Download or read book Experimental Study of the Emissions and Performance of Premixed Combustion Within the Non homogeneous Porous Ceramic Burners written by Timothy Tin-Yam Lai and published by . This book was released on 1995 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Low NOx Porous Ceramics Burner Performance Study written by and published by . This book was released on 2007 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Computational and Experimental Investigation of Flow and Combustion Physics in Porous Media written by Sadaf Sobhani and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As emission regulations become increasingly more stringent and policies evolve to combat global climate change impacts, reducing pollutant and greenhouse gas emissions emerge as one of the most important goals of combustion research. Techniques such as staged combustion, lean premixed combustion, catalytic combustion, and advanced mixing and fuel atomization are some of the methods examined to reduce emissions of pollutants such as nitrogen oxides (NOx), carbon monoxide (CO), and unburned hydrocarbons (UHCs). Porous media combustion represents an advanced combustion concept that is capable of achieving low emissions, enhanced flame stabilization, and improved fuel efficiency. Conventionally, Porous Media Burners (PMBs) utilize a two-zone ``step" burner design, which operates on the principal that the upstream high pore-density region serves as a flame arrestor and flame stability is observed at the interface between the two regions of high and low pore density. This dissertation contributes to the analysis of combustion in porous media, characterization of its performance in conventional PMBs, and the development and testing of a novel porous matrix design for enhanced combustion performance. First, a characterization of the combustion stability, pressure drop and pollutant emissions of conventional two-zone ``step" PMB is presented for a range of operating conditions and burner designs. Long-term material durability tests at steady-state and cycled on-off conditions were performed under operation with methane-fuel at atmospheric pressure. Thermocouple temperature measurements and pressure drop data are presented and compared to results obtained from 1D volume-averaged simulations. Additionally, the burner design with the maximum combustion stability regime was identified and tested in subsequent high-pressure experiments at 2, 8, and 20 bar with fully vaporized and preheated n-heptane and methane fuels, at fuel-lean equivalence ratios. Second, in an effort to expand the combustion stability regime beyond the capability of two-zone ``step" PMBs, a novel burner design having a spatially graded porous matrix is proposed, resulting from the theoretical analysis of the governing equations and constitutive relations. This analysis reveals the significance of the pore topology on interphase heat exchange and radiative heat transfer properties, quantified by the local Stanton number and optical depth, respectively. Gradation in topology (i.e. porosity, pore diameter, cell diameter, etc.) enables the flame to stabilize dynamically within the porous matrix and for a wider range of operating conditions. Computational stability maps, temperature profiles, and emissions data are presented for comparable two-zone ``step'' and ``graded" burner concepts, which predict significant performance enhancements in the latter. The theoretical and computational investigation of matrix gradation in PMBs as well as experiments reveal the potential for tailoring the internal heat transfer properties to optimize performance, and thus motivates the subsequent work in leveraging recent advancements in additive manufacturing to enable smoothly graded porous structures. The next part of this dissertation achieves the use of Lithography-based Ceramic Manufacturing for the fabrication of functionally graded matrix structures, designed using periodic surface equations. The manufactured samples were operated in a PMB over a range of operating conditions to test the feasibility and performance of additive manufactured materials in PMBs. Thermal and durability testing of the manufactured parts are characterized, along with combustion stability maps from the ``step" and ``graded" PMB experiment, which, consistent with the previous theoretical, computational, and experimental results, show significant performance improvements of the ``graded" burner.

Download or read book Experimental Study of Premixed Combustion Within a Cylindrical Dual layer Porous Inert Medium written by Christopher Matthew Hyvonen and published by . This book was released on 2005 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1992 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Combustion of Liquid Fuel Sprays written by Alan Williams and published by Butterworth-Heinemann. This book was released on 2013-10-22 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combustion of Liquid Fuel Sprays outlines the fundamentals of the combustion of sprays in a unified way which may be applied to any technological application. The book begins with a discussion of the general nature of spray combustion, the sources of liquid fuels used in spray combustion, biomass sources of liquid fuels, and the nature and properties of fuel oils. Subsequent chapters focus on the properties of sprays, the atomization of liquid fuels, and the theoretical modeling of the behavior of a spray flame in a combustion chamber. The nature and control of pollutants from spray combustion, the formation of deposits in oil-fired systems, and the combustion of sprays in furnaces and engines are elucidated as well. The text is intended for students undertaking courses or research in fuel, combustion, and energy studies.

