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1
Young, Jacob. "Hydrogen injection into diesel engines for fuel efficiency improvement." Thesis, Young, Jacob (2008) Hydrogen injection into diesel engines for fuel efficiency improvement. Masters by Coursework thesis, Murdoch University, 2008. https://researchrepository.murdoch.edu.au/id/eprint/2079/.
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The purpose of this investigation was to determine whether hydrogen injected into a diesel internal combustion engine has the potential to reduce overall fuel consumption. The most economical means of performing the required tasks was used whenever possible in an attempt to mimic a small off-grid application. The genset was a small 4kW compression ignition diesel. The electrolyzer was an off-the-shelf model designed for automotive applications. It combines hydrogen and oxygen output and is currently found from many manufacturers over the internet. It was found that the H2/02 mixture actually did help conserve fuel by about 18% in a low load case but generally, savings were under 5%. At a higher proportion of generator rated load, fuel consumption was shown to increase with H2/02 injection by up to 5%, thus the H2/02 output must be optimized to achieve any savings. Reasons for this phenomenon are discussed and recommendations for further research are included.
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Wagner, Timothy Charles. "Ignition and flameholding in supersonic flow by injection of dissociated hydrogen." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/49905.
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The objective of this research was to investigate analytically and experimentally the use of free radicals for ignition and flameholding in supersonic flows. An analytical investigation of the effects of adding small quantities of radicals to a stoichiometric mixture of hydrogen and air was performed using a finite-rate chemical kinetics code. The results of these calculations indicate that small additions of hydrogen atoms, oxygen atoms, nitrogen atoms, or hydroxyl radicals are effective in promoting ignition. These analytical results were qualitatively verified in a Mach 2 flow experiment using hydrogen atoms generated by a plasma torch. The supersonic combustion tests were conducted in a direct-connect mode at atmospheric pressure with either ambient temperature air or burner-heated vitiated air with total temperatures from 1200 to 4000 R. Both semi-freejet and ducted configurations were used. The experimental results indicate that hydrogen atoms from a low-power plasma torch provide an effective ignition and flameholding source for hydrogen-fueled Mach 2 flows at total temperatures as low as 1065 R, the lowest temperature tested. A reduction in the minimum total temperature required for ignition of several hydrocarbon fuels was also demonstrated.
A piloted fuel injector configuration designed to take maximum advantage of the hydrogen atoms from the plasma torch was conceived and fabricated. The injector design consisted of five small upstream pilot fuel injectors, a rearward-facing step and three primary fuel injectors downstream of the step. The hydrogen atoms from the plasma torch were injected in the recirculation region downstream of the step. Three other ignition sources were also tested as comparisons: an argon plasma, a pyrophoric mixture of silane and hydrogen, and a surface discharge device. Hydrogen-fueled supersonic combustion tests were conducted at conditions similar to those described earlier. Hydrogen atoms generated by the plasma torch proved to be the most effective ignition source, causing ignition for a torch input power of 780 W, the lowest power tested. The combination of the hydrogen atoms and the piloted fuel injector was shown to be a very effective igniter and flameholder for scramjet operation over a simulated flight envelope (Mach 3 to Mach 6, low to moderate altitudes).<br>Ph. D.<br>incomplete_metadata
3
Cuesta, Daniel F. "Effects of hydrogen and ethylene injection schemes in a supersonic airstream." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0002725.
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Milne, Angela. "Marine biogeochemistry studies of iron and hydrogen peroxide using flow injection-chemiluminescence." Thesis, University of Plymouth, 2007. http://hdl.handle.net/10026.1/2007.
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Iron is an essential micronutrient for the growth of planktonic species. It is an integral element of numerous enzymes and proteins with important functions in photosynthesis and respiratory electron transport. In contrast to iron, hydrogen peroxide (H202) is ubiquitous in seawater. Phytoplankton are known to generate reactive oxygen species (ROS) such as superoxide and H202 . This production, in conjunction with membrane bound reductases, may affect an organism's ability to access nutrients such as iron. The work presented in this thesis describes the development and optimisation of sensitive flow injection-chemiluminescence techniques to assess redox processes at the cellular level and their application to investigate marine processes. Two flow injection methods, one based on direct sample injection and another involving the preconcentration of iron, were used to determine iron (II) and dissolved iron and assess potential interference from a number of metals and H202. The results demonstrated the increased oxidation of Fe(II) in the presence of H202 (half life reduced from 10.4 to 3.5 min at 50 nM H202) and confirmed the ability of the pre-concentration method to remove this matrix interference. The accuracy and precision of the pre-concentration method were confirmed through analysis of samples collected on two international intercomparison studies. The results demonstrated that the method was precise (- 8 %RSD) and provided a suitably low limit of detection (17 pM) for the determination of dissolved iron. Dust deposition is an important source of iron to remote open ocean regions. The solubility of iron and aluminium in North Atlantic waters was assessed through an on-deck dissolution experiment. Calculated solubilities of iron released from six differing dust samples were low and varied from 0.001 to 0.04 %, whereas the release of aluminium ranged from 0.06-9.0 %. Solubility was inversely correlated with particle concentration, where higher solubility was observed for lower particle concentrations. A versatile and adaptable FI system was developed, with a low detection limit (0.4 - 1.3 nM), excellent precision (1.1-1.8 %RSD) and the capability of sensitive real-time determination of H202 over a wide dynamic range. The results from laboratory based assays using a novel in-line filter approach demonstrated H202 production by the diatom species Thalassiaira ueiss weissflogii with observed concentrations in the range 30- 100 nM. In addition, through field studies carried out in two different oceanic regions (English Channel and Ross Sea), a previously unreported correlation between phytoplankton biomass and surface H20 1 concentrations was observed. The FI-CL instrumentation for the determination of Fe(II) was successfully adapted and optimised for the continuous in-line measurements of Fe(II) generated by diatoms. This technique provided a low detection limit (11 pM) and excellent precision (6.3 ± 3.2 % RSD). In further laboratory based assays with T. ueissflogii, preliminary results indicated pM changes in Fe(II) generation following the reduction of organically bound Fe(Ill).
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Mohammad, Ahmad A. A. "Experimental investigation of in situ upgrading of heavy oil by using a hydrogen donor and catalyst during steam injection." Texas A&M University, 2008. http://hdl.handle.net/1969.1/86051.
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Experiments were conducted to investigate the feasibility of in situ upgrading of
heavy oil by the use of an orgametallic catalyst and a hydrogen donor (tetralin). The
experiments used a vertical injection cell into which a mixture of sand, water, and Jobo
oil was thoroughly mixed and packed. Two types of runs were conducted: a run where
the tetralin and catalyst were mixed within the mixture before packing into the cell, and
the other was conducted by injecting a slug of the tetralin-catalyst solution before
commencing with the steam injection. The Jobo oil used had an oil gravity of 12.4° API
and a viscosity of 7800 cp at 30°C. The injection cell was placed in a vacuum jacket and
set to a reservoir temperature of 50°C. Superheated steam at 273°C was then injected
into the injection cell at a rate of 5.5 cc/min (cold water equivalent). The cell outlet
pressure was maintained at 500 psig. Produced liquid samples were collected
periodically through a series of separators. The produced oil was divided into two halves
and several measurements and analyses were carried out on them. These included
viscosity, density, elemental analysis and liquid composition. Experimental results indicated that tetralin alone was a worthy additive and
increased recovery by 15% compared to that of pure steam. The premixed tetralincatalyst
run showed improved recovery to that of pure steam by 20%. Experiments also
showed that, when the tetralin-catalyst solution was injected rather than mixed, the
results were equivalent to tetralin injection runs. Oil production acceleration was
displayed by all the runs with tetralin and tetralin-catalyst but was more pronounced with
the availability of catalyst.
6
Shigeta, Takanobu. "Luminal injection of hydrogen-rich solution attenuates intestinal ischemia-reperfusion injury in rats." Kyoto University, 2015. http://hdl.handle.net/2433/199174.
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Verreault, Jimmy. "Design of a Shock-Induced Combustion Experiment in an Axisymmetric Configuration with Hydrogen Injection." Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24967/24967.pdf.
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Price, David. "The determination of hydrogen peroxide in sea water using flow injection with chemiluminescence detection." Thesis, University of Plymouth, 1995. http://hdl.handle.net/10026.1/1735.
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This thesis describes the design, assembly and optimisation of a flow injection-chemiluminescence (FI-CL) procedure for the determination of hydrogen peroxide (H2O2) in seawater. An overview of the biogeochemical importance of H2O2 in seawater is presented in Chapter One. The use of both flow injection and chemiluminescence based methods are also reviewed. Chapter Two describes the type of analytical instrumentation used in both flow injection and chemiluminescence methods. Each component is described and its suitability to the FI-CL method discussed. Two detection systems; photomultiplier tube and photodiode, and two flow cell designs; coiled glass and lamina, were compared for their suitability to the method. A charge coupled device was used to obtain the CL spectra of the luminol CL reaction and automation of the FI manifold is also described. Chapters Three and Four describe the optimisation of the FI-CL method and its suitability to the determination of H2O2 in natural waters (river, estuarine and sea). Matrix efifects are investigated and a standard addition procedure described. The analytical figures of merit for H2O2 determination include a limit of detection of 10 nM and a linear range of 10-500 nM. The application of the fully optimised method to the in situ determination of H2O2 in the western Mediterranean is described in Chapter Five. Hydrogen peroxide depth profiles are presented from different geographical areas and diurnal variations in H2O2 concentration discussed. The final experimental chapter investigates the photochemical generation of H2O2 in both synthetic and natural water matrices. Ambient light incubations at sea and artificial light incubations in the laboratory were made.
