Dissertations / Theses on the topic 'Liquid oxygen and methane'
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Lechner, Valentin. "Experimental study of LOX/CH4 flames in rocket engines." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST040.
Using methane as a fuel in rocket engines would have many advantages but the combustion with pure oxygen at high pressure remains poorly understood. From a thermodynamic point of view, methane and oxygen share very similar critical point values, making it challenging to predict propellant mixing, flame anchoring, stability and structure. Moreover, when methane is injected in excess, aerosols can be produced, which can clog the lines, damage the turbine, and reduce the efficiency.Therefore, a thorough update of the knowledge of LOX/CH4 combustion is necessary. These challenges are tackled within the consortium composed of EM2C laboratory, ONERA, CNES, and ArianeGroup. Two test campaigns are carried out at the MASCOTTE facility from ONERA, aiming to study three central topics: the flame structure, wall heat transfers, and aerosol production. To this end, various experimental diagnostics are implemented simultaneously during high-pressure hot-fire tests.Various imaging diagnostics are implemented to analyze the flame structure and the dense liquid jets. Despite the acquisition difficulties encountered in these extreme conditions, the analyses reveal a complex flame structure. In the subcritical regime, atomization and evaporation mechanisms dominate. The flame is much more opened and longer than at higher pressures, where diffusive mixing mechanisms prevail. Characterizing flame anchoring remains a challenge. A water ice ring surrounding, and masking, the flame foot has been identified. Formation mechanisms are proposed, and a growth/destruction temporal cycle is highlighted. Its presence strongly affects flame visualizations, and may lead to misinterpretations of its topology.Laser-induced phosphorescence (LIP) is implemented for the first time at MASCOTTE. Various LIP methods exist, but they are not well suited to the MASCOTTE conditions: wide temperature range, thermal transients, and two-phase flow environment favoring laser absorption/diffusion. Therefore, a specific method, the Full Spectrum Fitting method (FSF method), has been developed. It exploits the spectral dependence on temperature, enabling instantaneous measurements from 100 to 900 K with a precision of 17 K, with no dependence on the laser excitation energy. A detailed data analysis highlights the predominant wall heat transfer modes, studies the influence of the operating points, and compares the experimental data with a wall heat transfer model, which is particularly well suited for deducing the convective properties of the flow.Three diagnostics are used to characterize aerosols. An intrusive probe samples particles and burnt gases downstream of the flame. The particles are sampled on TEM grids and analyzed by Transmission Electron Microscopy. Detailed images of the aerosol morphology reveal that the particles are soot. Combustion products are analyzed by gas chromatography. This makes it possible to identify soot precursor molecules such as benzene and acetylene. Soot are quantified temporally by laser extinction. A dedicated post-processing method is developed and various hypotheses are discussed to explain the spatial variations of the soot production downstream of the flame
Hartwig, Jason W. "Liquid Acquisition Devices for Advanced In-Space Cryogenic Propulsion Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1396562473.
Salusbury, Sean. "Premixed methane stagnation flames with oxygen enrichment." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=87008.
The experimental apparatus that is used to gather data in this study is a stagnation flame burner. Particle image velocimetry, a laser-based flow visualization technique, is used to measure velocity in both the axial and radial directions. The results are analyzed first to confirm the validity of the one-dimensional, axisymmetric model commonly used to describe impinging-jet flow. Experimental results are found to have good agreement with theoretical approximations and numerical models. Tests are then conducted to reproduce previously published data for methane-air flames at lean, stoichiometric and rich conditions in order to prove the reliability of the experimental apparatus. There is agreement between published data and the new experimental results.
Experiments with oxygen enrichment are then conducted at equivalence ratios not normally within the flammability limits of methane-air mixtures, from the very lean, phi = 0.55, to the very rich, phi = 1.45. Results show marked disagreement between model and experiment at equivalence ratios far from stoichiometric. These experimental data will allow the chemical kinetic model for premixed methane combustion to be improved -- by correcting divergence in the model at very lean and very rich conditions, the model should be improved appreciably over the narrower range of equivalence ratios typically seen in methane-air combustion.
