development of an ignition system for modern pulverised. coal fired furnaces. This ignition system is novel in that its primary fuel is pulverised coal ignited directly by an electric arc plasma torch.
The project has many facets including: plasma generation; pulverised coal collection, storage and delivery; and pulverised coal combustion using plasma as an ignition source.
The first aspect of experimenta l work described herein is directed toward the production of a stable, highenthalpy, nitrogen plasma jet. Stability of the plasma jet was gained through modifying the geometry of the plasma torch anode. Evidence is provided which illustrates the nature of arc movement within the tubular anode of a plasma torch. It is shown that in regard to stability, the most important movement of the arc is that of restriking or shunting. The causes of shunting are investigated and a case is presented to suggest that the principal factor in the cause of arc restrike is the production of N2 ions in the gas surrounding the arc.
Details are also given on the design of a plasma torch which can operate at the required. power level without water cooling of the cathode.
Further to the design of the plasma torch itself, details are provided on the development of a plasma torch power supply which can contend with the rapid changes in arc voltage whilst maintaining an accurately regulated arc current.
Information is also provided on several aspects of the pulverised coal feeding system. Novel techniques and components have been developed to provide the plasma igniter with a smooth, continuous flow of pulverised coal.
When combined to form an ignition system, the plasma torch and a suitable pulverised coal supply may supplant the use of volatile fuels such as fuel oil and gas in many industrial applications and could have a significant impact on the development and use of plasmas as an industrial tool.
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Rocha, Ana Maura Araujo. "Estudo experimental de chamas difusivas livres turbulentas de gás natural submetidas a oscilações acústicas /." Guaratinguetá, 2007. http://hdl.handle.net/11449/106440.
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Orientador: Pedro Teixeira LacavaCoorientador: João Andrade de Carvalho Junior
Banca: Paulo Magalhães Filho
Banca: Luiz Roberto Carrocci
Banca: Demetrio Bastos Neto
Banca: Amir Antonio Martins de Oliveira Junior
Resumo: O processo de queima que se utiliza um campo acústico (combustão pulsante) para obter oscilação acústica, apresenta algumas vantagens já estabelecidas na literatura, tendo-se por referência o processo de queima convencional, podendo ser o campo acústico induzido por atuadores externos ou não. Exemplos destas vantagens incluem a minimização da emissão de poluentes e dos custos de investimento/operação, incluindo a redução de consumo de combustíveis e a maximização das taxas de transferência convectiva de calor. Entretanto, para sua aplicação prática, torna-se necessário o estudo dos fenômenos que envolvem o processo de combustão, ainda não devidamente equacionados. Desta forma, o objetivo principal deste trabalho é realizar uma criteriosa investigação experimental sobre como os diversos parâmetros que controlam ou descrevem a situação de queima em uma chama difusiva livre turbulenta de gás natural se comportam com a presença de um campo acústico. Para tal foi adaptada uma instalação (queimador de Delft), disponível no Laboratório Associado de Combustão e Propulsão do Instituto Nacional de Pesquisas Espaciais, com um sistema de atuação acústica. Tal sistema operacional possui chama turbulenta difusiva de gás natural, tipo jato, tendo sido escolhido, devido à sua geometria de chama ser mais simples e por apresentar na literatura um banco de dados já disponível, no que se refere aos processos físicos e químicos que ali se desenvolvem na situação sem atuação acústica, o que possibilita uma melhor compreensão da influência acústica sobre tais processos
Abstract: A burning process using an acoustic field to obtain pulse combustion presents potential advantages over the conventional combustion process. The acoustic field can be introduced by external actuators or not. Examples of these advantages include minimization of pollutants emission rates as well as of investment and operation cost reductions and maximization of convective heat transfer rates. However, for practical applications of pulse combustion it is necessary to further study the phenomena involved in this process, which are still not properly known yet. The main objective of this work is to conduct a though experimental investigation on the parameters that control and describe combustion in a free turbulent diffusion flame of natural gas under an acoustic field. An existing Delft burner was adapted for the study. This system was chosen because, besides its simplicity, there is also an extensive data set in the literature, describing the physical and chemical processes that occur under conventional combustion operation, allowing a better understanding of the influence of the acoustic field
Doutor
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Sjölander, Johan. "Prediction of ignition limits with respect to fuel fraction of inert gases. : Evaluation of cost effective CFD-method using cold flow simulations." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-109094.
