Дисертації з теми "Hydrogen methane combustion"
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Gersen, Sander. "Experimental study of the combustion properties of methane/hydrogen mixtures." [S.l. : Groningen : s.n. ; University Library of Groningen] [Host], 2007. http://irs.ub.rug.nl/ppn/30528004X.
Повний текст джерелаOztarlik, Gorkem. "Numerical and experimental investigations of combustion instabilities of swirled premixed methane-air flames with hydrogen addition." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0076.
Повний текст джерелаIn this work, hydrogen assisted (hydrogen enrichment and piloting) swirl stabilized flames are studied experimentally via MIRADAS experiment. First of all, static stability characteristics, such as flame lengths and flame attachment characteristics are studied via CH* chemiluminescence flame images and cases with hydrogen piloting, methane piloting and hydrogen enrichment are compared to the reference case of perfectly premixed methane-air combustion for a wide range of equivalence ratios and bulk velocities. It is found out that hydrogen piloting is the most efficient method to attach the flames and extend operating ranges of the combustion chamber. Next the dynamic stability characteristics of the setup is studied experimentally via stability maps and it is shown that injection of a very small portion of the thermal power worth of hydrogen results in a more stable system and an extension in the stable operating points in the stability maps, meaning safer overall operation. Hydrogen enrichment and methane piloting are also explored, and it is demonstrated that these methods are not effective in changing stability maps, stability maps are not effected. Subsequently, the forced flame responses are studied experimentally and it is shown that hydrogen piloting and hydrogen enrichment causes a drop in the global time delay of the flame transfer function. With hydrogen piloting, there is a global drop in the flame transfer function gain, however for hydrogen enriched cases, the gain is increased. For methane piloted cases, there is a global reduction in the flame transfer function gain, however the time delay is not affected. Consequently, to explore why and how the global flame transfer function is changed with different injection strategies, forced flame images are studied. It is shown that the changes in flame transfer function is caused by the competition behavior between the local heat release responses for hydrogen piloted cases. Simply put, there is a phase difference between the local responses near the injection tube and the flame edges, causing a "pull-back" effect, which in turn causes a drop in the flame transfer function gain. Next the effect of different injection strategies on the pollutant emissions are investigated. It is demonstrated that adding hydrogen, in pilot injection or hydrogen enrichment configuration, causes a drop in \mathrm{CO_2} emissions for the same thermal power. Piloting strategies cause a slight increase in NOx emissions, however results show that an optimization is possible to obtain flames that are stable, low mathrm{CO_2} and low NOx. Finally, LES calculations and their comparisons with experimental results are presented. The capability of LES calculations in predicting flame responses is demonstrated and it is shown that the flame responses originate from the interactions of the vortices that are formed as a result of acoustic pulsations and the flames. Flames are wrapped around these vortices which increase the flame surface area. Further down the forcing cycle, the rolled up portions of the flames start touching the combustion chamber walls and gets quenched which causes a loss of flame surface area. These changes in flame surface area result in a fluctuating heat release rate, consisting the flame response
Kojok, Ali Tarraf. "Hot jet ignition delay characterization of methane and hydrogen at elevated temperatures." Thesis, Pro Quest, 2017. https://doi.org/10.7912/C2CH35.
Повний текст джерелаThis study contributes to a better understanding of ignition by hot combustion gases which finds application in internal combustion chambers with pre-chamber ignition as well as in wave rotor engine applications. The experimental apparatus consists of two combustion chambers: a pre chamber that generates the transient hot jet of gas and a main chamber which contains the main fuel air blend under study. Variables considered are three fuel mixtures (Hydrogen, Methane, 50\% Hydrogen-Methane), initial pressure in the pre-chamber ranging from 1 to 2 atm, equivalence ratio of the fuel air mixture in the main combustion chamber ranging from 0.4 to 1.5, and initial temperature of the main combustion chamber mixture ranging from 297 K to 500 K. Experimental data makes use of 4 pressure sensors with a recorded sampling rate up to 300 kHz, as well as high speed Schlieren imaging with a recorded frame rate up to 20,833 frame per seconds. Results shows an overall increase in ignition delay with increasing equivalence ratio. High temperature of the main chamber blend was found not to affect hot jet ignition delay considerably. Physical mixing effects, and density of the main chamber mixture have a greater effect on hot jet ignition delay.
Ayoub, Mechline. "Etude de l’extension du régime de combustion sans flamme aux mélanges Méthane/Hydrogène et aux environnements à basse température." Thesis, Rouen, INSA, 2013. http://www.theses.fr/2013ISAM0010/document.
Повний текст джерелаMild flameless combustion is a massively diluted combustion regime associating high energy efficiency and very low pollutant emissions from industrial furnaces. The fuel composition and walls temperature are two very influential parameters of this combustion regime. In previous works realized at CORIA, flameless combustion of methane - hydrogen mixtures at 18% of excess air has shown very promising results. In another hand, high walls temperature is an essential element for flameless combustion stabilization. Within the framework of the project CANOE in collaboration with GDF SUEZ and ADEME, the objective of this PhD thesis is to complete the study of flameless combustion for methane-hydrogen mixtures in operating conditions similar to classical operating conditions of burners (10% of excess air), and in another hand, to study the stability limits of this combustion regime in low temperature environment like in industrial boiler.Experiments realized on the CORIA high temperature pilot facility, have proved that hydrogen addition in the fuel keep flameless combustion regime stable for all methane - hydrogen proportions, with very ultra-low pollutant emissions. An increase of excess air is however necessary for some operating conditions.Experiments realized with wall temperature progressive decrease allowed to study the influence of this parameter on flameless combustion, and to reach its stability limits. Similar results are obtained on the semi-industrial facility of GDF SUEZ. With hydrogen addition, flameless combustion is less sensitive to wall temperature decrease. An analytical representation of confined turbulent jets has been then developed to represent interaction between the reactant jets and their environment in the combustion chamber allowing reaching fameless combustion regime by entrainment, dilution and preheating. The effect of each parameter on the development of the jets can be then studied, which can be used as convenient tool of flameless combustion burners design. The heat quantity necessary for the low wall temperature stabilization has been quantified. On this base, a burner adapted to the configurations with cold walls has been designed. The applicability of the flameless combustion with this burner has been studied in a combustion chamber with low wall temperature specially designed for this purpose during this thesis. A mild diluted combustion regime has been achieved, but the high levels of unburnt gases have to be reduced
Michelon, Nicola. "Modelling and experimental investigation of microkinetic in heterogeneous catalysis: hydrogen combustion and production." Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424703.
