Influence of dust particles on the characteristics of premixed methane-air flames has been studied in this dissertation. Experiments are performed in a Bunsen burner type experimental set-up called Hybrid Flame Analyzer (HFA), which can be used to measure the burning velocity of gas, dust, and hybrid (gas and dust) premixed flames at constant pressure operating conditions. In the current study, analysis of particle-gas-air system of different types of dust particles (at particle size, dp = 75-90 µm) in premixed methane-air (ϕg = 0.8, 1.0 and 1.2) flames. Coal, sand, and sodium bicarbonate particles are fed along with a premixed methane-air mixture at different concentrations (λp = 0-75 g/m3) in both laminar and turbulent conditions. First, the variation of laminar burning velocity with respect to the concentration of dust particles, and type of dusts are investigated for different equivalence ratios. Second, the laminar premixed flame extinction with inert and chemical suppressant particles are studied. Third, the variation of turbulent burning velocity of these hybrid mixtures are investigated against different turbulent intensities apart from the different concentrations and types of dusts. Fourth, the radiative fraction of heat released from turbulent gas-dust premixed flames are also presented against the operating parameters considered. Combustible dust deflagration hazard is normally quantified using the deflagration index (Kst) measured using a constant volume explosion sphere, which typically is a sealed 20-liter metal sphere where a premixed mixture is ignited at the center and the progression of the resulting deflagration wave is recorded using the pressure measured at the vessel wall. It has been verified from prior studies that the quantification of the turbulence by this method is questionable and there is a need to analyze the controlling parameters of particle-gas-air premixed system accurately through a near constant pressure operated experimental platform. Thus, the main objective of this study is to analyze the influence of dust particles on premixed methane-air flames at near constant pressure conditions. The turbulent burning velocity is calculated by averaging the measured flame heights and the laminar burning velocity is calculated through the premixed cone angle measurements from several high-speed shadowgraph images obtained from the experiments. The turbulent intensity and length scale of turbulence generated by a perforated plate in the burner is quantified from the hot-wire anemometer measurements. Radiative heat flux is also measured for each of the turbulent test conditions. The outcomes from these experiments are: 1. An understanding of the variation of turbulent burning velocity of gas-dust premixed flames as a function of dust type, turbulent intensity, integral length scale, dust concentration and gas phase mixture ratio. 2. An understanding of the flame extinction characteristics and variation of laminar burning velocity of gas-dust premixed flames as a function of dust concentration and gas phase mixture ratio. 3. Quantify the radiative heat flux and radiative fraction of heat released from gas-dust turbulent premixed flames as a function of dust type, turbulent intensity, dust concentration and gas phase mixture ratio. Dust type and concentration play an important role in deciding the trend in the variation of both laminar (SL) and turbulent burning velocity (ST). Coal particles, with the release of volatile (methane), tend to increase burning velocities except for fuel rich conditions and at higher coal concentrations at larger turbulent intensities. At a higher turbulent intensity and larger concentrations, higher ST values are observed with the addition of sand. Sodium bicarbonate addition, with the release of CO2 and H2O, decreased the burning velocity at all the concentrations, turbulent intensities and equivalence ratios. Laminar flame extinction was observed with the addition of sand and sodium bicarbonate particles at conditions exceeding certain critical dust concentrations. These critical concentrations varied with the equivalence ratios of gaseous premixed flames. The turbulence modulation exhibited by particles and particle concentration is evident in these observations. The independent characteristic time scale analysis performed using the experimental data provided further insights to the results. The chemical and convective times in gas phase confirm the broadened preheat thin reaction zone regime in the current test cases, which has an effect of attenuating turbulence and thereby the resulting turbulent burning velocity. The particle time scale analysis (Stokes number) show that the effect of particles and particle concentration is to slightly enhance the turbulence and increase the turbulent burning velocity at lower concentrations. However, the time scale analysis of particle vaporization (vaporization Damköhler number) indicate an increase in the vaporization rate for particles (coal and sodium bicarbonate) resulting in a decrease in their turbulent burning velocities at higher concentrations and turbulent intensities. Sodium bicarbonate has higher evaporation rate than coal at same level of turbulence and the absence of this effect for inert (sand) results in higher turbulent burning velocities at higher concentrations. An increase in the turbulent intensity increases the vaporization rate of particles. The investigation on radiative fraction of heat released by methane-air-dust turbulent premixed flames identified that, the addition of dust particles increases the radiative fraction irrespective of the dust type due to the radial and axial extension of flame. A unified approach to couple this multiple complex phenomenon of turbulence, particle interaction, particle vaporization and combustion in particle laden premixed gaseous flames is the direction for future research.