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Improving fuel flexibility for gas turbines is one advantageous property on the market. It may lead to increased feasibility by potential customers and thereby give increased competiveness for production and retail companies of gas turbines such as Siemens Industrial Turbomachinery in Finspång. For this reason among others SIT assigned Anton Berg to perform several ignition tests at SIT’s atmospheric combustion rig (ACR) as his master thesis project. In the ACR he tested the limits for how high amounts of inert gases (N2 and CO2) that the rig, prepared with the 3rd generation DLE-burner operative in both the SGT-700 and SGT-800 engine, could ignite on (Berg, 2012). Research made by Abdel-Gay and Bradley already in 1985 summarized methane and propane combustion articles showing that a Karlovitz number (Chemical time scale/Turbulent time scale) of 1.5 could be used as a quenching limit for turbulent combustion (Abdel-Gayed & Bradley, 1985). Furthermore in 2010 Shy et al. showed that the Karlovitz number showed good correlation to ignition transition from a flamelet to distributed regime (Shy, et al., 2010). They also showed that this ignition transition affected the ignition probability significantly. Based on the results of these studies among others a CFD concept predicting ignition probability from cold flow simulations were created and tested in several applications at Cambridge University (Soworka, et al., 2014) (Neophytou, et al., 2012). With Berg’s ignition tests as reference results and a draft for a cost effective ignition prediction model this thesis where started. With the objectives of evaluating the ignition prediction against Berg’s results and at the same time analyze if there would be any better suited igniter spot 15 cold flow simulations on the ACR burner and combustor geometry were conducted. Boundary conditions according to selected tests were chosen with fuels composition ranging from pure methane/propane to fractions of 40/60 mole% CO2 and 50/75 mole% N2. By evaluating the average Karlovitz number in spherical ignition volumes around the igniter position successful ignition could be predicted if the Karlovitz number were below 1.5. The results showed promising tendencies but no straightforward prediction could be concluded from the evaluated approach. A conclusion regarding that the turbulence model probably didn’t predict mixing good enough was made which implied that no improved igniter position could be recommended. However by development of the approach by using a more accurate turbulence model as LES for example may improve the mixing and confirm the good prediction tendencies found. Possibilities for significantly improved ignition limits were also showed for 3-19% increase in equivalence ratio around the vicinity of the igniter.
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Wilcox, Jennifer. "On the path to elucidating the speciation of mercury in the flue gases of coal combustion." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280573.
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The goal of this research is to understand the speciation of mercury in the flue gases of coal combustion. As the flue gas cools, thermochemical equilibrium calculations indicate that elemental mercury, Hg⁰, is converted to oxidized mercury, Hg²⁺, in the form of HgO or HgCl₂. Hg⁰ is insoluble in water, HgO has low solubility in water and HgCl₂ is highly soluble in water. Since HgCl₂ is water-soluble, it can be captured in wet chemical scrubbers to prevent its release to the atmosphere. Therefore, the understanding of the mechanisms of mercury's oxidation in flue gases is paramount when considering mercury capture. This research attempts to elucidate the mechanisms of oxidation through a detailed kinetic and thermodynamic analysis. The current research focuses specifically on the oxidation of mercury via chlorine-containing compounds. Future research will involve the oxidation via oxygen-containing compounds and the effect of SO₂ and NOₓ compounds on mercury's oxidation. Quantum chemistry is used to determine accurate transition structures, which are required for the calculation of activation energies and rate constants from theory. Simultaneous to the theoretical work, an experimental apparatus has been designed and fabricated with the inclusion of a quadrupole mass spectrometer. The mass spectrometer is used in conjunction with a laminar flow reactor to simulate the oxidation of mercury via chlorine-containing compounds in flue gases. The ultimate goal of this research is to obtain a potential mercury oxidation mechanism based upon theoretically predicted kinetic parameters, which are then validated through concentration profiles obtained from experimental measurements. In addition, results from the experimental work indicate that at ambient conditions, the oxidation of mercury via chlorine may result as a consequence of heterogeneous reactions involving the Pyrex reactor surface. This work not only allows for a more thorough understanding of mercury's speciation in the flue gas environment, but also questions current sampling devices and their potential interference with reactivity measurements involving mercury-chlorine species.
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Attili, Viswatej. "Capture and mineralization of carbon dioxide from coal combustion flue gas emissions." Laramie, Wyo. : University of Wyoming, 2009. http://proquest.umi.com/pqdweb?did=1939354121&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Jen, Jen-Fon. "Analysis of Acid Gas Emissions in the Combustion of the Binder Enhanced d-RDF by Ion Chromatography." Thesis, University of North Texas, 1988. https://digital.library.unt.edu/ark:/67531/metadc331848/.
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Waste-to-energy has become an attractive alternative to landfills. One concern in this development is the release of pollutants in the combustion process. The binder enhanced d-RDF pellets satisfy the requirements of environmental acceptance, chemical/biological stability, and being storeable. The acid gas emissions of combusting d-RDF pellets with sulfur-rich coal were analyzed by ion chromatography and decreased when d-RDF pellets were utilized. The results imply the possibility of using d-RDF pellets to substitute for sulfur-rich coal as fuel, and also substantiate the effectiveness of a binder, calcium hydroxide, in decreasing emissions of SOx.
In order to perform the analysis of the combustion sample, sampling and sample pretreatment methods prior to the IC analysis and the first derivative detection mode in IC are investigated as well. At least two trapping reagents are necessary for collecting acid gases: one for hydrogen halides, and the other for NOx and SOx. Factors affecting the absorption of acid gases are studied, and the strength of an oxidizing agent is the main factor affecting the collection of NOx and SOx. The absorption preference series of acid gases are determined and the absorption models of acid gases in trapping reagents are derived from the analytical results. To prevent the back-flushing of trapping reagents between impingers when leak-checking, a design for the sampling train is suggested, which can be adopted in sample collections. Several reducing agents are studied for pretreating the sample collected in alkali-permanganate media. Besides the recommendation of the hydrogen peroxide solution in EPA method, methanol and formic acid are worth considering as alternate reducing agents in the pretreatment of alkaline-permanganate media prior to IC analysis. The first derivative conductivity detection mode is developed and used in IC system. It is efficient for the detection and quantification of overlapping peaks as well as being applicable for non-overlapping peaks.