Повний текст джерелаQuesta tesi investiga sia la combustion che la produzione di idrogeno, con particolare attenzione verso aspetti fondamentali della ossidazione catalizzata da platino e la reazione di steam reforming del metano su catalizzatori a base di nickel. Per quanto riguarda il primo aspetto, siamo partiti dall’osservare ed approfondire discrepanze sulla struttura e sui risultati di modelli cinetici di reazioni superficiali presenti in Letteratura, per la reazione di H2 e O2 su Pt. I confronti quantitativi sono stati fatti utilizzando un Modello di reattore chiuso ben mescolato con le superfici interne catalitiche. Le differenze nelle perizie dei diversi modelli sembrano discendere da differenze nei dati sperimentali su cui sono stati calibrati. Il fatto che se non state utilizzate diverse configurazioni sperimentali, e probabilmente strutture delle superfici di Pt , ci ha stimolato a intraprendere una campagna sperimentale per ottenere dati propri, utilizzando superfici di platino planari in opportuni reattori. Un nuovo reattore di laboratorio, a flusso stagnante, per indagare reazioni su Pt in forma di dischi e stato progettato sulla base di una` modellazione dettagliata e realizzato in laboratorio. I risultati sperimentali hanno dimostrato che l’attivita del Pt può variare enormemente. Pretrattamenti con H2 o O2 Hanno chiarito il meccanismo della competizione per siti superficiali e la possibilita di ristrutturazione la superficie. Sono state misurate trasformazioni di lunga durata, soprattutto dopo pretrattamenti con O2, che non trova una spiegazione in nessuno dei modelli cineticidettagliati di letteratura. Mediante misure in rampa di temperatura si e studiato` l’innesco di miscele povere di H2 in aria. Il confronto con dati di letteratura suggerisce una plausibile interpretazione della discrepanza dei dati riportati. Successivamente simulazioni transitorie della combustione di idrogeno in canali rivestiti di platino e stato utilizzato per valutare il comportamento della`reazione eterogenea con e senza reazione omogenea. L’effetto delle proprieta`del supporto del catalizzatore sono stati confrontati, considerando leghe Fe-Cre cordierite. Le implicazioni pratiche per l’operativita di questi reattori sono state`delineate. Per quanto riguarda la produzione di idrogeno abbiamo studiato sia dal punto di vista teorico che sperimentale la reazione di reforming di gas naturale mediante7 vapore. Abbiamo identificato intervalli significativi da un punto di vista industriale per le variabili operative, per studiare la cinetica dei catalizzatori. Abbiamo progettato un reattore di laboratorio mediante regole di scala rispetto a un impianto modello industriale di riferimento, con l’obiettivo di studiare la reazione a pressioni elevate (10bars). Abbiamo confrontato tre catalizzatori basati su Nickel con formulazioni diverse, modificando rapporto vapore/carbonio in alimentazione, per avvicinarsi alle condizioni stechiometriche. Si sono raccolti numerosi ,dati sia di attivita cataliticha che di formazione di carbone, utili per uno sviluppo di modelli` cinetici dettagliati della reazione superficiale.
Luo, Siwei. "Conversion of Carbonaceous Fuel to Electricity, Hydrogen, and Chemicals via Chemical Looping Technology - Reaction Kinetics and Bench-Scale Demonstration." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397573499.
Повний текст джерелаBurguburu, Joseph. "Etude expérimentale de la stabilité d’une flamme dans une chambre de combustion aéronautique par recirculation de gaz brûlés et par ajout d’hydrogène." Thesis, Rouen, INSA, 2012. http://www.theses.fr/2012ISAM0010/document.
Повний текст джерелаEnvironmental standards on aircraff NOx emissions are strict. Technics for reducing them have drawbacks. Two options are explored in this study to supress them. The first one is to fundamentally change the current combustion chamber architecture, to stabilize them by a cavity, the second, to dope fuel at idle.Little information on the mechanisms of stabilization and on the flame structure on Trapped Vortex Combustor is available. To remedy this, a TVC is built. The stabilizing ans destabilizing parameters are pointed out by the cold flow investigation and the temporally resolved study of the combustion. The impact of the flame structure on pollutant emissions is also considered.The second part of this stud, deals with the addition of pure hydrogen an of reformer gas in a conventional combustuion chamber. Despite a slight increase in NOx emissions, the addition of hydrogenated compounds reduces drastically CO emissions, increases the flame stability and reduces the LBO limit
Gordon, Robert Lindsay. "A numerical and experimental investigation of autoignition." Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/4944.
Повний текст джерелаGordon, Robert Lindsay. "A numerical and experimental investigation of autoignition." University of Sydney, 2008. http://hdl.handle.net/2123/4944.