Turbulent premixed propane/air and methane/air flames were studied using planar Rayleigh scattering and particle image velocimetry on a stabilized Bunsen type burner. The fuel-air equivalence ratio was varied from Φ=0.7 to 1.0 for propane flames, and from Φ=0.6 to 1.0 for methane flames. The non-dimensional turbulence intensity, u'/SL (ratio of fluctuation velocity to laminar burning velocity), covered the range from 3 to 24, equivalent to conditions of corrugated flamelets and thin reaction zones regimes. Temperature gradients decreased with the increasing u'/SL and levelled off beyond u'/SL > 10 for both propane and methane flames. Flame front thickness increased slightly as u'/SL increased for both mixtures, although the thickness increase was more noticeable for propane flames, which meant the thermal flame front structure was being thickened. A zone of higher temperature was observed on the average temperature profile in the preheat zone of the flame front as well as some instantaneous temperature profiles at the highest u'/SL. Curvature probability density functions were similar to the Gaussian distribution at all u'/SL for both mixtures and for all the flame sections. The mean curvature values decreased as a function of u'/SL and approached zero. Flame front thickness was smaller when evaluated at flame front locations with zero curvature than that with curvature. Temperature gradients and FSD were larger when the flame curvature was zero. The combined thickness and FSD data suggest that the curvature effect is more dominant than that of the stretch by turbulent eddies during flame propagation. Integrated flame surface density for both propane and methane flames exhibited no dependance on u'/SL regardless of the FSD method used for evaluation. This observation implies that flame surface area may not be the dominant factor in increasing the turbulent burning velocity and the flamelet assumption may not be valid under the conditions studied. Dκ term, the product of diffusivity evaluated at conditions studied and the flame front curvature, was a magnitude smaller than or the same magnitude as the laminar burning velocity.

Depuis plusieurs années, la diminution des réserves de pétrole incite les différents pays à accroitre leur indépendance énergétique. De plus, diminuer l’impact environnemental de la voiture est devenu l’une des priorités de notre société. En ce sens, les normes Européennes anti-pollution sont devenues plus strictes, tandis que certains polluants sont pointés du doigt pour avoir un impact néfaste sur la santé et l’environnement. Pour répondre à cette double problématique, l’utilisation de biocarburants de type alcools dans les moteurs à allumage commandé est l’une des voies envisagées. Ce virage a déjà été entrepris à petite échelle par l’Union Européenne qui a tout d’abord autorisé l’ajout de 5%, puis de 10% d’éthanol dans l’essence. En plus de l’éthanol déjà commercialisé, le Biobutanol, biocarburant de seconde génération, apparait comme un candidat à fort potentiel pour une utilisation dans les moteurs à allumage commandé. L’objectif de ce travail de thèse est d’étudier le potentiel de l’utilisation de mélanges isooctane/butanol dans les moteurs à allumage commandé, en termes de performances et d’émissions polluantes. De plus, ces résultats sont comparés à ceux de mélanges isooctane/éthanol. Le dégagement de chaleur dans un moteur à allumage commandé est en partie piloté par la vitesse de combustion laminaire. Cette caractéristique a été étudiée de manière expérimentale et numérique pour différentes conditions initiales (pression et richesse) dans une enceinte à volume constant. Puis, une étude sur les premières étapes de la propagation de la combustion a été réalisée dans un moteur monocylindre à accès optique. Ces résultats en moteur ont été corrélés avec les informations laminaires. Enfin, les émissions de polluants réglementés et non-réglementés, ainsi que les performances ont été étudiées dans un moteur monocylindre à allumage commandé. Une baisse de la plupart de ces émissions a été observée avec l’ajout des deux alcools. / For the past few years, the oil stock decrease encourages the different countries to increase their energy independence. Moreover, reducing the environmental impact of transportation became one of the priorities of our society. In this way, European emissions standards are stricter while several pollutants have been identified to have a negative impact on health and the environment. To answer this double problem, the use of alcohols biofuels in spark-ignition engines is one the promising ways. The European Union have already taken a small step in that direction by allowing a maximum of 10% of ethanol into gasoline. As well as ethanol is already marketed, Biobutanol, a 2nd generation biofuel, appears as a serious candidate with a strong potential for a spark-ignition engines use. The objective of this dissertation is to study the potential of the iso-octane/butanol blends use in spark-ignition engines, in terms of performance and pollutants emissions. Moreover, these results are compared to isooctane/ethanol blends. The heat release in spark-ignition engine is piloted for a part by laminar burning velocity. This characteristic was studied experimentally and numerically for different initial conditions (pressure and equivalence ratio) in a constant volume bomb. Then, the early flame kernel growth was studied in a spark-ignition single cylinder engine equipped with optical accesses. Those results were correlated with the results on the laminar burning velocity. Finally, regulated and non-regulated pollutants emissions and engine performance were investigated in a spark-ignition single cylinder engine. A decrease of most pollutant emissions was observed with both alcohols addition.