Download or read book Numerical and Experimental Investigation of Heat Transfer and Pollutant Formation in Porous Direct fired Radiant Burners written by Marc David Rumminger and published by . This book was released on 1996 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Premixed Burner Experiments written by and published by . This book was released on 1995 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research program is exploring techniques for improved fuel-air mixing, with the aim of achieving combustor operations up to stoichiometric conditions with minimal NO(subscript x) and maximum efficiency. The experimental studies involve the use of a double-concentric natural gas burner that is operable in either premixed or non-premixed modes, and the system allows systematic variation of equivalence ratio, swirl strength shear length region and flow momentum in each annulus. Flame structures formed with various combinations of swirl strengths, flow throughput and equivalence ratios in premixed mode show the significant impact of swirl flow distribution on flame structure emanating from the mixedness. This impact on flame structure is expected to have a pronounced effect on the heat release rate and the emission of NO(subscript x). Thus, swirler design and configuration remains a key factor in the quest for completely optimized combustion. Parallel numerical studies of the flow and combustion phenomena were carried out, using the RSM and the k-E turbulence models. These results have not only indicated the strengths and limitations of CFD in performance and pollutants emission predictions, but have provided guidelines on the size and strength of the recirculation produced and the spatio-temporal structure of the combustion flowfield. The first stage of parametric studies on geometry and operational parameters at Morgan State University have culminated in the completion of a one-dimensional flow code that is integrated with a solid, virtual model of the existing premixed burner. This coupling will provide the unique opportunity to study the impact of geometry on the flowfield and vice-versa, with particular emphasis on concurrent design optimization.

Download or read book Multidimensional modelling and calculation of combustion in porous media written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Em comparação a sistemas de aquecimento domésticos que utilizam queimadores convencionais de chama não confinada, queimadores baseados na técnica de combustão em pré-mistura no interior de meios porosos caracterizam-se pela compacidade, pela elevada eficiência térmica e pela alta razão de operação, isto é, a razão entre a máxima e a mínimapotências entre as quais pode operar de modo estável. Além disso, queimadores porosos, nos quais a chama permanence ancorada no interior dos poros da camada de suporte da chama, apresentam reduzida formação de poluentes, em particular de CO e NOx, e possibilitam a queima de misturas mais pobres ou de combustíveis de mais baixo poder calorífico. A modelação numérica desempenha um importante papel no desenvolvimento de queimadores porosos, permitindo a verificação, a priori, de novas propostas ou da introduçãode modificações em configurações existentes. Nesta dissertação são apresentados e discutidos os modelos físico-matemáticos e numéricos desenvolvidos para o estudo de uma nova concepção de queimador poroso, o qual consiste de uma placa fina de espuma cerâmica (carbeto de silício) de alta porosidade precedida por uma placa de material isolante térmico (alumina) finamente perfurada, apresentando uma baixa porosidade equivalente. Devido às características construtivas do novo queimador, em particular a diferença de porosidade entre as camadas difusora e de suporte da chama, e também ao facto de acâmara de combustão estar sendo desenvolvida para operar acoplada a um sistema inovador de vaporização, à saída do qual a mistura ar-combustível pode não se encontrarperfeitamente homogeneizada, estudos foram conduzidos com o objectivo de investigar os fenómenos oriundos da imersão de uma placa de espuma cerâmica porosa em um escoamento. Inicialmente, a dispersão de um escalar no escoamento através de um meio poroso é considerada. Este estudo, no qual se faz uso de modelos uni e bidimensionais do escoamento em meio poroso, mostra que o modelo de Koch e Brady (1985), desenvolvido para a dispersão de um escalar em escoamentos de baixa velocidade através de leitos empacotados de esferas, reproduz os resultados da dispersão de um tracer no escoamento numa espuma cerâmica ao se considerar o efeito da espessura da placa porosa na direcção do escoamento e introduzir o diâmetro de poro como comprimento caraterístico. Com base nos resultadosdeste estudo, um modelo para a conductividade efectiva da placa perfurada como um meio poroso de baixa porosidade é obtido. Adicionalmente, a estabilidade de um escoamento isotérmico na interface de entrada de uma espuma cerâmica imersa num escoamento é investigada, apresentando-se a comparação de dois modelos para o escoamento turbulento no interior de meios porosos disponíveis na literatura. Considerando o escoamento através de uma placa de espuma cerâmica inserida num tubo recto e a jusante de uma expansão súbita, é mostrado que o modelo de Antohe e Lage (1997) prevê a relaminarização do escoamento logo após a entrada no meio poroso, enquanto o modelo de Pedras e de Lemos (2001) indica que a turbulência do escoamento pode ser destruída ou aumentada, em função da condição de turbulência doescoamento na secção de entrada da placa porosa. Ainda nesta análise do escoamento nas regiões de interface do escoamento num meio poroso, um estudo sobre a estabilidade de chama na região de interface entre as placas porosas é apresentado. Por meio de cálculos tridimensionais da câmara de combustão, é mostrada a importância da correcta especificação do diâmetro dos furos da placa perfurada para se evitar a ocorrência de flashback da chama para a região a montante da câmara de combustão. Um modelo tridimensional foi desenvolvido para estudar o desempenho do novo queimador poroso. Este modelo consiste na solução numérica das equações de Navier-Stokese dos balanços de energia e de massa das espécies químicas. O modelo considera a radiação térmica na espuma cerâmica e o não equilíbrio térmico local entre as duas fases. Mecanismosde reacção detalhados são aplicados para modelar a oxidação de metano e heptano, permitindo o cálculo da formação de poluentes. A validação do modelo foi efectuadacomparando-se previsões com resultdos experimentais do queimador operando com metano como combustível. O desempenho do queimador foi calculado utilizando heptano como combustível modelo. A influência das condições operacionais sobre a estabilização e a estrutura da chama, sobre o escoamento, e sobre a formação de poluentes é discutida. Dentre outros resultados, é observado que a frente de chama é estabilizada no interior da camada de espuma de carbeto de silício para toda a faixa de operação, e que a formação prevista de CO e NOx está compreendida nos limites observados na operação de equipamentos similares operados com outros combustíveis líquidos.