La cinétique chimique est la science de la modélisation des étapes d'une réaction chimique au niveau moléculaire. Ce mémoire s'interesse aux réactions chimique qui se produisent durant la combustion. Les modèles cinétique présentement acceptés sont en besoin d'amélioration et d'autres enplus, il existe plusieurs réactions qui n'ont aucun modèle. Pour mieux développer les modèles et pour en créer des nouveaux, il fault rassembler assez de données expérimentales pour produire une base solide sur laquelle des modèles de plus en plus compliqués peuvent etre construits.
Pour générer des données, cette étude utilise un appareil expérimental avec une géométrie de point d'arrêt, dans laquelle une flamme aplatie peut exister. Les vitesses dans la direction axiale et radiale sont mesurées par la vélocimétire image-particule, une technique à base de laser. Les résultats sont d'abord analisés pour vérifier que le modèle unidimensionnel est valide. Une bonne concordance est observée entre la théorie et les résultats et entre les modèles numériques et les résultats. Subséquemment, des expériences sont effectuées pour reproduire des données déjà publiées pour le méthane et l'air aux rapports d'équivalence oxydants, stoechiométriques et réducteurs, afin de prouver la fiabilité de l'appareil expérimental. Il ya une bonne concordance entre les données publiées et les résultats expérimentaux.
Des expériences dans lequelles l'air est enrichi avec de l'oxygène sont effectuées à des rapports d'équivalence de phi = 0.55 juste qu'à phi = 1.45; ces rapports d'équivalence ne sont normalement pas dans les limites d'inflammabilité des mélanges de méthane-air. Ici, les résultats montrent un désaccord marqué entre le modèle et les expériences pour les rapports d'équivalence très loin de phi = 1.0. Les données permettent le modèle cinétique chimique pour la combustion du méthane prémélangée d'être amélioré. En corrigeant les divergences entre le modèle et les resultats experimentales pour rapports d'équivalence très oxydants et très réducteurs, le modèle sera amélioré pour rapports d'équivalences généralement vus dans la combusiton de méthane dans l'air.
Williams, Gareth Richard. "Liquid phase catalytic partial oxidation of methane." Thesis, University of Bath, 2002. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760824.
Pedersen, Tom. "A study of liquid film, liquid motion, and oxygen absorption from hemispherical air/oxygen bubbles." Thesis, Brunel University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242980.
Wishnow, Edward Hyman. "Far-infrared absorption by liquid nitrogen and liquid oxygen." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25072.
Science, Faculty of
Physics and Astronomy, Department of
Graduate
Teeple, Brian S. (Brian Scott). "Feasibility of producing lunar liquid oxygen." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/47360.
Lee, Colleen Su-Ming. "Reactions of oxygen with methane using microwave and conventional heating." Thesis, Imperial College London, 2000. http://hdl.handle.net/10044/1/8073.
Rivera-Rivera, Ramiro Luis. "Simulation and validation of liquid oxygen and liquid hydrogen pressurization systems." Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04072004-180151/unrestricted/rivera-rivera%5Framiro%5Fl%5F200312%5Fms.pdf.
Agarwal, Nishtha. "Low temperature selective oxidation of methane using hydrogen peroxide and oxygen." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/117851/.
Liu, Yan. "Nanoscaled Oxygen Carrier Development for Chemical Looping Partial Oxidation of Methane." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1618754731709306.
Osterwalder, Neil. "Catalytic conversion of methane to higher alkanes in oxygen free atmosphere." kostenfrei, 2007. http://e-collection.ethbib.ethz.ch/view/eth:29838.
Warren, Richard. "Towards in-situ analysis of liquefied natural gas with near infrared spectroscopy." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246257.
CAVUOTO, GIUSEPPE. "Speed of Sound Measurements of liquid methane at cryogenic temperature." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2858357.
Krothapalli, Deep. "Gas-liquid Mass Transfer in Oxygen Delignification Systems." Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/KrothapalliD2004.pdf.
Roy, Surajit. "Fluidized bed steam methane reforming with high-flux membranes and oxygen input." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0032/NQ38500.pdf.
Di, Nardo Thomas. "Mesoporous Ceria Catalyst Synthesis: Effects of Composition on Thermal Stability and Oxygen Depletion in Methane Rich and Lean Environments." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/23781.
Partridge, Jonathan Koert. "Experimental studies of liquefaction and densification of liquid oxygen." Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4574.