A velocidade de queima laminar adiabática é um importante parâmetro da combustão que dita o comportamento de chamas pré-misturadas. Dos métodos disponíveis para a medição desse parâmetro, o método do fluxo de calor destaca-se pela simplicidade e precisão. No presente trabalho, esse método é utilizado para medir a velocidade de queima de biogás (modelado como CH4 com diferentes níveis de diluição com CO2) e de gás de síntese (modelado como uma mistura de CH4, H2, CO, CO2 e N2) em ar a 298 K e 1 atm. Tais gases são de crescente interesse para a sociedade em função de aspectos ambientais, porém, suas velocidades de queima não foram amplamente estudadas ainda. Os resultados obtidos são comparados com as previsões de cinco mecanismos cinéticos (GRI-Mech 3.0, Davis et al., Konnov, San Diego e USC Mech II) a fim de avaliar a sua capacidade preditiva. Os resultados experimentais e numéricos das velocidades de queima de biogás e ar apresentam uma boa concordância e as incertezas encontradas foram condizentes com as relatadas na literatura. Os resultados experimentais desse gás foram parametrizados em uma correlação empírica de fácil utilização em modelos numéricos. As medições da velocidade de queima de gás de síntese e ar, por outro lado, apresentaram valores inferiores às previsões numéricas de todos os mecanismos estudados. Os dados experimentais da literatura, para a mesma mistura, diferem tanto em valores quanto em comportamento dos resultados do presente trabalho. Tal comportamento está provavelmente relacionado a alguma contaminação no CO utilizado, já que quando esse gás está presente observa-se uma chemi-luminescência não relatada na literatura. / The adiabatic laminar burning velocity is an important combustion parameter that dictates premixed flames characteristics. Among the measuring methods available in literature, the heat flux method stands out for its simplicity and accuracy. In the present work, this method is used to measure the adiabatic laminar burning velocity of biogas (modeled as CH4 with different dilution levels with CO2) and syngas (modeled as a CH4, H2, CO, CO2 and N2 mixture) in air at 298 K and 1 atm. Such gases are of growing society interest due to environmental aspects, however, their adiabatic laminar burning velocity have not been widely studied yet. The experimental results are compared to predictions of five kinetic mechanisms (GRI-Mech 3.0, Davis et al., Konnov, San Diego e USC Mech II) to evaluate their predictive capacity. Experimental and numerical results of biogas/air mixtures adiabatic laminar burning velocity show good agreement and the found uncertainties are in agreement with literature. Experimental results of this gas were fitted in an empiric correlation of simple numerical application. Experimental results of the laminar burning velocity of syngas/air, on the other hand, show lower values than the numerical predictions of all studied kinetic mechanisms. Literature available data for the same mixture differ both in values and behavior of the present work results. Such behavior is probably related to some contamination on the CO used since a chemi-luminescence not reported in literature can be noted when this gas is present.