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Kleut, Petar. "Recuperation of the exhaust gases energy using a Brayton cycle machine." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/76807.
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Lately, car manufacturers have been put to a big challenge to reduce the CO2 emission of their entire fleets. Norms of pollutant emissions limit the ways to achieve the desired CO2 emission goals, as some of the solutions that would lead to lower CO2 emission also lead to higher pollutant emission. Waste Heat Recovery (WHR) could be a good solution to lower the CO2 emission of the Internal Combustion Engine (ICE) without increasing the pollutant emission. In the present thesis different WHR strategies are analysed and the results suggested it would be interesting to further study the Brayton cycle machine.
Air Brayton Cycle (ABC) represents a way to recover a part of the heat energy of the ICE exhaust gases and transform it into mechanical energy. Recovered mechanical energy would then be returned to the crankshaft of the ICE, thereby reducing the amount of energy that has to be liberated by combustion of fuel which lowers the fuel consumption and CO2 emission.
The study of ABC started with an analysis of the ideal cycle in order to obtain the theoretical maximum of the system. The study continued with an analysis of the semi ideal cycle where all losses are taken into account only by two efficiency coefficients. This analysis showed that for the diesel engine efficiency of the ABC is very low because of the low exhaust gas temperature. For the gasoline engine the cycle could be viable when the ICE is working under steady condition and higher load. These conditions could be fulfilled when the vehicle is driven on the highway.
Detailed analysis was aimed at determining the cycle main losses. They were determined to be: pumping losses, losses caused by heat transfer and mechanical losses. Taking into account these main losses along with other direct and indirect losses it was concluded that the cycle is not viable for the types of the WHR machines that were considered in this study.
In order for the cycle to be viable some other either existing or new machine type should be tested, that would lower the main losses and offer good isentropic and mechanical efficiency for desired conditions.Últimamente los fabricantes de automóviles se han puesto el gran reto de reducir la emisión de CO2 en la totalidad de sus flotas. Las nuevas normativas para la reducción de las emisiones contaminantes limitan los medios para lograr los objetivos deseados en la emisión de CO2 porque algunas de las soluciones que llevan a la reducción en la emisión de CO2 también dan lugar a un incremento en la emisión de otros contaminantes. La recuperación de calor residual (WHR) podría ser una buena solución para reducir las emisiones de CO2 del motor de combustión interna (ICE) sin poner en peligro la emisión de contaminantes. En la presente Tesis se analizaron diferentes estrategias de WHR y se concluyó que sería interesante estudiar más a fondo la máquina de ciclo Brayton. El Ciclo Brayton de Aire (ABC) permite recuperar una parte del calor de los gases de escape del ICE y transformar este calor en energía mecánica. La energía mecánica recuperada se devuelve al cigüeñal del ICE, reduciendo de ese modo la cantidad de energía que tiene que ser liberada por la combustión del combustible, lo cual permite reducir el consumo de combustible y las emisiones de CO2. En esta Tesis se estudia el ABC mediante un análisis del ciclo ideal con el fin de obtener el máximo teórico del sistema. El modelo se mejora con un análisis del ciclo semi-ideal donde se tienen en cuenta todas las pérdidas mediante el uso de dos coeficientes generales. Este análisis muestra que para el motor diesel la eficiencia del ciclo ABC es muy baja debido a la baja temperatura del gas de escape. Para el motor de gasolina el ciclo podría ser viable cuando el ICE está trabajando bajo condiciones estacionarias y una carga mayor. Estas condiciones se podrían cumplir cuando el vehículo está circulando en autopista. El análisis detallado de este ciclo tiene como objetivo determinar las pérdidas principales de ciclo. Las pérdidas principales se identificaron como: las pérdidas de bombeo, las pérdidas causadas por la transferencia de calor y las pérdidas mecánicas. Teniendo en cuenta estas pérdidas principales junto con otras pérdidas directas e indirectas, se concluyó que el ciclo no es viable para los tipos de máquinas WHR que fueron considerados en este estudio. Para que el ciclo sea viable se tiene que buscar alguna otra máquina existente o un nuevo tipo de máquina que reduzca las principales pérdidas y ofrezca un buen rendimiento isentrópico y mecánico para las condiciones deseadas.