ID: 029049996; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.M.E.)--University of Central Florida, 2010.; Includes bibliographical references (p. 127-129).
M.S.M.E.
Masters
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering
Aleknaviciute, Irma. "Plasma assisted decomposition of methane and propane and cracking of liquid hexadecane." Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/8574.
Kay, Helen. "Deoxidation mechanisms in liquid steel." Thesis, Sheffield Hallam University, 1996. http://shura.shu.ac.uk/19899/.
Deans, Matthew Charles. "A Computational Study of the Ignition of Premixed Methane and Oxygen via a Hot Stream." Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1238698624.
Abstract Department of Mechanical & Aerospace Engineering Title from PDF (viewed on 20 April 2009) Available online via the OhioLINK ETD Center
Martinho, Susana Teresa Antunes. "Development of new oxygen therapeutics using fluorinated ionic liquids." Master's thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/8482.
The last decade of the 20th century has yielded a remarkable progress in the field of first generation artificial blood substitutes. Emulsions based on perfluorocarbons (PFCs) became one of the main candidates for a safe and reliable artificial blood substitute. The final objective of the present work is to study the fluorinated ionic liquids (FILs) with the purpose of replacing, partially or totally, the PFCs actually used as artificial blood substitutes, thus providing new fluids with tailored advanced properties. With this goal in mind, the thermophysical and thermodynamic characterization of several FILs, was carried out with the aim to select the most appropriate candidate. This characterization involves the measurement and analysis of the decomposition and melting temperature, density, viscosity, refractive index, and ionic conductivity at atmospheric pressure in a temperature range from 298.15 to 353.15 K. Furthermore, the liquid-liquid equilibria of binary mixtures of PFCs and FILs were studied, at atmospheric pressure in a temperature range usually from 293.15 to 343.15 K. The knowledge of the phase behaviour is crucial to the formulation of emulsions used nowadays as suitable oxygen carriers. Finally, Non-Random Two Liquid (NRTL) thermodynamic model was successfully applied to correlate the behaviour of the binary mixtures of PFCs and FILs
Ylihautala, M. (Mika). "NMR of small solutes in liquid crystals and molecular sieves." Doctoral thesis, University of Oulu, 1999. http://urn.fi/urn:isbn:9514252748.
Ab, Rahim Mohd Hasbi. "Heterogeneous gold, palladium and copper based catalysts for liquid phase oxidation of methane." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/55125/.
Chung, Elena Yin-Yin. "Investigation of Chemical Looping Oxygen Carriers and Processes for Hydrocarbon Oxidation and Selective Alkane Oxidation to Chemicals." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469182957.
Walker, Brian Christopher. "SHOCK-TUBE INVESTIGATION OF IGNITION DELAY TIMES OF BLENDS OF METHANE AND ETHANE WITH OXYGEN." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3473.
M.S.A.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Aerospace Engineering MSAE
kaya, mine. "Experimental Study and Numerical Simulation of Methane Oxygen Combustion inside a Low Pressure Rocket Motor." ScholarWorks@UNO, 2016. http://scholarworks.uno.edu/td/2240.
Moore, Bryce Kirk. "Gas-liquid flows in adsorbent microchannels." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47519.
Knipping, Etienne. "Design of new ionic liquid-based electrolytes for lithium-oxygen battery." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/663959.
The lithium-oxygen (Li-O2) battery has received much interest in the last few years as global energy demand is growing and availability of fossil energies becomes limited. With its high theoretical energy density approaching that of gasoline, this technology is potentially one of the best solutions for electric vehicles (EV). However, this new technology will remain a research topic for at least the next 20 following years, due to the low cyclability, the limited electrical efficiency, the low rate capability and the difficulty of assembling a safe practical cell working in ambient atmosphere as good as at the laboratory scale under well-controlled conditions. Recently, Room Temperature Ionic Liquids (RTILs) attracted much attention. Indeed, their high thermal stability, non-flammability, low vapor pressure and wide potential window can offer an interesting alternative to the traditional organic solvents for Li-O2 battery electrolyte. In this context, the chemical and physical properties of RTILs are determined in order to design a suitable RTIL-based electrolyte. The study of these parameters, compared to the electrochemical performance of the battery, enables to find a correlation between the viscosity, the lithium solvation of the electrolyte and the capacity of the battery. Given that RTILs viscosity is too high for adequate battery reaction kinetics, a mixture of an organic solvent and a RTIL is then studied. Electrolytes composed by dimethylsulfoxide (DMSO), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI TFSI) and LiClO4 are characterized, evaluating the suitability of such electrolyte. The optimum concentration of EMI TFSI enables to reduce the overpotential from 1.43 V to 1.06 V, with a cyclability of 69 cycles with 200 mAh g-1 of limited capacity. Thereafter, a real-time synchrotron X-ray diffraction technique is applied to analyze the oxidation/reduction of lithium oxide derivatives in an operating battery cell. Four different electrolytes composed of DMSO, a RTIL and LiClO4 are tested. This study proves that the lithium used as anode material is reacting with the RTIL, forming continuously LiOH, independently of the cycling stage. The comparisons between the different electrolytes provide insights for future investigation on the improvement of electrolyte design of this technology.
