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1
Yip, C. W. H. "Compressible discharge coefficients of branching flows." Thesis, University of Aberdeen, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233007.
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A two-dimensional numerical model for compressible branching flow through a slot is described for the purpose of predicting the discharge coefficients of film cooling holes in gas turbine blades. The method employs free-streamline theory and the hodograph transformation. It calculates the area ratio of hole to duct and the contraction coefficient from a set of prescribed boundary conditions. An approximate method for calculating the compressible contraction coefficients is also discussed in the thesis. It employs the incompressible theory previously developed by McNown and Hsu (1951) for the free efflux, the 'compressibility factor' and the flow parameter (P<sub>o</sub>-P<sub>j</sub>)/(P<sub>o</sub>-P<sub>1</sub>), where P<sub>o</sub>, P<sub>j</sub>, P<sub>1</sub> represent the stagnation pressure, the static pressure of the jet and the static pressure of the approach flow, respectively. The advantages of using this method are the direct input of the area ratio of hole to duct and its speed of calculation. Experimental tests were performed using a specially designed rig in a supersonic wind tunnel. The investigations included sharp-edged slots with three different widths, a single hole and a row of two holes. The approach velocity in terms of the characteristic Mach number ranged from 0.18 to 0.58 and the pressure ratio P<sub>o</sub>/P<sub>j</sub>, ranged from 1.10 to 1.97. Agreement between the experimental data and the theoretical values was good to within the experimental accuracy (typically around +/- 5%) for the slots and the 2-hole configuration. For the 1-hole configuration, less bleed flow than predicted was observed, with the discrepancy varying from 7% to 18%. The latter case is a very severe test of a purely two-dimensional theory. The results for the 2-hole plate suggest that the slot theory can in fact be used to predict the flow through a row of holes with small pitch to diameter ratios.
2
Dremetsika, Assimina V., Panayotis A. Siskos, and Nicholas A. Katsanos. "Coefficients in solid-state diffusion by inverse gas chromatography." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-196477.
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Dremetsika, Assimina V., Panayotis A. Siskos, and Nicholas A. Katsanos. "Coefficients in solid-state diffusion by inverse gas chromatography." Diffusion fundamentals 2 (2005) 89, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14424.
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Khaldi, A. "Discharge coefficient of film cooling holes with rounded entries or exits." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378758.
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Bentz, Julie A. "Measurements of viscosity, velocity slip coefficients and tangential momentum accommodation coefficients for gas mixtures using a spinning rotor gauge /." free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9946244.
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Gutierrez, Emmanuel David Mercado. "Thermal expansion coefficient for a trapped Bose gas during phase transition." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-27102016-102903/.
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Ultra cold quantum gas is a convenient system to study fundamental questions of modern physics, such as phase transitions and critical phenomena. This master thesis is devoted to experimental investigation of the thermodynamics susceptibilities, such as the isothermal compressibility and the thermal expansion coefficient of a trapped Bose-Einstein condensate (BEC) of 87Rb atoms. The critical phenomena and the critical exponents across the transition can explain the behavior of the isothermal compressibility and the thermal expansion coefficient near the critical temperature TC. By employing the developed formalism of global thermodynamics variables, we carry out a statistical treatment of Bose gas in a 3D harmonic potential. After that, comparison of obtained results reveals the most appropriate state variables describing the system, namely volume and pressure parameter V and Π respectively. The both are related with the confining frequencies and BEC density distribution. We apply this approach to define the set of new thermodynamic variables of BEC, and also to construct the isobaric phase diagram V T. Its allows us to extract the compressibility κT and the thermal expansion coefficient βΠ. The behavior of the isothermal compressibility corresponds to the second-order phase transition, while the thermal expansion coefficient around the critical point behaves as β ∼ tr-α, where tr is reduced temperature of the system and α is the critical exponent on the basic of these. Results we have obtained the critical exponent α = 0.15±0.09, which allows us to determine the system dimensionality by means of the scaling theory, relating the critical exponents with the dimensionality. As a result, we found out that the dimensionality of the system to be d ∼ 3, one is in agreement with the real dimension of the system.<br>Amostras atômicas ultrafrias de um gás de Bose são convenientes para estudar questões fundamentais da física moderna, como as transições de fase e fenômenos críticos em condensados de Bose-Einstein (BEC). A minha dissertação dedica se à investigação das susceptibilidades termodinâmicas como a compressibilidade isotérmica e o coeficiente de expansão térmica de a traves da transição de um BEC de 87Rb. Os fenômenos críticos e os exponentes críticos a traves da transição podem explicar o comportamento da compressibilidade isotérmica e do coeficiente de expansão térmica perto da temperatura crítica TC. Ao empregar o desenvolvido formalismo das variáveis termodinâmicas globais, levamos a cabo o tratamento estatístico de um gás de Bose num potencial harmônico 3D. Depois da comparação dos resultados obtidos, revelam as mais apropriadas variáveis de estado descrevendo o sistema, chamadas parâmetro de volume e pressão, V e Π respectivamente. As duas estão relacionadas com as frequências de confinamento e a distribuição de densidade do BEC. Nós aplicamos esta abordagem para definir um conjunto de novas variáveis termodinâmicas do BEC, e também para construir o diagrama de fase isobárico V T. O anterior nós permite extrair a compressibilidade κT e o coeficiente de expansão termina βΠ. O comportamento da compressibilidade isotérmica corresponde a uma transição de fase de segunda ordem enquanto que o coeficiente de expansão térmica ao redor do ponto crítico comporta se como β ∼ tr-α, onde tr é a temperatura reduzida do sistema, e α o exponente crítico. Deste resultado nós obtemos um exponente critico, α = 0.15 ± 0.09, que permite determinar a dimensionalidade do sistema a traves da teoria de escala, relacionando os exponentes críticos com a dimensionalidade. Como resultado, encontramos que a dimensionalidade do sistema é d ∼ 3 que está de acordo como a dimensão real do sistema.
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Davies, Stephen Nigel. "The evaluation of overall gas-liquid mass transfer coefficients in gas sparged agitated vessels." Thesis, University College London (University of London), 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263106.
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Lu, Yuan. "A Study on Gas Quench Steel Hardenability." Digital WPI, 2015. https://digitalcommons.wpi.edu/etd-theses/125.
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Gas quench technology has been rapidly developed recently with the intent to replace water and oil quench for medium and high hardenability steel. One of the significant advantages is to reduce the distortion and stress, compared to water and oil quench. However, not like liquid quench, no gas quench steel hardenability test standard exists. The fundamental difference between liquid quench and gas quench is heat transfer coefficient. The workpiece with the same hardness after liquid and gas quench process may have different microstructure due to different cooling curves. The concept of equivalent gas quench heat transfer coefficient (HTC) is proposed to have the same cooling curve, microstructure and hardness when compared with liquid quench. Several influencing factors on steel hardenability have been discussed, such as austenizing temperature, heating rate, holding time, composition variation and grain size difference. The phase quantification by X-ray Diffraction and Rietveld Refinement method is developed to measure phase percentage for steel microstructure, including martensite, ferrite and carbides. The limitations and improvements of modified Jominy gas quench test are discussed. The fundamental limitation of Jominy gas quench test is that one gas quench condition cannot be used for both low hardenability steel and high hardenability steel at the same time. The same steel grade would have different hardenability curves under different gas quench conditions, which made it difficult to compare the hardenability among different steels. The critical HTC test based on Grossmann test is proposed to overcome the limitations. In the test, different gas quench HTC conditions are applied to the sample with the same geometry. After sectioning each bar at mid-length, the bar that has 50% martensite at its center is selected, and the applied gas quench HTC of this bar is designated as the critical HTC. This test has many advantages to take the place of modified Jominy gas quench test. Since one of the advantages of gas quench is greater process flexibility to vary cooling rates, gas marquenching technology is proposed to obtain martensite with less sever cooling rate and reduce the distortion and stress.
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Kerr, Bradley Gray. "Experimental and theoretical rotordynamic coefficients and leakage of straight smooth annular gas seals." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1518.
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Results are presented for experimental and theoretical rotordynamic coefficients
and leakage of straight smooth annular gas seals. Experimental rotordynamic
coefficients were measured and trends in changes of rotordynamic coefficients with
operating variables such as rotor speed, back-pressure, fluid preswirl, and seal clearance
are analyzed.
Experimental results show that cross-coupled stiffness coefficients are highly
influenced by fluid preswirl and only moderately influenced by other operating
parameters, whereas direct damping is nearly unaffected by changes in operating
parameters. Effective damping, a good indicator of stability, is highly affected by fluid
preswirl. Although rotordynamic coefficients of straight smooth annular gas seals are
assumed to be frequency independent, experimental results suggest a frequency
dependent nature at high back-pressures and high excitation frequencies.
Experimental results for rotordynamic coefficients and leakage are compared
with theoretical predictions of ISOTSEAL, an isothermal-flow, two-control-volume,
bulk-flow rotordynamic analysis program. All rotordynamic coefficients are underpredicted.
Direct stiffness is poorly predicted while cross-coupled stiffness and direct
damping are predicted reasonably well. Leakage is also consistently under-predicted.
Theory predicts a slight frequency dependent nature for a limited number of test
configurations.
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Teixeira, José Reinaldo Paranaíba Vilela Alves. "High spatial variability of carbon emission and gas exchange coefficient in three tropical reservoirs." Universidade Federal de Juiz de Fora (UFJF), 2017. https://repositorio.ufjf.br/jspui/handle/ufjf/5656.
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Previous issue date: 2017-02-22<br>FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais<br>-<br>Reservoirs are significant sources of carbon emission to the atmosphere. However the magnitude of this emission has huge uncertainties, partly related to the methods of sampling and partly related to the unconsidered spatial-temporal variability. Here we examined the spatial variability and its drivers of partial pressure, gas exchange coefficient and diffusive flux of CO2 and CH4 in three tropical reservoirs. We observed high spatial variability in CO2 and CH4 concentration and flux within the reservoirs. Our results suggest that all reservoirs were supersaturated in both gases, even considering that some areas were CO2 sinks. A large spatial variability in k600 for CO2 and CH4, and consistently observed k600CH4 values higher than k600CO2 were also observed in all reservoirs. We could explain the high spatial variability of CO2 and CH4 by a combination of parameters such as dissolved oxygen, pH, chlorophyll, wind speed and bathymetry. Finally, we suggest a minimum sampling effort required to representatively cover a study site. Our results illustrate the first specially-resolved analysis of CH4 emissions in reservoirs, and we suggest that in large systems (area ≥ 1,000 km²) and small systems (area ≤ 100 km²), 600 and 200 measurements sites, respectively, are need for a representative dry period carbon flux estimates.
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Brunner, Matthias Herbert. "In-situ measurement of blade heat transfer coefficients and gas recovery temperature." kostenfrei, 2007. http://e-collection.ethbib.ethz.ch/view/eth:29954.