Повний текст джерелаThis body of research uses numerical and experimental investigative techniques to further the understanding of autoignition. Hydrogen/nitrogen and methane/air fuel configurations of turbulent lifted flames in a vitiated coflow burner are used as model flames for this investigation. Characterisation was undertaken to understand the impact of controlling parameters and the overall behaviour of the flames, and to provide a body of data for modelling comparisons. Modelling of the flames was conducted using the PDF-RANS technique with detailed chemistry incorporated using In-situ Adaptive Tabulation (ISAT) within the commercial CFD package, FLUENT 6.2. From these investigations, two numerical indicators for autoignition were developed: convection-reaction balance in the species transport budget at the mean flame base; and the build-up of ignition precursors prior to key ignition species. These indicators were tested in well defined autoignition and premixed flame cases, and subsequently used with the calculated turbulent lifted flames to identify if these are stabilised through autoignition. Based on learnings from the modelling, a quantitative, high-resolution simultaneous imaging experiment was designed to investigate the correlations of an ignition precursor (formaldehyde: CH2O) with a key flame radical (OH) and temperature. Rayleigh scattering was used to measure temperature, while Laser Induced Fluorescence (LIF) was used to measure OH and CH2O concentrations. The high resolution in the Rayleigh imaging permitted the extraction of temperature gradient data, and the product of the OH and CH2O images was shown to be a valid and useful proxy for peak heat release rate in autoigniting and transient flames. The experimental data confirmed the presence of formaldehyde as a precursor for autoignition in methane flames and led to the identification of other indicators. Sequenced images of CH2O, OH and temperature show clearly that formaldehyde exists before OH and peaks when autoignition occurs, as confirmed by images of heat release. The CH2O peaks decrease later while those of OH remain almost unchanged in the reaction zone.
Thellmann, Andreas [Verfasser], Christian [Akademischer Betreuer] Mundt, and Klaus [Akademischer Betreuer] Hornung. "Impact of Gas Radiation on Viscous Flows, in particular on Wall Heat Loads, in Hydrogen-Oxygen vs. Methane-Oxygen Systems, based on the SSME Main Combustion Chamber / Andreas Thellmann. Betreuer: Christian Mundt. Gutachter: Klaus Hornung. Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik." Neubiberg : Universitätsbibliothek der Universität der Bundeswehr, 2010. http://d-nb.info/1007710314/34.
Повний текст джерелаKennel, Claire. "Mesures expérimentales et modélisation de la formation des oxydes d'azote dans les flammes d'hydrocarbures dopées à l'amoniac." Rouen, 1989. http://www.theses.fr/1989ROUES001.
Повний текст джерелаBurguburu, Joseph. "Etude expérimentale de la stabilité d'une flamme dans une chambre de combustion aéronautique par recirculation de gaz brûlés et par ajout d'hydrogène." Phd thesis, INSA de Rouen, 2012. http://tel.archives-ouvertes.fr/tel-00771860.
Повний текст джерелаCesário, Moisés Rômolos. "Vaporeformage catalytique du méthane : amélioration de la production et de la sélectivité en hydrogène par absorption in situ du CO2 produit." Phd thesis, Université de Strasbourg, 2013. http://tel.archives-ouvertes.fr/tel-00999401.
Повний текст джерелаLee, Bai-Jheng, and 李百正. "Combustion Characteristics of Methane-Hydrogen Inverse Jet Diffusion Flames." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/53854458907442771797.
Повний текст джерела崑山科技大學
機械工程研究所
101
In this study, combustion characteristics of inverse methane jet diffusion flames were investigated using a triple-port Jet burner. The results showed that as the middle stream velocity of methane (V2) and the outer stream velocity of air (V3) are fixed, the gradual increase in the inner stream velocity of air (V1) will result in the transition of inverse diffusion flame from a single cone-shaped flame (Type A) to a double cone-shaped flame (Type B) to a M-shpaed flame with inner and outer open tips, so-called Type C flame, to a Type D flame with lifted inner flame. When V2 and V3 are kept constant, flame height decreases with increasing V1. As V3 was fixed, the critical velocities of inner air stream (V1) corresponding to the occurrence of Type B and Type C flames increased with V2, while the corresponding V1 for the onset of Type D flame decreased with increasing V2. With increasing central-flow air velocity or hydrogen concentration, radiative heat transfer rate (radiative heat flux) decreased for a fixed radial direction distance 50 cm at a constant fuel velocity. Additionally, with an increase in central-flow air velocity, the CO2 and NOx emissions increased, but the CO emission decreased. Moreover, the measurement of temperature distribution showed that, as V1=V2=V3=250 cm/s, the maximum temperature is about 1400 ℃ for pure methane but around 1600 ℃for the mixture of 80% methane and 20% hydrogen. Meanwhile, the latter also had a wider high temperature zone, leading to higher radiation for the latter.
Hsu, Wen-Chen, and 許文振. "Effects of Thermal Radiation on Methane/Hydrogen Combustion in Porous Medium Burner." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/64742628375111452000.
Повний текст джерела國立中央大學
機械工程研究所
90
The lean combustion of hydrogen/methane mixtures within a highly porous medium has been investigated by experiment and numerical simulation. According to the ceramics arrangement and the gap, four burner structures are built. we use the LabView program to measure the flow rates, flame temperature, the NOx/CO emission. for the numerical simulation. we use STAR-CD to build a model and to compute the solution. results show that for burners without a gap, the flame tends to stabilize at the upstream half. for the burners with a gap, the flame can stabilized in either the upstream half ot the downstreams one. Using small-pore ceramics blocks at the inlet and exit can cut radiative heat loss and lower the lean limit. Addition of hydrogen in the fuel doesn't change the flame temperature greatly. the flame speed, however, increases with the hydrogen fraction in the fuel.
Khan, Md Nazmuzzaman. "Three-dimensional transient numerical study of hot-jet ignition of methane-hydrogen blends in a constant-volume combustor." Thesis, 2015. http://hdl.handle.net/1805/7960.