Últimament els fabricants d'automòbils s'han posat el gran repte de reduir l'emissió de CO2 de la totalitat de les seues flotes. Les noves normatives de reducció de les emissions contaminants limiten els mitjans per assolir els objectius desitjats d'emissió de CO2 perquè algunes de les solucions que porten a la reducció en l'emissió de CO2 també donen lloc a un increment a l'emissió de altres contaminants. La recuperació de calor residual (WHR) podria ser una bona solució per reduir les emissions de CO2 del motor de combustió interna (ICE) sense posar en perill l'emissió de contaminants. En la present Tesi s'han analitzat diferents estratègies WHR i es va concloure que seria interessant estudiar més a fons el cicle Brayton. El Cicle Brayton d'Aire (ABC) representa una manera de recuperar una part de la calor dels gasos d'escapament de l'ICE i transformar calor a l'energia mecànica. L'energia mecànica recuperada es retorna al cigonyal de l'ICE reduint d'aquesta manera la quantitat d'energia que ha de ser alliberada per la combustió del combustible permitint la reducció del consum de combustible i les emissions de CO2. En aquesta Tesi s'ha començat estudiant un ABC amb una anàlisi del cicle ideal per tal d'obtenir el màxim teòric del sistema. Este model es millora amb una anàlisi del cicle semiideal on es tenen en compte totes les pèrdues amb tan sols dos coeficients d'eficiència. Aquesta anàlisi va mostrar que per al motor dièsel l'eficiència del cicle ABC és molt baixa a causa de la baixa temperatura del gas d'escapament. Per al motor de gasolina el cicle podria ser viable quan l'ICE està treballant sota condicions estacionàries i una càrrega més gran. Aquestes condicions es podrien complir quan el vehicle està circulant en autopista. L'anàlisi detallada del cicle va tenir com a objectiu determinar les pèrdues principals de cicle. Les pèrdues principals es van identificar com: les pèrdues de bombament, les pèrdues causades per la transferència de calor i les pèrdues mecàniques. Tenint en compte aquestes pèrdues principals juntament amb altres pèrdues directes i indirectes, es va concloure que el cicle no és viable per als tipus de màquines WHR que van ser considerats en aquest estudi. Perquè el cicle puga ser viable s'ha de buscar alguna altra màquina existent o un nou tipus de màquina que puga reduir les principals pèrdues i puga oferir un bon rendiment isentròpic i mecànic per a les condicions desitjades.
Kleut, P. (2016). Recuperation of the exhaust gases energy using a Brayton cycle machine [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/76807
TESIS
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Siqueira, Rafael MagalhÃes. "Filtration combustion applied to biogas containing high concentration of Sulfide Hydrogen." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=15116.
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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgicoUsing Natural Gas or Biogas in natura, containing high hydrogen (H2S) sulfide concentrations, to apply in conventional combustion processes, can cause several damages to equipment. This is due to the fact that it is a very corrosive gas that can form a sulfur acid reaction with water from combustion. In addition, using these fuels without pretreatment can cause instability on reaction, even under flame risk deletion, which implies in efficiency and oxide carbon (CO) and nitrogen oxide (NOx) emission levels. Therefore, this study refers to the experimental method of non-conventional combustion process application, the porous media combustion, also known as filtration combustion, to deal with these special fuels, impossible to use in known thermal systems. A burner all filled with alumina spheres (Al2O3) was the equipment used for these experiments. This inert porous media fills even the heat exchangers located on the ends of the burner. The equivalent ratio, flow velocity and gas composition influence in the process, are experimental analyzed. Preliminary results have suggested that when using an ultra-lean air-fuel mixture, the reaction can remain steady with a good H2S conversion and low CO and NOx emissions.
O uso do gÃs natural ou biogÃs in natura, contendo elevadas concentraÃÃes de sulfeto de hidrogÃnio (H2S), para aplicaÃÃo em processos de combustÃo convencionais, pode acarretar em diversos danos aos equipamentos, devido esse gÃs ser bastante corrosivo e, tambÃm, por formar Ãcido sulfÃrico ao reagir com a Ãgua resultante da combustÃo. AlÃm do que, a utilizaÃÃo dos citados combustÃveis sem um tratamento prÃvio pode ocasionar instabilidade da reaÃÃo, inclusive sob risco de apagamento da chama, o que implica na eficiÃncia e nos nÃveis de emissÃo de monÃxido de carbono (CO) e Ãxido de nitrogÃnio (NOx). Portanto, o presente trabalho refere-se ao estudo experimental da aplicaÃÃo de um processo de combustÃo nÃo-convencional, a combustÃo em meios porosos, tambÃm conhecida como combustÃo de filtraÃÃo (CF), para lidar com esses combustÃveis especiais, impossÃvel para os sistemas tÃrmicos conhecidos. O equipamento utilizado nos experimentos à um queimador, preenchido totalmente por esferas de alumina (Al2O3), em que esse meio poroso inerte envolve inclusive os trocadores de calor localizados nas extremidades do queimador. A influÃncia da razÃo de equivalÃncia, velocidade de escoamento e composiÃÃo do gÃs sob o processo à analisada experimentalmente. Os resultados sugerem que, mesmo utilizando uma mistura ar-combustÃvel ultra pobre, a reaÃÃo pode se manter estÃvel, apresentando boa conversÃo do H2S e baixas emissÃes de NOx.
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Rutar, Shuman Teodora. "NOx and CO formation for lean-premixed methane-air combustion in a jet-stirred reactor operated at elevated pressure /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/7117.