A velocidade de queima laminar adiabática é um importante parâmetro da combustão que dita o comportamento de chamas pré-misturadas. Dos métodos disponíveis para a medição desse parâmetro, o método do fluxo de calor destaca-se pela simplicidade e precisão. No presente trabalho, esse método é utilizado para medir a velocidade de queima de biogás (modelado como CH4 com diferentes níveis de diluição com CO2) e de gás de síntese (modelado como uma mistura de CH4, H2, CO, CO2 e N2) em ar a 298 K e 1 atm. Tais gases são de crescente interesse para a sociedade em função de aspectos ambientais, porém, suas velocidades de queima não foram amplamente estudadas ainda. Os resultados obtidos são comparados com as previsões de cinco mecanismos cinéticos (GRI-Mech 3.0, Davis et al., Konnov, San Diego e USC Mech II) a fim de avaliar a sua capacidade preditiva. Os resultados experimentais e numéricos das velocidades de queima de biogás e ar apresentam uma boa concordância e as incertezas encontradas foram condizentes com as relatadas na literatura. Os resultados experimentais desse gás foram parametrizados em uma correlação empírica de fácil utilização em modelos numéricos. As medições da velocidade de queima de gás de síntese e ar, por outro lado, apresentaram valores inferiores às previsões numéricas de todos os mecanismos estudados. Os dados experimentais da literatura, para a mesma mistura, diferem tanto em valores quanto em comportamento dos resultados do presente trabalho. Tal comportamento está provavelmente relacionado a alguma contaminação no CO utilizado, já que quando esse gás está presente observa-se uma chemi-luminescência não relatada na literatura. / The adiabatic laminar burning velocity is an important combustion parameter that dictates premixed flames characteristics. Among the measuring methods available in literature, the heat flux method stands out for its simplicity and accuracy. In the present work, this method is used to measure the adiabatic laminar burning velocity of biogas (modeled as CH4 with different dilution levels with CO2) and syngas (modeled as a CH4, H2, CO, CO2 and N2 mixture) in air at 298 K and 1 atm. Such gases are of growing society interest due to environmental aspects, however, their adiabatic laminar burning velocity have not been widely studied yet. The experimental results are compared to predictions of five kinetic mechanisms (GRI-Mech 3.0, Davis et al., Konnov, San Diego e USC Mech II) to evaluate their predictive capacity. Experimental and numerical results of biogas/air mixtures adiabatic laminar burning velocity show good agreement and the found uncertainties are in agreement with literature. Experimental results of this gas were fitted in an empiric correlation of simple numerical application. Experimental results of the laminar burning velocity of syngas/air, on the other hand, show lower values than the numerical predictions of all studied kinetic mechanisms. Literature available data for the same mixture differ both in values and behavior of the present work results. Such behavior is probably related to some contamination on the CO used since a chemi-luminescence not reported in literature can be noted when this gas is present.

A velocidade de queima laminar adiabática é um importante parâmetro da combustão que dita o comportamento de chamas pré-misturadas. Dos métodos disponíveis para a medição desse parâmetro, o método do fluxo de calor destaca-se pela simplicidade e precisão. No presente trabalho, esse método é utilizado para medir a velocidade de queima de biogás (modelado como CH4 com diferentes níveis de diluição com CO2) e de gás de síntese (modelado como uma mistura de CH4, H2, CO, CO2 e N2) em ar a 298 K e 1 atm. Tais gases são de crescente interesse para a sociedade em função de aspectos ambientais, porém, suas velocidades de queima não foram amplamente estudadas ainda. Os resultados obtidos são comparados com as previsões de cinco mecanismos cinéticos (GRI-Mech 3.0, Davis et al., Konnov, San Diego e USC Mech II) a fim de avaliar a sua capacidade preditiva. Os resultados experimentais e numéricos das velocidades de queima de biogás e ar apresentam uma boa concordância e as incertezas encontradas foram condizentes com as relatadas na literatura. Os resultados experimentais desse gás foram parametrizados em uma correlação empírica de fácil utilização em modelos numéricos. As medições da velocidade de queima de gás de síntese e ar, por outro lado, apresentaram valores inferiores às previsões numéricas de todos os mecanismos estudados. Os dados experimentais da literatura, para a mesma mistura, diferem tanto em valores quanto em comportamento dos resultados do presente trabalho. Tal comportamento está provavelmente relacionado a alguma contaminação no CO utilizado, já que quando esse gás está presente observa-se uma chemi-luminescência não relatada na literatura. / The adiabatic laminar burning velocity is an important combustion parameter that dictates premixed flames characteristics. Among the measuring methods available in literature, the heat flux method stands out for its simplicity and accuracy. In the present work, this method is used to measure the adiabatic laminar burning velocity of biogas (modeled as CH4 with different dilution levels with CO2) and syngas (modeled as a CH4, H2, CO, CO2 and N2 mixture) in air at 298 K and 1 atm. Such gases are of growing society interest due to environmental aspects, however, their adiabatic laminar burning velocity have not been widely studied yet. The experimental results are compared to predictions of five kinetic mechanisms (GRI-Mech 3.0, Davis et al., Konnov, San Diego e USC Mech II) to evaluate their predictive capacity. Experimental and numerical results of biogas/air mixtures adiabatic laminar burning velocity show good agreement and the found uncertainties are in agreement with literature. Experimental results of this gas were fitted in an empiric correlation of simple numerical application. Experimental results of the laminar burning velocity of syngas/air, on the other hand, show lower values than the numerical predictions of all studied kinetic mechanisms. Literature available data for the same mixture differ both in values and behavior of the present work results. Such behavior is probably related to some contamination on the CO used since a chemi-luminescence not reported in literature can be noted when this gas is present.