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Homitz, Joseph. "A Lean-Premixed Hydrogen Injector with Vane Driven Swirl for Application in Gas Turbines." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/36334.
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Hydrogen, as an alternative to conventional aviation fuels, has the potential to increase the efficiency of a gas turbine as well as reduce emissions of greenhouse gases. In addition to significantly reducing the number of pollutants due to the absence of carbon, burning hydrogen at low equivalence ratios can significantly reduce emissions of oxides of nitrogen (NOx). Because hydrogen has a wide range of flammability limits, fuel lean combustion can take place at lower equivalence ratios than those with typical hydrocarbon fuels. <p>
Numerous efforts have been made to develop gas turbine fuel injectors that premix methane/natural gas and air in fuel lean proportions prior to the reaction zone. Application of this technique to hydrogen combustion has been limited due to hydrogen's high flame rate and the concern of the reaction zone propagating into the premixing injector, commonly referred to as flashback. In this investigation, a lean-premixing hydrogen injector has been developed for application in small gas turbines. The performance of this injector was characterized and predictions about the injector's performance operating under combustor inlet conditions of a PT6-20 Turboprop have been made.<br>Master of Science
10
Calisesi, Federico. "The analysis of the injection of hydrogen-oxygen mixtures in gasoline-powered internal combustion engines." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15553/.
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The effects on combustion derived by the blending of hydrogen with traditional fuels adopted for internal combustion engines have been studied. Results derived by emission tests of a gasoline-fed vehicle equipped with a system for the production of hydrogen on-board have been analysed. The energy balance for the engine was evaluated. It demonstrated the increase of fuel consumptions to perform electrolysis process on-board the vehicle. Afterwards, numerical simulations based on a detailed kinetic model have been performed to calculate pollutant emissions produced by methane and iso-octane (which represents gasoline) compared with a mixture composed of 10% mol/mol by hydrogen. Chemical species studied were residual hydrocarbons, nitrous oxides and carbon monoxide. Notable variations of pollutant has not been calculated for methane, wherease iso-octane showed a reduction of the aforementioned pollutants when hydrogen was introduced. In the end operating costs have been analysed. The use of stored hydrogen produced by methane steam reforming found a reduction by 7% of costs, compared to the production via electrolysis.
11
Rüscher, Claus H., Lars Schomborg, and Josef-Christian Buhl. "Thermally controlled water injection into BH 4 -sodalite for hydrogen formation investigated by IR absorption." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-186744.
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Rüscher, Claus H., Lars Schomborg, and Josef-Christian Buhl. "Thermally controlled water injection into BH 4 -sodalite for hydrogen formation investigated by IR absorption." Diffusion fundamentals 12 (2010) 37, 2010. https://ul.qucosa.de/id/qucosa%3A13881.
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Gerke, Udo. "Numerical analysis of mixture formation and combustion in a hydrogen direct injection internal combustion engine." Göttingen Cuvillier, 2007. http://d-nb.info/987455966/04.
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Brazzale, Pietro. "Numerical and experimental study at the pilot scale of the hydrogen injection into liquid sodium by permeation through nickel membrane." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0101.
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Dans le cadre des Réacteurs à Neutrons Rapides refroidis à Sodium (RNR-Na), le contrôle de la contamination du tritium dans les circuits sodium et la maitrise de sa diffusion dans l’atmosphère est fondamentale. Afin de piéger et récupérer le tritium, il est nécessaire de maintenir une quantité minimale d’hydrogène dissous dans le sodium liquide. L’injection d’hydrogène par perméation à travers une membrane dense de nickel a été proposée afin de fournir un apport d’hydrogène continu au flux de sodium liquide et obtenir la concentration en hydrogène souhaitée. Des membranes de nickel similaires ont été conçues dans le passé pour les RNR-Na (hydrogènemètres), mais un manque de connaissance et d’applications demeurent en ce qui concerne l’injection d’hydrogène par perméation. Dans cette étude, un nouveau prototype de perméateur a été conçu et testé expérimentalement à l’échelle pilote dans un circuit sodium expérimental, sous différentes conditions opératoires (température : 375°C-450°C; pression partielle d’hydrogène à l’alimentation : 5 kPa-28 kPa). Un système métrologique dédié a été élaboré, basé sur la chromatographie appliquée au gaz rétentat et couplé à la détection d’hydrogène dans le sodium via un hydrogène-mètre associé à un spectromètre de masse. Il fournit une estimation précise du flux de perméation d’hydrogène transféré de la phase gaz au sodium liquide. Des tests ont été menés en configuration gaz-vide et gaz-sodium : dans les deux cas, le flux de perméation dépend linéairement de la racine carrée de la pression partielle d’hydrogène en alimentation jusqu’à 20 kPa, démontrant ainsi que, dans cet intervalle, le processus est limité par la diffusion de l’hydrogène à travers la membrane de nickel. En particulier, la présence du sodium dans le côté perméat ne semble pas avoir d’influence significative sur le transfert de masse de l’hydrogène. Les résultats, comparés avec la loi théorique de la perméation, fournissent un coefficient de perméabilité expérimental, spécifique à la géométrie et à la configuration du prototype. La comparaison avec les résultats de la littérature, concernant des petits échantillons de nickel, révèle dans cette étude des coefficients de perméabilité légèrement plus élevés ainsi qu’une énergie d’activation plus faible. Cela pourrait s’expliquer par des phénomènes ayant lieu dans le réticule cristallin de la membrane, probablement liés à la déformation à froid subie lors de sa fabrication, avec un impact sur la perméation. Globalement, le processus expérimental a été validé avec succès tout en démontrant la faisabilité de cette application à l’échelle pilote. Un modèle analytique 1D a été développé avec une approche multi-physique, afin d’établir le transfert de masse radial de l’hydrogène à travers les trois domaines physiques : gaz, nickel et sodium liquide. Il utilise des corrélations de référence pour le transfert de masse convectif dans la phase gaz et sodium en géométrie tubulaire, la loi de Sieverts pour les équilibres H-Ni et H-Na, la loi de Richardson pour la perméation de l’hydrogène à travers la membrane de nickel, considérée limitée par la diffusion. Des simulations CFD, réalisées dans une géométrie 2D axisymétrique avec Comsol-Multi-physics, ont fourni une meilleure compréhension des phénomènes de transport ayant lieu et ont confirmé les résultats obtenus par le plus simple modèle 1D sous certaines conditions, spécifiques au prototype expérimental. En conclusion, l’activité expérimentale a montré un bon accord avec le modèle 1D et les simulations CFD tout au long de l’intervalle de température et jusqu’à des pressions partielles d’hydrogène de 20 kPa. En rassemblant les éléments expérimentaux et numériques obtenu par cette étude, une loi constituée d’une simple équation a été définie pour décrire les performances du prototype afin d’aider l’activité de conception de cette application à l’échelle industrielle<br>In the framework of the SFR (Sodium-cooled Fast Reactors), the management of tritium contamination in sodium circuits and the control of its release in atmosphere is fundamental. In order to capture and recover the tritium, it is necessary to maintain a certain amount of hydrogen dissolved in the liquid sodium stream. The hydrogen injection by permeation through nickel dense membranes has been proposed to provide a continuous hydrogen intake to liquid sodium stream, thus allowing the desired hydrogen concentration to be reached. Similar nickel-based membranes have been developed in the past for SFR (i.e. hydrogen-meters), but a lack of knowledge and applications is found for what concerns the hydrogen injection by permeation. In this study, an original permeator prototype has been designed and an experimental activity at pilot-scale has been carried out on an experimental sodium loop, under different operating conditions (temperature: 375°C-450°C; hydrogen supply partial pressures: 5 kPa-28 kPa). A dedicated measurement system, based on the gas chromatography on the retentate side, coupled to the hydrogen detection inside sodium (through a dedicated hydrogen-meter using mass spectrometry), has provided an accurate estimation of the hydrogen permeation flowrate. Tests are carried out for both a gas-vacuum and a gas-sodium configuration: in both cases, the global hydrogen permeation flowrate depends linearly on the square root of the hydrogen partial pressure in the feed side up to 20 kPa, thus demonstrating that the process in this range is limited by the hydrogen diffusion inside the nickel membrane. In particular, the presence of sodium in the permeate side does not affect significantly the whole mass transfer process. The results, compared to the permeation theoretical laws, provide an experimental permeability coefficient, specific to the prototype geometry and configuration. Comparison to values from the literature results for small nickel samples, showed that some metal-lattice phenomenon, probably linked to the membranes deformation by cold-working, could affect the hydrogen permeation in this study. In fact, slightly higher permeation coefficient with a lower activation energy is found here if compared to the literature. Finally, the experimental process has been successfully validated, thus demonstrating the feasibility of this application at the pilot-scale. An analytical 1D model has been set up with a multi-physics approach, in order to assess the radial hydrogen mass transfer in steady conditions over three physical domains, including gas, nickel and liquid sodium. It includes benchmark literature correlations for the convective mass transfer inside gas and sodium phase in tubular geometry, the Sieverts law for the H-Ni and H-Na equilibrium, coupled to the Richardson’s law for the hydrogen permeation through the nickel membrane, assumed to be diffusion-limited. CFD simulations, performed in a 2D axial-symmetric geometry with the software Comsol Multiphysics, have provided a better comprehension of the transport phenomena taking place and have confirmed the results of the straightforward 1D model under certain conditions, specific to the experimental prototype. Finally, the experimental results have shown a good agreement with the 1D model and CFD simulations in the whole temperature interval and up to a hydrogen partial pressure of 20 kPa. By resuming all the elements provided by this study, both at the experimental and numerical stage, a single equation law has been defined to describe the prototype performance and to enhance the industrial scale-up design activity
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Evans, John P. "Experimental Evaluation of the Effect of Inlet Gas Humidification on Fuel Cell Performance." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9597.