Download or read book Industrial Combustion Pollution and Control written by Jr., Charles E. Baukal and published by CRC Press. This book was released on 2003-10-15 with total page 920 pages. Available in PDF, EPUB and Kindle. Book excerpt: This reference overflows with an abundance of experimental techniques, simulation strategies, and practical applications useful in the control of pollutants generated by combustion processes in the metals, minerals, chemical, petrochemical, waste, incineration, paper, glass, and foods industries. The book assists engineers as they attempt to meet e

Download or read book Evaluations of Porous Burner Characteristic Diagrams and Process Water Production Possibilities written by Fatih Bacaksız and published by . This book was released on 2002 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, there has been a trend to new developments in gas and oil burners, which have been dominated by the aim of reducing pollutant emissions, reducing burner size and increasing the power modulation range. Several methods have been proposed in order to obtain more efficient combustion systems with low pollutant emissions. Over the past few years, a great deal of investigation on combustion in porous medium has been performed. In its efforts to optimize combustion processes, the Institute of Fluid Dynamics in Friedrich-Alexander University, Erlangen (LSTM-Nürnberg/Germany) has succeeded in developing the technology of combustion in porous media and this burner was used in this study. This thesis was focused on the evaluation of the porous burner characteristic diagrams and determined the possibility of the process water production. The experimental works were consisted of two main parts. One of them was carried out at the Institute of Fluid Dynamics in Erlangen. The second was performed at Izmir Institute of Technology. The aim of the experimental work for 25 kW porous burner was to analyse temperature distribution of exhaust gases close to the outer surface of ceramic matrix as well as pollutant emissions as a function of the burner surface. The aim of the second part was to investigate pollutant emissions as a function of the burner power and excess air ratio numbers, analyse the exhaust gases and cooling water temperature distribution with respect to burner power. Liquefied Petroleum Gas (%70 Butane + %30 Propane) was used as a fuel, which is utility gas in Turkey. It was concluded that the 25 kW burner allow very stable combustion with turn down ratio of around 6:1, and 4:1 for 10 kW burner, and excess air ratio numbers in the range 1.40 - 2.0. The exhaust gas temperature could easily reach 1100ʻC with a more and less uniform distribution over the 25 kW burner.s exit surface area. It was noticeable that the emission values lie lower than the values given by both German Norm 4702 and International Energy Agency, for 25 kW porous burner. CO an NOX emission values for 10 kW porous burner were quite lower than the emission limits for large new combustion facilities in Turkey. The burner showed that considerable amount of heat was transferred from exhaust gas to cooling water. Finally, porous burner can be used for process water production in various fields of energy engineering.