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Arduini, Tommaso. "Volumetric mass transfer coefficient in viscous batch in mechanically agitated fermenters." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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L’industria di processo è basata su diverse operazioni unitarie, le quali possono essere divise in due gruppi principali: il primo contenente quelle volte alla produzione vera e propria dei prodotti, mentre le rimanenti hanno come scopo la separazione dei prodotti d’interesse da quelli ritenuti di scarto. Per questo motivo, un corretto dimensionamento delle apparecchiature coinvolte è strettamente consigliato. Tuttavia, in situazioni complesse come i sistemi bifase, ciò non è sempre possibile. Infatti, lo scambio di materia che avviene tra il liquido e il gas non può essere calcolato analiticamente con formule puramente teoriche, ma al contrario, diversi dati sperimentali sono richiesti. Per questo motivo, spesso il dimensionamento di questo tipo di reattori è spesso fatto a tentativi, senza seguire una procedura ingegnerizzata. Per risolvere questo problema, diversi studi stanno cercando di costruire una corretta procedura per predire, in modo più accurato possibile il valore del coefficiente di scambio volumetrico. Il valore di questo parametro, infatti, è strettamente richiesto nella soluzione dei bilanci di materia che permettono il dimensionamento dell’apparecchiatura. In particolare, questo parametro può essere ricavato da misurazioni sperimentali. Tuttavia, diverse metodologie impiegate restituiscono risultati differenti. Per questo motivo, la letteratura contiene numerosi articoli con risultati significativamente diversi tra di loro.
Tuttavia, metodi di misurazione più efficaci sono stati introdotti. Tra questi si ricorda il Dynamic Pressure Method, il quale sarà utilizzato in questo elaborato per la valutazione del coefficiente di trasporto di materia volumetrico. Inoltre saranno proposte diverse correlazioni come un utile strumento per il dimensionamento di fermentatori industriali con più di una girante.
13
Prausa, Jeffrey Nathaniel. "Heat Transfer Coefficient and Adiabatic Effectiveness Measurements for an Internal Turbine Vane Cooling Feature." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/76790.
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Aircraft engine manufacturers strive for greater performance and efficiency by continually increasing the turbine inlet temperature. High turbine inlet temperatures significantly degrade the lifetime of components in the turbine. Modern gas turbines operate with turbine inlet temperatures well above the melting temperature of key turbine components. Without active cooling schemes, modern turbines would fail catastrophically. This study will evaluate a novel cooling scheme for turbine airfoils, called microcircuit cooling, in which small cooling channels are located extremely close to the surface of a turbine airfoil. Coolant bled from the compressor passes through the microcircuits and exits through film cooling slots. On further cooling benefit is that the microcircuit passages are filled with irregular pin fin features that serve to increase convective cooling through the channels.
Results from this study indicate a strong interaction between the internal microcircuit features and the external film-cooling from the slot exit. Asymmetric cooling patterns downstream of the slot resulted from the asymmetric pin fin design within the microcircuit. Adiabatic effectiveness levels were found to be optimum for the slot design at a blowing ratio of 0.37. The pin fin arrangement along with the impingement cooling at the microcircuit entrance increased the area-averaged heat transfer by a factor of three, relative to an obstructed channel, over a Reynolds range of 5,000 to 15,000.<br>Master of Science
14
Acinan, Sezen. "Determination Of Runoff Coefficient Of Basins By Using Geographic Information Systems." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609522/index.pdf.
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Turkey has very different geomorphologic, hydrologic and climatic conditions, so the runoff coefficient should be different from one basin to another. But only one constant value, which is 0.37, is being used for all the basins in Turkey. In this thesis, monthly, seasonal and annual runoff coefficients of 48 sub-basins in western and southern part of Anatolia are determined by using synchronous and average rainfall, runoff data of 26 year record period. Their temporal and spatial distributions are investigated. The relationship between the basin parameters and the runoff coefficient are also examined. Some of the basins have unrealistic large runoff coefficients, therefore excluded from the analyses.
The basin boundaries and parameters are determined by using Geograhic Information System (GIS), and areal average precipitations are found by a program written in visual basic language that uses ArcObjects. The Box-Cox transformed data are used in regression analysis. There are a number of dams in the region, which affect the natural flow. Such streams are found and their sub-basins are not used in the analyses. The results revealed that there is not a strong the relationship between the basin parameters and annual and seasonal runoff coefficients for the whole region, but there are significant relations between them for some basins.
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Seo, Dongjin. "Measurement and Control of Slip-Flow Boundary Conditions at Solid-Gas Interfaces." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/50650.
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This thesis describes measurements of the gas-solid flow boundary condition at moderate Knudsen number, i.e., where the dimensions of the flow are similar to the mean free path, and thus partial slip is expected. This regime has become more important with increased focus on nano-scale devices, but there is currently no consensus on how the slip length should vary for different solids and gases, or whether it can be controlled. In this thesis, I describe unambiguous measurements showing that partial slip occurs, that the slip length depends both on gas and solid, and that the slip length can be altered in situ. The slip length is determined from analysis of the vibration of a small sphere adjacent to a solid. I also describe applications of these findings both to the separation of gases, and to inhalants.
The effect of water films, gas species, organic films, and electric fields on gas flow was studied. Water films had a large, but complex effect. On bare hydrophobilic glass, the tangential momentum accommodation coefficient (TMAC) for nitrogen on hydroxyl-terminated silica changed from 0.25 to 0.88 when the humidity changed from 0 to 98 %. On hydrophobized glass, TMAC changed from 0.20 to 0.56 in the same range.
The effect of the gas on TMAC was measured for five different gases (helium, nitrogen, argon, carbon dioxide, hexafluoride sulfur) on octadecyltrichlorosilane-coated glass surfaces. A lower
TMAC occurred for greater molar mass, and this trend was explained using a simple model representing both the gas and the monolayer by spheres. The existence of this gas-dependent difference in TMAC suggests that gases can be separated based on their collisions with surfaces.
Methods for controlling the flow boundary condition were also developed by adsorbing monolayers on the solid, and altering the monolayers in situ. Both temperature and electric fields altered the boundary condition, and these changes were attributed to changes in the surface roughness. The effect of roughness was modeled with grooved surfaces. Possible applications of this effect of roughness include changing the flow of aerosol droplets for deeper delivery of therapeutic drugs into the lung.<br>Ph. D.
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Mercy, Michel. "Contribution à l'étude des relations entre coefficients d'accommodation et physisorption." Nancy 1, 1989. http://www.theses.fr/1989NAN10221.
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Le présent travail vise à déterminer dans quelle mesure la physisorption d'un gaz A sur une surface peut modifier le coefficient d'accomodation thermique d'un gaz B sur cette même surface. Le système considéré est celui de l'hélium s'accomodant sur une surface de tungstène nue ou recouverte de xénon ou de krypton physisorbé
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Jun, Byung Soon. "Measurement of thermal accommodation coefficients of inert gas mixtures on a surface of stainless steel /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3025627.
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Delimont, Jacob M. "Experimental Investigation of Temperature Effects on Microparticle Sand Rebound Characteristics at Gas Turbine Representative Conditions." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/47805.
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When a gas turbine operates in a particle laden environment, such as a desert, small solid particles are ingested into the engine. The ingested sand particles can cause damage to engine components and reduce the service life of the engine. Particle ingestion causes the erosion of metal blades and vanes, and, if the firing temperature is hot enough, deposition of molten particles in the hot sections of the engine. Both deposition and erosion phenomena can severely reduce overall engine performance. The Coefficient of Restitution (COR) is a measure of the particle-wall interaction, and has been widely used to quantify particle rebound characteristics in past particle impact studies. This work investigates the effects of temperature on sand particle impact characteristics by measuring the COR and other deposition related impact parameters.
The first study presented as part of the dissertation contains a description of a novel method used to measure COR using a Particle Tracking Velocimetry (PTV) method. This is combined with Computational Fluid Dynamics (CFD) flow field to allow for an accurate determination of the particle impact velocity. The methodology described in this paper allows for measurement of the COR in a wide range of test conditions in a relatively simple manner. The COR data for two different sizes of Arizona Road Dust (ARD) and one size of glass beads are presented in this paper. Target material was stainless steel 304 and the impact angle was varied from 25 to 85 degrees.
The second study details the first quantification of the COR of san particles at elevated temperatures. Temperatures used in this study were 533 K, 866 K, and 1073 K. In this study the mass flow rate through the experimental setup was fixed. This meant that velocity and temperature were coupled. Target material for this study was stainless steel 304 and the impact angle was varied from 30° to 80°. The COR was found to decrease substantially at the temperatures and velocity increased. It was determined that the decrease in COR was almost certainly caused by the increase in velocity, and not the decrease in temperature.
The third study contains COR results at elevated temperatures. Significant improvements from the method used to calculate COR in the first paper are described. The particle used for these tests was an ARD sand of 20-40 μm size. Target materials used were stainless steel 304 and Hastelloy X. The particles impinged on the target coupon at a velocity of 28m/s. Tests were performed at three different temperatures, 300 K (ambient), 873 K, and 1073 K to simulate temperatures seen in gas turbine cooling flows. The angle of impingement of the bulk flow sand on the coupon was varied between 30° and 80°. A substantial decrease in COR was discovered at the elevated temperatures of this experiment. Hastelloy X exhibited a much larger decrease in COR than does stainless steel 304. The results were compared to previously published literature.
The final study also used the ARD size of 20-40 μm. The target material was a nickel alloy Hastelloy X. Experiments for this study were performed at a constant velocity of 70m/s. Various temperatures ranging from 1073 K up to and including 1323 K were studied. Particle angle of impact was varied between 30° and 80°. Significant deposition was observed and quantified at the highest two temperatures. The COR of the ARD sand at the highest temperatures was found not to change despite the occurrence of deposition. At elevated temperatures, many of the particles are not molten due to sand's non-homogenous and crystalline nature. These particles rebound from the target with little if any change in COR.<br>Ph. D.
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La, Rosa Rivero Renzo Josue. "Effects on Heat Transfer Coefficient and Adiabatic Effectiveness in Combined Backside and Film Cooling with Short-Hole Geometry." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/97010.
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Heat transfer experiments were done on a flat plate to study the effect of internal counter-flow backside cooling on adiabatic film cooling effectiveness and heat transfer coefficient. In addition, the effects of density ratio (DR), blowing ratio (BR), diagonal length over diameter (L/D) ratio, and Reynolds number were studied using this new configuration. The results are compared to a conventional plenum fed case. Data were collected up to X/D =23 where X=0 at the holes, an S/D = 1.65 and L/D=1,2. Testing was done at low L/D ratios since short holes are normally found in double wall cooling applications in turbine components. A DR of 2 was used in order to simulate engine-like conditions and this was compared to a DR of 0.92 since relevant research is done at similar low DR. The BR range of 0.5 to 1.5 was chosen to simulate turbine conditions as well. In addition, previous research shows that peak effectiveness is found within this range. Infrared (IR) thermography was used to capture temperature contours on the surface of interest and the images were calibrated using a thermocouple and data analyzed through MATLAB software. A heated secondary fluid was used as 'coolant' in the present study. A steady state heat transfer model was used to perform the data reduction procedure. Results show that backside cooling configuration has a higher adiabatic film cooling effectiveness when compared to plenum fed configurations at the same conditions. In addition, the trend for effectiveness with varying BR is reversed when compared with traditional plenum fed cases. Yarn flow visualization tests show that flow exiting the holes in the backside cooling configuration is significantly different when compared to flow exiting the plenum fed holes. We hypothesize that backside cooling configuration has flow exiting the holes in various directions, including laterally, and behaving similar to slot film cooling, explaining the differences in trends. Increasing DR at constant BR shows an increase in adiabatic effectiveness and HTC in both backside cooling and plenum fed configurations due to the decreased momentum of the coolant, making film attachment to the surface more probable. The effects of L/D ratio in this study were negligible since both ratios used were small. This shows that the coolant flow is still underdeveloped at both L/D ratios. The study also showed that increasing turbulence through increasing Reynolds number decreased adiabatic effectiveness.<br>MS
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Winroth, Marcus. "On Gas Dynamics of Exhaust Valves." Licentiate thesis, KTH, Strömningsfysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202719.