Les enjeux environnementaux et sociétaux de la combustion de combustibles fossiles pour la production d'énergie (électrique, chauffage ou transport), nécessitent le développement de nouveaux modes de combustion, de nouvelles technologies de brûleurs et de combustibles alternatifs (gazéification de la biomasse, biofuels, ...). La vitesse de combustion laminaire est un des paramètres fondamentaux utilisé pour caractériser la combustion pré-mélangée de ces nouveaux mélanges combustibles. Cette vitesse est une donnée de référence pour le processus de validation et d'amélioration des schémas cinétiques ainsi qu'un paramètre d'entrée pour estimer la vitesse de combustion turbulente de la plupart des codes de combustion turbulente. Mais bien qu'étudiée depuis plus de 100 ans, la détermination expérimentale précise de cette vitesse reste encore un défi de par les limitations inhérentes aux configurations expérimentales utilisées, en particulier pour les conditions de pression et de température élevées. Dans ce contexte, les objectifs de ces travaux de thèse concernent l'étude, l'analyse et la caractérisation des techniques de détermination de la vitesse de combustion laminaire à partir des flammes en expansion sphérique, en proposant une réflexion sur la minimisation de l'ensemble des sources d'incertitudes possibles sur la détermination de cette vitesse. Cette approche est réalisée pour la configuration de flamme en expansion sphérique, permettant des températures et pressions élevées et maitrisées.Dans une première partie, le formalisme des définitions des vitesses de flamme laminaire existantes dans cette configuration est rappelé afin de définir les facteurs d'incertitudes liés à la mesure expérimentale de ces vitesses (grandeurs cinématiques locales et cinétique globale). En particulier, les effets liés à l'estimation de l'état thermodynamique des gaz brûlés, du rayonnement et de la diffusion différentielle sont discutés. Dans une seconde partie, plusieurs dispositifs numériques et expérimentaux utilisés au cours de cette thèse et permettant l'étude de flammes sphériques en expansion sont présentés. Une étude utilisant quatre dispositifs expérimentaux différents est proposée afin d'analyser et caractériser les incertitudes inhérentes aux mesures et à leur traitement. Enfin dans une troisième partie, une définition rigoureuse de la vitesse de consommation est proposée et une nouvelle méthodologie pour la mesurer est développée. Une validation numérique complète est présentée. Puis les incertitudes liées aux rayonnement, à la diffusion différentielle et à l’extrapolation des données mesurées sont étudiées en détails. Cette dernière étape introduit un biais qui peut être conséquent, et une nouvelle méthodologie pour exploiter des mesures brutes est proposée par une comparaison directe avecdes simulations DNS reproduisant les expériences. / Environmental and social challenges concerning the combustion of fossil fuels for energy production (electricity, building and transport) require the development of new combustion processes, new burner technologies and alternative fuels (gasification of biomass, biofuels, ...). Laminar burning velocity is one of the fundamental parameters used to characterize premixed combustion for these new fuels. This speed is a reference for the validation and improvement of kinetic schemes and an input parameter to estimate the turbulent burning velocity of most turbulent combustion codes. But even if it has been studied over 100 years, the precise experimental measurement of this velocity is still complicated due to inherent limitations in experimental configurations used, especially for high pressure and temperature conditions. In this context, this thesis work focuses on the study, analysis and characterization of the different techniques used to determine the laminar burning velocity from spherically expanding flames and proposes a reflection on the minimization of all possible uncertainty sources. This approach is achieved with confined spherical flames which allow to obtain high temperature and pressure initial conditions. In the first part, the formalism of existing laminar flame speeds in spherical expanding configuration is reminded to define the factors of uncertainty related to the experimental measurement (local kinematic and global kinetic variables). In particular, the effects associated with the estimation of the burned gases thermodynamic state, radiation and differential diffusion are discussed. In the second part, several numerical and experimental devices used in this thesis are presented. A study on four different experimental setups is proposed to analyze and characterize the uncertainties in the measurements and processing. Finally, in the third part, a rigorous definition of the consumption speed is proposed and a new methodology to measure it is developed. A complete validation based on numerical results is presented. Then uncertainties related to radiation, differential diffusion and extrapolation to zero stretch rate of measured data are detailed. This last step introduces a non-negligible bias and a new methodology to exploit raw data by a direct comparison with DNS reproducing the experiments is proposed.

