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Navaei, Milad. "Quartz crystal microbalance adsorption apparatus for high pressure gas adsorption measurements in nanomaterials." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41057.
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The primary objective of this study was to develop a sensitive and cost-effective sorption system to analyze adsorption and diffusion of different gases on micro porous materials and nanotubes. A high pressure Quartz Crystal Microbalance (QCM) based adsorption apparatus for single-component gas was developed. A QCM is an acoustic-wave resonator in which the acoustic wave propagates through the crystal. Therefore, it is highly responsive to addition or removal of small amounts of mass adsorbed or deposited on the surface of the crystal. This mass sensitivity makes the QCM an ideal tool for the study of gas adsorption. The QCM-based adsorption apparatus is advantageous over the commercialized none-gravimetric and gravimetric equipment in a way that it is low-cost, highly sensitive and accurate for mass sorption applications, satisfactorily stable in a controlled environment, and can be used for thin films.
The high pressure apparatus was calibrated using Matrimid 5218, whose thermodynamic properties and adsorption parameters are known. The Matrimid was spin-coated onto a 14 mm-diameter QCM, and sorption equilibrium data for were obtained for CO₂ gas at 25, 30, 48, and 52 ºC and partial pressure range between 0 to 4 bar. In order to compare the experimental data with available literature data, the experimental data was fitted into a dual-mode adsorption model. The model results from Henry's law and a Langmuir mechanism. Comparison of the experimental adsorption isotherm of Matrimide for CO₂ gas with literature data showed reasonable agreement between the experimental and literature data.
In this study, the adsorption parameters of aluminosilicate nanotubes are observed. Aluminosilicate nanotubes are ideal materials for chemical sensing, molecule separation, and gas storage; hence, there is a need for adsorption and diffusion data on this material.
The adsorption of CO₂, N₂, and CH₄ gases on aluminosilicate nanotubes samples has been studied in the temperature range of 20° to 120° Celsius and pressure range of 0 to 8 bar. The experimental results yield the CO₂ and N₂ heat of adsorptions of -32.9 and -28.1 kJ/mol respectively.
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De, Angelis Giacomo. "Modeling of a differential volumetric system for high pressure gas adsorption." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23313/.
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The volumetric system is a widely used experimental method for gas adsorption equilibrium measurements and for the determination of adsorption kinetics. A predictive model was developed in the gPROMS ProcessBuilder platform.
Equations for mass and energy balance were implemented firstly for the description of a single-branch volumetric apparatus, and then for a differential (double-branched) system.
The model was built starting from the simplest case (Isothermal and ideal gas behaviour) and subsequentially its complexity was increased in order to have a system which is able of describing an adsorption process in any operative conditions (non-isothermal system, non-linear equilibrium, real gas behaviour).
The validation of the model was made through the assumption that all the complex systems must collapsed to the simplest one through the adjustment of the different parameters. In certain cases, the validation was done comparing the results obtained in the simulation with the one got from analytical solutions developed by other authors.
In general, at the end of each section, a case study was analysed in order to underline what are the factors that can affect the kinetic of the process, providing also possible solution which can minimize these effects, that if not taken into account can lead to an incorrect interpretation of the data.
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Tang, Xu. "Measurements, Modeling and Analysis of High Pressure Gas Sorption in Shale and Coal for Unconventional Gas Recovery and Carbon Sequestration." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/74237.
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In order to exploit unconventional gas and estimate carbon dioxide storage potential in shale formations and coal seams, two key questions need to be initially answered:
1) What is the total gas-in-place (GIP) in the subsurface reservoirs?
2) What is the exact ratio between bulk gas content and adsorbed gas content?
Both questions require precise estimation of adsorbed phase capacity of gases (methane and carbon dioxide) and their adsorption behavior in shale and coal. This dissertation therefore analyzes adsorption isotherms, thermodynamics, and kinetics properties of methane and carbon dioxide in shale and coal based on experimental results to provide preliminary answers to both questions.
It was found that the dual-site Langmuir model can describe both methane and carbon dioxide adsorption isotherms in shale and coal under high pressure and high temperature conditions (up to 27 MPa and 355.15K). This allows for accurate estimation of the true methane and carbon dioxide GIP content and the relative quantity of adsorbed phases of gases at in situ temperatures and pressures representative of deep shale formations and coal seams. The concept of a deep shale gas reservoir is then proposed to optimize shale gas development methodology based on the successful application of the model for methane adsorption in shale.
Based on the dual-site Langmuir model, the isosteric heat of adsorption is calculated analytically by considering both the real gas behavior and the adsorbed phase under high pressure, both of which are ignored in the classic Clausius–Clapeyron approximation. It was also found that the isosteric heat of adsorption in Henry's pressure region is independent of temperature and can serve as a quantified index to evaluate the methane adsorption affinity on coal.
In order to understand the dynamic response of gas adsorption in coal for carbon sequestration, both gas adsorption kinetics and pore structure of coal are investigated. The pseudo-second order model is applied to simulate the adsorption kinetics of carbon dioxide in coals under different pressures. Coal particle size effects on pore characterization of coal and carbon dioxide and nitrogen ad/desorption behavior in coal was also investigated.Ph. D.
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Ceteroni, Ilaria. "High-pressure adsorption differential volumetric apparatus (HP-ADVA) for accurate equilibrium measurements." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22274/.