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With increasing effects of global warming, efforts are made to make transportation in general more fuel efficient. When it comes to internal combustion engines, the most common way to improve fuel efficiency is through ‘downsizing’. Downsizing means that a smaller engine (with lower losses and less weight) performs the task of a larger engine. This is accomplished by fitting the smaller engine with a turbocharger, to recover some of the energy in the hot exhaust gases. Such engine systems need careful optimization and when designing an engine system it is common to use simplified flow models of the complex geometries involved. The exhaust valves and ports are usually modelled as straight pipe flows with a corresponding discharge or loss coefficient, typically determined through steady-flow experiments with a fixed valve and at low pressure ratios across the valve. This means that the flow is assumed to be independent of pressure ratio and quasi-steady. In the present work these two assumptions have been experimentally tested by comparing measurements of discharge coefficient under steady and dynamic conditions. The steady flow experiments were performed in a flow bench, with a maximum mass flow of 0.5 kg/s at pressures up to 500 kPa. The dynamic measurements were performed on a pressurized, 2 litre, fixed volume cylinder with one or two moving valves. Since the volume of the cylinder is fixed, the experiments were only concerned with the blowdown phase, i.e. the initial part of the exhaustion process. Initially in the experiments the valve was closed and the cylinder was pressurized. Once the desired initial pressure (typically in the range 300-500 kPa) was reached, the valve was opened using an electromagnetic linear motor, with a lift profile corresponding to different equivalent engine speeds (in the range 800-1350 rpm). The results of this investigation show that neither the quasi-steady assumption nor the assumption of pressure-ratio independence holds. This means that if simulations of the exhaustion process is made, the discharge coefficient needs to be determined using dynamic experiments with realistic pressure ratios. Also a measure of the quasi-steadiness has been defined, relating the change in upstream conditions to the valve motion, i.e. the change in flow restriction, and this measure has been used to explain why the process cannot be regarded as quasi-steady.<br><p>QC 20170306</p>
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Breedlove, Anthony Wayne. "Experimental identification of structural force coefficients in a bump-type foil bearing." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1936.
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Kalinger, James Phillip. "Heat transfer coefficient and pressure drop gas cooling measurements for CO2/oil mixture in a micro channel tube." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2632.
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Thesis (M.S.) -- University of Maryland, College Park, 2005.<br>Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Playford, William. "Well-conditioned heat transfer measurements on engine scale gas turbine rigs." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274997.
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High combustion temperatures are required in gas-turbine engines to achieve high cycle efficiencies. With increasing temperature, however, the life span of the turbine components are reduced. The ability to accurately predict engine component temperature as a function of combustion temperature is required to strike this balance correctly. An experimental heat transfer measurement technique is developed in this thesis, which builds on a large body of existing literature. The technique enables a detailed quantification of turbine heat transfer on test rigs which closely represent gas-turbine engine configurations. Fundamental improvements are made to existing methods, in the definition of the ‘semi- infinite limit’ for transient measurement techniques, in Infra-red camera calibration, and in thermal effusivity measurement. The improvements were developed from first principles, verified experimentally, and have been used on a world leading heat transfer rig (the FACTOR combustor-turbine interaction rig, run on the NG-Turb facility at DLR Göttingen). It was found that optimisation of a number of measurement parameters was required to minimise the measurement uncertainty. It is shown that the optimum measurement parameters are dependant, and sensitive to the specific configuration of the test rig. An experimental procedure was developed and tested, which has been ‘tuned’ for measurements on the FACTOR test rig. Despite the challenging measurement environment on the FACTOR rig, it was found that state-of-the-art heat transfer measurement uncertainties of approximately 5%, could nevertheless still be achieved, by using the new methods. General principles and rules are established which can be used to guide the design of future heat transfer measurements, with the aim of minimising measurement uncertainty.
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Seifert, Brent Alan. "Measurements versus predictions for rotordynamic coefficients and leakage rates for a novel hole-pattern gas seal." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4782.
Full textAbstract:
Results are presented for measured and predicted rotordynamic coefficients and
leakage for hole-pattern seals with a hole depth that varies axially along the seal.
Testing was done to discover how pressure ratio, inlet preswirl, and rotor speed affect
the sealsâ rotordynamic characteristics and leakage. The results were compared to a
constant hole depth hole-pattern seal.
Experimental results show that the sealsâ rotordynamic characteristics are not
strongly influenced by pressure ratio.
There were three preswirl conditions tested, each separated by a 6.9 bar (100
psi) difference in inlet pressure. Therefore, normalized preswirl results were compared.
The normalized results indicate that introducing inlet fluid preswirl affects the crosscoupled
stiffness and effective damping coefficients. Inlet preswirl increases the
magnitude of cross-coupled stiffness. Effective damping decreases with inlet preswirl,
as well as the effective damping cross-over frequency increasing. These results
indicate that swirl brakes would be of great value.
Rotor speed had a significant effect on the cross-coupled coefficients; both
increased with speed.
Experimental results were compared to results for a constant hole depth holepattern
seal. The variable hole-depth seal has higher direct damping. The crosscoupled
stiffness and cross-coupled damping coefficients were very similar. The direct
stiffness was always lower at lower frequencies and higher at higher frequencies for the
variable hole depth hole-pattern seal. This was also the case for effective stiffness.
The effective damping of the variable hole-depth seal was not only larger than for the constant hole depth seal, it also had a drastically lower cross-over frequency. The
difference in cross-over frequency was 40 percent on average.
Experimental results for rotordynamic characteristics and leakage were
compared to theoretical predictions by ISOTSEAL 2, a modified version of ISOTSEAL.
Both cross-coupled stiffness and damping are reasonably predicted. Direct damping is
always under-predicted. ISOTSEAL 2 does a poor job of predicting direct stiffness.
Direct stiffness is over-predicted at lower frequencies and under-predicted at higher
frequencies. This is also the case for effective stiffness. ISOTSEAL 2 under-predicts
the direct damping, but does an excellent job of predicting the direct damping crossover
frequency. Seal leakage is well predicted by ISOTSEAL 2.
25
Urupina, Darya. "Uptake and reactivity of sulfur dioxide gas onto Icelandic volcanic dusts." Electronic Thesis or Diss., Ecole nationale supérieure Mines-Télécom Lille Douai, 2020. http://www.theses.fr/2020MTLD0022.
Full textAbstract:
Ces travaux de thèse portent sur l’étude des interactions du dioxyde de soufre (SO2) gazeux avec des poussières volcaniques islandaises. Ils intègrent cinq échantillons naturels de poussières volcaniques: Hagavatn, Mýrdalssandur, Maelifellssandur, Dyngjusandur and Eyjafjallajökull. Les interactions hétérogènes entre SO2 et les poussières volcaniques sont abordées avec plusieurs techniques expérimentales complémentaires. Les profils temporels associés à la capture de SO2, caractérisés par les coefficients de capture en régime stationnaire ont été renseignés expérimentalement. Ces paramètres sont des données d’importance pour les modèles atmosphériques. Des mécanismes réactionnels décrivant la formation des espèces de surface résultant de l’interaction de SO2 avec la surface des poussières sont proposés. Une nouvelle méthode analytique permettant l’extraction et la quantification d’espèces soufrées de surface a été développée et validée. Cette méthode est à présent disponible tant pour l’étude de processus hétérogènes en laboratoire que pour la caractérisation d’échantillons de terrain. Il a été mis en évidence que l’interaction de SO2 avec les poussières volcaniques est un processus de long terme. Les produits formés en surface sont stables et influencent les propriétés des particules minérales. Il a été démontré expérimentalement que l’humidité relative présente une influence marquée sur la capture et la transformation de SO2. La composition de surface des particules minérales est aussi un élément clé, particulièrement pour des humidités relatives inférieures à 30%. Enfin, ces travaux montrent l’importance d’avoir recours à des échantillons minéraux naturels pour assurer une bonne représentativité des études portant sur les processus atmosphériques hétérogènes impliquant des particules minérales<br>This thesis investigates the interactions of sulfur dioxide (SO2) gas with Icelandic Volcanic Dusts. Five natural volcanic dust samples were used for the study: Hagavatn, Mýrdalssandur, Maelifellssandur, Dyngjusandur and Eyjafjallajökull. The heterogeneous interactions of gas-phase SO2 with volcanic dusts are investigated using a number of complimentary techniques. Temporal profiles of SO2 uptake and, more precisely, the steady state uptake coefficients have been determined experimentally. These are important kinetic parameters that can be implemented in models. Mechanisms of formation of various surface species resulting from the interactions of SO2 with the surface of dusts are proposed. A new method for quantification of surface sulphur species has been developed and validated. This method can now be used both for further laboratory investigations and in field measurements. It is evidenced that the interactions of SO2 gas with the volcanic dust is a long continuous process. The products formed on the surface are stable and definitely influence the mineral particle properties. It is evidenced that the interactions of SO2 gas and volcanic particles are highly influenced by humidity and by UV light. The influence of surface composition also plays an important role especially at levels of humidity equal or lower than 30% RH. This work emphasizes the importance of using relevant natural dust samples in order to study the heterogeneous atmospheric phenomena involving natural solid particles
26
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.
Full textAbstract:
Thesis (MEng)--Stellenbosch University, 2015.<br>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.<br>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.
27
Santosa, I. Dewe. "Optimisation gas coolers for CO2 refrigeration application." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/12161.