Kapilasharmi, Era. "Investigation of Interactions between Liquid Iron Containing Oxygen and Aluminosilicate Refractories." Doctoral thesis, KTH, Materials Science and Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3625.
The present work was initiated to investigate runnerrefractory corrosion by molten steel. The aim was to understandthe mechanism of inclusion formation during ingot casting. Thework is also of interest to other unit processes in steelmaking, where refractory corrosion and erosion are seriousproblems. The oxides investigated in the present work werealumina, silica and mullite, which are the main components inrunner refractory. In addition, industrial refractory materialwas investigated.
Two types of experiments were conducted. The first, "rodexperiments", involved dipping a rod of the oxide into an ironbath containing varying amounts of oxygen. After quenching, therods were examined through SEM/EDS analysis. In the second setsof experiments, the wetting behaviour of molten iron onrefractory oxides was investigated by means of the sessile-dropmethod. The reactions were followed in static as well asdynamic modes through contact angle measurements. Temperatureand oxygen partial pressure were, besides time the parametersthat were investigated in the present study. Oxygen partialpressure was defined by introducing a gas mixture of CO-CO2-Ar into the furnace.
The experimental studies were preceded by a thermodynamicinvestigation of the refractory systems, in order to get afundamental understanding of the reactions that occurred. Phasestability diagrams for the systems were constructed based onthe data available in literature. The diagrams showed that thereaction between alumina and oxygen containing iron would leadto the formation of hercynite at a critical oxygen level in themetal. With silica, the reaction would lead to the formation offayalite. In the mullite case, the reaction products would behercynite at moderate oxygen levels in the melt and hercynitetogether with fayalite at slightly higher oxygenpotentials.
For all substrates, the contact angles started decreasing asthe surface-active oxygen came into contact with the iron drop.At a critical level of oxygen in the metal, a reaction productstarted forming at the drop/substrate interface. The reactionproducts were identified through SEM/EDS analysis and werefound to be in agreement with thermodynamic predictions. In thecase of SiO2substrate, there were also deep erosion tracksalong the periphery of the drops, probably due to Marangoniflow.
Alumina-graphite refractory reactions with molten iron werealso investigated through Monte Carlo simulations. The resultsshowed that, with increased alumina content in the refractory,the carbon dissolution into the melt decreased. Further, thewetting behaviour at the interface was found to be an importantfactor to considerably reduce the carbon dissolution fromalumina-graphite refractories.
The experimentation was extended to the commercialrefractories used in the ingot casting process at UddeholmTooling AB, Sweden. The analysis of the plant trial samplesindicates that there is less likelihood of a strong corrosionof the refractories that could lead to a significant populationof inclusions in the end product. The impact of the presentexperimental results on refractory erosion is discussed. Theimportance of the results to clean steel processing anddevelopment of new generation refractories are alsopresented.
Radjenovic, P. M. "Novel ionic liquid based electrolytes for non-aqueous lithium-oxygen batteries." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3019782/.
Bernus, Borbala. "Design Investigation into Liquid Oxygen Vaporisation Systems : Atomisation and Heat Loads." Thesis, KTH, Energiteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-283243.