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Urban, David Raymond. "A kinetic investigation of As and Se speciation within coal combustion flue gases using ab initio methods." Link to electronic thesis, 2006. http://www.wpi.edu/Pubs/ETD/Available/etd-042806-133423/.
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Hory, Rogerio Ishikawa. "Avaliação das emissões de S'O IND.2' em leito fluidizado circulante na combustão de carvão mineral brasileiro e dolomita." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264647.
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Orientador: Arai Augusta Bernardez PecoraTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Este trabalho apresenta o estudo experimental do processo de combustão de carvão mineral brasileiro em reator de Leito Fluidizado Circulante (LFC) com o objetivo de avaliar as taxas de emissões de di óxido de enxofre (S02) e eficiência de conversão de carbono no processo de combustão. Para diminuir a emissão do S02 nos gases de exaustão, foi adicionado, ao carvão, quantidades de calcário dolomítico (dolomita), de modo que a relação molar entre o cálcio (Ca) presente no calcário e o enxofre (S) presente no carvão variou entre 0,0 e 2,0. A variação na relação molar Ca/S, como é denominada na literatura, foi um dos dois fatores avaliados neste trabalho. O outro fator envolvido nos testes foi o excesso de ar utilizado para combustão do carvão. Trabalhou-se com excesso de ar na faixa de 20 a 30%. Foram realizados 11 ensaios seguindo um planejamento experimental estatístico do tipo CCD (Composite Central Design) e mais 02 ensaios complementares. A relação molar Ca/S de 0,6 apresentou emissão zero de S02 e propôs-se utilizar uma nova relação molar: (Ca+Mg)/S para retratar processos de sorção com dolomitas. Para emissão zero de S02, uma relação molar (Ca+Mg)/S de 1,8 já é suficiente. Foram obtidas eficiências de conversão do carbono entre 86,0 e 93,0% para combustão do carvão
Abstract: This work presents an experimental study with Brazilian mineral coal combustion in a Circulating Fluidized Bed (CFB) reactor with the objective to evaluate the sulphur dioxide emissions (S02) and the carbon conversion efficiency in the combustion processo Dolomite was added to the coal to minimize the S02 emissions during combustion. The quantity of dolomite added was calculated based on the molar relation of calcium (Ca) present in the dolomite and sulphur (S) present in the coal. Ca/S molar relation had a variation between 0,0 and 2,0. Two factors were evaluated in this work: Ca/S relation and excess of air during combustion which had a variation between 20 and 30%. Eleven (11) experimental tests were evaluated following a statistical experimental design called CCD (Composite Central Design) and 02 (two) more complementary tests. Emissions of S02 with zero value were obtained for a Ca/S of 0,6. It was also proposed in this work a new relation for sorption of S02 with dolomite: (Ca+Mg)/S relation. Tests showed that a relation of 1.8 for (Ca+Mg)/S is sufficient for zero emissions of S02. Carbon conversion efficiency between 86.0 and 93.0 was also obtained during coal combustion
Doutorado
Termica e Fluidos
Mestre em Engenharia Mecânica
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VEGA, BUSTILLOS JOSE O. W. "Procedimentos analiticos aplicados ao estudo de gases provenientes da combustao de metanol por automovel." reponame:Repositório Institucional do IPEN, 1996. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10468.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Prata, José Eduardo. "Estimativa e recuperação da água presente nos produtos de combustão de centrais termelétricas." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/106/106131/tde-27042018-115515/.
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Usinas Termelétricas (UTEs), compostas por ciclo simples a vapor e ciclo combinado, são instalações industriais que consomem elevadas quantidades de água, sobretudo por conta de suas operações de resfriamento e de geração de vapor. Paralelamente, tem-se observado a redução de oferta deste recurso em muitas regiões onde se encontram instaladas unidades termelétricas, fato que suscita a preocupação, o debate e a pesquisa acerca do desenvolvimento de tecnologias e estratégias direcionadas à mitigação do consumo e reaproveitamento de água em UTEs. Em contrapartida, do mesmo modo que UTEs são intensivas no consumo de água, esta é também produzida na forma de vapor em escalas significativas como resultado do processo de combustão. Contudo, a parcela de água produzida é lançada para a atmosfera juntamente com os demais gases produzidos (CO2, N2, O2, SO2). Frente a esse contexto, este trabalho se divide em duas etapas distintas. A primeira voltada à estimativa da quantidade de água e demais componentes presentes nos gases de combustão de trinta e seis UTEs brasileiras, dentre as quais vinte e duas são movidas a gás natural (ciclos simples e combinados) e quatorze a carvão mineral (ciclos simples). Tais estimativas levam em conta as condições ambientais do local de operação, a eficiência típica do ciclo e a composição do combustível empregado. A segunda etapa trata da modelagem e da simulação, sob diferentes condições operacionais (pressão, temperatura de resfriamento e porcentagem de vapor de água nos gases), de um condensador duplo tubo vertical operando sob regime de convecção natural no lado do resfriamento, a partir do qual se estuda o processo de condensação do vapor de água na presença dos demais gases produzidos, estes conhecidos como gases não condensáveis (GNC). Tais simulações tem o propósito de avaliar as taxas de recuperação de água capazes de serem obtidas por meio do condensador/processo idealizado.Single and combined steam cycle thermoelectric plants are power plants that consume high amounts of water, mainly from the cooling and steam generation operations. At the same time, there have been a reduction in the supply of this resource in many regions where thermoelectric units are installed. This fact increases the concern, discussion, and research on the development of technologies and new strategies directed to the mitigation of the consumption and reutilization of water. On the other hand, likewise UTEs are intensive in water consumption, they also produce it at significant amounts of steam from the combustion process, and that amount of water produced is released to the atmosphere together with gases produced (CO2, N2, O2, SO2). In this sense, this work is divided into two distinct parts. The first one is aimed at estimating the amount of water and other components present in the flue gases of thirty Brazilian thermal power plants, of which twenty-two are powered by natural gas (single and combined cycles) and eight moved by coal (single cycles). Such estimates consider environmental conditions of the operation site, typical cycle efficiency, and fuel composition employed. The second part deals with a numerical modeling and simulation, at different operating conditions (pressure, cooling temperature, and water vapor content in the gases), of a double vertical tube condenser operating by natural convection on the cooling side, from which the condensation process of the water vapor is studied in the presence of the other gases produced (known as non-condensable gases, NCG). These simulations have the fundamental purpose of evaluating the rates of condensate that can be recovered by means of the condenser/idealized process.