Повний текст джерелаIgnition by a jet of hot combustion product gas injected into a premixed combustible mixture from a separate pre-chamber is a complex phenomenon with jet penetration, vortex generation, flame and shock propagation and interaction. It has been considered a useful approach for lean, low-NOx combustion for automotive engines, pulsed detonation engines and wave rotor combustors. The hot-jet ignition constant-volume combustor (CVC) rig established at the Combustion and Propulsion Research Laboratory (CPRL) of the Purdue School of Engineering and Technology at Indiana University-Purdue University Indianapolis (IUPUI) is considered for numerical study. The CVC chamber contains stoichiometric methane-hydrogen blends, with pre-chamber being operated with slightly rich blends. Five operating and design parameters were investigated with respect to their eff ects on ignition timing. Di fderent pre-chamber pressure (2, 4 and 6 bar), CVC chamber fuel blends (Fuel-A: 30% methane + 70% hydrogen and Fuel-B: 50% methane + 50% hydrogen by volume), active radicals in pre-chamber combusted products (H, OH, O and NO), CVC chamber temperature (298 K and 514 K) and pre-chamber traverse speed (0.983 m/s, 4.917 m/s and 13.112 m/s) are considered which span a range of fluid-dynamic mixing and chemical time scales. Ignition delay of the fuel-air mixture in the CVC chamber is investigated using a detailed mechanism with 21 species and 84 elementary reactions (DRM19). To speed up the kinetic process adaptive mesh refi nement (AMR) based on velocity and temperature and multi-zone reaction technique is used. With 3D numerical simulations, the present work explains the e ffects of pre-chamber pressure, CVC chamber initial temperature and jet traverse speed on ignition for a speci fic set of fuels. An innovative post processing technique is developed to predict and understand the characteristics of ignition in 3D space and time. With the increase of pre-chamber pressure, ignition delay decreases for Fuel-A which is the relatively more reactive fuel blend. For Fuel-B which is relatively less reactive fuel blend, ignition occurs only for 2 bar pre-chamber pressure for centered stationary jet. Inclusion of active radicals in pre-chamber combusted product decreases the ignition delay when compared with only the stable species in pre-chamber combusted product. The eff ects of shock-flame interaction on heat release rate is observed by studying flame surface area and vorticity changes. In general, shock-flame interaction increases heat release rate by increasing mixing (increase the amount of deposited vorticity on flame surface) and flame stretching. The heat release rate is found to be maximum just after fast-slow interaction. For Fuel-A, increasing jet traverse speed decreases the ignition delay for relatively higher pre-chamber pressures (6 and 4 bar). Only 6 bar pre-chamber pressure is considered for Fuel-B with three di fferent pre-chamber traverse speeds. Fuel-B fails to ignite within the simulation time for all the traverse speeds. Higher initial CVC temperature (514 K) decreases the ignition delay for both fuels when compared with relatively lower initial CVC temperature (300 K). For initial temperature of 514 K, the ignition of Fuel-B is successful for all the pre-chamber pressures with lowest ignition delay observed for the intermediate 4 bar pre-chamber pressure. Fuel-A has the lowest ignition delay for 6 bar pre-chamber pressure. A speci fic range of pre-chamber combusted products mass fraction, CVC chamber fuel mass fraction and temperature are found at ignition point for Fuel-A which were liable for ignition initiation. The behavior of less reactive Fuel-B appears to me more complex at room temperature initial condition. No simple conclusions could be made about the range of pre-chamber and CVC chamber mass fractions at ignition point.
Singh, Satyapaul A. "Synthesis of Thermally Stable Catalysts for Methane Reforming and CO Abatement." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/4123.
Повний текст джерелаPaik, Kyong-Yup. "Experimental investigation of hot-jet ignition of methane-hydrogen mixtures in a constant-volume combustor." Thesis, 2016. https://doi.org/10.7912/C2XW8T.
Повний текст джерелаInvestigations of a constant-volume combustor ignited by a penetrating transient jet (a puff) of hot reactive gas have been conducted in order to provide vital data for designing wave rotor combustors. In a wave rotor combustor, a cylindrical drum with an array of channels arranged around the axis spins at a high rpm to generate high-temperature and high-pressure product gas. The hot-gas jet ignition method has been employed to initiate combustion in the channels. This study aims at experimentally investigating the ignition delay time of a premixed combustible mixture in a rectangular, constant-volume chamber, representing one channel of the wave rotor drum. The ignition process may be influenced by the multiple factors: the equivalence ratio, temperature, and the composition of the fuel mixture, the temperature and composition of the jet gas, and the peak mass flow rate of the jet (which depends on diaphragm rupture pressure). In this study, the main mixture is at room temperature. The jet composition and temperature are determined by its source in a pre-chamber with a hydrogen-methane mixture with an equivalent ratio of 1.1, and a fuel mixture ratio of 50:50 (CH4:H2 by volume). The rupture pressure of a diaphragm in the pre-chamber, which is related to the mass flow rate and temperature of the hot jet, can be controlled by varying the number of indentations in the diaphragm. The main chamber composition is varied, with the use of four equivalence ratios (1.0, 0.8, 0.6, and 0.4) and two fuel mixture ratios (50:50, and 30:70 of CH4:H2 by volume). The sudden start of the jet upon rupture of the diaphragm causes a shock wave that precedes the jet and travels along the channel and back after reflection. The shock strength has an important role in fast ignition since the pressure and the temperature are increased after the shock. The reflected shock pressure was examined in order to check the variation of the shock strength. However, it is revealed that the shock strength becomes attenuated compared with the theoretical pressure of the reflected shock. The gap between theoretical and measured pressures increases with the increase of the Mach number of the initial shock. Ignition delay times are obtained using pressure records from two dynamic pressure transducers installed on the main chamber, as well as high-speed videography using flame incandescence and Schileren imaging. The ignition delay time is defined in this research as the time interval from the diaphragm rupture moment to the ignition moment of the air/fuel mixture in the main chamber. Previous researchers used the averaged ignition delay time because the diaphragm rupture moment is elusive considering the structure of the chamber. In this research, the diaphragm rupture moment is estimated based on the initial shock speed and the longitudinal length of the main chamber, and validated with the high-speed video images such that the error between the estimation time and the measured time is within 0.5%. Ignition delay times decrease with an increase in the amount of hydrogen in the fuel mixture, the amount of mass of the hot-jet gases from the pre-chamber, and with a decrease in the equivalence ratio. A Schlieren system has been established to visualize the characteristics of the shock wave, and the flame front. Schlieren photography shows the density gradient of a subject with sharp contrast, including steep density gradients, such as the flame edge and the shock wave. The flame propagation, gas oscillation, and the shock wave speed are measured using the Schlieren system. An image processing code using MATLAB has been developed for measuring the flame front movement from Schlieren images. The trend of the maximum pressure in the main chamber with respect to the equivalence ratio and the fuel mixture ratio describes that the equivalence ratio 0.8 shows the highest maximum pressure, and the fuel ratio 50:50 condition reveals lower maximum pressure in the main chamber than the 30:70 condition. After the combustion occurs, the frequency of the pressure oscillation by the traversing pressure wave increases compared to the frequency before ignition, showing a similar trend with the maximum pressure in the chamber. The frequency is the fastest at the equivalence ratio of 0.8, and the slowest at a ratio of 0.4. The fuel ratio 30:70 cases show slightly faster frequencies than 50:50 cases. Two different combustion behaviors, fast and slow combustion, are observed, and respective characteristics are discussed. The frequency of the flame front oscillation well matches with that of the pressure oscillation, and it seems that the pressure waves drive the flame fronts considering the pressure oscillation frequency is somewhat faster. Lastly, a feedback mechanism between the shock and the flame is suggested to explain the fast combustion in a constant volume chamber with the shock-flame interactions.