Computational Fluid Dynamics (CFD) simuleringar presenteras i denna studie för superkyld flytande syreförstoftning och förgasning i en underkritisk kammare som arbetar vid SI 1 MPa. Relativt billiga simuleringstekniker har använts och deras noggrannhet utvärderats. Förgasningseffektivitet som förväntas från teorin jämförs med simuleringsresultat och fysisk begränsning utöver detta diskuteras modelleringsberäkningarna. Stötstrålar har använts inom simuleringarna med avsikt att finfördela det inkommande flytande syret, följt av injektion av varm vattenånga vinkelrätt, för att öka turbulent blandning, uppehållstid och i sin tur förväntad förgasningseffektivitet. En beräkningsenhetsanalys för uppvärmningsdynamik ingår också för att belysa begränsningar för kammargeometri som införs genom övergående gränser för snabb oxidation. 316 rostfritt stål och 3D-printad Inconel 718 undersöktes experimentellt för att identifiera deras övergående makroskopiska snabba oxidationsgränser. Denna information kompletterar befintlig publicerad litteratur för drift vid höga temperaturer under en kort tid i syrgasrika miljöer. ANSYS Fluent 2020R1, och dess nyligen inkluderade volym av vätska till diskret partikel (VOF-DPM) -modell, används för CFD-simulering av LOxatomisering och förångning. CFD-simuleringstekniken diskuteras i detalj för att göra det möjligt för läsaren att få kunskap om områden där beräkningskraft kan sparas medan man fortfarande tillåter bedömning av trender för att göra relativt snabba genomförbarhetsgranskningar, t.ex. för olika kammarkonfigurationer. CFD-simuleringsresultaten jämförs med publicerade experimentella data och dess noggrannhet när den utvidgas till denna applikation diskuteras. Resultaten indikerar att förgasning av LOx i en kompakt kammare kan vara möjlig vid tillräcklig turbulens, vilket resulterar i längre uppehållstider är närvarande som ger tillräcklig tid för värme och massöverföring från den kontinuerliga fasen. Simuleringar indikerar att på grund av blandnings- och förgasningsprocessen är LOx-partiklarna i kammaren som inte har gått in i gasfasen mindre än den från ren förgasning och därför mer mottagliga för förgasning om de injiceras i huvudmotorns förbränningskammare. Resultat antyder den potentiella fördelen med virvelinjektion av heta gaser för att öka uppehållstiden och i sin tur förgasningseffektivitet, därför rekommenderas detta för ämnet för framtida forskning.
Rodulfo-Baechler, Serbia. "Oxygen flux through unmodified and modified La0.6Sr0.4Co0.2Fe0.8O3-8 hollow fibre membranes and application to methane oxidation." Thesis, University of Newcastle upon Tyne, 2013. http://hdl.handle.net/10443/2309.
Silvestri, Simona [Verfasser]. "Investigation on Heat Transfer and Injector Design Criteria for Methane/Oxygen Rocket Combustion Chambers / Simona Silvestri." München : Verlag Dr. Hut, 2019. http://d-nb.info/1200754840/34.
Cai, Andrew. "CHEMICAL EXPANSIVITY IN CERAMIC OXYGEN TRANSPORT MATERIALS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case159439738367673.
Damiano, Leonard Francis. "The effect of charge stratification on the combustion of lean methane-oxygen mixtures under constant volume. conditions." Thesis, University of Canterbury. Mechanical Engineering, 1993. http://hdl.handle.net/10092/6409.
Bauer, Christian Anton [Verfasser]. "Design and Test of Resonance Ignition Systems for Methane/Oxygen In-Space Propulsion Systems / Christian Anton Bauer." München : Verlag Dr. Hut, 2021. http://d-nb.info/1232847976/34.
Sinnathambi, Chandra Mohan. "Mo- modified HZSM-5 zeolite for the dehydro-oligomerisation and aromatisation of methane in the absence of oxygen." Thesis, University of Liverpool, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426121.
Dawson-Amoah, James. "Gas-liquid mass transfer rates by gas pumping : agitators in oxygen pressure leaching systems." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/29931.
Applied Science, Faculty of
Materials Engineering, Department of
Graduate
Ferrari, Federica. "Data analytics for hydrogen safety: prediction of Liquid hydrogen release characteristics." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
Boulware, Jeffrey C. "Experiment and Simulation on the Dynamics of a Slug of Liquid Oxygen Displaced by a Pulsed Magnetic Field." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/690.