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Ruusunen, M. (Mika). "Signal correlations in biomass combustion – an information theoretic analysis." Doctoral thesis, Oulun yliopisto, 2013. http://urn.fi/urn:isbn:9789526201924.
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Abstract Increasing environmental and economic awareness are driving the development of combustion technologies to efficient biomass use and clean burning. To accomplish these goals, quantitative information about combustion variables is needed. However, for small-scale combustion units the existing monitoring methods are often expensive or complex. This study aimed to quantify correlations between flue gas temperatures and combustion variables, namely typical emission components, heat output, and efficiency. For this, data acquired from four small-scale combustion units and a large circulating fluidised bed boiler was studied. The fuel range varied from wood logs, wood chips, and wood pellets to biomass residue. Original signals and a defined set of their mathematical transformations were applied to data analysis. In order to evaluate the strength of the correlations, a multivariate distance measure based on information theory was derived. The analysis further assessed time-varying signal correlations and relative time delays. Ranking of the analysis results was based on the distance measure. The uniformity of the correlations in the different data sets was studied by comparing the 10-quantiles of the measured signal. The method was validated with two benchmark data sets. The flue gas temperatures and the combustion variables measured carried similar information. The strongest correlations were mainly linear with the transformed signal combinations and explicable by the combustion theory. Remarkably, the results showed uniformity of the correlations across the data sets with several signal transformations. This was also indicated by simulations using a linear model with constant structure to monitor carbon dioxide in flue gas. Acceptable performance was observed according to three validation criteria used to quantify modelling error in each data set. In general, the findings demonstrate that the presented signal transformations enable real-time approximation of the studied combustion variables. The potentiality of flue gas temperatures to monitor the quality and efficiency of combustion allows development toward cost effective control systems. Moreover, the uniformity of the presented signal correlations could enable straightforward copies of such systems. This would cumulatively impact the reduction of emissions and fuel consumption in small-scale biomass combustionTiivistelmä Kasvava ympäristö- ja kustannustietoisuus ohjaa polttoteknologioiden kehitystä yhä tehokkaampaan biomassan hyödyntämiseen ja puhtaampaan palamiseen. Näiden tavoitteiden saavuttamiseen tarvitaan mittaustietoa palamismuuttujista. Nykyiset palamisen seurantaan tarkoitetut ratkaisut ovat kuitenkin pienpolttolaitteita ajatellen usein kalliita tai monimutkaisia. Tässä työssä tutkittiin mitattujen savukaasun lämpötilojen riippuvuussuhdetta tyypillisiin kaasukomponentteihin, lämpötehoon ja tehokkuuteen. Tätä varten analysoitiin mittausaineistot neljästä erityyppisestä pienpolttolaitteesta ja suuresta kiertoleijupeti-kattilasta. Puupolttoaineina olivat klapi, hake, pelletti ja hakkuujäte. Analyysi tehtiin alkuperäisillä mittaussignaaleilla ja niistä matemaattisesti muunnetuilla signaaleilla. Riippuvuussuhteiden selvittämiseksi johdettiin informaatioteoriaan perustuva monimuuttuja-etäisyysmitta, jonka lukuarvolla mitataan signaalien samankaltaisuutta. Esitetty analyysimenetelmä sisälsi myös riippuvuuksien ajallisen muutoksen ja suhteellisten aikaviiveiden arvioinnin. Tulosten arvojärjestys perustui etäisyysmitan arvoon. Riippuvuussuhteiden samankaltaisuutta mittausaineistojen välillä vertailtiin 10-kvantiileilla. Analyysimenetelmän toimivuus vahvistettiin kahdella tunnetulla koeaineistolla. Savukaasun lämpötilojen ja palamismuuttujien mittaussignaaleissa oli samankaltainen informaatiosisältö. Vahvimmat riippuvuudet olivat muunnettujen signaalien yhdistelmillä pääosin lineaarisia ja palamisteorian mukaisia. Merkittävää oli, että tietyillä signaalimuunnos- ja palamismuuttujapareilla oli sama riippuvuussuhde kaikissa mittausaineistossa. Tämä todettiin myös simuloinneilla arvioitaessa savukaasujen hiilidioksidipitoisuutta lineaarisella, kiinteällä mallirakenteella. Mallin tarkkuus oli riittävä kolmella erityyppisellä kriteerillä jokaisessa mittausaineistossa. Tulosten perusteella signaalimuunnoksilla voidaan arvioida palamismuuttujia reaaliaikaisesti. Savukaasujen lämpötilojen potentiaali palamisen laadun ja tehokkuuden seurannassa mahdollistaa kustannustehokkaiden säätöratkaisujen kehityksen. Löydettyjä yleistettäviä riippuvuussuhteita hyödyntämällä niiden käyttöönotto lukuisissa polttolaitteissa helpottuisi. Pienpolton päästöjen ja polttoaineen kulutuksen vähentyminen olisi tällöin kumulatiivista
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Lima, Leonardo Lopes. "Identificação dos fenômenos de combustão e detonação em um motor ciclo Otto através da corrente iônica." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-01112016-090618/.