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The development and evaluation of a fuel cell test stand incorporating various methods for controlling the temperature and humidity of fuel cell reactants is described. The test stand is capable of accurately metering gas flows, controlling the temperature and humidity of the gases, and delivering the gases to the fuel cell in a safe manner. Additionally, the test stand can measure the voltage and current produced by the fuel cell during operation. Two test stands were constructed and evaluated, one using steam injection for fuel cell stacks and the other using flash evaporation for individual fuel cells. Both test stands were shown to provide adequate control at the upper end of the design range. The flash evaporation test apparatus was used to investigate the effect of inlet gas humidity on fuel cell performance. The results from this investigation showed that, for a fuel cell and reactant temperature of 75°C, the best performance was achieved with a high relative humidity (90%RH) for the hydrogen and a comparatively low relative humidity (60%) for the air.<br>Master of Science
16
Rothstein, Andrew D. (Andrew David). "A study of the normal injection of hydrogen into a heated supersonic flow using planar laser-induced fluoresence." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/43249.
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Bonanos, Aristides Michael. "Scramjet Operability Range Studies of an Integrated Aerodynamic-Ramp-Injector/Plasma-Torch Igniter with Hydrogen and Hydrocarbon Fuels." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28847.
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An integrated aerodynamic-ramp-injector/plasma-torch-igniter of original design was tested in a Mâ = 2, unvitiated, heated flow facility arranged as a diverging duct scramjet combustor. The facility operated at a total temperature of 1000 K and total pressure of 330 kPa. Hydrogen (H2), ethylene (C2H4) and methane (CH4) were used as fuels, and a wide range of global equivalence ratios were tested. The main data obtained were wall static pressure measurements, and the presence of combustion was determined based on the pressure rises obtained.
Supersonic and dual-mode combustion were achieved with hydrogen and ethylene fuel, whereas very limited heat release was obtained with the methane. Global operability limits were determined to be 0.07 < Ï < 0.31 for hydrogen, and 0.14 < Ï < 0.48 for ethylene. The hydrogen fuel data for the aeroramp/torch system was compared to data from a physical 10º unswept compression ramp injector and similar performance was found with the two arrangements. With hydrogen and ethylene as fuels and the aeroramp/plasma-torch system, the effect of varying the air total temperature was investigated. Supersonic combustion was achieved with temperatures as low as 530K and 680K for the two fuels, respectively. These temperatures are facility/operational limits, not combustion limits.
The pressure profiles were analyzed using the Ramjet Propulsion Analysis (RJPA) code. Results indicate that both supersonic and dual-mode ramjet combustion were achieved. Combustion efficiencies varied with Ï from a high of about 75% to a low of about 45% at the highest Ï . With a theoretical diffuser and nozzle assumed for the configuration and engine, thrust was computed for each fuel. Fuel specific impulse was on average 3000 and 1000 seconds for hydrogen and ethylene respectively, and air specific impulse varied from a low of about 9 sec to a high of about 24 sec (for both fuels) for the To = 1000K test condition.
The GASP RANS code was used to numerically simulate the injection and mixing process of the fuels. The results of this study were very useful in determining the suitability of the selected plasma torch locations. Further, this tool can be used to determine whether combustion is theoretically possible or not.<br>Ph. D.
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Feleke, Abisake. "Determination of Cholesterol in Foods by Flow Injection Analysis with Perroxyoxalate Chemiluminescence." Digital Commons @ East Tennessee State University, 2006. https://dc.etsu.edu/etd/2231.
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Cholesterol is an important biological molecule with many important functions. However, high serum cholesterol is a health hazard. Thus analysis of cholesterol is important and many analytical techniques have been developed. The objectives of the proposed research are to develop an economical, rapid method for the determination of total cholesterol with good selectivity and enhanced sensitivity. For evaluation of proposed flow injection analysis with peroxyoxalate chemiluminescence (FIA-POCL) method, figures of merit such as accuracy, precision, and linear dynamic range will be assessed. The proposed procedure was then applied to the determination of total cholesterol in foods. The procedure was linear for cholesterol from 0.01 to 0.120 mg/mL. The relative standard deviation was 2.57%. The recoveries were 97.5-103.3% for commercial standard cholesterol sample, and 101.5-108.0% for butter. The proposed method was applied to analysis of cholesterol in food and the results were consistent with expected values.
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Kroniger, Daniel [Verfasser], Manfred Christian [Akademischer Betreuer] Wirsum, and Thomas [Akademischer Betreuer] Sattelmayer. "Prediction of NO$_\textrmx}$ emissions for a hydrogen fueled industrial gas turbine combustor with water injection / Daniel Kroniger ; Manfred Christian Wirsum, Thomas Sattelmayer." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1192308662/34.
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Duncan, Corey Scott. "Techno-economical modeling of a PtG plant for operational optimization in the context of gas grid injection in France." Thesis, KTH, Kemiteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-288978.
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Klimatförändringar är den enskilt största utmaningen som mänskligheten står inför under 2000-talet. För att ta itu med denna utmaning förutses förnybara energikällor en stor ökning av andelen primärenergi globalt. Den naturliga variabiliteten hos sol och vind kräver att energilagring används tillsammans med dem för en energisystemövergång. Power-to-Gas (PtG) -teknologier erbjuder en attraktiv lösning genom att möjliggöra omvandling av elektrisk energi till vätgas eller metan, vilket möjliggör integration över nätverk och sektorövergripande integration. Denna avhandling undersöker lönsamheten för en PtG-anläggning med enprimär applikation för att producera syntetisk metan (SNG) för injektion av naturgas(NG). En teknik-ekonomisk modell skapades för att simulera anläggningens drift under ett år och extrapolera resultaten för projektets livslängd. Modellen designades baserat på ett pilotprojekt som utvecklades i Frankrike med namnet HYCAUNAIS och har använt partner-samt litteraturdata för bearbetning. På grund av begränsningar i den lokala NG-nätkapaciteten undersöktes era scenarier som inkluderade att lägga till ytterligare investeringar som möjliggör ökad driftstid och intäktsströmmar, inklusive: fast elpris eller day-ahead (DA) marknadsdeltagande; nätuppgradering för ökad NG-nätkapacitet; och CH4 och H2 mobilitet. Elektrolysörers deltagande i frekvensbegränsningsreserven (FCR) ansågs också förökad lönsamhet. Resultaten visade att standardfallsscenariot (inga ytterligare investeringar) med deltagande på DA-elmarknaden var det mest attraktiva när det gäller tre undersökta mål: nettonuvärde (NPV), återbetalningsperiod (PBP) och nivåniserad metankostnad (LCOM). Driftstiden för standardfallet befanns vara cirka 90% av året; produktionen hindrades inte av begränsad nätkapacitet tillräckligt för att anse ytterligare investeringar nödvändiga. Vidare bör deltagande på DA-marknaden bestämmas av en upphörd betalningsvilja (WTP) för el i motsats till marginell vinst (MP). Att använda WTP som avgörande faktor tillät ökade driftstimmar och lägre LCOM. Men i alla undersökta scenarier var inga lönsamma; vilket innebär att marknadsförhållandena fortfarande måste förbättras kraftigt innan PtG kan få fart. En känslighetsanalys gjordes på standardfallsscenariot för att se vilka parametrar som påverkar lönsamheten mest och bör vara i fokus för vidare forskning och utveckling. SNG-taxan visade sig vara den mest inytelserika på NPV, vilket krävde att en tariff på minst 188 e=MWh (120 e=MWh användes för modellering) för att vara lönsam. Elpriset var det näst mest inytelserika och krävde ett genomsnittligt marknadspris på 25 e=MWh för att vara lönsamt. Eftersom PtG-teknik kan ge era externa fördelar som inte realiseras ekonomiskt av investerare, kan intäktsgenerering av dem ge ett sätt att förbättra lönsamheten. Detta inkluderar nätbalansering och exibilitet, avkolning, lägre nätkostnader ochförbättrad energisäkerhet. Sammanfattningsvis måste kapitalkostnaderna för utrustning,elpriser och avgifter i samband med dessa samt taxor för gröna gaser förbättras dramatiskt för att SNG-produktionen ska vara en attraktiv lösning för minskning och avkolning av el.<br>Climate change is the single largest challenge facing humanity in the 21st century. To tackle this challenge, renewable energies are seeing a large increase in primary energy share globally. The natural variableness of solar and wind requires energy storage to be used in conjuction with them for an energy system transition. Power-to-Gas (PtG) technologies offer an attractive solution by allowing conversion of electrical energy to hydrogen or methane, enabling cross-energy-network and cross-sectoral integration. This thesis investigates profitability of a PtG plant with a primary application of producing synthetic methane (SNG) for natural gas (NG) grid injection. A techno-economical model was created to simulate plant operation over one year and extrapolate the results for the project lifespan. The model was designed based off of a pilot project being developed in France named HYCAUNAIS and used partner as well as literature data for processing. Due to limitations inlocal NG grid capacity, several scenarios were investigated that included adding additional investments that allow increased operational time and revenue streams, including: fixed electrical price or day-ahead (DA) market participation; mesh upgrade for increased NG grid capacity; and CH4 and H2 mobility. Electrolyser participation in the frequency containment reserve (FCR) was also considered for increased profitability. The results determined the standard case scenario (no additional investments) with participation in the DA electricity market was the most attractive in terms of three objectives investigated: net present value (NPV), payback period (PBP) and levelized cost of methane (LCOM). The operational hours of the standard case was found to be approximately 90% of the year; production was not hindered by limited grid capacity sufficiently to deem additional investments necessary. Further, participation in the DA market should be determined by a cut-off willingness to pay (WTP) for electricity as opposed to marginal profit (MP). Using WTP as the determining factor allowed increased operational hours and lower LCOM. However, in all of the scenarios investigated, none were profitable; meaning that market conditions still need to greatly improve before PtG can gain momentum. A sensitivity analysis was done on the standard case scenario to see which parameters influence profitability the most and should be the focus of further research and development. The SNG tariff was found to be the most influential on NPV, requiring a tariff of at least 188 e=MWh (120 e=MWh was used for modeling) to be profitable. Electricity price was the second most inuential and required an average market price of 25 e=MWh to be profitable. As PtG technologies can provide several external benefits that are not economically realized by investors, monetization of them could provide a means of improving profitability. This includes, grid balancing and exibility, decarbonization, lower grid costs and improved energy security. Inconclusion, capital costs of equipment, electricity prices and fees associated to them, and tariffs for green gases all need to improve dramatically for SNG production tobe an attractive solution for electricity curtailment and decarbonization.