Full textAbstract:
Carbon dioxide (CO2) is a natural, low cost refrigerant with good thermo-physical properties. CO2 is a good alternative for replacing HFC refrigerants that possess high global warming potential and reducing the direct impacts of refrigeration systems on the environment. However, CO2 refrigeration systems operate at relatively high condenser/gas cooler pressures and this imposes special design and control considerations. The gas cooler is a very important part of the system and can have significant influence on its performance. In sub-critical operation, good gas cooler/condenser design can reduce the condenser pressure and delay switching to supercritical operation which increases system efficiency. In supercritical operation optimum design and control can enable the system to operate at pressures that maximise system efficiency. In air cooled systems, gas coolers/condensers are of the finned-tube type. This type of heat exchanger is well established in the HVAC and refrigeration industries. The large changes in the CO2 properties in the gas cooler, however, during supercritical operation impose special design and manufacturing considerations. This research project considered the influence of the unique heat transfer characteristics of CO2 on the design and performance of finned tube air cooled condensers/gas coolers for CO2 refrigeration applications. A combined experimental and modelling approach using Computational Fluid Dynamics (CFD) was employed. A CO2 condenser/gas cooler test facility was developed for the experimental investigations. The facility employs a ‘booster’ hot gas bypass CO2 refrigeration system, with associated condenser/gas cooler test rig and evaporator load simulation facility. A series of experimental tests were carried out with two gas coolers which incorporated horizontal and horizontal-vertical slit fins and was obtained adequate experimental data concerning gas cooler performance. CFD modelling was used to study the performance of the gas coolers. The model was validated against test results and was shown to predict the air outlet temperature and heat rejection of the gas cooler with an accuracy of within ±5%. The model was subsequently used to evaluate the effect of a fin slit between the 1st and 2nd row of tubes of the gas cooler as well as a vertical slit on the 1st row before the last tube of the section. The results showed a 6%-8% increase in the heat rejection rate of the gas cooler compared to the performance without the horizontal slit. The vertical slit in the fin of the last tube has resulted in an additional increase in heat rejection over and above that for the horizontal slit of 1%-2%. CFD modelling was also used to investigate the variation of the refrigerant side, air side and overall heat transfer coefficient along the heat exchanger. The results showed that the refrigerant heat transfer coefficient increases with the decreasing of bulk refrigerant temperature and reaches its maximum when the specific heat of the refrigerant is highest. Furthermore, increasing the refrigerant mass flux, increases the refrigerant side heat transfer coefficient and heat rejection. This can reduce the size of the gas cooler for a given capacity at the expense of higher pressure drop and compressor power consumption. Air side and overall heat transfer coefficient correlations were developed for the specific gas cooler designs which were investigated and showed the heat transfer coefficients increase with increasing Reynolds Number.
28
Lawrence, Michael James. "An Experimental Investigation of High Temperature Particle Rebound and Deposition Characteristics Applicable to Gas Turbine Fouling." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1376653488.
Full text
29
Sprowl, Tony Brandon. "A study of the effects of inlet preswirl on the dynamic coefficients of a straight-bore honeycomb gas damper seal." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1617.
Full textAbstract:
In high-pressure centrifugal compressors, honeycomb seals are often used as replacements for labyrinth seals to enhance dynamic stability. A concern exists with the loss of this enhanced stability if the honeycomb cavities become clogged with debris over time. So, as a first objective, static and dynamic tests were conducted on a constant-clearance honeycomb and a constant-clearance smooth-bore seal under three inlet preswirl conditions to determine the effects of inlet preswirl. The resulting leakage flowrate and dynamic parameters, effective stiffness and damping of the seal, were measured for each seal and then compared, with the smooth-bore seal representing the honeycomb seal with completely clogged cells. The second objective was to evaluate a two-control volume theory by Kleynhans and Childs with the measured data under the influence of preswirl.
Both seals have a 114.7mm bore with a radial clearance of 0.2mm from the test rotor. The honeycomb seal has a cell width of 0.79mm and cell depth of 3.2mm. The target test matrix for each preswirl setting consisted of three exit-to-inlet pressure ratios of 15%, 35%, and 50%, and three rotor speeds out to 20,200 rpm. The target inlet air pressure was 70 bar-a.
Experimental results show that, for a clean honeycomb seal, preswirl has little effect on effective stiffness, Keff*, and decreases effective damping, Ceff*, by about 20% at the high inlet preswirl ratio (~0.6). However, comparing smooth and honeycomb seal results at higher inlet preswirl shows a potential reduction in Keff* by up to 68%, and a large drop and shift in positive Ceff* values, which could cause an instability in the lower frequency range. Measured leakage shows a potential increase of about 80%, regardless of test conditions. A swirl brake at the seal entrance would fix this loss in stability by significantly reducing inlet preswirl.
The two-control-volume theory model by Kleynhans and Childs seems to follow the frequency-dependent experimental data well for the honeycomb seal. Theory predicts conservatively (under-predicts) for stability parameters such as k* and Ceff* and for leakage. Predictions for K and Keff may possibly be improved with better measured friction factor coefficients for each seal.
30
Bose, Rana. "Unloading using auger tool and foam and experimental identification of liquid loading of low rate natural gas wells." Texas A&M University, 2003. http://hdl.handle.net/1969.1/5890.
Full textAbstract:
Low-pressure, low-producing natural gas wells commonly encounter liquid loading
during production. Because of the decline in the reservoir pressure and the flow
capacity, wells can fall below terminal velocity. Identifying and predicting the onset
of liquid loading allows the operators to plan and prepare for combating the liquid
loading hence saving valuable reserves and downtime. The present industrial
applications of artificial lift, wellhead pressure reduction by compressor installation
at the wellheads and reduction in tubing size are costly and often intermittent. The
thesis examines the above aspects to generate a workflow for identifying and
predicting the liquid loading conclusively and also assessing the application of
Auger Tool and foam combination towards achieving a cost effective and more
efficient solution for liquid unloading.
In chapters I-IV, I describe the process of using production surveillance software of
Halliburton Digital Consulting Services, named DSS (Dynamic Surveillance
Software), to create a workflow of identifying the liquid loaded wells based on well
data on daily basis for field personnel and engineers. This workflow also decides the most cost effective solution to handle it. Moreover, it can perform decline
analysis to predict the conditions of liquid loading.
In chapters V-VIII of the thesis, I describe the effort of handling the problem of
liquid loading in a cost effective manner by introduction of an inexpensive Auger
Tool in the bottomhole assembly and using WhiteMax surfactant soapstick from
J&J Solutions. Four different combinations of well completion and fluid were tested
for performance in respect to liquid hold up, pressure loss in the tubing, unloading
efficiency and critical flow requirement. The test facilities and instruments, along
with the operational methods, are discussed in chapter VI.
Except for the reduction of the operational envelope with the inclusion of Auger
Tool, the performance improved with the insertion of Auger Tool. The best
combination of Auger and foam system could be a result of flow modification by the
Auger Tool caused by reduced pressure loss and increase in drag coefficient and
also by reduced density and surface tension of foam.
31
Chery, Olivier. "Étude hydrodynamique et transfert de matière dans un contacteur gaz-liquide à film centrifuge dans le cadre de procédés de traitement d'effluents gazeux contenant du dioxyde de soufre et/ou des oxydes d'azote." Vandoeuvre-les-Nancy, INPL, 1994. http://docnum.univ-lorraine.fr/public/INPL_T_1994_CHERY_O.pdf.
Full textAbstract:
Dans le cadre d'un programme B. R. I. T. E. De la C. C. E. , nous étudions un procédé de traitement d'effluents gazeux contenant du dioxyde de soufre et/ou des oxydes d'azote, par absorption suivie de l'oxydation de ces espèces. Dans une première phase, nous avons utilisé un contacteur gaz-liquide ayant des caractéristiques de transfert de matière élevées: le réacteur à film centrifuge. La caractérisation hydrodynamique du contacteur a permis de mettre en évidence les régimes de fonctionnement, le comportement, du réacteur piston au réacteur parfaitement agité, ainsi que les paramètres essentiels: la vitesse de rotation et la contre-pression. Nous avons ensuite déterminé les caractéristiques de transfert de matière de l'absorbeur par la mesure des coefficients volumiques de transfert de matière cote gaz et liquide. La dernière étape de cette étude a été une application du réacteur à film centrifuge à l'absorption d'un mélange dilué d'oxyde et de dioxyde d'azote dans une solution aqueuse d'urée. Il s'avère que les temps de séjour rencontrés dans le contacteur sont trop faibles pour que certaines réactions d'élimination de ces polluants puissent avoir lieu. La seconde partie a consisté à concevoir et à mettre en œuvre un réacteur à film tombant laminaire cylindrique, destiné à déterminer la cinétique de la réaction chimique suivant l'absorption du dioxyde de soufre dans une solution aqueuse acide de cérium quatre. Seules, quelques expériences ont pu être réalisées montrant que la réaction est probablement intermédiaire. D’autres expériences doivent également être menées afin de mieux caractériser ce réacteur
32
Wade, Jonathan Leigh. "Test versus predictions for rotordynamic coefficients and leakage rates of hole-pattern gas seals at two clearances in choked and unchoked conditions." Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/424.
Full textAbstract:
This thesis documents the results of high pressure testing of hole-pattern annular gas seals conducted at the Texas A&M University's Turbomachinery Laboratory. The testing conditions were aimed at determining the test seals sensitivity to pressure ratio, inlet fluid preswirl, rotor speed, and rotor to seal clearance. The rotordynamic coefficients showed only small changes resulting from the different pressure ratios tested. Only the damping terms at the lower frequencies showed some influence. One other notable result from the testing of different pressure ratios is that the seals were tested in a choked flow condition, and there was not a significant change in the seal behavior when the seals transitioned to the choked condition. The inlet fluid preswirl only had a notable effect on the cross-coupled stiffness in the larger clearance tests. These results lead to the conclusion that a swirl brake could have some rotordynamic value, but only if the seals have sufficiently large clearance. Conversely this also means that if hole-pattern seals are being implemented with a small clearance, then a swirl brake would not be an effective way to improve the rotordynamic stability of the system. The only significant effect that the rotor speeds had on the rotordynamic coefficients were that the cross-coupled coefficients increased as the rotor speed increased. This is the expected result because as the rotor speed increases there is a greater shear force on the gas as it passes through the seal resulting in more fluid circumferential velocity, which results in stronger cross-coupled coefficients. The changes in clearance resulted in drastic changes in the magnitude of the coefficients. The smaller clearance yielded much higher coefficients than the larger clearance. All of the rotordynamic coefficients were predicted well by ISOTSEAL. The code was found to do a good job predicting the seal leakage as well. This gives more credence to the coefficients and leakage that ISOTSEAL predicts.
33
Boumaaza, Mouna. "Experimental investigation of gas diffusivity and CO2-binding capacity of cementitious materials." Thesis, La Rochelle, 2020. https://tel.archives-ouvertes.fr/tel-03285120.