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As legislações com restrições nos níveis de emissões de poluentes e a grande concorrência entre as montadoras fomentaram o desenvolvimento de sistemas mais eficientes de gerenciamento de motores a combustão interna. Entretanto, a falta de sensores que identifiquem as propriedades da combustão, e que sejam economicamente viáveis, dificulta o desenvolvimento de novos sistemas. Visando suprir parte dessas limitações, este trabalho propõe o uso do sensor de corrente iônica com duas finalidades: identificação dos fenômenos de combustão e detonação. Para identificação da combustão, atualmente é utilizado o sensor de fase instalado no motor, o que encarece o sistema de gerenciamento. Uma alternativa a este sensor seria utilizar a vela de ignição, já instalada dentro do cilindro do motor, como sensor de ionização da mistura ar/combustível durante a queima. Comparando a área sob a curva do sinal da corrente iônica durante a combustão com a área sob a curva durante a admissão, foi possível verificar que é viável a utilização do sinal da corrente iônica para substituição de uma funcionalidade do sensor de fase. Quanto à identificação do fenômeno da detonação, foi mostrado que o uso do sensor de corrente iônica possibilita a remoção do sensor de detonação. Para isso, foi realizada a correlação entre a energia de uma faixa de frequências dos harmônicos do sinal da corrente iônica com a energia do sinal proveniente do sensor de detonação. Dessa forma, este trabalho mostrou que é possível usar somente as velas de ignição, já presentes no veículo, como sensores. Além disso, os resultados positivos obtidos propiciam oportunidades para novas aplicações e novas pesquisas.The laws that restrict pollutant emission levels and the competition among manufacturers fostered the development of more efficient internal combustion engine management systems. However, the lack of sensors to identify the properties of combustion, and which are economically viable, hinders the development of new systems. In order to address such limitations, this investigation proposes using the ionic current sensor with two purposes: identification of combustion and knock phenomena. The combustion identification is currently identified by the camshaft position sensor installed in the motor, which becomes more expensive for the management system. An alternative is using the spark plug, already installed inside the engine cylinder, such as ionization sensor of air/fuel mixture during combustion. Comparing the area under the curve of the ion current signal during combustion to the area under the curve during admission, it was found that it is feasible the use of ionic current signal to replace one feature of the camshaft position sensor. Concerning the identification of the knock phenomenon, it was shown that the use of the ionic current sensor allows the removal of the knock sensor. For this, the correlation between the energy signal in a frequency range of the ionic current harmonic with the energy of the signal from the knock sensor was performed Therefore, the use of spark plugs as sensors is very promising, in replacement to two existing sensors. Moreover, the positive results provide opportunities for new applications and researches.
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Milkov, Nikolay. "Waste heat recovery from the exhaust gases of a diesel engine by means of Rankine cycle." Thesis, Paris, CNAM, 2017. http://www.theses.fr/2017CNAM1149/document.