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GOEL, PRASHANT. "Numerical modelling and analysis of combustion in DI and PFI CNG engines - A study under different EGR dilution and Hydrogen doping conditions." Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2945175.
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Boukarkour, Youness. "Étude de systèmes électro-catalytiques pour l’amélioration des performances de véhicules à moteurs thermiques." Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0081.
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Aujourd’hui, la recherche de solutions énergétiques durables est devenue une préoccupation essentielle due à la crise environnementale que nous vivons, le secteur des transports étant parmi les domaines les plus polluants en raison de l’utilisation des moteurs à combustion interne (MCI). Bien que la transition vers des moteurs électriques est en cours, elle prendra du temps, car ces équipements ne seront pas accessibles à tous et présentent également leurs propres inconvénients. Les MCI vont donc rester d’actualité pendant longtemps malgré les politiques environnementales en cours. Logikko, l’entreprise avec qui nous avons travaillé, a eu l’idée d’accompagner la transition énergétique vers les moteurs électriques en injectant du H2 dans les MCI. Cette injection, même à de petites quantités, peut avoir un effet positif sur les émissions polluantes et sur le moteur lui-même en le gardant propre et efficace. Pour cela, il est nécessaire de produire localement l’hydrogène sous le capot du véhicule en mettant en oeuvre un électrolyseur alcalin qui peut être embarqué sous le capot. Dans ce contexte général, l’objectif de mon travail de thèse CIFRE a été centré sur l’amélioration des électrolyseurs développés par Logikko afin de les rendre plus résistants à la corrosion et aussi plus efficaces sur un plan énergétique. Le chapitre 1 décrit les notions nécessaires pour comprendre les mécanismes de la production de H2 par électrolyse alcaline et les processus qui les régissent. Nous discutons des conséquences de l’injection de ce gaz et du rôle qu’il peut jouer dans la réduction des polluants émis par le moteur. Dans le chapitre 2, nous étudions l’optimisation de l’électrolyte utilisé par l’entreprise, notamment peut réduire la corrosion. Différents matériaux d’électrodes ont été étudiés par voltammétrie cyclique ainsi que par chronoampérométrie. À l’issue de ce chapitre, nous avons proposé deux nouveaux matériaux d’électrodes prometteurs à l’entreprise. Dans le chapitre suivant, nous optimisons l’électrolyseur en changeant sa conception. Pour ce faire, nous avons approfondi le principe de l’électrochimie bipolaire pour identifier le rôle des plaques neutres et leur impact sur l’efficacité de l’électrolyseur. Comme résultat de cette étude, nous avons pu réduire encore plus les effets de la corrosion ainsi que les pertes énergétiques de l’électrolyseur. Poursuivant notre objectif, nous avons envisagé dans le chapitre 4 l’application d’un champ magnétique externe comme une innovation stratégique pour induire des effets magnétohydrodynamiques (MHD). Ils peuvent permettre d’augmenter l’efficacité énergétique de l’électrolyseur et la production d’hydrogène, en ouvrant la voie à des applications innovantes et économiquement viables. Enfin, le chapitre 5 décrit des travaux connexes que nous avons menés en parallèle. Ils concernent la détection du Cr(VI) dans l’électrolyte après un temps de fonctionnement ainsi que des méthodes analytiques utilisant l’électrochimie bipolaire pour analyser rapidement et efficacement le potentiel de matériaux d’électrodes alternatifs en vue de développements futurs<br>Today, the search for sustainable energy solutions has become a key concern due to the environmental crisis we are experiencing, with the transport sector among the most polluting areas due to the use of internal combustion engines (ICEs). While the transition to electric motors is underway, it will take time, as this equipment will not be accessible to everyone, and also has its own drawbacks. Therefore, despite current environmental policies, ICEs will still be around for a while. Logikko, the company we worked with, came up with the idea of supporting the energy transition by injecting H2 into ICEs. This injection, even in small quantities, can have a positive effect on pollutant emissions and on the engine itself, keeping it clean and efficient. To achieve this, it is necessary to produce hydrogen locally using an alkaline electrolyser that can be fitted under the hood of the vehicle. In this general context, the aim of my CIFRE thesis work was to improve the electrolysers developed by Logikko to make them more resistant to corrosion and also more energy efficient. Chapter 1 describes the concepts needed to understand the mechanisms of H2 production by alkaline electrolysis and the processes that govern them. We discuss the consequences of injecting this gas and the role it can play in reducing the pollutants emitted by the engine. In Chapter 2, we look at how the electrolyte used by the company can be optimised to reduce corrosion. Different electrode materials were studied using cyclic voltammetry and chronoamperometry. At the end of this chapter, we proposed two promising new electrode materials to the company. In the following chapter, we optimise the electrolyser by changing its design. To do this, we have delved into the principle of bipolar electrochemistry to identify the role of neutral plates and their impact on electrolyser efficiency. As a result of this study, we were able to further reduce the effects of corrosion and energy losses in the electrolyser. Pursuing our objective, in Chapter 4 we considered the application of an external magnetic field as a strategic innovation for inducing magnetohydrodynamic (MHD) effects. These can help increase electrolyser energy efficiency and hydrogen production, paving the way for innovative and economically viable applications. Finally, Chapter 5 describes related work we have been carrying out in parallel. These deal with the detection of Cr (VI) in the electrolyte after an operating time, as well as analytical methods using bipolar electrochemistry to rapidly and efficiently analyse the potential of alternative electrode materials for future developments
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Zhang, Wei. "Development of Photochemically Initiated Direct and Indirect Luminescence Detection Methods for Liquid Chromatography (LC) and Study of Aromatic Sulfonates and Phospholipids Using Reversed Phase Ion-Pair LC-Mass Spectrometry." Miami University / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=miami1068739487.
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MUSCOLINO, Emanuela. "Polysaccharide hydrogels for regenerative medicine applications." Doctoral thesis, Università degli Studi di Palermo, 2022. http://hdl.handle.net/10447/535885.
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Sykes, David Michael. "Design and Evaluation of a Lean-Premixed Hydrogen Injector with Tangential Entry in a Sector Combustor." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/31722.
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Hydrogen use in a gas turbine engine has many benefits. Chief among these is the elimination of carbon based emissions. The only products and emissions from the combustion process are water vapor and oxides of nitrogen (NOx). However due to the lower flammability limit of hydrogen, it can be burned at much lower equivalence ratios that typical hydrocarbon fuels, and thus reducing the emissions of NOx. Multiple efforts have been made for the design of premixing injectors for gaseous hydrocarbon fuels, but very few attempts have been made for hydrogen.
<p> To this end a premixing hydrogen injector was designed for the cruise engine condition for a PT6-20 turboprop engine. Swirl generated by tangential entry was utilized as a means to enhance mixing and as a convenient means to stabilize the flame. A prototype was designed to prevent flashback and promote a high degree of mixing, as well as a test combustor to evaluate the performance of the injector at scaled engine conditions. Numerical simulations were also performed to analyze the flowfield at the engine conditions. Performance and emissions data are used to draw conclusions about the feasibility of the injectors in the PT6 engine.<br>Master of Science
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Wang, Hua. "COMPUTATIONAL INVESTIGATION OF TRANSMURAL DIFFERENCES IN LEFT VENTRICULAR CONTRACTILITY AND HYDROGEL INJECTION TREATMENT FOR MYOCARDIAL INFARCTION." UKnowledge, 2017. http://uknowledge.uky.edu/me_etds/92.
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Heart failure (HF) is one of the leading causes of death and impacts millions of people throughout the world. Recently, injectable hydrogels have been developed as a potential new therapy to treat myocardium infarction (MI). This dissertation is focused on two main topics: 1) to gain a better understanding the transmural contractility in the healthy left ventricle (LV) wall and 2) investigate the efficacy of the hydrogel injection treatment on LV wall stress and function. The results indicate that a non-uniform distribution of myocardial contractility in the LV wall provide a better representation of normal LV function. The other important study explored the influence altering the stiffness of the biomaterial hydrogel injections. These results show that a larger volume and higher stiffness injection reduce myofiber stress the most and maintaining the wall thickness during loading. The computational approach developed in this dissertation could be used in the future to evaluate the optimal properties of the hydrogel. The last study used a combination of MRI, catheterization, finite element (FE) modeling to investigate the effects of hydrogel injection on borderzone (BZ) contractility after MI. The results indicate that the treatment with hydrogel injection significantly improved BZ function and reduce LV remodeling, via altered MI properties. Additionally, the wall thickness in the infarct and BZ regions were significantly higher in the treated case. Conclusion: hydrogel injection could be a valuable clinical therapy for treating MI.