Laminar burning velocity is very useful for both combustion modeling and kinetic scheme validationand improvement. Accurate experimental data are needed. To achieve this, the spherical flame method was chosen. However various expression for burning velocity from the spherically expanding flame can be found. A theorical review details all the expressions and models for the burning veolcity and shows how they can be obtained experimentally. These models were comparated considering basic fuels - various Lewis numbers. As a result, it is shown that the pure kinematic measurement method is the only one thet does not introduce any assumptions. This kinematic measurement had needed the development and validation of an original post-processing tool. Following the theorical review, a parametric experimental study is presented. The new technique is extended to extract burning velocity and Markstein length relative to the fresh gas for pure ethanol, isooctane and blended fuels at high pressure.

La présence de fines particules de matières oxydables est rencontrée dans de nombreuses situations industrielles. Le risque d'explosion de poussières présente une menace constante pour les industries de transformation qui fabriquent, utilisent ou manipulent des poudres ou despoussières de matières combustibles. Dans le secteur nucléaire, les scénarios envisagés traitent,en particulier, le risque d'explosion de poussières de graphite liées aux opérations dedémantèlement des réacteurs Uranium Naturel Graphite Gaz. La problématique considérée, dans le cadre de ce travail de thèse, est celle de la combustion d'un mélange dilué gaz-particules.L'objectif de cette thèse est de développer un modèle Euler-Lagrange macroscopique permettantde prédire la vitesse laminaire de flamme qui est une des données essentielles pour les modèlesde vitesse de flamme turbulente utilisés dans l'évaluation des risques d'explosion de poussières.Dans un premier temps, les équations macroscopiques de transferts massique et thermique sont dérivées à partir de la méthode de prise de moyenne volumique. L'intérêt de l'approche utilisée ici est de proposer des problèmes de fermeture permettant d'estimer les coefficients de transfertseffectifs, tels que les coefficients d'échanges thermiques et le coefficient effectif de la réactionhétérogène. Dans un deuxième temps, des simulations Euler-Lagrange sont utilisées pourdéterminer la vitesse de flamme laminaire diphasique plane en fonction des caractéristiques du mélange gazeux et des poussières de graphite. Le modèle proposé dans ce travail est comparé au modèle Euler-Lagrange classique basé sur la résolution du problème de couche limite pourune particule isolée en milieu infini. Cette étude montre que les effets du taux de dilution et deséchanges indirects entre les particules ne sont pas systématiquement négligeables dans leséchanges macroscopiques entre les deux phases. D'autre part, la présente étude laisse entrevoir la potentialité de l'approche proposée pour les simulations détaillées de l'écoulement diphasique / The presence of fine particles of oxidizable materials is encountered in many industrial situations.The risk of dust explosion presents a constant threat in transformation industries that manufacture,use or manipulate powders or combustible materials dusts. In nuclear safety analysis, one of themain scenarios is the risk of graphite dust explosion that may occur during decommissioningoperations of Uranium Natural Graphite Gas reactors. The issue considered in this thesis isrelated to combustion of a dilute gas-particle mixture. This work aims at developing a macroscopicEuler-Lagrange model for predicting laminar flame velocity, which is one of the essential data forturbulent flame velocity models used to evaluate the risk of dust explosion. First, the macroscopicheat and mass transfer equations are derived using the volume averaging method. The majorinterest of the proposed approach is to provide closure problems that allow to estimate theeffective transport coefficients, such as heat exchange coefficients and the effective coefficient ofthe heterogeneous reaction. Second, Euler-Lagrange simulations are used to determine the planetwo-phase laminar flame velocity as a function of gas mixture and graphite dust characteristics.The proposed model is compared to the classical Euler-Lagrange model based on the resolutionof the boundary layer problem in the vicinity of an isolated particle in infinite medium. Results showthat the dilution rate and the indirect particle-particle exchanges are not systematically negligible inthe macroscopic exchanges between the two-phases. On the other hand, this study suggests thepotentiality of the proposed approach for detailed simulations of two-phase flow