Full textAbstract:
Actuellement, les méthodes d’essais normalisées, couramment utilisées pour étudier la carbonatation du béton, s’appuient sur l’évaluation de la chute du pH (<9) de la solution interstitielle d'un échantillon de béton exposé à des concentrations ambiantes ou très élevées de CO2 (2% à 50% en volume). Ces méthodes sont souvent critiquées car soit, elles nécessitent beaucoup de temps (plus d’une année pour la carbonatation naturelle), soit elles sont coûteuses et d’une faible fiabilité (la carbonatation accélérée, notamment quand la concentration de CO2 est supérieure à 3% CO2). Deux mécanismes principaux pilotent la carbonatation: le transport diffusif du dioxyde de carbone gazeux, qui est régi par le coefficient de diffusion effectif de cette espèce dans le milieu poreux, et la consommation de CO2 par la quantité de produits carbonatables présente dans la matrice cimentaire. Ces deux propriétés du matériau sont requises pour les modèles prédictifs de la profondeur de carbonatation des matériaux cimentaires. L’objectif de ce travail est donc de développer deux méthodes d’essai simples et fiables pour déterminer ces deux propriétés.D’abord, nous avons développé et validé une méthode d’essai permettant de déterminer le coefficient de diffusion effectif d’oxygène (De,O2) de neufs pâtes de ciment durcies et 44 bétons pré-conditionnés à différentes humidités relatives. L'influence de la durée d'hydratation, du rapport eau sur liant, de la carbonatation accélérée (1% CO2) et du type de liant sur la diffusivité de l'oxygène est étudiée sur des bétons et pâtes de ciment durcies. L’influence de l’épaisseur de l’échantillon de béton testé sur le De,O2 est évaluée à l'état sec et après conditionnement des bétons à une humidité relative de 93%. La corrélation entre la perméabilité à l'oxygène et le coefficient de diffusion effective d’oxygène est étudiée sur 44 mélanges de béton.Une deuxième méthode d’essai est développée pour étudier le taux instantané de fixation de CO2 et la quantité de produits carbonatables de pâtes de ciment hydratées, de phases pures d’hydrates et anhydres synthétisées. Les échantillons ont été carbonatés dans des systèmes ouverts sous humidités relatives contrôlées et concentration ambiante de CO2, puis le système bascule en configuration fermée pour mesurer la quantité de CO2 fixée par le matériau testé pendant une courte période. Cette méthode d’essai permet de déterminer l’évolution en fonction de temps du taux instantané de réaction de carbonatation et de la capacité de fixation de CO2 sous différents environnements. Un bon accord entre les résultats de la nouvelle méthode d’essai et l'analyse thermogravimétrique a été observé, ce qui met en évidence la fiabilité et la précision de la méthode de test développée.Les résultats obtenus des essais de diffusion et les quantités de produits carbonatables sont intégrés dans des modèles de prédiction de la profondeur de carbonatation. Ces profondeurs de carbonatation ont été comparées aux profondeurs de carbonatation déterminées directement sur les mêmes matériaux par pulvérisation de phénolphtaléine, en carbonatation naturelle et accélérée<br>The current standardized methods used to investigate the carbonation performance of concrete are based on the direct determination of the pH variation on the surface of a concrete specimen exposed to ambient or higher CO2 concentration. These methods are either time-consuming (natural carbonation) or of a questionable accuracy (accelerated carbonation). The carbonation physicochemical process involves two major mechanisms: gaseous CO2 diffusion into the cementitious material’s porous network and its dissolution and reaction with CaO of the hardened cement paste. Most carbonation depth prediction models require the CO2-effective diffusion coefficient and the amount of carbonatable products as input parameters. Hence the aim of this work is to develop two simple and reliable test methods to determine these two properties in a reliable and cost-effective manner.First we developed and validated a test method to determine the oxygen-effective diffusion coefficient (De,O2) of nine different hardened cement pastes preconditioned at different relative humidity levels, and 44 concrete mixtures. The influence of the hydration duration, water-per-binder ratio, accelerated carbonation, and binder type on the oxygen diffusivity was investigated. The dependence of the De,O2 on the tested concrete specimen thickness was investigated at the dry state and after conditioning at 93%RH. The De,O2 was determined before and after full carbonation of six concrete mixtures previously conditioned at different RH. A correlation between oxygen permeability and diffusivity is investigated on 44 concrete mixtures.A second test method is developed to determine the instantaneous CO2 binding rate and the amount of carbonatable products of powdered hydrated cement pastes and synthetic anhydrous and hydrates. The samples were carbonated in open systems at ambient CO2 concentration and controlled relative humidity, and then the system switches into a closed configuration while the measurement of the CO2-uptake is performed over a short period of time. The test method allows for the measurement of the carbonation reaction rate and capacity; and their evolution as function of time under different RH. The developed method shows advantages for being nondestructive, allowing the samples to carbonate at controlled CO2 concentration and humidity, and providing measurements with low cost equipment. A good agreement between the test method results and thermogravimetric analysis was observed, which highlights the reliability and accuracy of the developed test method.The results obtained from the gaseous diffusion coefficient and carbonatable products test methods were used as inputs for carbonation depth prediction models. A correlation was investigated between the measured carbonation depth on different concrete and hydrated cement pastes mixtures by means of phenolphthalein solution under both natural and accelerated exposure. The results were compared with the calculated carbonation depth using our experimental results<br>Die zurzeit verwendeten Methoden zur Untersuchung des Karbonatisierungs-widerstandes von Beton basieren auf der direkten Bestimmung des pH-Wertes der oberflächennahen Betonrandzone, die zuvor einer bestimmten Prüflagerung ausgesetzt war (relative Luftfeuchte, spezifische CO2-Konzentrationen). Diese Methoden sind jedoch entweder sehr zeitaufwändig (natürliche Karbonatisierung) oder von fraglicher Praxisnähe (beschleunigte Karbonatisierung). Der physikalisch-chemische Karbonatisierungsprozess beinhaltet zwei Hauptmechanismen: die Diffusion von gasförmigem CO2 in das poröse Netzwerk des Betons und dessen Auflösung und Reaktion mit CaO der ausgehärteten Zementsteins. Die meisten Modelle zur Vorhersage der Karbonatisierungstiefe erfordern den effektiven CO2-Diffusionskoeffizienten und die Menge an karbonatisierbarer Masse als Eingabeparameter. Ziel dieser Arbeit ist es, zwei einfache und zuverlässige Testmethoden zu entwickeln, um diese beiden Eigenschaften zuverlässig und kostengünstig zu bestimmen.Nach Entwicklung und Validierung einer geeigneten Testmethode zur Messung von Sauerstoffdiffusionskoeffizienten (De,O2), wurden diese an neun verschiedenen Zementproben gemessen, die bei unterschiedlichen relativen Luftfeuchten vorkonditioniert wurden. Anschließend wurden 44 verschiedene Betonmischungen geprüft. Bei diesen wurde die Hydratationsdauer und der Wasserbindemittelwert variiert. Die Abhängigkeit des Sauerstoffdiffusionskoeffizienten De,O2 von der getesteten Betonprobendicke wurde im trockenen Zustand und nach Konditionierung bei 93% relativer Luftfeuchtigkeit untersucht. Der Sauerstoffkoeffizient De,O2 wurde vor und nach der vollständigen Carbonisierung von sechs Betonmischungen bestimmt, die zuvor bei unterschiedlicher relativer Luftfeuchtigkeit vorkonditioniert worden waren. Eine zweite Testmethode wurde entwickelt, um die momentane CO2-Bindekapazität und die Menge an karbonatisierbarer Masse aus pulverförmigen Zementhydratpasten und synthetischen wasserfreien Produkten und Hydraten zu bestimmen. Die Proben wurden zunächst in offenen Systemen bei einer CO2-Konzentration in der Umgebung und einer kontrollierten relativen Luftfeuchtigkeit gegeben, um danach dann in eine geschlossene Konfiguration umzuwechseln. So konnte man die CO2-Aufnahme über einen kurzen Zeitraum nachverfolgen. Die Testmethode ermöglicht die Messung der Karbonatisierungsreaktionsrate und –kapazität in Abhängigkeit der Zeit unter verschiedenen relativen Luftfeuchten der Umgebungsluft. Es wurde eine gute Übereinstimmung zwischen den Ergebnissen der Testmethode und der thermogravimetrischen Analyse festgestellt, was die Zuverlässigkeit und Genauigkeit der entwickelten Untersuchungsmethodik unterstreicht.Die Ergebnisse beider Tests wurden als Input für Vorhersagemodelle für den zeitabhängigen Karbonatisierungsfortschritt von Beton verwendet. Es wurde eine Korrelation zwischen der gemessenen Karbonatisierungstiefe an verschiedenen Beton- und Zementhydratmischungen mittels Phenolphthaleinlösung untersucht, wobei u. a. Karbonatisierungstiefen bestimmt nach natürlicher Lagerung mit berechneten/vorhergesagten Karbonatisierungstiefen, die mithilfe der vorgestellten Modellierung und Inputdaten aus Test miteinander verglichen wurden
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Isaksson, Frida. "Pressure loss characterization for cooling and secondary air system components in gas turbines." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-64528.
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There is a constant struggle to increase the efficiency in gas turbines, where one method is to have a higher inlet temperature to the turbine. Often, this results in temperatures higher than the critical temperature of the materials, which makes cooling of the components an important part of the turbine. The cooling air is tapped from the compressor, and has hence required work while being compressed, but since it is removed from the thermodynamic cycle it will not provide any work in the turbine stages. Therefore, it is important to understand the losses in the cooling system to be able to use the smallest amount of cooling air possible, while still cool sufficiently to not decrease the turbine’s lifetime. The pressure losses in the cooling and secondary air systems are due to either friction or minor losses; contractions, expansions and bends. The losses can be described by a discharge coefficient, ; a rate of how close the actual mass flow is to the ideal mass flow, or a pressure loss coefficient, ; a rate of the pressure drop. In the cooling and secondary air systems there are orifices and cooling geometries. These can have different geometrical properties depending on application, and thereby have different heat transfer performances and causing a higher or lower pressure drop. At Siemens Industrial Turbomachinery AB, SIT AB, a one-dimensional in-house program named C3D is used for thermal calculations and calculations of flow properties of internal cooling flow networks. The program uses hydraulic networks consisting of nodes and branches to simulate the flow inside the components. Correlations used for describing pressure losses have been collected and divided depending on their valid ranges, with the aim to make pressure loss calculations easier. A MATLAB code have been developed, which, depending on input parameters, separates the correlations and returns a plot with the correlations that can be used. In order to make the code as useful as possible, a few assumptions were made; curve fitting of correlations which were only available as plots and interpolation to get larger valid ranges for some cases. These assumptions will influence the results, but the code will still be able to give an indication of which correlation to use, and hence, the objective is fulfilled. Simulations in one dimension are commonly used, since it is less time consuming than three-dimensional modelling. Therefore, with focus on the pressure losses, a one-dimensional model of a blade in the in-house program C3D has been evaluated using a three-dimensional model in the CFD program Ansys CFX. Also, two new models were created in C3D; both with geometrical properties and pressure loss coefficients adjusted to the CFX model, but the first model is using the same hydraulic network as in the evaluated, reference, model while the second is using a new network, built according to the streamlines in CFX. The resulting mass flows in the C3D models were compared to the mass flows in the CFX model, which ended in the conclusion that it is hard for the one-dimensional models to understand the complex, three-dimensional flow situations, even when adjusting them to the CFX model. Anyhow, the adjustments made the model somewhat closer to the three-dimensional case, and hence CFX should be used in an earlier stage when developing C3D models.
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Domeij, Bäckryd Rebecka. "Simulation of Heat Transfer on a Gas Sensor Component." Thesis, Linköping University, Department of Mathematics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-131.
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<p>Gas sensors are today used in many different application areas, and one growing future market is battery operated sensors. As many gas sensor components are heated, one major limit of the operation time is caused by the power dissipated as heat. AppliedSensor is a company that develops and produces gas sensor components, modules and solutions, among which battery operated gas sensors are one targeted market.</p><p>The aim of the diploma work has been to simulate the heat transfer on a hydrogen gas sensor component and its closest surroundings consisting of a carrier mounted on a printed circuit board. The component is heated in order to improve the performance of the gas sensing element.</p><p>Power dissipation occurs by all three modes of heat transfer; conduction from the component through bond wires and carrier to the printed circuit board as well as convection and radiation from all the surfaces. It is of interest to AppliedSensor to understand which factors influence the heat transfer. This knowledge will be used to improve different aspects of the gas sensor, such as the power consumption.</p><p>Modeling and simulation have been performed in FEMLAB, a tool for solving partial differential equations by the finite element method. The sensor system has been defined by the geometry and the material properties of the objects. The system of partial differential equations, consisting of the heat equation describing conduction and boundary conditions specifying convection and radiation, was solved and the solution was validated against experimental data.</p><p>The convection increases with the increase of hydrogen concentration. A great effort was made to finding a model for the convection. Two different approaches were taken, the first based on known theory from the area and the second on experimental data. When the first method was compared to experiments, it turned out that the theory was insufficient to describe this small system involving hydrogen, which was an unexpected but interesting result. The second method matched the experiments well. For the continuation of the project at the company, a better model of the convection would be a great improvement.</p>
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Lim, Nancy Joy. "Topographic data and roughness parameterisation effects on 1D flood inundation models." Thesis, University of Gävle, Ämnesavdelningen för samhällsbyggnad, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-5039.