Lai, Pei-Chen, and 賴沛晨. "Hydrogen production from dry reforming of methane using Ni/MgAl2O4 spinel catalyst via solution combustion method." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/90615000823200771984.
Повний текст джерела國立中興大學
環境工程學系所
105
Since Industrial Revolution, people use fossil fuel as energy sources. At present, the dependence on fossil fuels to meet energy demand have created environmental issues by the generation of anthropogenic greenhouse gases. As the demand for energy increases, it is important to seek alternative energy. Dry reforming of methane reaction has received much attention because it can provide a good way to convert the methane and carbon dioxide into a valuable synthesis gas, which is a mixture of hydrogen and carbon monoxide. However, because both reactants of CH4 and CO2 contain carbon, the dry reforming of methane reaction typically suffers deactivation from severe coke formation. In this study, MgAl2O4 spinel was synthesized by solution combustion method. Then, 10% nickel was impregnated onto the MgAl2O4−supported by impregnation method. We adjusted four parameters (magnesium metal precursor species, fuel type, fuel to oxidizer ratio and synthesis temperature) during the combustion process to realizing the influence of the spinel morphology. The effects of preparation parameters for the spinel supports on catalytic activity for dry reforming of methane reaction were studied. From the results, the MgAl2O4 spinel was highly effective prepared by magnesium nitrate and urea at 500 oC, and that nickel particles dispersed well on the MgAl2O4 support, and it has a strong interaction between Ni and spinel. The Ni/MgAl2O4 inhibited reverse-water shift reaction, which leads to a high catalytic performance and H2/CO. When the combustion reactions of fuel/magnesium metal precursor were carried out in stoichiometric condition, the Ni/MgAl2O4 catalyst generated high catalytic activity and hydrogen yield. As the fuel-to-metal precursor molar ratio increased, the catalyst exhibited high activity and superior anti-coking for dry reforming of methane due to the increased metal-support interaction.
Rodhiya, Akash. "Numerical simulations of hydrogen flames in reheat gas turbine combustor: effect of pressure scaling and fuel blending." Thesis, 2022. https://etd.iisc.ac.in/handle/2005/5760.
Повний текст джерелаSantos, Daniela Filipa Martins. "Combustion of CH4, H2, and CH4 -H2 Mixtures in a Gas Turbine Can Combustor." Master's thesis, 2014. http://hdl.handle.net/10400.6/6451.
Повний текст джерелаO facto do preço dos combustíveis fósseis estar cada vez mais elevado, e de estarem a ocorrer mudanças ambientais devido à emissão de poluentes por parte destes combustíveis torna imperativo encontrar combustíveis alternativos mais baratos e menos poluentes. As turbinas de gás têm sido particularmente desenvolvidas como motores de aeronaves, no entanto nos dias que correm elas podem encontrar aplicabilidade nas mais diversas áreas, e aliando a isto o facto das turbinas de gás possuírem diferentes aplicabilidades de combustíveis faz delas um importante tema de estudo. Sendo assim o principal objectivo desta dissertação é avaliar através de uma análise CFD no FLUENT o desempenho da combustão num ?can combustor? de uma turbina de gás, quando alimentado com metano, hidrogénio e misturas de metano-hidrogénio, tendo especial interesse na emissão de poluentes. Posto isto foi realizada uma optimização do combustível por forma a avaliar os valores médios da fracção mássica dos poluentes CO, CO2 e NOx à saída do "can combustor", e de notar que uma breve análise à temperatura estática, à pressão estática e à magnitude da velocidade das várias simulações foi também executada.
Chowdhury, M. Arshad Zahangir. "Traversing hot jet ignition delay of hydrocarbon blends in a constant volume combustor." Thesis, 2018. https://doi.org/10.7912/C2XQ02.