Rabie, Samuel Liversage. "SO2 and O2 separation by using ionic liquid absorption / S.L. Rabie." Thesis, North-West University, 2012. http://hdl.handle.net/10394/9100.
Thesis (MIng (Chemical Engineering))--North-West University, Potchefstroom Campus, 2013
Xu, Kemu. "Simulation of Electrical Characteristics in Oxyfuel Flame Subject to An Electric Field." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/103816.
Master of Science
Oxyfuel cutting is essential to numerous industries, such as shipbuilding, rail, earth moving equipment, commercial building construction, etc. Tuning the process parameters and diagnosing problems with the oxyfuel process still relies on experienced operators. The main obstacles to the automation of the oxyfuel process come from the limitations of the sensing suites currently in use. Since typical sensors are highly unreliable in the harsh environment near the high-temperature flame, an alternate method is proposed to find the co-dependence between the flame's electrical characteristics and critical parameters of the oxyfuel cutting system (standoff, flow rate, F/O ratio, etc.). The relevant electrical characteristics are the electrical potential and distribution of ions and electrons. Two-dimensional models are created to analyze the combustion of methane-oxygen flame and transport of ions and electrons. The models allow the derivation of the current-voltage characteristic between the torch and work surface. Also, the way sheath phenomena of ions and electrons on the surface affect the current-voltage relationship can be analyzed from ions and electrons distribution. The electric field is added to the model by applying a constant voltage to the torch tip surface. To validate the models, a laboratory experiment with a similar geometry arrangement is used as a comparision. The models' results reveal three different regimes in the current-voltage relationship.
Hu, Yushan. "OXYGEN TRANSPORT AS A STRUCTURE PROBE FOR HETEROGENEOUS POLYMERIC SYSTEMS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1112902488.
Papargyriou, Despoina. "Materials and catalysts incorporation for the fuel oxidation layer of oxygen transport membranes." Thesis, University of St Andrews, 2017. http://hdl.handle.net/10023/12113.
Conradie, Frederik Hendrik. "Utilizing the by-product oxygen of the hybrid sulfur process for synthesis gas production / by F.H. Conradie." Thesis, North-West University, 2009. http://hdl.handle.net/10394/4000.
Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2009.
Cloete, Jannean Christelle. "Oxygen transfer in a model hydrocarbon bioprocess in a bubble column reactor." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96981.
ENGLISH ABSTRACT: The expansion of the global fuels industry has caused an increase in the quantity of hydrocarbons produced as a by-product of refinery gas-to-liquid processes. Conversion of hydrocarbons to higher value products is possible using bioprocesses, which are sustainable and environmentally benign. Due to the deficiency of oxygen in the alkane molecule, the supply of sufficient oxygen through aeration is a major obstacle for the optimization of hydrocarbon bioprocesses. While the oxygen solubility is increased in the presence of hydrocarbons, under certain process conditions, the enhanced solubility is outweighed by an increase in viscosity, causing a depression in overall volumetric oxygen transfer coefficient (KLa). The rate at which oxygen is transferred is defined in terms of a concentration driving force (oxygen solubility) and the overall volumetric oxygen transfer coefficient (KLa). The KLa term comprises an oxygen transfer coefficient (KL) and the gas-liquid interfacial area (a), which are dependent on the uid properties and system hydrodynamics. This behaviour is not well understood for hydrocarbon bioprocesses and in a bubble column reactor (BCR). To provide an understanding of oxygen transfer behaviour, a model hydrocarbon bioprocess was developed using a BCR with a porous sparger. To evaluate the interfacial area, the Sauter mean bubble diameter (D32) was measured using an image analysis algorithm and gas holdup (ϵG) was measured by the change in liquid height in the column. Together the D32 and ϵG were used in the calculation of interfacial area in the column. The KLa was evaluated with incorporation of the probe response lag, allowing more accurate representation