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<p>A big responsibility lies in the hand of local authorities to exercise measures in preventing fatalities and damages during flood occurrences. However, the problem is how flooding can be prevented if nobody knows when and where it will be occurring, and how much water is expected. Therefore, the utilisation of flood models in such studies can be helpful in simulating what is anticipated to occur.</p><p> </p><p>In this study, the HEC-RAS steady flow model was used in calibrating different flood events in Testeboån river, which is situated in the municipality of Gävle in Sweden. The purpose is to provide inundation maps that show the water surface profiles for the various flood events that can help authorities in planning within the area. Moreover, the study would try to address certain issues, which concern one-dimensional models like HEC-RAS in terms of the effects of topographic data and the parameters used for friction coefficient.</p><p> </p><p>Various flood maps were produced to visualise the extents of the floods. In Oppala and Norra Åbyggeby, the big water extents for both the 100-year and the highest probable floods were visible in the forested areas and grasslands, although a few houses were within the predicted flooded areas. In Södra Åbyggeby, Varva, Forsby, and in the northern parts of Strömsbro and Stigslund, the majority of the residential places were not inundated during the 100-year flood calibration, but became flooded during the maximum probable flood. The southern portions of Strömsbro and Stigslund had lesser flood extents and houses were situated within the boundaries of the highest flood. In Näringen, there were also some areas close to the estuary that were flooded for both events.</p><p> </p><p>With the other calibrations performed, two factors that greatly affect the flood extents in the floodplain, particularly in flatter areas were topographic data and the parameters used as friction coefficient. The use of high resolution topographic data was important in improving the performance of the software. Nevertheless, it must be emphasised that in areas characterised by gentler slopes that bounded the channel and the floodplain, data completeness became significant whereby both ground data and bathymetric points must be present to avoid overestimation of the inundation extent. The water extents also varied with the use of the various Manning’s <em>n</em> for the overbanks, with the bigger value showing greater water extents. Else, in areas with steeper slopes and where the water was confined to the banks, the effect was minimal.</p><p> </p><p>Despite these shortcomings of one-dimensional models, HEC-RAS provided good inundation extents that were comparable to the actual extent of the 1977 flooding.</p><p> </p><p>Modelling real floods has its own difficulties due to the unpredictability of real-life flood behaviours, and more especially, there are time dependent factors that are involved. Although calibrating a flood event will not exactly determine what is to arise as they might either under- or overestimate such flooding occurrences, still, they give a standpoint of what is more or less to anticipate, and from this, planning measures can be undertaken.</p>
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Lim, Nancy Joy. "Performance and uncertainty estimation of 1- and 2-dimensional flood models." Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-9642.
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Performance-based measures are used to validate and quantify how likely the system’s results resemble that of the actual data. Its application in inundation studies is performed by comparing the extents of the predicted flood to the real event by measuring their overlap size and getting the percentage of this size to the union of both data. In this study, performances of 1- and 2-dimensional flow models were assessed when used with different topographic data sources, rasterisation cell sizes, mesh resolution and Manning’s values with the help of Geographic Information Systems (GIS). The Generalised Likelihood Uncertainty Estimation (GLUE) was also implemented to evaluate the behaviour and the uncertainties of the Hydrologic Engineering Center-River Analysis System (HEC-RAS) steady-flow model in delineating the inundation extents when various sets of friction coefficients for floodplain and channel were utilised as inputs. Although it was not possible to perform the GLUE procedure with Telemac-2D due to the simulation time, Manning’s n performances’ effects were evaluated using ten randomly selected sets of friction for the channel and floodplain. The LiDAR data, which had the highest resolution, performed well in all simulations, followed by Lantmäteriet data at 50 m resolution. The lowest resolution Digital Terrain Elevation Data (DTED) showed poor resemblance to the actual event and big misrepresentations of flooded areas. Rasterisation cell sizes in HEC-RAS showed minimal effect to the inundation limits when used between 1 m and 5 m, but performance started to deteriorate at 10 m (Lantmäteriet) and 20 m (LiDAR). The 10 m mesh resolution used for LiDAR behaved poorer than the 20 m mesh, which performed well in the different 2D simulations. For HEC-RAS, =0.033 to 0.05 performed well when paired with =0.02 to 0.10. It was apparent, therefore, that the channel’s Manning’s n affected the performances of the floodplain’s . Furthermore, the study also showed that using heterogeneous roughness values corresponding to the different land use classes is not as effective as using single channel and floodplain’s Manning. The dependence of the floodplain’s roughness to the channel’s friction values had also been manifested by Telemac, even though it required lower values than the 1D simulator. = 0.007 to 0.019 and =0.01 to 0.04 gave good performance to the 2D system. In terms of the overall model performance, HEC-RAS 1D exhibited good results for Testeboån. Even when the average distances to the actual data were estimated, the breadths were shorter compared to the most optimal output of the two-dimensional simulator, which showed more overestimated areas, despite the fact that the overlap size with the 1977 actual event was better than HEC-RAS. It could be because the measures-of-fit took into consideration the areal sizes that were over- and under-predicted aside from the overlap sizes between the observed and modelled results. This could be the same reason with the mean distances produced, wherein higher values were computed for Telemac-2D due to its bigger gap from the actual flood as brought by the enlargement in the flood extents. But it was also made known in the study that such ambiguities in the model performance were further contributed by the characteristics of the floodplain’s topography of being flat. Testeboån’s inclination to the banks was averaged at 0.027 m/m, with the central portion at 0.002 m/m. The middle portion of the floodplain was illustrated to contain more uncertain regions, where water extents changed easily as the parameters were altered. Distances greater than 200 m were also mostly located within these inclination values or within 0.005 to 0.006 m/m. The response of distance to the floodplain’s gradient improved when the slope value became higher, and this had been particularly noticed between 0 to 50 m.
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Virk, Akashdeep Singh. "Heat Transfer Characterization in Jet Flames Impinging on Flat Plates." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/52985.
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The experimental work involves calculation of radial distribution of heat transfer coefficient at the surface of a flat Aluminium plate being impinged by a turbulent flame jet. Heat transfer coefficient distribution at the surface is computed from the measured heat flux and temperature data using a reference method and a slope method. The heat transfer coefficient (h) has a nearly bell shaped radial distribution at the plate surface for H/d =3.3. The value of h drops by 37 % from r/d =0 to r/d= 2. Upon increasing the axial distance to H/d = 5, the stagnation point h decreased by 15%. Adiabatic surface temperature (AST) distribution at the plate surface was computed from the measured heat flux and temperature. AST values were found to be lower than the measured gas temperature values at the stagnation point. Radial distribution of gas temperature at the surface was estimated by least squares linear curve fitting through the convection dominated region of net heat flux data and was validated by experimental measurements with an aspirated thermocouple. For low axial distances (H/d =3.3), the gas temperature dropped by only 15 % from r/d = 0 to r/d = 2. Total heat flux distribution is separated into radiative and convective components with the use of calculated heat transfer coefficient and estimated gas temperatures. At H/d = 3.3, the radiation was found to be less than 25 % of the net heat flux for r/d ≤ 2.<br>Master of Science
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Whitaker, Steven Michael. "Informing Physics-Based Particle Deposition Models Using Novel Experimental Techniques to Evaluate Particle-Surface Interactions." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500473579986028.
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Singh, Sukhjinder. "Large Eddy Simulations of Sand Transport and Deposition in the Internal Cooling Passages of Gas Turbine Blades." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/56613.
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Jet engines often operate under dirty conditions where large amounts of particulate matter can be ingested, especially, sand, ash and dirt. Particulate matter in different engine components can lead to degradation in performance. The objective of this dissertation is to investigate sand transport and deposition in the internal cooling passages of turbine blades. A simplified rectangular geometry is simulated to mimic the flow field, heat transfer and particle transport in a two pass internal cooling geometry. Two major challenges are identified while trying to simulate particle deposition. First, no reliable particle-wall collision model is available to calculate energy losses during a particle wall interaction. Second, available deposition models for particle deposition do not take into consideration all the impact parameters like impact velocity, impact angle, and particle temperature. These challenges led to the development of particle wall collision and deposition models in the current study.
First a preliminary simulation is carried out to investigate sand transport and impingement patterns in the two pass geometry by using an idealized elastic collision model with the walls of the duct without any deposition. Wall Modeled Large Eddy Simulations (WMLES) are carried to calculate the flow field and a Lagrangian approach is used for particle transport. The outcome of these simulations was to get a qualitative comparison with experimental visualizations of the impingement patterns in the two pass geometry. The results showed good agreement with experimental distributions and identified surfaces most prone to deposition in the two pass geometry.
The initial study is followed by the development of a particle-wall collision model based on elastic-plastic deformation and adhesion forces by building on available theories of deformation and adhesion for a spherical contact with a flat surface. The model calculates deformation losses and adhesion losses from particle-wall material properties and impact parameters and is broadly applicable to spherical particles undergoing oblique impact with a rigid wall. The model is shown to successfully predict the general trends observed in experiments.
To address the issue of predicting deposition, an improved physical model based on the critical viscosity approach and energy losses during particle-wall collisions is developed to predict the sand deposition at high temperatures in gas turbine components. The model calculates a sticking or deposition probability based on the energy lost during particle collision and the proximity of the particle temperature to the softening temperature. For validation purposes, the deposition of sand particles is computed for particle laden jet impingement on a coupon and compared with experiments conducted at Virginia Tech. Large Eddy Simulations are used to calculate the flow field and heat transfer and particle dynamics is modeled using a Lagrangian approach. The results showed good agreement with the experiments for the range of jet temperatures investigated.
Finally the two pass geometry is revisited with the developed particle-wall collision and deposition model. Sand transport and deposition is investigated in a two pass internal cooling geometry at realistic engine conditions. LES calculations are carried out for bulk Reynolds number of 25,000 to calculate flow and temperature field. Three different wall temperature boundary conditions of 950 oC, 1000 oC and 1050 oC are considered. Particle sizes in the range 5-25 microns are considered, with a mean particle diameter of 6 microns. Calculated impingement and deposition patterns are discussed for different exposed surfaces in the two pass geometry. It is evident from this study that at high temperatures, heavy deposition occurs in the bend region and in the region immediately downstream of the bend.
The models and tools developed in this study have a wide range of applicability in assessing erosion and deposition in gas turbine components.<br>Ph. D.
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Omer, Muhammad. "Impingement Cooling: Heat Transfer Measurement by Liquid Crystal Thermography." Thesis, Linköping University, Applied Thermodynamics and Fluid Mechanics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-52859.