Повний текст джерелаA chemically reactive turbulent traversing hot-jet issued from a pre-chamber to a relatively long combustion chamber is experimentally investigated. The long combustion chamber represents a single channel of a wave rotor constant-volume combustor. The issued jet ignites the fuel-air mixture in the combustion chamber. Fuel-air mixtures are prepared with different hydrocarbon fuels of different reactivity, namely, methane, propane, methane-hydrogen blend, methane-propane blend and methane-argon blend. The jet acts as a rapid, distributed and moving source of ignition, traversing across one end of the long combustion chamber entrance, induces complex flow structures such as a train of counter rotating vortices that enhance turbulent mixing. In general, a stationary hot-jet ignition process lack these structures due to absence of the traversing motion. The ignition delay of the fuels and fuel blends are measured in order to obtain insights about constant-volume pressure-gain combustion process initiated by a moving source of ignition and also to glean useful data about design and operation of a wave rotor combustor. Reactive hot-jets are useful to ignite fuel-air mixtures in internal combustion engines and novel wave rotor combustors. A reactive hot-jet or puff of gas issued from a suitably designed pre-chamber can act as rapid, distributed and less polluting ignition source in internal combustion engines. Each cylinder of the engine is provided with its own pre-chamber. A wave rotor combustor has an array of circumferentially arranged channels on a rotating drum. Each channel acts as a constant-volume combustor and produces high pressure combustion products. Implementation of hot-jet igniter in a wave rotor combustor offers utilization of available high temperature and high pressure reactive combustion products residing in each of the wave rotor channels as a distributed source of ignition for other channels, thus requiring no special pre-chamber in ultimate implementation. Such reactive products or partially combusted and radical-laden gases can be issued from one or more channels to ignite the fuel-air mixture residing in another channel. Due to the rotation of the rotor channels, the issued hot-jet would have relative motion with respect to one end of the channels and traverse across it. This thesis aims to investigate the effects of jet traverse time experimentally on ignition delay along with other important factors that affect the hot-jet ignition process such as fuel reactivity, fuel-air mixture preparation quality and stratification and equivalence ratio. In this study, the traversing motion of the hot-jet at one end of the main combustion chamber is implemented by keeping the main combustion chamber stationary and rotating a pre-chamber at speeds of 400 RPM, 800 RPM and 1200 RPM. The rotational speeds correspond to jet traverse times of 16.9 ms, 8.4 ms and 5.6 ms respectively. The fuel-air mixture inside the channel is at room temperature and pressure initially and its equivalence ratio is varied from 0.4 to 1.3. The cylindrical pre-chamber is initially filled with a 50%-50% methane-hydrogen blend fuel and air mixture at room pressure and temperature and at an equivalence ratio of 1.1. These conditions were chosen based on prior evidence of ignition rapidity with the jet properties. The hot-jet is issued by rupturing a thin diaphragm isolating the chambers. Using high frequency dynamic pressure transducer pressure histories, the diaphragm rupture moment and onset of ignition is measured. Pressure traces from two transducers are employed to measure the initial rupture shock speed and ignition delay. Schlieren images recorded by a high speed camera are used to identify ignition moment and validate the measured ignition delay times. Ignition delay is defined as time interval from the rupture moment to onset of ignition of fuel-air mixture in the main combustion chamber. The ignition system is designed to produce diaphragm rupture at almost exactly the moment when jet traverse begins. Ignition delay times are measured for methane, propane, methane-hydrogen blends, methane-propane blend and methane-argon blend. The equivalence ratio of the fuel-air mixtures varied from 0.4 to 1.3 in steps of 0.1 for stationary-hot jet ignition experiments and in steps of 0.3 for traversing hot-jet ignition experiments. Hot-jet ignition delay of fuel-air mixtures, for both stationary hot-jet ignition process and traversing hot-jet ignition process, generally increased with increasing equivalence ratio. For stationary hot-jet ignition delay, the minimum ignition delay occurs between Ф = 0.4 to Ф = 0.6 for the tested fuel-air mixtures. Both stationary and traversing hot-jet ignition delay depended on fuel reactivity. In particular, the shortest ignition delay times were observed for a fuel blend containing hydrogen. Among pure fuels propane exhibited slightly shorter ignition delay times, on average, compared to pure methane fuel. The addition of argon to pure methane, intended to control fuel density and buoyancy, increased the ignition delay. The traversing hot-jet ignition delay generally increased with increasing jet traverse times. To explain the variations in the measured hot-jet ignition delay and investigate qualitatively the effect of buoyancy on flame propagation and mixture stratification, the fuel-air mixture inside the main combustion chamber was ignited using a spark plug to generate a propagating laminar flame. The laminar flame propagated within the flammable regions of the channel in ways that sensitively reveal variations in local fuel-air mixture equivalence ratio. Flame luminosity images from a high speed camera and schlieren images revealed the fuel-air mixture being highly stratified depending on the density difference between the fuel and air and provided mixing time (0 s, 10s ,30s for most fuels). The lack of buoyancy-driven spreading caused the fuel to remain in the vicinity of the fuel injector resulting in significant longitudinal stratification of the fuel-air mixture. Lighter fuels stratified to the top of the chambers and heavier fuel stratified to the bottom of the chamber. Increasing the mixing time, which is defined as the time interval from end of fuel injection into the chamber to the triggering of the spark plug, improved the buoyancy-driven spreading and extended the flammable region as evidenced by the schlieren and flame luminosity images. The maximum pressure developed in the combustor for the three ignition processes, namely, stationary hot-jet ignition, traversing hot-jet ignition and spark ignition process in laminar flame propagation experiments were compared. Stationary hot-jet ignition process generally exhibited the highest pressure being developed in the chamber. Variations in heat loss, fuel-air mixture leakage and mass addition mechanisms reduced the maximum pressure for spark ignition and traversing hot-jet ignition process.
Chinnathambi, Prasanna. "Experimental investigation on traversing hot jet ignition of lean hydrocarbon-air mixtures in a constant volume combustor." Thesis, 2013. http://hdl.handle.net/1805/4439.