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Pitorre, Marion. "Développement de deux plateformes pharmaceutiques gélifiées : un hydrogel de nanocapsules lipidiques et un organogel avec le même agent de réticulation." Thesis, Angers, 2017. http://www.theses.fr/2017ANGE0074/document.
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Une nouvelle plateforme hydrogel uniquement formée par l’association de nanocapsules lipidiques (NCLs) a été développée en s’inspirant de précédents travaux utilisant une gemcitabine modifiée. Afin de limiter la toxicité de l’hydrogel, la gemcitabine a été remplacée par la cytidine, rendue amphiphile par une chaîne aliphatique (Cyt-C16). Placée à l’interface huile/eau des NCLs, la Cyt-C16 permet la formation d’un réseau tridimensionnel de NCLs à l’origine de la gélification. Un plan de mélange a permis d’optimiser les procédés de formulation de 4 tailles de NCLs modèles. Les propriétés viscoélastiques des hydrogels sont modulables. Plus les concentrations en NCLs et Cyt-C16 sont élevées, plus le gel est « rigide », indépendamment de la taille des NCLs qui doit être supérieure à 50 nm pour permettre la gélification. Les hydrogels sont injectables et permettent une libération prolongée de NCLs (de taille mono-disperse), sans toxicité supplémentaire in vitro, du fait de la présence de la Cyt-C16. De plus, uniquement solubilisée dans l’huile,la Cyt-C16 permet d’obtenir un organogel, dont les propriétés viscoélastiques sont renforcées en augmentant sa concentration. L’injection sous-cutanée (SC) in vivo des deux gels est bien tolérée et entraine une réaction inflammatoire locale comparable à celle provoquée par un excipient pharmaceutiquement acceptable. Ces deux formes pourront être utilisées pour libérer de façon prolongée différents actifs. Deux applications précliniques des hydrogels ont été explorées, l’une utilisant la voie SC pour cibler les ganglions lymphatiques, la seconde permettant un traitement local des suites opératoires d’une résection de glioblastome<br>An innovative hydrogel platform obtained by the association of lipid nanocapsules (LNCs) was based on the previous work on modified gemcitabine. To limit the inherent toxicity of the hydrogel, gemcitabine was replaced by cytidine, then modified by an aliphatic chain (Cyt-C16). The hydrogel network was allowed by H-bond interactions between cytidine moieties exposed at the oil/water interfaces of LNCs. An experimental plan provided the formulation processes for 4 optimized sizes of model LNCs. The gelation was only possible for LNC sizes higher than 50 nm, and the hydrogel viscoelastic properties are versatile. The hydrogel is more “rigid” when LNC and Cyt-C16 concentrations increase, independently of the LNC size. The hydrogels are injectable and allow a sustained release of LNCs (withmonodisperse size), without additional in vitrocytotoxicity due to Cyt-C16. Moreover, when solubilized in oil, Cyt-C16 alone produced an organogel platform, whose viscoelastic properties are strengthened increasing its concentration. Both types of gels showed a good biocompatibility after an in vivo subcutaneous (SC) injection, with a local inflammatory response similar to that of induced by an approved excipient. These two forms could be used to sustain the release of various drugs, and two preclinical applications of hydrogels have been explored : one using the SC route to target lymph nodes, and the second for local treatment after glioblastoma resection
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Urbahn, John A. (John Arthur). "The design and performance of a twenty barrel hydrogen pellet injector for Alcator C-Mod." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11627.
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Mochalskyy, Serhiy. "Modeling of the negative ion extraction from a hydrogen plasma source : application to ITER neutral beam injector." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00672140.
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The development of the negative ion source constitutes a crucial step in the construction of the neutral beam injector of ITER. To fulfil the ITER requirements in terms of heating and current drive, the negative ion source should deliver 40 A of D-. The achievement of such a source is challenging from technical and scientific points, and it requires a deeper understanding of the underlying physics. The present knowledge of the ion extraction mechanism from the negative ion source is limited due to the complexity of the problem that involves the comprehension of the behaviour of magnetized plasma sheaths when negative ions and electrons are pulled out from the plasma. Moreover, due to the asymmetry induced by the crossed magnetic configuration used to filter the electrons, any realistic study of this problem must consider the three spatial dimensions. To address this problem in a realistic way, a 3D Particles-in-Cell electrostatic code specifically designed for this system was developed. The code uses Cartesian coordinate system and it can deal with complex boundary geometry as it is the case of the extraction apertures. The complex magnetic field that is applied to deflect electrons is also taken into account. This code, called ONIX, was used to investigate the plasma properties and the transport of negative ions and electrons close to a source extraction aperture. Results on the formation of the plasma meniscus and the screening of the extraction field by the plasma are presented here, as well as negative ions trajectories. Negative ion extraction efficiency from volume and surfaces was investigated showing the capital importance of the surface negative ion production.
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Wang, Hua. "Computational Investigation of Injectable Treatment Strategies for Myocardial Infarction." UKnowledge, 2014. http://uknowledge.uky.edu/me_etds/33.
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Heart failure is an important medical disease and impacts millions of people throughout the world. In order to treat this problem, biomaterial injectable treatment injected into the myocardium of the failing LV are currently being developed. Through this treatment, the biomaterial material injections can reduce wall stresses during the cardiac remodeling process. By using computational techniques to analyze the effects of a treatment involving the injection of biomaterial material into the LV after MI, the material parameters of the hydrogel injections can be optimized. The results shows that the hydrogel injections could reduce the global average fiber stress and the transmural average stress seen from optimization. These results indicated that the hydrogel injections could influence the stiffness in passive LV tissue, but there is still need for more research on the active part of ventricular contraction. Conclusion: hydrogel injection is a viable way to alter ventricular mechanical properties.
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Overend, Elizabeth. "Structural design and CFD modelling of a new type of hydrogen fuel injector for internal combustion engine applications." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/12743.
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A new type of fuel injector, incorporating a steel, annular diaphragm as the open/close device has been designed. This design would avoid sliding contact between components and exhibit low wear when metering hydrogen fuel. Further, it has been shown by simulation that the injector can a designed to withstand cyclic stresses and deliver hydrogen fuel at a rate suitable for direct injection to the cylinder of an IC engine. Investigation of the possibility of incorporating a pump in the injector unit to provide elevated pressure shows that a minimum of 3.4% of the fuel energy supplied would be required to power hydrogen compression. Structural analysis of the clamped diaphragm component shows that bending stress would be at least 236 MPa when sufficient deflection is achieved. Material such as spring steel, with a high yield strength and fatigue endurance limit, would need to be used to avoid failure. CFD analysis of compressible flow models of two commercial injectors shows good agreement with published data, indicating the expected linear relationship of mass flow rate to supply pressure in the super-sonic range. A model of a commercial annular plate injector on which the new design is based indicates mass flow rate up to 50% lower than published data, and the model indicates a discharge coefficient of 22%. This is the result of key differences between actual and modelled injector geometries. Good agreement between results of a CFD model of the diaphragm injector geometry and compressible flow theory is obtained. These results show agreement of the relationship between back pressure and shock wave formation, and sub- and super-sonic mass flow rate-pressure relationship. The model suggests that 66 bar supply pressure would be required to achieve the highest design mass flow rate of 23 g/s, and that the discharge coefficient of the new injector design would be 90% under these conditions.
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CARFAGNA, GIUSEPPE. "Integrated energy interchange platform between green system of smart housing and smart mobility." Doctoral thesis, Università degli Studi di Camerino, 2018. http://hdl.handle.net/11581/408083.
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In recent years, the need for personal urban mobility has increased a lot especially in emerging and developing countries. It becomes increasingly important to explore propulsion systems that use alternative energy sources and are related to the chain of production, storage and use of renewable energy. Several studies have been conducted in this area, but very few have achieved solutions for the interaction of the vehicle with the building by which it is parked in terms of a multi-energy exchange. Technological innovation of house plant parts, of large residences / hotels, of shelter stations for vehicles, it is now crucial to implement the integration of more renewable energy sources within the same building structure: this is one of the aspects covered by the most general definition of "Smart Housing". Sustainable mobility is perceived as a strong need to match individual urban and sub-urban mobility, to the least environmental and social impact of such personal need.
This research project proposes a possible scenario for energy integration between smart housing and smart mobility using a common energy platform that allows self-generation, storage and energy exchange between residential district buildings and smart vehicles. The project integrates multidisciplinary approaches with the aim of designing, evaluating technical and industrial feasibility for the development of: 1) Modular and scalable energy storage devices dedicated to a smart house. 2) a modular city vehicle, with high flexibility of use, with energy storage system and energy-efficient switching capabilities with smart building.
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Sacadura, Jean-Christian. "Etude expérimentale des flammes non-prémélangées hydrogène-oxygène. Caractérisation des champs dynamiques et scalaires." Rouen, 1997. http://www.theses.fr/1997ROUES045.
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Les flammes non-prémélangées hydrogène-oxygène stabilisées sur des injecteurs de type coaxial ont été étudiées. La technique de vélocimétrie Doppler laser a été utilisée pour caractériser les champs dynamiques. La tomographie laser a permis de visualiser la structure interne du jet d'oxygène. Les mesures des composantes de vitesse et des fluctuations associées réalisées sur trois injecteurs différents ont révélé l'existence de trois zones principales dans les flammes non-prémélangées hydrogène-oxygène : -la zone du jet d'oxygène -la zone de réaction -la zone d'expansion les effets de la température sur l'augmentation de la vitesse et sur l'atténuation ou la production de la turbulence ont été mis en évidence. Parallèlement les visualisations du jet d'oxygène ont montré l'influence de la turbulence de l'écoulement sur la structure globale de la flamme. La dissymétrie des profils moyens de fluorescence, nous a permis de calculer le coefficient d'atténuation et de déduire le coefficient d'absorption. Les valeurs moyennes du OH dans la flamme ont contribué à l'estimation de la population du niveau pompé et de la concentration totale du radical OH intégré sur la zone de réaction.