Download or read book Experimental Study on Standing Wave Regimes of Premixed H2 air Combustion in Planar Micro combustors Partially Filled with Porous Medium written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Journal of Thermophysics and Heat Transfer written by and published by . This book was released on 1998 with total page 1234 pages. Available in PDF, EPUB and Kindle. Book excerpt: This journal is devoted to the advancement of the science and technology of thermophysics and heat transfer through the dissemination of original research papers disclosing new technical knowledge and exploratory developments and applications based on new knowledge. It publishes papers that deal with the properties and mechanisms involved in thermal energy transfer and storage in gases, liquids, and solids or combinations thereof. These studies include conductive, convective, and radiative modes alone or in combination and the effects of the environment.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental and Analytical Study of a Porous Media Burner with Passive Air Entrainment written by Sudhamshu Addamane Ramachandra and published by . This book was released on 2015 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: A porous media burner is demonstrated that utilizes passive entrainment of air, heat of combustion and upstream mixing to form a combustible, preheated and premixed fuel/air mixture at the burner outlet, and therefore requires no auxiliary resources beyond a source of compressed fuel gas for operation. Potential applications for a burner with these features include an improved design for flaring gas that is produced during oil and gas production, and a heat source for cooking in rural areas. The porous media burner design presented in this study incorporates an eductor, swirl mixing chamber, and porous media bed in order to achieve premixed fuel before combustion. A range of fuel flow rates to the burner was tested in this study, and the effect on air entrainment, and therefore equivalence ratio, was examined. A wide range of stable operating conditions shows a large turndown ratio of the burner. The surface-stabilized flame exhibited flame speeds above the adiabatic flame speed, producing flame speed ratios greater than unity and indicating effective heat recirculation by the porous media. Species measurements of methane, carbon monoxide and carbon dioxide are presented and show product compositions near equilibrium and a high extent of fuel conversion efficiency. An analytical model of the burner that accounts for burner geometry and operating conditions to predict equivalence ratio is presented and compared with the experimental results. The analytical model compares favorably with the experimental results and can guide future burner development.

Download or read book Proceedings of the 30th Intersociety Energy Conversion Engineering Conference written by and published by . This book was released on 1995 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Experimental and Theoretical Investigations of Lean Partially Premixed Combustion Burning Speed Flame Instability and Plasma Formation of Alternative Fuels at High Temperatures and Pressures written by Omid Askari and published by . This book was released on 2016 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation investigates the combustion and injection fundamental characteristics of different alternative fuels both experimentally and theoretically. The subjects such as lean partially premixed combustion of methane/hydrogen/air/diluent, methane high pressure direct-injection, thermal plasma formation, thermodynamic properties of hydrocarbon/air mixtures at high temperatures, laminar flames and flame morphology of synthetic gas (syngas) and Gas-to-Liquid (GTL) fuels were extensively studied in this work. These subjects will be summarized in three following paragraphs. The fundamentals of spray and partially premixed combustion characteristics of directly injected methane in a constant volume combustion chamber have been experimentally studied. The injected fuel jet generates turbulence in the vessel and forms a turbulent heterogeneous fuel-air mixture in the vessel, similar to that in a Compressed Natural Gas (CNG) Direct-Injection (DI) engines. The effect of different characteristics parameters such as spark delay time, stratification ratio, turbulence intensity, fuel injection pressure, chamber pressure, chamber temperature, Exhaust Gas recirculation (EGR) addition, hydrogen addition and equivalence ratio on flame propagation and emission concentrations were analyzed. As a part of this work and for the purpose of control and calibration of high pressure injector, spray development and characteristics including spray tip penetration, spray cone angle and overall equivalence ratio were evaluated under a wide range of fuel injection pressures of 30 to 90 atm and different chamber pressures of 1 to 5 atm. Thermodynamic properties of hydrocarbon/air plasma mixtures at ultra-high temperatures must be precisely calculated due to important influence on the flame kernel formation and propagation in combusting flows and spark discharge applications. A new algorithm based on the statistical thermodynamics was developed to calculate the ultra-high temperature plasma composition and thermodynamic properties. The method was applied to compute the thermodynamic properties of hydrogen/air and methane/air plasma mixtures for a wide range of temperatures (1,000-100,000 K), pressures (10−6-100 atm) and different equivalence ratios within flammability limit. In calculating the individual thermodynamic properties of the atomic species, the Debye-Huckel cutoff criterion has been used for terminating the series expression of the electronic partition function. A new differential-based multi-shell model was developed in conjunction with Schlieren photography to measure laminar burning speed and to study the flame instabilities for different alternative fuels such as syngas and GTL. Flame instabilities such as cracking and wrinkling were observed during flame propagation and discussed in terms of the hydrodynamic and thermo-diffusive effects. Laminar burning speeds were measured using pressure rise data during flame propagation and power law correlations were developed over a wide range of temperatures, pressures and equivalence ratios. As a part of this work, the effect of EGR addition and substitution of nitrogen with helium in air on flame morphology and laminar burning speed were extensively investigated. The effect of cell formation on flame surface area of syngas fuel in terms of a newly defined parameter called cellularity factor was also evaluated. In addition to that the experimental onset of auto-ignition and theoretical ignition delay times of premixed GTL/air mixture were determined at high pressures and low temperatures over a wide range of equivalence ratios.