Повний текст джерелаA constant-volume combustor is used to investigate the ignition initiated by a traversing jet of reactive hot gas, in support of combustion engine applications that include novel wave-rotor constant-volume combustion gas turbines and pre-chamber IC engines. The hot-jet ignition constant-volume combustor rig at the Combustion and Propulsion Research Laboratory at the Purdue School of Engineering and Technology at Indiana University-Purdue University Indianapolis (IUPUI) was used for this study. Lean premixed combustible mixture in a rectangular cuboid constant-volume combustor is ignited by a hot-jet traversing at different fixed speeds. The hot jet is issued via a converging nozzle from a cylindrical pre-chamber where partially combusted products of combustion are produced by spark- igniting a rich ethylene-air mixture. The main constant-volume combustor (CVC) chamber uses methane-air, hydrogen-methane-air and ethylene-air mixtures in the lean equivalence ratio range of 0.8 to 0.4. Ignition delay times and ignitability of these combustible mixtures as affected by jet traverse speed, equivalence ratio, and fuel type are investigated in this study.
Karimi, Abdullah. "Numerical study of hot jet ignition of hydrocarbon-air mixtures in a constant-volume combustor." Thesis, 2014. http://hdl.handle.net/1805/6249.
Повний текст джерелаIgnition of a combustible mixture by a transient jet of hot reactive gas is important for safety of mines, pre-chamber ignition in IC engines, detonation initiation, and in novel constant-volume combustors. The present work is a numerical study of the hot-jet ignition process in a long constant-volume combustor (CVC) that represents a wave-rotor channel. The mixing of hot jet with cold mixture in the main chamber is first studied using non-reacting simulations. The stationary and traversing hot jets of combustion products from a pre-chamber is injected through a converging nozzle into the main CVC chamber containing a premixed fuel-air mixture. Combustion in a two-dimensional analogue of the CVC chamber is modeled using global reaction mechanisms, skeletal mechanisms, and detailed reaction mechanisms for four hydrocarbon fuels: methane, propane, ethylene, and hydrogen. The jet and ignition behavior are compared with high-speed video images from a prior experiment. Hybrid turbulent-kinetic schemes using some skeletal reaction mechanisms and detailed mechanisms are good predictors of the experimental data. Shock-flame interaction is seen to significantly increase the overall reaction rate due to baroclinic vorticity generation, flame area increase, stirring of non-uniform density regions, the resulting mixing, and shock compression. The less easily ignitable methane mixture is found to show higher ignition delay time compared to slower initial reaction and greater dependence on shock interaction than propane and ethylene. The confined jet is observed to behave initially as a wall jet and later as a wall-impinging jet. The jet evolution, vortex structure and mixing behavior are significantly different for traversing jets, stationary centered jets, and near-wall jets. Production of unstable intermediate species like C2H4 and CH3 appears to depend significantly on the initial jet location while relatively stable species like OH are less sensitive. Inclusion of minor radical species in the hot-jet is observed to reduce the ignition delay by 0.2 ms for methane mixture in the main chamber. Reaction pathways analysis shows that ignition delay and combustion progress process are entirely different for hybrid turbulent-kinetic scheme and kinetics-only scheme.
Huang, Shang-Yun, and 黃上芸. "Catalytic Hydrogen Combustor applied to Thermal Management for Methanol Reformer." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/68p5p6.
Повний текст джерелаLiu, Chang-Che, and 劉昌哲. "Modeling for a Catalytic Plate Reactor Coupling Endothermic Methanol Steam Reforming and Hydrogen Combustion." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/19247797344395818304.
Повний текст джерела大同大學
化學工程學系(所)
99
In this work, tubular and plate reactors for carrying out methanol steam reforming reactions are simulated using Fluent software. The simulation results using Fluent software are confirmed by the performance of an isothermal plug flow tubular reactor in which the methanol steam reforming reactions are performed. Among the eight different reactor designs, the catalytic plate reactor packed with small catalyst particles coupling endothermic methanol steam reforming and hydrogen combustion system give the best performance. The conversion of methanol is 0.63 for the isothermal (250℃) plug flow tubular reactor while that for the catalytic plate reactor packed with small catalyst particles coupling endothermic methanol steam reforming and hydrogen combustion system is 0.6 if the mass transfer resistance between the gas reactants and the catalyst particles is not included in the simulation using Fluent software.
Lu, Liang Chun, and 盧亮均. "Investigations on the high efficiency internal combustion engine using mixtures of methanol and reformed hydrogen." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/38484779283156540153.
Повний текст джерела國立中興大學
機械工程學系所
100
In this paper, a single-cylinder motorcycle engine and a steam reformer were used as a test stand to investigate the effect of adding hydrogen mixture on the engine efficiency and exhaust pollution. Addition of reformed gas may have two effects on engine efficiency. One is the enhancement of combustion due to the high speed of flame propagation characteristics of hydrogen, and the other is attributed to the recovery of exhaust thermal energy to improve the fuel heating value. It was found in experiment that the engine efficiency can be improved at low load condition as well as high load condition. As the reformulated gas flow was 12.1 L/min, the engine efficiency was promoted to 24.8%, compared with the efficiency of 21.5% for gasoline engine at the same running condition. However, at high load condition, the NO emission was increased to 2550 ppm as the reformulated gas flow was 14.7 L/min. The heat transfer model of the reforming process was also developed in this paper to evaluate the effectiveness of the reformer. It was found that as the engine speed was 5000 rpm and the exhaust temperature was 450℃, if the methanol flow rate was set to 7.92 g/min, a distance of 56 cm is required to complete the physical change of methanol solution, in which the heating of methanol and water vapor from 100℃ to 270℃ takes the major share of 47.1%.
Hwang, Bae-Yinn, and 黃百胤. "Reduction behavior and hydrogen production of CuCr1-xFexO2 nanopowder under methanol steam synthesized by self-combustion glycine nitrate process." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/bd259h.