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Colin, Pascal. "Analyse statistique d'images de fluorescence dans des jets diphasiques." Rouen, 1998. http://www.theses.fr/1998ROUES069.
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La nature quantitative, en terme de concentration locale, de la fluorescence induite par laser a permis de réaliser des études statistiques des images dans la zone de développement proche de l'injecteur de jets diphasiques coaxiaux avec ou sans combustion. Quand elle est superieure a trois diamètres d'injection, la longueur du dard liquide est gouvernée par le rapport des pressions dynamiques entre le gaz et le liquide injectes. Cependant l'étude de l'aire interfaciale du dard et l'examen des champs de vitesse instantanés du liquide montrent l'existence d'un régime avec troncature du dard. La fraction volumique et la probabilité de présence de liquide ont été analysées selon un schéma simplifié où le spray est localement décrit comme un réseau régulier de gouttes sphériques identiques. A Weber d'injection constant, la taille et la densité de ces gouttes équivalentes évoluent spatialement de façon très différentes selon la vitesse d'injection du liquide. Une technique originale a permis de mesurer de façon cumulative la PDF de la fraction volumique de liquide en tout point de l'écoulement : la distribution obtenue comporte en deux pics d'intermittence encadrant une fraction turbulente continue. Dans le cas où l'atomisation est véritablement gouvernée par l'écoulement gazeux, la fraction turbulente du spectre prend rapidement du poids et elle peut être décrite par une simple fonction d’Arrhenius à un paramètre local unique. Un simple changement de variable met en évidence la forme canonique de cette distribution et l'application des principes généraux de la physique statistique fournit le nombre de degrés de liberté des éléments du spray en tous points du champ. Cette approche prometteuse ne demande aucune hypothèse sur la forme des éléments liquides et il semble que la variable réduite utilisée soit directement reliée à l'énergie potentielle d'interaction des éléments par l'intermédiaire de la densité d'interface. La fluorescence de l'oxygène chaud induite par une nappe laser UV dans le banc cryogénique mascotte alimente en GH 2/LOx, nous a fourni des images instantanées de la surface réactive de combustion non prémélangée. Une analyse de cette surface en terme de probabilité de présence, de taux plissement et de courbure locale est proposé afin de confronter aux modèles de combustion turbulente à chimie rapide.
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Vandevraye, Mickael. "Microscopie et spectroscopie de photodétachement; mesure de la section efficace de photodétachement de H- à 1064 nm par observation du comportement asymptotique du régime saturé." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00932446.
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Dans cette thèse, nous initions la démonstration, à échelle réduite, de la faisabilité du photodétachement presque total, par laser, d'un jet d'ions négatifs d'hydrogène en cavité optique Fabry-Perot pour les futurs injecteurs de neutres destinés au chauffage des plasmas des réacteurs de fusion nucléaire.Nous élaborons une nouvelle méthode de mesure d'une section efficace de photodétachement, dont la connaissance à la longueur d'onde d'excitation est requise pour le dimensionnement de la cavité Fabry-Perot, basée sur l'observation de la saturation en régime d'éclairement impulsionnel. Le calcul analytique de l'accroissement du signal de détachement produit lors de l'éclairement d'un jet d'ions par une impulsion laser supposée gaussienne, fait apparaître une contrainte mathématique sur le flux requis pour transiter vers le régime saturé. Cette contrainte est une caractéristique de la transition vers la saturation pour toutes les expériences réalisées en faisceau gaussien et pour tous les processus d'interaction lumière-matière linéaires. Avec cette méthode, nous déduisons une section efficace de photodétachement de H- à 1064 nm - longueur d'onde sélectionnée pour les futurs injecteurs de neutres - en léger désaccord avec les prédictions théoriques.Pour réduire les exigences technologiques sur la cavité et le laser, nous étudions les résonances de Landau qui apparaissent dans le spectre de photodétachement en champ magnétique. S'asservir sur l'une de ces résonances permettrait d'augmenter la probabilité de photodétachement à un flux donné.Par ailleurs, nous présentons nos mesures des affinités électroniques du phosphore, du sélénium et de l'étain, réalisées avec le microscope de photodétachement. L'expérience de microscopie de photodétachement du phosphore est la première où l'atome neutre est laissé dans un terme excité.
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Foster, Matthew. "Design of a hydrogen injection system for a prechamber hydrogen-fueled internal combustion engine." 2009. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=958055&T=F.
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Hsieh, Ming-Fong, and 謝明峰. "Experimental study of hydrogen direct injection spark ignition engine." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/61958709169998335777.
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碩士<br>逢甲大學<br>機械工程學所<br>97<br>This study chooses the hydrogen direct injection on the performance of the hydrogen engine to explore. The experiment engine adopts single cylinder and four strokes which converts gasoline fuel into hydrogen fuel.
Moreover , modified on the engine, installed fuel injection systems,control systems, air intake system and power measuring device.
Experimental results show that fuel injection timing in the intake stroke (270-300ObTDC) can successfully start the hydrogen engine, WOT status and hydrogen injection pressure 60bar amount maximum speed 2200rpm.That is disagreed with default target of 3600rpm. The major cause of ignition timing is not correct, when equivalence ratio changes ignition timing could not in the maximum torque (MBT) sparking. Followed by reasons include fuel injection pressure could not be changed with the equivalence ratio and the control circuit trigger signals as may be
unstable.
This thesis discuss our experimental results with references , discussion of the ignition timing, injection pressure, control circuit and the relationship between the experimental results. This research is insufficient
ignition timing angle to crank angle 20O not yet reached the goal of the experiment caused.
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謝宗燁. "Study of Combustion Effects for Hydrogen Injection in Scramjet Engine Combustor." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/89420493458057462392.
Full textAbstract:
碩士<br>逢甲大學<br>航太與系統工程學系<br>103<br>This study describes using the finite volume method to solve Reynold average Navier-Stokes Equations, in order to simulates the flow field of external intake compression ramp to the internal combustion chamber on a supersonic combustion ramjet engine(Scramjet Engine). And this thesis uses non-premixed combustion model to simulate the combustion reaction process of supersonic combustion.
The operation theory of supersonic combustion ramjet engine is that in hypersonic flight conditions, air compressed by shock waves pass into the combustion chamber and produce combustion reaction with fuel. The flow through nozzle exchange for thrust at last. This research focuses on the phenomena of heat flow in the combustion chamber when the fluid combusts in the supersonic conditions. Previous study observes the sequence of external shock wave development through two dimension unsteady simulations with non-fuel injection. After that, the research observes the influence of Hydrogen injection velocity interact the combustion field by maintaining the total pressure and total temperature of fuel and changing the injection mach number to 2.5, 2.75, 3.0. This study discovers injection speed influence the deflection angle of shock wave. It indirectly affects times of shock reflection and merged position on the wall. The injection velocity also affects the thickness of the flame. Hydrogen injects more faster, the flame thickness become thinner.
The research further explores a three-dimensional combustion chamber, and uses unsteady simulation to observe the shape of flame in the three-dimensional supersonic combustion flow field. Then we acquire the combustion phenomena of profile section through the presentation of streamlines for the combustion chamber along the axial channel. This research discovers the supersonic combustion flow patterns closely linked with shock waves reflection and intersection.
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Ya-ChuChang and 張雅筑. "Observation of Supersonic Airflow over Backward-Facing Step with Hydrogen Injection." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75686649409884651716.
Full textAbstract:
碩士<br>國立成功大學<br>航空太空工程學系碩博士班<br>101<br>The efficient injection, mixing and combustion process inside the combustor have been the key elements of supersonic combustion ramjet (scramjet). This study is focused on how the backward-facing step model affects the mixing efficiency of free-stream and hydrogen jet in supersonic flow and the self-ignition process.
The study used the reflected shock tunnel re-equipped to double-diaphragm operation to replicate the scramjet combustor environment while the flight speed reaches Mach 6. The high enthalpy flow is provided by the impulse facility and by means of the Mach 2 nozzle, the test condition of free-stream is Mach 2, total temperature 1950 K, total pressure 9.2 bar, static temperature 1220 K, static pressure 1.2 bar. The hydrogen in room temperature is injected into supersonic flow by the high speed solenoid valve. The jet orifice is located at the bottom wall of the backward-facing step model and is 2 times of the step height away from the step corner. Schlieren image and OH-chemiluminescence methods are applied in this study to observe the flow feature and the combustion region.
The schlieren image shows that, the baroclinic torque induced by the recompression shock of the backward-facing step, rolls up the fuel on the model surface and thus has positive effect on the fuel-air mixing. And from the OH-chemiluminescence images, the ignition reactions take place at the top of the jet.
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Huang-JhihZhuang and 莊閎智. "Evaluation on Liquid Fueled with Hydrogen Injection Micro Turbine Engine Performance." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/13044034996328154947.
Full textAbstract:
碩士<br>國立成功大學<br>航空太空工程學系碩博士班<br>101<br>The purpose of this research is to inject hydrogen into a turbine engine which consumes liquid fuel (JP-8) as major fuel. The turbine engine is composed with a turbocharger (TD-08) and a combustor which is designed in laboratory. In all stations there are 5 thermocouples and 4 pressure sensors installed. The exhaust extractor combines with gas analyzer which is installed outside the turbine exit. Amount of hydrogen (7.67L/min~71.8L/min)less than 6% based on total heat of fuel are injected into the combustor in order to examinate the influence of combustion performance by monition parameters like temperature, pressure, RPM, and its exhaust(CO, HC and NOx), etc.