In einer zukünftig nachhaltigen Gesellschaft wird Wasserstoff eine bedeutende Rolle als Energieträger spielen. Der Übergangspfad von reinem Erdgas zur Verwendung von Gemischen bis 50 % Wasserstoff muss eingehender untersucht werden. Die in dieser Arbeit durchgeführte Forschung konzentriert sich auf die Sicherheitsaspekte, Schadstoffentwicklung und Stabilitätsfelder von laminaren Flammen. Ein entscheidender Parameter für die Sicherheit von Brenneranlagen ist die laminare Brenngeschwindigkeit. In dieser Arbeit wurden Methan-Wasserstoff-Gemische experimentell vermessen und mit numerischen Daten unter Verwendung verschiedener Reaktionsmechanismen verglichen. Zur hochgenauen Messung der laminaren Brenngeschwindigkeit wurde der Heat Flux Brenner verwendet. In der vorliegenden Untersuchung wurden die laminaren adiabaten Brenngeschwindigkeiten für Methan-Wasserstoff-Sauerstoff-Stickstoff-Gemische bei verschiedenen Äquivalenzverhältnissen und variierten Sauerstoffanteilen untersucht. Die experimentellen Daten bis 20 % Wasserstoff bei reduziertem Sauerstoffgehalt konnten durch zehn ausgewählte detaillierte Reaktionsmechanismen nur teilweise wiedergegeben werden. Weiterführende Messungen befassen sich mit Methan-Wasserstoff-Luft Gemischen bei verschiedenen Äquivalenzverhältnissen, Temperaturen und Wasserstoffgehalten bis zu 50 %. Für diese Parameter wurde anschließend in Abhängigkeit der Höhe über dem Brenner eine Abgasanalyse mit dem Ziel der lokalen Stickstoffoxidkonzentration durchgeführt. Dabei zeigte sich im laminaren adiabaten Zustand eine Verringerung der Stickstoffoxide, insbesondere im brennstoffreichen Bereich. Eine Überlagerung von erhöhter Brenngeschwindigkeit und einhergehender kürzerer Verweilzeit wurde in Wasserstoff-Methan-Flammen im Vergleich zu reinen Methan-Flammen als Ursache ermittelt und numerisch nachvollzogen. Die experimentellen Daten konnten durch ausgewählte Reaktionsmechanismen nur teilweise wiedergegeben werden. Final wurden für vergleichbare Bedingungen an einem Gegenstrombrenner auch nicht vorgemischte Flammen bis zu einem Wasserstoffanteil von 50 % detaillierter untersucht. Dabei lag das Hauptaugenmerk der Ermittlung der Verlöschungsstreckungsgrenzen. Es konnte gezeigt werden, dass sich diese im Fall der Wasserstoffbeimischung deutlich iivergrößern, was auch von den numerischen Modellen vorhergesagt wurde. Im Fall einer Sauerstoffreduktion kommt es hingegen zu einer deutlichen Verkleinerung des stabilen Flammenbereiches. Es konnte gezeigt werden, dass sich dieser Zusammenhang nichtlinear zwischen der Sauerstoff- und Brennstoffkonzentration verhält. Abschließend konnte ein umfassender Datensatz zu laminaren Brenngeschwindigkeiten, Erlöschungsstreckungsraten und Schadstoffen für Methan-Wasserstoff-Flammen bis zu einem Anteil von 50 % Wasserstoff erstellt werden. Dieser dient der Verbesserung bestehender Reaktionsmechanismen und liefert grundlegende Erkenntnisse zur Auslegung von Brennern.:1 Einleitung, Motivation und Aufgabenstellung der Arbeit 2 Stand der Wissenschaft und Technik 3 Versuchsaufbau, verwendete Messmethoden und experimentelle Versuchsdurchführung 4 Numerische Methoden 5 Experimentelle und numerische Ergebnisse zur laminaren Brenngeschwindigkeit 6 Experimentelle und numerische Ergebnisse zur Erlöschungsstreckungsrate 7 Einfluss der Wasserstoffbeimischung in Methan-Flammen auf die Schadstoffbildung 8 Zusammenfassung und Ausblick 9 Literatur 10 Anhang / In a future sustainable society, hydrogen is expected to play an important role as an energy carrier. The