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<p>In modern gas turbines parts of combustion chamber and turbine section are under heavy heat load, for example, the rotor inlet temperature is far higher than the melting point of the rotor blade material. These high temperatures causes thermal stresses in the material, therefore it is very important to cool the components for safe operation and to achieve desired component life. But on the other hand the cooling reduces the turbine efficiency, for that reason it is vital to understand and optimize the cooling technique.</p><p>In this project Thermochromic Liquid Crystals (TLCs) are used to measure distribution of heat transfer coefficient over a scaled up combustor liner section. TLCs change their color with the variation of temperature in a particular temperature range. The color-temperature change relation of a TLC is sharp and precise; therefore TLCs are used to measure surface temperature by painting the TLC over a test surface. This method is called Liquid Crystal Thermography (LCT). LCT is getting popular in industry due to its high-resolution results, repeatability and ease of use.</p><p>Test model in present study consists of two plates, target plate and impingement plate. Cooling of the target plate is achieved by impingement of air coming through holes in the impingement plate. The downstream surface of the impingement plate is then cooled by cross flow and re-impingement of the coolant air.</p><p>Heat transfer on the target plate is not uniform; areas under the jet which are called stagnation points have high heat transfer as compare to the areas away from the center of jet. It is almost the same situation for the impingement plate but the location of stagnation point is different. A transient technique is used to measure this non-uniform heat transfer distribution. It is assumed that the plates are semi-infinitely thick and there is no lateral heat transfer in the plates. To fulfill the assumptions a calculated time limit is followed and the test plates are made of Plexiglas which has very low thermal conductivity.</p><p>The transient technique requires a step-change in the mainstream temperature of the test section. However, in practical a delayed increase in mainstream temperature is attained. This issue is dealt by applying Duhamel’s theorem on the step-change heat transfer equation. MATLAB is used to get the Hue data of the recorded video frames and calculate the time taken for each pixel to reach a predefined surface temperature. Having all temperatures and time values the heat transfer equation is iteratively solved to get the value of heat transfer coefficient of each and every pixel of the test surface.</p><p>In total fifteen tests are conducted with different Reynolds number and different jet-to-target plate distances. It is concluded that for both the target and impingement plates, a high Reynolds number provides better overall heat transfer and increase in jet-to-target distance</p><p>decreases the overall heat transfer.</p>
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Wasson, Rachel Ann. "Separation of the Heat Transfer Components for Diffusion Flames Impinging onto Ceilings." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50588.
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Two series of experiments were performed to determine the flow characteristics and to quantify the heat transfer components from a propane diffusion flame impinging onto a ceiling. A 0.3 m square sand burner with propane as the fuel type provided a steady-state fire. In the first series of experiments, measurements of gas temperature and velocity were made at 76 mm vertical intervals above the burner up to the ceiling. Fire heat release rates (HRRs) of 50 kW and 90 kW with free flame length to ceiling height ratios, Lf/H, of 2, 1.5, 1, 0.8, 0.85 were used to determine their effects on the measured parameters. Gas temperatures within the continuous flaming region were relatively constant, and measured to be independent of ceiling height and HRR, while velocities increased with elevation and were independent of ceiling height yet weakly dependent on HRR. Within the intermittent region, gas temperature was weakly affected by the presence of the ceiling at various heights, while the effect on velocity was more pronounced. HRR had an effect on both temperature and velocity within the intermittent region of the fire plume. Comparisons with existing fire plume correlations showed that the unbounded correlations can be used to provide a good approximation of the gas temperature for the ceiling bounded case; while the correlations for the velocity can only be used for elevations up to approximately 60% of the ceiling height. Elevations above this cutoff were significantly affected by the presence of the ceiling.
The second series of experiments investigated HRRs of 50 kW and 90 kW with free flame length to ceiling height ratios, Lf/H, of 2, 1.5, and 1. Heat flux and gas temperature at the stagnation point of the ceiling were measured using hybrid heat flux gauges and an aspirated Type K thermocouple. Four methods of calculating the convective heat transfer coefficient, h, were developed and adapted; two reference methods and two slope methods. The components of heat transfer at the impingement point were separated using these calculated h values. The reference method 2, and both slope methods only required the use of the non-cooled hybrid gauge measurements and were in overall good agreement with one another. The reference method 1 differed significantly, being up to 15.8 times lower than the others. The trends in the two groups were contradictory, with the h calculated using the reference method 1 increasing with ceiling height while the others showed no strong trend with ceiling height. The disagreements between the methods greatly affected the components of heat transfer, particularly at the lowest ceiling heights. Convection calculated using the h from reference method 1 contributed only 2-5% of the total exposure heat flux at the lowest ceiling heights, whereas with the other methods convection contributed 20-50% of the total exposure heat flux. The limitations of each method are discussed. Further investigation is required for all methods to determine their applicability within the flaming region of a fire.<br>Master of Science
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Gervais, Aroquiaradj. "Étude de l'hydrodynamique et du transfert de matière gaz/liquide dans les lits fluidises tri phasiques : application aux lits fluidises tetraphasiques." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL084N.
Full textAbstract:
Si le design des colonnes a bulles est assez bien connu en général, celui des lits fluidises triphasiques requiert encore des études plus poussées. L'objectif de cette thèse est de mener une étude couplée de l'hydrodynamique et du transfert de matière gaz/liquide dans les lits fluidises triphasiques. Une nouvelle procédure d'étalonnage d'une sonde électroconductive dans un milieu triphasique a été mise au point. Ceci permet de déterminer les profils axiaux de rétention des phases. L'équation d'étalonnage tient compte de la composition et de la nature des phases dispersées. Quant au transfert gaz/liquide, le modèle de dispersion axiale du liquide généralement utilisé, suppose une ségrégation du réacteur en lit fluidise et freeboard. Cette hypothèse est remise en question par des expériences du traceur qui démontrent un retromélange du liquide à l'interface lit/freeboard. L'impact de ce retro-mélange sur le coefficient de transfert gaz/liquide est étudié en utilisant l'équation de dispersion axiale a coefficient k#l#a et d#z fonctions de la hauteur z. Les procédures développées pour le système triphasique sont appliqués a un lit fluidise tétraphasique gaz/slurry/particules du lit, l'objectif étant de démontrer l'efficacité d'un lit à améliorer le k#l#a d'une colonne a bulles avec slurry
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Derdar, Mawaheb M. Zarok. "Experimental and kinetic modelling of multicomponent gas/liquid ozone reactions in aqueous phase. Experimental investigation and Matlab modelling of the ozone mass transfer and multicomponent chemical reactions in a well agitatated semi-batch gas/liquid reactor." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4872.
Full textAbstract:
Due to the ever increasing concerns about pollutants and contaminants found in water, new treatment technologies have been developed. Ozonation is one of such technologies. It has been widely applied in the treatment of pollutants in water and wastewater treatment processes. Ozone has many applications such as oxidation of organic components, mineral matter, inactivation of viruses, cysts, bacteria, removal of trace pollutants like pesticides and solvents, and removal of tastes and odours. Ozone is the strongest conventional oxidant that can result in complete mineralisation of the organic pollutants to carbon dioxide and water. Because ozone is unstable, it is generally produced onsite in gas mixtures and is immediately introduced to water using gas/liquid type reactors (e.g. bubble columns). The ozone reactions are hence of the type gas liquid reactions, which are complex to model since they involve both chemical reactions, which occur in the liquid phase, and mass transfer from the gas to the liquid phase. This study focuses on two aspects: mass transfer and chemical reactions in multicomponent systems. The mass transfer parameters were determined by experiments under different conditions and the chemical reactions were studied using single component and multicomponent systems. Two models obtained from the literature were adapted to the systems used in this study.
Mass transfer parameters in the semi-batch reactor were determined using oxygen and ozone at different flow rates in the presence and absence of t-butanol. t-Butanol is used as a radical scavenger in ozonation studies and it has been found to affect the gas¿liquid mass transfer rates. An experimental study was carried out to investigate the effects of t-butanol concentrations on the physical properties of aqueous solutions, including surface tension and viscosity. It was found that t-butanol reduced both properties by 4% for surface tension and by a surprising 30% for viscosity. These reductions in the solution physical properties were correlated to enhancement in the mass transfer coefficient, kL. The mass transfer coefficient increased by about 60% for oxygen and by almost 50% for ozone. The hydrodynamic behaviour of the system used in this work was characterised by a homogeneous bubbling regime. It was also found that the gas holdup was significantly enhanced by the addition of t-butanol. Moreover, the addition of t-butanol was found to significantly reduce the size of gas bubbles, leading to enhancement in the volumetric mass transfer coefficient, kLa.
The multicomponent ozonation was studied with two systems, slow reactions when alcohols were used and fast reactions when endocrine disrupting compounds were used.
ii
These experiments were simulated by mathematical models. The alcohols were selected depending on their volatilization at different initial concentrations and different gas flow rates. The degradation of n-propanol as a single compound was studied at the lowest flow rate of 200 mL/min. It was found that the degradation of n-propanol reached almost 60% within 4 hours. The degradation of the mixture was enhanced with an increase in the number of components in the mixture. It was found that the degradation of the mixture as three compounds reached almost 80% within four hours while the mixture as two compounds reached almost 70%. The effect of pH was studied and it was found that an increase in pH showed slight increase in the reaction. Fast reactions were also investigated by reacting endocrine disrupting chemicals with ozone. The ozone reactions with the endocrine disrupters were studied at different gas flow rates, initial concentrations, ozone concentrations and pH. The degradation of 17¿-estradiol (E2) as a single compound was the fastest, reaching about 90% removal in almost 5 minutes. However estrone (E1) degradation was the lowest reaching about 70% removal at the same time. The degradation of mixtures of the endocrine disruptors was found to proceed to lower percentages than individual components under the same conditions. During the multicomponent ozonation of the endocrine disruptors, it was found that 17¿-estradiol (E2) converted to estrone (E1) at the beginning of the reaction.
A MATLAB code was developed to predict the ozone water reactions for single component and multicomponent systems. Two models were used to simulate the experimental results for single component and multicomponent systems. In the case of single component system, good simulation of both reactions (slow and fast) by model 1 was obtained. However, model 2 gave good agreement with experimental results only in the case of fast reactions. In addition, model 1 was applied for multicomponent reactions (both cases of slow and fast reaction). In the multicomponent reactions by model 1, good agreement with the experimental results was also obtained for both cases of slow and fast reactions.<br>Ministry of Higher Education in Libya and the Libyan Cultural Centre and Educational Bureau in London.
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Suara, Kabir Adewale. "Development and use of GPS-based technology to study dispersion in shallow water." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/102841/1/Kabir%20Adewale_Suara_Thesis.pdf.
Full textAbstract:
This project was a step forward for the measurement and management of shallow water estuaries using satellite technology. Newly developed Global Positioning System (GPS) high resolution drifters were used to investigate the flow field and the spreading behaviours of passive particles. It identified the dominant mechanisms responsible for the tidal scale spreading with a focus on tidal estuaries in Southeast Queensland. Importantly, this study provides a unique moving sensor (Lagrangian) approach to strengthen current modelling efforts in prediction of the transport of materials in tidal estuaries. This new approach provides a unique complement to the traditional fixed sensor (Eulerian) approach.