of the KLa behaviour. The probe response lag was measured at all experimental conditions to ensure accuracy and reliability of data. The model hydrocarbon bioprocess employed C14-20 alkane-aqueous dispersions (2.5 - 20 vol% hydrocarbon) with suspended solids (0.5 - 6 g/l) at discrete super ficial gas velocity (uG) (1 - 3 cm/s). For systems with inert solids (corn our, dp = 13.36 m), the interfacial area and KLa were measured and the behaviour of KLa was described by separation of the in uences of interfacial area and oxygen transfer coefficient (KL). To further the understanding of oxygen transfer behaviour, non-viable yeast cells (dp = 5.059 m) were used as the dispersed solid phase and interfacial area behaviour was determined. This interfacial area behaviour was compared with the behaviour of systems with inert solids to understand the differences with change in solids type. In systems using inert solids, a linear relationship was found between G and uG. An empirical correlation fo rthe prediction of this behaviour showed an accuracy of 83.34% across the experimental range. The interfacial area showed a similar relationship with uG and the empirical correlation provided an accuracy of 78.8% for prediction across the experimental range. In inert solids dispersions, the KLa increased with uG as the result of an increase in interfacial area as well as increases in KL. An increase in solids loading indicated an initial increase in KLa, due to the in uence of liquid-film penetration on KL, followed by a decrease in KL at solids loading greater than 2.5 g/l, due to diffusion blocking effects. In systems with yeast dispersions, the presence of surfactant molecules in the media inhibited coalescence up to a yeast loading of about 3.5 g/l, and resulted in a decrease in D32. Above this yeast loading, the fine yeast particles increased the apparent viscosity of the dispersion sufficiently to overcome the in uence of surfactant and increase the D32. The behaviour of G in yeast dispersions was similar to that found with inert solids and demonstrated a linear increase with uG. However, in yeast dispersions, the interaction between alkane concentration and yeast loading caused a slight increase in dispersion viscosity and therefore G. An empirical correlation to predict G behaviour with increased uG was developed with an accuracy of 72.55% for the experimental range considered. Comparison of yeast and inert solids dispersions indicated a 37.5% lower G in yeast dispersions compared to inert solids as a result of the apparent viscosity introduced by finer solid particles. This G and D32 data resulted in a linear increase in interfacial area with uG with no significant in uence of alkane concentration and yeast loading. This interfacial area was on average 6.7% lower than interfacial area found in inert solid dispersions as a likely consequence of the apparent viscosity with finer particles. This study provides a fundamental understanding of the parameters which underpin oxygen transfer in a model hydrocarbon bioprocess BCR under discrete hydrodynamic conditions. This fundamental understanding provides a basis for further investigation of hydrocarbon bioprocesses and the prediction of KLa behaviour in these systems.
AFRIKAANSE OPSOMMING: Die uitbreiding van die internasionale brandstofbedryf het 'n toename veroorsaak in die hoeveelheid koolwaterstowwe geproduseer as 'n deur-produk van raffinadery gas-tot-vloeistof prosesse. Omskakeling van koolwaterstowwe na hoër waarde produkte is moontlik met behulp van bioprosesse, wat volhoubaar en omgewingsvriendelik is. As gevolg van die tekort aan suurstof in die alkaan molekule, is die verskaffing van voldoende suurstof deur deurlugting 'n groot uitdaging vir die optimalisering van koolwaterstof bioprosesse. Terwyl die suurstof oplosbaarheid verhoog in die teenwoordigheid van koolwaterstowwe, onder sekere proses voorwaardes is die verhoogde oplosbaarheid oortref deur 'n toename in viskositeit, wat 'n depressive veroorsaak in die algehele volumetriese suurstofoordragkoëffisiënt (KLa). Die suurstof oordrag tempo word gedefinieer in terme van 'n konsentrasie dryfkrag (suurstof oplosbaarheid) en KLa. Die KLa term behels 'n suurstofoordragkoëffisiënt (KL) en die gas-vloeistof oppervlakarea (a), wat afhanklik is van die vloeistof eienskappe en stelsel hidrodinamika. Hierdie gedrag is nie goed verstaan vir