transition path from pure natural gas to the use of mixtures, up to 50 % hydrogen, has to be investigated in more detail. The research that has been conducted focuses on the safety, pollutant emission and the stability areas of laminar flames. A significant parameter for the safety of burner systems is the laminar burning velocity. In this work, methane-hydrogen mixtures were measured experimentally and compared with numerical approaches using different reaction mechanisms. The Heat Flux Burner was used to measure the laminar burning velocity with high accuracy. In the present study, the laminar adiabatic burning velocities for methane-hydrogen-oxygen-nitrogen mixtures at different equivalence ratios and varied oxygen contents was investigated. The experimental data up to 20 % hydrogen at reduced oxygen content could only be partially reproduced by ten selected detailed reaction mechanisms. Further measurements are concerned with methane-hydrogen-air mixtures at different equivalence ratios, temperatures and hydrogen contents up to 50 %. For these parameters, an exhaust gas analysis was carried out as a function of the height above the burner with the aim of nitrogen oxide detections. A reduction in nitrogen oxides in the laminar adiabatic state was observed, especially in the fuel-rich range. A superposition of increased burning velocity and accompanying shorter residence time in the hydrogen-methane mixtures compared to pure methane flames was determined as the cause which could also be shown numerically. The experimental results could only be partially reproduced by selected reaction mechanisms. Furthermore, for comparable conditions, non-premixed flames up to a hydrogen content of 50 % were investigated in more detail. The main focus was the determination of the extinction strain rate limits. It could be shown that these increase significantly in the case of hydrogen admixture, which could also be predicted by the numerical models. In the case of oxygen reduction, on contrary, there is a significant reduction of the stable flame area. It could be demonstrated that this relationship is non-linear between the oxygen and fuel concentration. Finally, a comprehensive data set on laminar burning rates, extinction stretching rates and pollutants for methane-hydrogen flames up to a proportion of 50 % hydrogen could be generated. This can contribute to the improvement of existing reaction mechanisms and provide fundamental knowledge for the design of burners.:1 Einleitung, Motivation und Aufgabenstellung der Arbeit 2 Stand der Wissenschaft und Technik 3 Versuchsaufbau, verwendete Messmethoden und experimentelle Versuchsdurchführung 4 Numerische Methoden 5 Experimentelle und numerische Ergebnisse zur laminaren Brenngeschwindigkeit 6 Experimentelle und numerische Ergebnisse zur Erlöschungsstreckungsrate 7 Einfluss der Wasserstoffbeimischung in Methan-Flammen auf die Schadstoffbildung 8 Zusammenfassung und Ausblick 9 Literatur 10 Anhang / 在未来的可持续发展社会中，氢气将作为一种能源载体发挥重要作用。从纯天然气到使用高达50 %的氢气混合物的过渡需要进行更详细的科研调查。本论文的研究重点集中于安全角度，污染物的演变以及层流火焰的稳定性领域。作为燃烧系统安全的一个关键参数文章使用层状燃烧率。本文献通过实验测量了甲烷-氢气混合物，并对在不同反应机制的形成的数字数据进行了比较。 热流量燃烧器被用来高精度地测量层状燃烧速度。本研究针对不同当量比和不同氧含量的甲烷-氢-氧-氮混合物进行了层流绝热燃烧速度的分析。在氧气减少的情况下，至20 % 的氢气实验数据只能由10个选定的详细反应机制部分地重现。进一步的测量针对不同当量比、温度和氢含量至50 %的甲烷-氢-空气混合物。然后对这些参数依赖于燃烧器上方的高度，进行了废气分析，目的是确定局部的氮氧化物浓度。结果表明在层状绝热条件下，特别是在燃料丰富的区域，氮氧化物有所减少。与纯甲烷火焰相比，氢-甲烷火焰的高燃烧速度和短暂的停留时间两者叠加被确定为其原因，文章对此并进行了数值重建。实验数据只能被选定的反应机理部分重现。最后，文章在逆流燃烧器上的可比条件下，也对氢气含量至50 %的非预混火焰进行了更详细的研究。研究在此特别进行了熄灭应变率的测定。 结果表明，如同数值模型所预测，在氢气掺入的情况下，以上数值都明显增加。 而在氧气减少的情况下，稳定的火焰面积明显减少。由此可以证明氧气和燃料浓度之间的非线性关系。最后，文章结果可以用于建立一个关于甲烷-氢气 （其氢气比例最高至50 %）火焰的层流燃烧速度、熄灭应变率和污染物的综合数据集。这有助于优化现有的反应机制，并为燃烧器的设计提供基本知识。:1 Einleitung, Motivation und Aufgabenstellung der Arbeit 2 Stand der Wissenschaft und Technik 3 Versuchsaufbau, verwendete Messmethoden und experimentelle Versuchsdurchführung 4 Numerische Methoden 5 Experimentelle und numerische Ergebnisse zur laminaren Brenngeschwindigkeit 6 Experimentelle und numerische Ergebnisse zur Erlöschungsstreckungsrate 7 Einfluss der Wasserstoffbeimischung in Methan-Flammen auf die Schadstoffbildung 8 Zusammenfassung und Ausblick 9 Literatur 10 Anhang