From results of this research, it was found out that with hydrogen injection the high temperature area moves upstream in the combustor which can verify hydrogen enhancing combustion process. Furthermore, its trends of CO, HC, NOx concentration can be expected downward with hydrogen injected into the turbine engine. There is 56% decrease of CO,78% decrease of HC and 44% reduction of NOx. In summary, hydrogen injection does enhance combustion performance in micro turbine engine even with only 6% in total heat addition.
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Lin, Lu-Hung, and 林律宏. "A study of heat transfer models in the direct injection hydrogen engine." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/48w579.
Full textAbstract:
碩士<br>中原大學<br>機械工程研究所<br>102<br>In consideration of petroleum shortage and global warming is getting worse. Therefore, countries of the world dedicated to develop alternative fuels which applying to internal combustion engine, in order to reduce consumption of fossil fuel and emission of greenhouse gas. Hydrogen fuel has been assessed to a well potential solution on internal combustion engine all over the world. Furthermore, as hydrogen fuel is depleted, it is almost zero pollution and has higher thermal efficiency than petrol, diesel and natural gas in internal combustion engine.
In this study, we utilized GT-Suite which is simulation software for internal combustion engine to investigate the heat transfer phenomena of direct injection hydrogen engine. The software verified the cylinder pressure, maximum pressure, indicated mean effective pressure, Brake Torque, and mass fraction burned of hydrogen engine. Finally, with the points above, we extended discussion to heat transfer coefficient.
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Liou, Wei-Zan, and 劉威瓚. "Analysis of the Performance in Injection Engine with Hydrogen and Gasoline Fuels." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/16624059196044118717.
Full textAbstract:
碩士<br>中原大學<br>機械工程研究所<br>103<br>Abnormal climate changes have been noticed increasingly because of various catastrophic phenomena attributable to the intensive use of fossil fuels. Abnormal climate changes have led to the occurrence of numerous unanticipated catastrophes, which severely influence the economy and threaten people’s lives and properties. To address global warming and the greenhouse effect, this study proposes using hydrogen fuel as an alternative to fossil fuels, which can serve as an ecofriendly energy source to protect the earth’s resources and render the earth a sustainable living place.
Considering the severity of the greenhouse effect, this study applied GT-Power, a simulation software which can be used to simulate the operation of internal combustion engines, to mimic the performance of common intake port injection engines fueled by fossil fuels and hydrogen. Subsequently, GT-Post software was used to analyze the exhaust gas emission, heat transfer efficiency, and power output of the simulated engines. The results revealed that the operation of the hydrogen-fueled engine emitted nearly zero emission pollutants. Moreover, the hydrogen-fueled engine emitted 1000 ppm less nitrogen oxides than did the gasoline-fueled engine. However, under the same operating condition, the hydrogen-fueled engine produced lower heat values per unit volume than did the gasoline-fueled engine because of the density difference between hydrogen and gasoline. Therefore, the power output of the hydrogen-fueled engine was approximately 80% of that of the gasoline-fueled engine. In this context, people must trade-off between engine power output and maintaining an energy-saving ecofriendly environment.
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Belanger, Jacques. "Studies of mixing and combustion in hypervelocity flows with hot hydrogen injection." Thesis, 1993. https://thesis.library.caltech.edu/3197/1/Belanger_jj_1993.pdf.
Full textAbstract:
<p>The ability to build an air-breathing single-stage-to-orbit propulsion system requires examination of key elements such as turbulent mixing rates, especially at the "zero shear" fuel-air mixing condition, and combustion efficiency. The required data can only be obtained in experiments which simultaneously match the flight total pressure and total enthalpy as well as the fuel conditions. GALCIT, with its new free piston shock tunnel T5, has the capability to do some of these combustion experiments. But prior to these tests, it was felt that there was a need to simulate the gas dynamical processes in the free piston shock tunnel and also in a new combustion driven shock tunnel built for these experiments so that both systems could be used as efficiently as possible. The numerical code helped explain the piston motion in the free piston shock tunnel. The code was also very useful for the design of the combustion driven shock tunnel.</p>
<p>Because hydrogen has to be injected into the combustion chamber of the propulsion system after being used as a cooling fluid, a combustion driven shock tunnel was built to reproduce this "hot" hydrogen fuel. The system has been used successfully to supply hydrogen at up to 1500 K for the experiments. To reduce the complexity of the problem, a very basic configuration for the hydrogen injection system was tested. This was first done with an injection system mounted flush with the surface of a flat plate in the test section of T5. Different test conditions as well as Mach 2 and 5 nozzle injectors at angles of 15° or 30° were tested to determine criteria for significant combustion. Lower limits in pressure and enthalpy were found where hydrogen combustion becomes very limited using this "hot" hydrogen fuel. The second set of experiments still used an injection system mounted flush with the surface but involved a small combustor model previously tested in the hypervelocity HYPULSE facility. Low pressure experiments were performed to reproduce some of the HYPULSE tests and excellent agreement was found. Experiments at high pressure were also performed to better match the real flight total pressure and some hydrogen combustion was detected in these tests.</p>
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Adolfo, Dominique. "Modelling and simulation of natural gas distribution networks in the presence of hydrogen injection." Doctoral thesis, 2020. http://hdl.handle.net/2158/1213924.
Full textAbstract:
The 2050 long-term strategy, defined by the European Commission, leads towards zero greenhouse gas emissions by 2050. Reduction of carbon dioxide emissions can be achieved substituting high carbon fossil fuels (coal and oil) with natural gas, renewable sources and green fuels. In the next years, the gas system will play a central and crucial role in the global energy market. Due to modifications of international gas trade flows and rise of demand, the existing gas infrastructures will necessarily have to be expanded, upgraded and renovated in the immediate future. Furthermore, power-to-gas technology is a potential solution to support and accelerate the penetration of renewable sources and the decarbonization of the energy sector. The excess of power generated by renewable energy sources is used by power-to-gas facilities to produce alternative green fuels. The resulting gas, such as hydrogen or synthetic natural gas, can be injected and stored into the existing gas grid. Subsequently, the green low/zero-carbon fuel blended with the traditional natural gas would enable to reduce carbon dioxide emission of industrial, commercial and residential gas customers.
In this new scenario, it is essential to study, model and simulate the integration and operation of gas networks in the energy system. It is also very important to evaluate the impact of alternative fuel injections on the properties and composition of the gas delivered to the users connected to the gas grid.
In this thesis, a steady-state and dynamic one-dimensional gas network tool, named "Gas Network Solver", is developed. The research focuses on mathematical modelling of city gate station (source), pipe, reducing station, valve, demand node and interchange node elements, which compose a gas distribution network. Particular attention is dedicated to the implementation of the mathematical model of the gas and the algorithm for quality tracking in order to analyse and simulate multiple types of gas sources.
The tool proposed is validated by comparing results of three test cases to solutions obtained with a commercial software application, named "Scenario Analysis Interface for Energy Systems" (SAInt), and data from other models available in the literature.
Finally, a case study considering a real medium-pressure and low-pressure gas distribution network, composed by about 2289 elements and located in a hilly area of central Italy, is analysed. After the simulation and analysis of the network in the actual scenario, a possible solution to decarbonize the network is carried out. The installation of a power-to-gas facility, associated effects on behaviour of the network and quality of the gas delivered are studied. The investigation also aims to evaluate the maximum amount of hydrogen injectable respecting gas standards defined by the Italian Regulatory Authority for Energy, Networks and Environment.
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Geh, Martin. "Development of analytical & optimization tools for double-acting hydrogen direct injection technology." Thesis, 2008. http://hdl.handle.net/1828/2495.
Full textAbstract:
One of the market leaders in hydrogen injection systems for internal combustion engines has developed double acting direct injection technology for a wide range of fuel pressures. This thesis outlines the development and validation of a solenoid model which predicts static magnetic forces as well as the development of a dynamic lift model which predicts injector motion and impact forces. The solenoid force model found that iron cobalt can be replaced by iron silicon materials as there performance is comparable. The dynamic lift model shows that the seat and stop impact forces can be calculated which allows engineers to optimize injector designs before prototypes are built. These models allow engineers to optimize the performance and geometric parameters of the double acting technology in preparation of series production.
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Chen, Jyun-Lin, and 陳鈞琳. "The Study on Using Mixed Hydrogen Fuel in Multi-point Injection SI Engine." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/01425756279638191457.
Full textAbstract:
碩士<br>大葉大學<br>車輛工程學系碩士班<br>95<br>Due to the impending depletion of fossil fuels on earth, new and alternative energy sources are important issues both for industry and household. Among the frequently addressed alternative fuel, hydrogen energy definitely deserves the most attentions. There are two problems to overcome before it can be commercially accepted：1.high cost in the production of hydrogen, 2.safety and reliability in the storage and transportation of hydrogen. Hydrogen is a secondary energy fuel. It can not be obtained directly from the planet. The industrial production of hydrogen is energy consuming and therefore expensive. The low boiling temperature, volatile and flammable become the keys to the storage and transportation of hydrogen energy. In this thesis, the performance of a multiple injection spark ignitron engine with the introduction of hydrogen fuel mixed with the original fuel-gasoline or LPG was studied. It is found that the introduction of hydrogen into the fuel supply system improves the combustion inside the combustion chamber. Without reducing the output horsepower and torque, the emission in 1%~2% CO, 1%~20% CO2 and 15%~24%HC etc. is decreased. It is demonstrated that the use of hydrogen fuel can increase the power output and help to decrease the global warming of the earth in the long term.
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Biju, Kumar K. S. "Role Of Hydrogen Injection Temperature On The Combustion Instability Of Cryogenic Rocket Engine." Thesis, 2012. http://etd.iisc.ac.in/handle/2005/2297.