koolwaterstof bioprosesse nie, asook in kolom reaktors (BCR). Om 'n begrip van suurstof oordrag gedrag te voorsien, is 'n model koolwaterstof bioproses ontwikkel met 'n BCR met 'n poreuse besproeier. Om die oppervlakarea te evalueer, is die gemiddelde Sauter deursnit (D32) gemeet deur 'n foto-analise algoritme en gas vasvanging ( G) is gemeet deur die verandering in vloeibare hoogte in die kolom. Saam is die D32 en G gebruik in die berekening van die oppervlakarea in die kolom. Die KLa is geëvalueer met insluiting van die meter se reaksie sloering, om n meer akkurate voorstelling van die KLa gedrag te bereken. Die meter reaksie sloering was gemeet op alle eksperimentele toestande om die akkuraatheid en betroubaarheid van data te verseker. Die model koolwaterstof bioproses gebruik n-C14-20 alkaan-water dispersies (2.5 - 20 vol% koolwaterstof) solide partikels (0.5 - 6 g/l) op diskrete oppervlakkige gas snelhede (1 - 3 cm/s). Vir stelsels met inerte solides (koring meel, dp = 13.36 m), is die oppervlakarea en KLa gemeet en die gedrag van KLa beskryf deur skeiding van die invloede van oppervlakarea en KL. Om die begrip van suurstof oordrag se gedrag te bevorder, is nie-lewensvatbare gisselle (dp = 5.059 m) gebruik as die verspreide solide fase en oppervlakarea is bepaal. Hierdie oppervlakarea gedrag is vergelyk met die van stelsels met inerte solides om die verskille met verandering in solide tipes te verstaan. In stelsels met inerte solides, is 'n line^ere verwantskap gevind tussen G en uG. 'n Empiriese korrelasie vir die voorspelling van hierdie gedrag is opgestel met 'n akkuraatheid van 83.34% in die eksperimentele reeks. Die oppervlakarea het 'n soortgelyke verhouding met uG en die empiriese korrelasie verskaf 'n akkuraatheid van 78,8% vir die voorspelling van oppervlakarea oor die eksperimentele reeks. In inerte solide dispersies, het die KLa toegeneem met uG as die gevolg van 'n toename in grens oppervlak asook stygings in KL. 'n Toename in solides belading het n aanvanklike styging in KLa aangedui, as gevolg van die invloed van die vloeistof-film penetrasie op KL, gevolg deur 'n afname in KL op vastestowwe ladings groter as 2.5 g/l, te danke aan diffusie blokkeer effekte. In stelsels met gis dispersies, het die teenwoordigheid van benattings molekules in die media samesmelting geïnhibeer tot 'n gis lading van ongeveer 3.5 g/l, en het gelei tot 'n afname in D32. Bo hierdie gis lading, het die fyn gis partikels die skynbare viskositeit van die verspreiding verhoog genoegsaam om die invloed van benattings molekules te oorkom en die D32 te verhoog. Die gedrag van G in gis dispersies was soortgelyk aan die van inerte solides en dui op 'n lineêre toename met uG. Maar in gis dispersies, het die interaksie tussen alkaan konsentrasie en gis lading 'n effense toename veroorsaak in die verstrooiing viskositeit en dus in G. 'n Empiriese korrelasie is ontwikkel om G gedrag te voorspel en het 'n akkuraatheid van 72,55% vir die eksperimentele verskeidenheid beskou. Vergelyking van gis en inerte patrikel dispersies wys 'n 37.5% laer G in gis dispersies in vergelyking met inerte vaste stowwe as 'n gevolg van die skynbare viskositeit bekendgestel deur fyner vastestowwe partikels. Hierdie G en D32 data het gelei tot 'n linere toename in grens oppervlak met uG met geen beduidende invloed van alkaan konsentrasie en gis lading nie. Die oppervlakarea was gemiddeld 6.7% laer as oppervlakarea gevind in inerte partikel dispersies as 'n waarskynlike gevolg van die skynbare viskositeit met fyner partikels. Hierdie studie bied 'n fundamentele begrip van die veranderlikes wat die suurstof oordrag definieer in 'n model koolwaterstof bioproses BCR onder diskrete hidrodinamiese voorwaardes. Hierdie fundamentele begrip bied n basis vir verdere ondersoek van koolwaterstof bioprosesse en en die voorspelling van KLa gedrag in hierdie stelsels.
Messenger, David James. "Impact of UV light on the plant cell wall, methane emissions and ROS production." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/4347.
Sridhar, Deepak. "Oxygen Carrier Development and Integrated Process Demonstration for Chemical Looping Gasification Systems." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338322340.
Crawford, Jessica F. "Using room-temperature liquid metals as a new reaction environment." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/232783/1/Jessica_Crawford_Thesis.pdf.