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Cette étude est motivée par la protection de l'environnement et la réduction des émissions de CO2 émis par les moteurs à combustion interne. L'objectif de la thèse est d'étudier les possibilités de la réduction de la consommation de carburant d'un moteur diesel d’automobile grâce à la récupération de la chaleur des gaz d'échappement basée sur un cycle de Rankine. Afin de déterminer l'énergie perdue, le moteur a été testé sur un banc d’essais et les paramètres des gaz d’échappement ont été mesurés. Un modèle de simulation du moteur a également été développé et validé grâce aux résultats expérimentaux. Le potentiel de récupération de chaleur sur les gaz d’échappement et sur le refroidissement a été estimé. Cette analyse a révélé que le potentiel sur les gaz d’échappement est plus élevé que celui sur le refroidissement. Grâce au modèle numérique et aux essais, la puissance et l'efficacité du cycle de Rankine ont été étudiées. Enfin, l'impact du système de récupération d’énergie sur les performances du moteur a été analysé. Les résultats montrent que la puissance du moteur augmente de 4,3% au point de puissance maximale du moteurThis study is motivated by the environment protection and the reduction of emissions CO2 from internal combustion engines. The aim of the thesis is to study the possibilities of fuel consumption reduction of a diesel engine intended for a passenger car by means of waste heat recovery from exhaust gases based on thermodynamic cycle (Rankine cycle). In order to determine the waste heat, the engine was tested on a test bench as the exhaust parameters were measured. A simulation model of the engine has also been developed and validated by means of experimental results. The recovery potential of the exhaust gases and the cooling system has been estimated. This analysis revealed that the waste heat recovery potential of the exhaust gases is higher that the cooling sys-tem. By means of Rankine cycle numerical model and experimental test, the output power and efficiency of the Rankine cycle were studied. Finally, the impact of the heat recovery system on engine performance was studied. The results revealed that the engine power increases by 4.3% at the operating point which corresponds to the maximum engine power
Това изследване е мотивирано от опазването на околната среда и намаляването на емисиите на CO2 от двигателите с вътрешно горене. Целта на дисертацията е да проучи възможнос-тите за намаляване на разхода на гориво на дизелов двигател, предназначен за лек автомо-бил, чрез рекупериране на енергия с цикъл на Ранкин. За да се определи неоползотворената енергия в отработилите газове бе използван изпитателен стенд. Симулационен модел на двигателя е разработен и валидиран чрез експерименталните резултати. Направена е оценка на потенциала за рекупериране на енергия от отработилите газове и охладителната система. Този анализ показва, че потенциала за рекупериране е по-голям в изпускателната система. С помощта на експериментален стенд и числен модел на цикъла на Ранкин са установени мощността и ефективността на системата. Въздействието на системата за рекупериране на енергия е изследвано. Данните показват, че мощността на двигателя се увеличава с до 4,3%
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Morren, William Earl. "Interferences with measurements of CO, CO₂, and O₂ in woodstove flue gases." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/101455.
Full textAbstract:
Concentrations of CO, CO₂, and O₂ in woodstove flue gases are some of the measured inputs required by algorithms used to calculate woodstove efficiency by the stack loss method. Since these algorithms have been shown to be very sensitive to small errors in these input values, it was necessary to determine whether measurements of these compounds are subject to interference.
Concentrations of CO, CO₂, and O₂ in a series of flue gas samples were measured using a variety of independent measurement techniques for each compound. The concentrations indicated by each of the measurement techniques for each compound and sample were compared to check for agreement. Disagreement among the measurement techniques for a given compound could indicate interference if some trend could be established. Tests were conducted on four samples taken randomly during each of three stove firings.M.S.
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Eggenspieler, Gilles. "Numerical simulation of pollutant emission and flame extinction in lean premixed systems." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-06222005-132512/.
Full textAbstract:
Thesis (Ph. D.)--Aerospace Engineering, Georgia Institute of Technology, 2006.Yedidia Neumeier, Committee Member ; Jerry Seitzman, Committee Member ; Fotis Sotiropoulos, Committee Member ; Tim Lieuwen, Committee Member ; suresh menon, Committee Chair.
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Santos, Rodrigo Fernando Estella dos. "Análise experimental do desempenho e da combustão de um motor de ignição por compressão alimentado por uma mistura ternária de combustíveis: diesel, biodiesel e etanol." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-01022016-151906/.
Full textAbstract:
É analisado o desempenho de um motor de ignição por compressão turboalimentado por uma mistura temária de combustíveis (diesel, biodiesel e etanol) através do comportamento do motor operando com um combustível principal, o qual poderá ser o diesel ou biodiesel ou misturas destes dois, com e sem sua substituição parcial por etanol no coletor de admissão. A análise do desempenho é feita através das curvas de torque, potência, rendimento térmico e consumo específico de combustível. A combustão do motor é estudada através de um programa simulador que utiliza um modelo zero-dimensional, que avalia a taxa de liberação de calor durante a combustão e tem como dado de entrada a curva de evolução da pressão dentro do cilindro. Faz-se a identificação e quantificação do fenômeno da detonação utilizando análise espectral, através do sinal de pressão da câmara de combustão, para o motor operando com diversas misturas combustíveis. São analisadas também as emissões gasosas do motor com as misturas, e a viabilidade técnica do uso de biodiesel em motores de ignição por compressão, além de um estudo geral sobre o uso do éster de óleo vegetal.The performance of a three-fuel system (diesel, biodiesel and ethanol) turbocharged compression-ignition engine is analyzed, through the engine behavior supplied by mixtures of diesel or biodiesel or mixtures of these fuels with ethanol in the intake manifold. The performance analysis is made by torque, power, specific fuel consumption and thermal efficiency curves. The engine combustion is studied by a simulator program that uses a zero-dimensional model, that evaluate the heat release rate during the combustion and it has as input data the pressure evolution curves inside the cylinder. The knocking phenomenon is studied by spectral analysis. The pollutant gases emissions and the technical viability of the utilization of biodiesel also are analyzed, beyond a general study about of vegetal oil ester.