Full textAbstract:
Physical mechanism for high frequency instability in cryogenic engines at low hydrogen injection temperature has been a subject of debate for long time. Experimental and early developmental studies revealed no instabilities and it was only much later when liquid hydrogen at lower initial temperature (~50 to 100 K) was injected into the combustion chamber that instabilities were detected. From the compilations of the experimental data related to the instability of cryogenic engines by Hulka and Hutt, it was found that the instability was strongly connected to the temperature of hydrogen. Experiments conducted with hydrogen temperature ramping from a higher value to lower values indicated that the temperatures in excess of 90 K favor stability under most practical operating conditions. Even though this has been known for over forty years, there has been no clear and simple explanation for this. Many physical mechanisms have been hypothesized to explain how temperature ramping causes instability, but all appear to have limited range of applicability. Current understanding of cryogenic engine combustion instability has been achieved through a combination of experimental investigation and approximate analytical models as well as CFD tools.
Various researchers have tried to link the low hydrogen injection temperature combustion instability phenomena with various potential mechanisms for combustion instability. They involve coupling of combustion acoustics with atomization, vaporization, mixing, chemical kinetics or any combination of these processes. Various studies related to the effect of recess, injector hydrodynamics, acoustic damping of gas liquid scheme injectors and effect of drop size distribution on the stability characteristics of cryogenic engines were compiled in the thesis. Several researchers examined fuel droplet vaporization as the rate controlling mechanism. Recently a new method for the evaluation of stability characteristics of the engine using model chamber were proposed by Russians and this is based on mixing as the rate controlling mechanism. Pros and cons of this method were discussed. Some people examined the combustion instability of rocket engines based on chemistry dynamics. A considerable amount of analytical and numerical studies were carried out by various researchers for finding out the cause of combustion instability. Because of the limitations of their analysis, they could not successfully explain the cause of combustion instability at low hydrogen injection temperature. A compilation of previous numerical studies were carried out. A number of researchers have applied CFD in the study of combustion instabilities in liquid propellant rocket engines. In the present thesis, a theoretical model has been developed based on the vaporization of droplets to predict the stability characteristics of the engine. The proposed concept focuses on three dimensional simulation of combustion instability for giving some meaningful explanations for the experimental work presented in the literature.
In the present study the pressure wave corresponding to the transverse modes were superimposed on a three dimensional steady state operating conditions. Steady state parameters were obtained from the three dimensional combustion modeling. The conservation equations for mass, momentum and energy are non dimensionalized for facilitating the order of magnitude analysis. In order to do the stability analysis, variables are represented as the sum of their steady values and deviation from the steady state. A harmonic time dependence is assumed for the perturbations. For the transverse mode of oscillations independent variables of the zeroth order equations are r and θ only and the dependant variables are not functions of the axial distance. The axial dependence comes only through the first order equations. In this analysis, the wave motion in the combustion chamber is assumed to be linear, confining the nonlinearity to the vaporization process only. The reason behind making this assumption is that the vaporization process is the major mechanism driving the instability. Vaporization histories of liquid oxygen drops in a combustor with superimposed transverse oscillations were computed and stability characteristics of the engine were estimated. The stability characteristics of the engine are accessed from the solutions of first order equations. Effects of various parameters like droplet diameter, hydrogen injection temperature and hydrogen injection area on the stability characteristics of cryogenic engines are studied. A comparison of predicted and published experimental results was made which showed general agreement between experiment and computation.
The present study and experimental results show clearly that hydrogen injection velocity is the critical parameter for instability rather than hydrogen injection temperature. What has happened in actual experiments when hydrogen injection temperature is varied is an effective alteration of the injection velocity that leads to the situation of instability. For higher relative velocity between hydrogen and liquid oxygen, the response of the vaporization rate in the presence of pressure wave is minimum compared to lower relative velocity. Due to this cryogenic engines will go to unstable mode at lower relative velocity.
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Biju, Kumar K. S. "Role Of Hydrogen Injection Temperature On The Combustion Instability Of Cryogenic Rocket Engine." Thesis, 2012. http://etd.iisc.ernet.in/handle/2005/2297.
Full textAbstract:
Physical mechanism for high frequency instability in cryogenic engines at low hydrogen injection temperature has been a subject of debate for long time. Experimental and early developmental studies revealed no instabilities and it was only much later when liquid hydrogen at lower initial temperature (~50 to 100 K) was injected into the combustion chamber that instabilities were detected. From the compilations of the experimental data related to the instability of cryogenic engines by Hulka and Hutt, it was found that the instability was strongly connected to the temperature of hydrogen. Experiments conducted with hydrogen temperature ramping from a higher value to lower values indicated that the temperatures in excess of 90 K favor stability under most practical operating conditions. Even though this has been known for over forty years, there has been no clear and simple explanation for this. Many physical mechanisms have been hypothesized to explain how temperature ramping causes instability, but all appear to have limited range of applicability. Current understanding of cryogenic engine combustion instability has been achieved through a combination of experimental investigation and approximate analytical models as well as CFD tools.
Various researchers have tried to link the low hydrogen injection temperature combustion instability phenomena with various potential mechanisms for combustion instability. They involve coupling of combustion acoustics with atomization, vaporization, mixing, chemical kinetics or any combination of these processes. Various studies related to the effect of recess, injector hydrodynamics, acoustic damping of gas liquid scheme injectors and effect of drop size distribution on the stability characteristics of cryogenic engines were compiled in the thesis. Several researchers examined fuel droplet vaporization as the rate controlling mechanism. Recently a new method for the evaluation of stability characteristics of the engine using model chamber were proposed by Russians and this is based on mixing as the rate controlling mechanism. Pros and cons of this method were discussed. Some people examined the combustion instability of rocket engines based on chemistry dynamics. A considerable amount of analytical and numerical studies were carried out by various researchers for finding out the cause of combustion instability. Because of the limitations of their analysis, they could not successfully explain the cause of combustion instability at low hydrogen injection temperature. A compilation of previous numerical studies were carried out. A number of researchers have applied CFD in the study of combustion instabilities in liquid propellant rocket engines. In the present thesis, a theoretical model has been developed based on the vaporization of droplets to predict the stability characteristics of the engine. The proposed concept focuses on three dimensional simulation of combustion instability for giving some meaningful explanations for the experimental work presented in the literature.
In the present study the pressure wave corresponding to the transverse modes were superimposed on a three dimensional steady state operating conditions. Steady state parameters were obtained from the three dimensional combustion modeling. The conservation equations for mass, momentum and energy are non dimensionalized for facilitating the order of magnitude analysis. In order to do the stability analysis, variables are represented as the sum of their steady values and deviation from the steady state. A harmonic time dependence is assumed for the perturbations. For the transverse mode of oscillations independent variables of the zeroth order equations are r and θ only and the dependant variables are not functions of the axial distance. The axial dependence comes only through the first order equations. In this analysis, the wave motion in the combustion chamber is assumed to be linear, confining the nonlinearity to the vaporization process only. The reason behind making this assumption is that the vaporization process is the major mechanism driving the instability. Vaporization histories of liquid oxygen drops in a combustor with superimposed transverse oscillations were computed and stability characteristics of the engine were estimated. The stability characteristics of the engine are accessed from the solutions of first order equations. Effects of various parameters like droplet diameter, hydrogen injection temperature and hydrogen injection area on the stability characteristics of cryogenic engines are studied. A comparison of predicted and published experimental results was made which showed general agreement between experiment and computation.
The present study and experimental results show clearly that hydrogen injection velocity is the critical parameter for instability rather than hydrogen injection temperature. What has happened in actual experiments when hydrogen injection temperature is varied is an effective alteration of the injection velocity that leads to the situation of instability. For higher relative velocity between hydrogen and liquid oxygen, the response of the vaporization rate in the presence of pressure wave is minimum compared to lower relative velocity. Due to this cryogenic engines will go to unstable mode at lower relative velocity.
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"Design of a Shock-Induced Combustion Experiment in an Axisymmetric Configuration with Hydrogen Injection." Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24967/24967.pdf.
Full text
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Trusca, Bogdan. "High pressure direct injection of natural gas and hydrogen fuel in a diesel engine." Thesis, 2001. http://hdl.handle.net/2429/11481.
Full textAbstract:
Emissions and performance of an HPDI single-cylinder diesel engine fueled by natural gas and by a mixture of hydrogen-natural were investigated. A DDC 1-71 engine with electronic controls was used. Natural gas or hydrogen-natural gas mixture was injected late in the compression stroke after a pilot quantity of a diesel was injected.
Engine performance and emissions have been measured over a wide range of parameters: gas injection pressure, engine load, injection delay and mass flow percentages for the gaseous fuels. These results were compared with conventional diesel fueling.
The purpose of this research was to investigate the potential for reducing the diesel exhaust emissions while maintaining high thermal efficiency. With HPDI of natural gas and hydrogen-natural gas, NOx emissions can be reduced to almost half of those with diesel fueling, by appropriately adjusting the injection timing. NOx concentration is observed to increase with gas injection pressure. For hydrogen-natural gas fueling, an increase of the hydrogen percentage produces an increase in NOx. This is attributed to the higher combustion temperature as the percentage of hydrogen increases.
Thermal efficiency of HPDI of natural gas was greater than conventional diesel fueling at high loads but almost identical for medium and low loads. For HPDI of hydrogen-natural gas mixture the thermal efficiency is less than with natural gas fueling. The drop in thermal efficiency has not yet been explained.
With hydrogen addition, the unburned hydrocarbons are greatly reduced, for almost all the engine loads. Carbon monoxide emission with HPDI was reduced for high and low loads.