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Derdar, Mawaheb M. Zarok. "Experimental and kinetic modelling of multicomponent gas/liquid ozone reactions in aqueous phase : experimental investigation and Matlab modelling of the ozone mass transfer and multicomponent chemical reactions in a well agitated semi-batch gas/liquid reactor." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4872.
Full textAbstract:
Due to the ever increasing concerns about pollutants and contaminants found in water, new treatment technologies have been developed. Ozonation is one of such technologies. It has been widely applied in the treatment of pollutants in water and wastewater treatment processes. Ozone has many applications such as oxidation of organic components, mineral matter, inactivation of viruses, cysts, bacteria, removal of trace pollutants like pesticides and solvents, and removal of tastes and odours. Ozone is the strongest conventional oxidant that can result in complete mineralisation of the organic pollutants to carbon dioxide and water. Because ozone is unstable, it is generally produced onsite in gas mixtures and is immediately introduced to water using gas/liquid type reactors (e.g. bubble columns). The ozone reactions are hence of the type gas liquid reactions, which are complex to model since they involve both chemical reactions, which occur in the liquid phase, and mass transfer from the gas to the liquid phase. This study focuses on two aspects: mass transfer and chemical reactions in multicomponent systems. The mass transfer parameters were determined by experiments under different conditions and the chemical reactions were studied using single component and multicomponent systems. Two models obtained from the literature were adapted to the systems used in this study. Mass transfer parameters in the semi-batch reactor were determined using oxygen and ozone at different flow rates in the presence and absence of t-butanol. t-Butanol is used as a radical scavenger in ozonation studies and it has been found to affect the gas-liquid mass transfer rates. An experimental study was carried out to investigate the effects of t-butanol concentrations on the physical properties of aqueous solutions, including surface tension and viscosity. It was found that t-butanol reduced both properties by 4% for surface tension and by a surprising 30% for viscosity. These reductions in the solution physical properties were correlated to enhancement in the mass transfer coefficient, kL. The mass transfer coefficient increased by about 60% for oxygen and by almost 50% for ozone. The hydrodynamic behaviour of the system used in this work was characterised by a homogeneous bubbling regime. It was also found that the gas holdup was significantly enhanced by the addition of t-butanol. Moreover, the addition of t-butanol was found to significantly reduce the size of gas bubbles, leading to enhancement in the volumetric mass transfer coefficient, kLa. The multicomponent ozonation was studied with two systems, slow reactions when alcohols were used and fast reactions when endocrine disrupting compounds were used. ii These experiments were simulated by mathematical models. The alcohols were selected depending on their volatilization at different initial concentrations and different gas flow rates. The degradation of n-propanol as a single compound was studied at the lowest flow rate of 200 mL/min. It was found that the degradation of n-propanol reached almost 60% within 4 hours. The degradation of the mixture was enhanced with an increase in the number of components in the mixture. It was found that the degradation of the mixture as three compounds reached almost 80% within four hours while the mixture as two compounds reached almost 70%. The effect of pH was studied and it was found that an increase in pH showed slight increase in the reaction. Fast reactions were also investigated by reacting endocrine disrupting chemicals with ozone. The ozone reactions with the endocrine disrupters were studied at different gas flow rates, initial concentrations, ozone concentrations and pH. The degradation of 17β-estradiol (E2) as a single compound was the fastest, reaching about 90% removal in almost 5 minutes. However estrone (E1) degradation was the lowest reaching about 70% removal at the same time. The degradation of mixtures of the endocrine disruptors was found to proceed to lower percentages than individual components under the same conditions. During the multicomponent ozonation of the endocrine disruptors, it was found that 17β-estradiol (E2) converted to estrone (E1) at the beginning of the reaction. A MATLAB code was developed to predict the ozone water reactions for single component and multicomponent systems. Two models were used to simulate the experimental results for single component and multicomponent systems. In the case of single component system, good simulation of both reactions (slow and fast) by model 1 was obtained. However, model 2 gave good agreement with experimental results only in the case of fast reactions. In addition, model 1 was applied for multicomponent reactions (both cases of slow and fast reaction). In the multicomponent reactions by model 1, good agreement with the experimental results was also obtained for both cases of slow and fast reactions.
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Chau, Nguyen. "Étude et comparaison de trois contacteurs gaz-liquide a auto-aération." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL115N.
Full textAbstract:
Une méthodologie d'étude de contacteurs gaz-liquide a été analysée et appliquée à l'étude de trois contacteurs gaz-liquide alimentés en gaz par autoaspiration selon trois mécanismes: vortex assisté par tube de tirage, turbine autoaspirante et arbre creux, éjecteur et boucle de recirculation. Le dimensionnement et la réalisation des maquettes ont été menés successivement a partir d'une base commune constituée par une cuve de dimension semi-industrielle et de capacité avoisinant les 200 l. L'hydrodynamique et les paramètres de transfert de matière gaz-liquide ont été examinés dans l'optique d'une comparaison des performances et d'une interprétation en terme de modèles de zones
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Alahmad, Malik I. N. "Heat transfer in upward flowing two-phase gas-liquid mixtures : an experimental study of heat transfer in two-phase gas-liquid mixtures flowing upwards in a vertical tube with liquid phase being driven by a pump or air injection." Thesis, University of Bradford, 1987. http://hdl.handle.net/10454/3629.
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An experimental investigation has been carried out to study the heat transfer in a two-phase two-component mixture flowing upward inside a 1" double pipe heat exchanger. The heat transfer coefficient was measured using either air to lift the liquid (air-lift system) or a mechanical pump. The heat transfer coefficient results have been extensively studied and compared with other workers' results. An attempt was made to correlate the present heat transfer data in dimensionless correlations. Possible factors affecting the two-phase heat transfer coefficient have been studied with special attention being given to the fluid properties, particularly the liquid viscosity. Experiments were also carried out to investigate the effect of solid particles added to a liquid flow on the measured heat transfer coefficient. The present investigation was carried out using air as the gas-phase ranging from 2x 10-5 up to 80 x 10-5 m3/s. Liquids used were water and glycerol solutions with viscosity ranging from 0.75 up to 5.0 C. P. and flowrates between 4x 10-5 and 25 x 10-5 m3/s. Void fraction and pressure drop were also measured during the heat transfer process. Flow pattern in gas-liquid mixture was investigated in a perspex tube of identical dimensions to the heat exchanger tube.
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Ксенич, А. І. "Прогнозування пропускної здатності та гідравлічної енерговитратності поліетиленових газових мереж". Thesis, Івано-Франківський національний технічний університет нафти і газу, 2012. http://elar.nung.edu.ua/handle/123456789/1851.
Full textAbstract:
Вирішена наукова задача виявлення ефективності та енерговитратності поліетиленових газових мереж населених пунктів.
Шляхом проведення теоретичних досліджень у рамках існуючих гідродинамічних підходів виявлені чинники і ступінь їх впливу на зменшення енерговитратності транспортування газу в газових мережах при використанні поліетиленових труб замість сталевих.
Виконано теоретичні дослідження впливу профілю траси на енерговитратність та пропускну здатність газових мереж низького тиску. Запропоновані уточнені математичні вирази для визначення зміни гідростатичного тиску на ділянці залежно від різниці геодезичних позначок і температури газу.
Проведено експериментальні дослідження газодинамічних процесів руху газу в поліетиленових газових мережах, які виявили існування різних режимів руху, що відрізняються законом тертя. Знайдені числа Рейнольдса, які розділяють різні режими руху газу в поліетиленових газопроводах, та одержані регресійні моделі для коефіцієнта гідравлічного опору.
На основі проведених досліджень розроблений комплекс методів і комп'ютерних програм дая прогнозування пропускної здатності та енерговитратності газових мереж населених пунктів з урахуванням особливостей газодинаміки поліетиленових труб, впливу профілю траси та умов навколишнього середовища. Запропоновано методи прокладання. та реконструкції газових мереж, що характеризуються економічною доцільністю.<br>Scientific problem about detection of polyethylene gas systems efficiency is solved by using the gas-dynamic methods.
Theoretical researches in the sphere of hydrodynamic methods are done. In the process of these researches some factors and the degree of their influence on decreasing of energy consumption, connected with gas transmission in case of using the polyethylene pipelines instead of steel ones were revealed.
Theoretical investigations, connected with pipeline route profile’s influence on energy efficiency and productive capacity of low pressure gas systems, were done. Specified mathematical expressions are offered in order to calculate the hydrostatic pressure change at the selected length of the pipeline depending on geodesic marks’ difference and gas temperature.
Experimental investigations of gas-dynamic processes (gas transit) in polyethylene gas network systems were made. As a result there were found various modes of gas motion that differ by the friction law. There were also found Reynold’s numbers that set apart the right mode of gas motion through the polyethylene gas pipelines. There were formed special regression models for description of the friction laws.
There was developed a system of different forecasting methods and computer programs for prognostication of productive capacity and energy efficiency of gas locality systems including all the features of gas dynamics in the polyethylene pipes, pipeline profile’s effect and environment conditions on the basis of these investigations. The methods of laying and reconstruction of gas network systems that are characterized by economic expediency are suggested.
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Yuan, Haifeng. "Caractérisation expérimentale des propriétés de poromécaniques et de transfert de l’argilite du COx." Thesis, Ecole centrale de Lille, 2017. http://www.theses.fr/2017ECLI0030/document.
Full textAbstract:
L’argilite du COx a été choisie comme roche hôte pour le stockage des déchets radioactifs de haute activité et vie longue (HAVL) en France. Ce matériau subira l'intrusion de gaz et d'eau sous, parfois, des conditions thermiques sévères. Par conséquent, afin d'évaluer la sécurité de cette barrière naturelle, il est très important de comprendre les propriétés poromécaniques et de transfert de ce matériau ainsi que l’effet de la température. Ce travail aborde les mesures au gaz du coefficient de Biot et montrent que celui-ci est presque égal à 1 en conditions humides. Il y a cependant sur le matériau sec un effet de l'adsorption du gaz et une déformation supplémentaire de gonflement du matériau. Cet effet a aussi un effet important sur les propriétés de transfert du gaz selon sa nature. Les propriétés de transfert et de saturation ont été examinées par des techniques gaz et comparées aux mesures usuelles. Les essais montrent aussi que la perméabilité à l'eau de site est d'environ 10-20 - 10-21 m² et beaucoup plus faible que celle au gaz. Enfin, on constate que le coefficient de Biot n'est pas affecté significativement par les effets thermiques mais que ces effets jouent sur la perméabilité relative au gaz de l'argilite<br>COx argillite has been selected as the host rock for the storage of high-activity long-live (HALL) radioactive waste in France. It will suffered the gas and water intrusion, sometimes suffered the severe thermal conditions during the sealing process. Therefore, in order to evaluate the safety of this natural barrier, it is very important to understand the poromechanical properties and transport properties of this material as well as the thermal effects. This work use gas to measure Biot’s coefficient and shows that it is nearly equal to 1 in humid conditions. However, there is a gas adsorption and induced an additional swelling deformation on dry material, this effect also has a significant effect on the transport properties of the gas according to its nature. The transport and saturation properties were examined by gas technique and compared with the usual measurements. The tests also show that the permeability of in situ water is about 10-20-10-21 m² and much lower than gas. Lastly, it is found that Biot’s coefficient is not significantly affected by the thermal effect, but the relative gas permeability of argillite is significantly affected by this effect