Повний текст джерела國立臺北科技大學
材料科學與工程研究所
105
The delafossite structure CuCr1-xFexO2 nanopowders (x = 0-1) was successfully synthesized by self-combustion glycine nitrate process (GNP) which has much higher surface area than bulk powder prepared by traditional solid state reaction. In this study, CuCr1-xFexO2 nanopowders as a precursor for copper based catalyst were applied to steam reforming of methanol (SRM) process for hydrogen production. Catalytic performance was enhanced with the nanoization of CuCr1-xFexO2 powders which leads to a higher surface area and the well dispersion of copper particles. Furthermore, CuCr1-xFexO2 nanopowders could be directly reduced by methanol steam without the typically activation process in hydrogen. Changes of CuCr1-xFexO2 nanopowders were determined by the X-ray diffraction (XRD) analysis. The cotton candy-like porous structure and the dispersion of Cu particles after the SRM process were revealed by scanning electron microscopy (SEM) together with the EDX elemental analysis. Microstructure of as-combusted nanopowders was determined by a transmission electron microscopy (TEM). The BET measurement showed the surface area of self-combusted CuCr1-xFexO2 nanopowders was over ten times larger than the powder prepared by traditional solid-state reaction and basically increased with the iron contents decreased. The production rate of hydrogen was analyzed with a gas chromatograph (GC) equipped with a thermal conductivity detector (TCD).
Damodharan, Shalini. "Determination of Optimal Process Flowrates and Reactor Design for Autothermal Hydrogen Production in a Heat-Integrated Ceramic Microchannel Network." Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10851.
Повний текст джерелаTzu-TingHsu and 徐子庭. "Investigation on Combustion Characteristics and Emissions of a Diesel Engine Running with Hydrogen Rich Gas by Methanol Reforming with Exhaust Heat Recovery." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/8a26uy.
Повний текст джерела國立成功大學
系統及船舶機電工程學系
103
Exhaust emission from internal combustion engines is one of the major sources of air pollution, so the scholars at home and abroad in recent decades have put lots of effort on the pollution reducing technologies of engine and alternative fuels research. Because of the excellent combustion characteristics of hydrogen, the issue of it combined with the engine has received considerable attention. However, the carrying and storage problems of hydrogen still need to be resolved. This thesis is to explore diesel engine exhaust heat recovery system integrated with the methanol steam reforming method and discuss the performance and exhaust emission characteristics. Research is divided into two parts: the first part is to discuss the operating parameters of hydrogen-producing conditions and change feed rate of methanol-water solution under the appropriate working condition. Employing the concentration of hydrogen-rich gas and flow rate of carrier gas can obtain the hydrogen flow rate. The second part is to conduct experiments with diesel engine at different loads, and the author also adjusts the input rate of methanol water solution to control the hydrogen-rich gas production and changes the exhaust gas recirculation proportion for experiment. The inlet tank makes hydrogen-rich gas and air mix uniformly before conducting into cylinder. The cylinder gas pressure crank angle data, intake air temperature, exhaust gas temperature, air flow rate, exhaust flow rate, and exhaust pollution concentrations (NOX, Smoke, and PM2.5) are measured by changing exhaust gas recirculation (EGR) ratio and amount of hydrogen-rich gas for diesel engine operating under fixed engine speed and various loads. The BTE, heat release rate, and the concentrations of exhaust pollution are then analyzed. In addition, this thesis applies KIVA3V-RELEASE2 adding detailed chemical reaction for numerical computation to analyze effect of using hydrogen-rich gas reformed from aqueous methanol solution. Comparison of experimental results with numerical results can confirm the reliability of the experiment. Experimental results indicate that the reaction temperature directly influences hydrogen production. If there is insufficient supply of heat to decrease the reaction temperature, the production of hydrogen-rich gas will decrease significantly. While the temperature and S/C ratio is set up under the optimal working condition, the author changes the feed rate of the aqueous methanol solution to adjust the producing amount of hydrogen. The simulation and experimental results show that adding hydrogen-rich gas in diesel engines can increase the heat release rate under the premixed combustion phase. The appropriate proportion of exhaust gas recirculation helps reduce the exhaust pollution such as Smoke, PM2.5, and NOX. However, the higher peak pressures and temperatures in the engine cylinder will lead to harmful NOX when the hydrogen-rich gas is added.
Παπαβασιλείου, Ιωάννα. "Παραγωγή υδρογόνου μέσω αναμόρφωσης της μεθανόλης με οξειδικούς καταλύτες χαλκού". 2008. http://nemertes.lis.upatras.gr/jspui/handle/10889/1691.
Повний текст джерелаThe scope of the present thesis was the development of an effective catalytic copper-based system for methanol reforming. The catalytic properties of three different copper-based systems prepared via the non conventional combustion method, were investigated for the aforementioned process: CuO-CeO2, modified CuO-CeO2 and Cu-Mn-O, as well as the optimal CuO-CeO2 and Cu-Mn-O oxide cata¬lysts supported on Al metal foam. The physicochemical characteristics of CuO-CeO2 catalysts were found to be influenced by the parameters of the synthesis. The optimal catalyst was prepared with Cu/(Cu+Ce) ratio equal to 0.15. In the case of modified CuO-CeO2 catalysts, at least part of dopant cations gets incorporated into the CeO2 lattice leading to solid solution formation. As a result, the physicochemical characteris¬tics of the samples were influenced, as well as their catalytic performance. Cu-Mn spinel oxide catalysts were found to be highly active despite their low surface area. Their activity is comparable to that of commercial Cu-Zn-Al catalysts. The optimal catalyst was prepared with a Cu/(Cu+Mn) ratio equal to 0.30. Structured Cu-Ce/Al foam and Cu-Mn/Al foam catalysts prepared via in situ combustion method were equally effective for hydrogen production via methanol reforming. Based on the findings of an isotopic study, a mechanism has been proposed for the reforming reaction over Cu-Mn-O, where methyl formate is formed as a reaction intermediate. An additional reaction mechanism is taking place over Cu-Ce-O and commercial Cu/ZnO/Al2O3 catalysts, resulting in the intermediate dioxomethylene.