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The volumetric system is a commonly used experimental method for gas adsorption measurements. Starting from the conventional volumetric system (single-branched), the development of differential (double-branched) apparatus has been proposed to overcome some criticalities connected to the original design. The following study is focused on the assessment of the high-pressure differential volumetric apparatus (HP-ADVA) built at the University of Edinburgh in order to discover and characterise system peculiarities at different experimental conditions, in terms of temperature and pressure. To do this, an integrated approach is proposed: an initial experimental campaign has been performed to take confidentiality with the apparatus, then, the experimental results were the starting point for the development of a sensitivity and error analysis aimed at describing the effect of each operating parameter into the final result. In this regard, a different analytical approach, compared to the ones commonly proposed in literature, has been proposed to closely reproduce the real system. Beyond having obtained promising results, some criticalities, matching what originally hypothesized from the experimental campaign, have been noted: valve volume effect and temperature control and measurements have been discovered being crucial aspects, and, supposedly, source of errors leading to explain the unexpected results obtained by the experimental campaign. Moreover, the importance of symmetry maintenance among the branches has been repeatedly confirmed in the analysis. Some recommendations aimed at improving the system set-up have been moved regarding the installation of a temperature control system and more accurate temperature measurement devices. Additionally, an accurate assessment and characterisation of pneumatically-actuated valves, as well as of the differential pressure transducer used for pressure measurement, before the installation, could be useful to reduce inaccuracies.
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Borchardt, Lars, Winfried Nickel, Mirian Casco, Irena Senkovska, Volodymyr Bon, Dirk Wallacher, Nico Grimm, Simon Krause, and Joaquín Silvestre-Albero. "Illuminating solid gas storage in confined spaces – methane hydrate formation in porous model carbons." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-221847.
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Methane hydrate nucleation and growth in porous model carbon materials illuminates the way towards the design of an optimized solid-based methane storage technology. High-pressure methane adsorption studies on pre-humidified carbons with well-defined and uniform porosity show that methane hydrate formation in confined nanospace can take place at relatively low pressures, even below 3 MPa CH4, depending on the pore size and the adsorption temperature. The methane hydrate nucleation and growth is highly promoted at temperatures below the water freezing point, due to the lower activation energy in ice vs. liquid water. The methane storage capacity via hydrate formation increases with an increase in the pore size up to an optimum value for the 25 nm pore size model-carbon, with a 173% improvement in the adsorption capacity as compared to the dry sample. Synchrotron X-ray powder diffraction measurements (SXRPD) confirm the formation of methane hydrates with a sI structure, in close agreement with natural hydrates. Furthermore, SXRPD data anticipate a certain contraction of the unit cell parameter for methane hydrates grown in small pores.
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Borchardt, Lars, Winfried Nickel, Mirian Casco, Irena Senkovska, Volodymyr Bon, Dirk Wallacher, Nico Grimm, Simon Krause, and Joaquín Silvestre-Albero. "Illuminating solid gas storage in confined spaces – methane hydrate formation in porous model carbons." Royal Society of Chemistry, 2016. https://tud.qucosa.de/id/qucosa%3A30232.
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Methane hydrate nucleation and growth in porous model carbon materials illuminates the way towards the design of an optimized solid-based methane storage technology. High-pressure methane adsorption studies on pre-humidified carbons with well-defined and uniform porosity show that methane hydrate formation in confined nanospace can take place at relatively low pressures, even below 3 MPa CH4, depending on the pore size and the adsorption temperature. The methane hydrate nucleation and growth is highly promoted at temperatures below the water freezing point, due to the lower activation energy in ice vs. liquid water. The methane storage capacity via hydrate formation increases with an increase in the pore size up to an optimum value for the 25 nm pore size model-carbon, with a 173% improvement in the adsorption capacity as compared to the dry sample. Synchrotron X-ray powder diffraction measurements (SXRPD) confirm the formation of methane hydrates with a sI structure, in close agreement with natural hydrates. Furthermore, SXRPD data anticipate a certain contraction of the unit cell parameter for methane hydrates grown in small pores.
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Minhas, Rizwan. "Spin Crossover (SCO) Hofmann clathrate with switchable property, for the design of a new gas storage/separation material." Electronic Thesis or Diss., Pau, 2024. http://www.theses.fr/2024PAUU3049.
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Les réseaux organo-métalliques (MOF) ont été identifiés ces dernières années comme des alternatives avancées pour le stockage des gaz, les séparations moléculaires, la détection ou la catalyse, grâce à leurs remarquables propriétés hôte-invité et à leur polyvalence. Plus récemment, la combinaison du phénomène de transition de spin ferreux (Spin crossover : SCO) avec les MOF a permis d'obtenir des architectures poreuses commutables où le spin électronique des centres métalliques du fer(II) peut être contrôlé par différents stimuli. Ce travail se concentre sur l'un de ces SCO MOF, également appelés clathrates d’Hofmann, (FeNi[CN]4.Pyrazine) avec une propriété de commutation qui est étudiée ici pour ses propriétés de stockage et de séparation de gaz.Ce matériau est d'abord synthétisé à l'aide d'un mélange de réactifs respectueux de l'environnement, employant des sels de fer et de nickel avec de la pyrazine comme agent de liaison organique. La poudre microcristalline obtenue est ensuite caractérisée par différentes techniques expérimentales, notamment la porosimétrie à l'azote et à l'argon, l'analyse thermogravimétrique (ATG), la diffraction des rayons X, la microscopie électronique à balayage (SEM) et la spectroscopie IR, confirmant ainsi la réussite de la synthèse de ce matériau.L'un des objectifs de cette recherche était de concevoir et de construire un nouveau dispositif volumétrique, pour étudier l'adsorption à haute pression de gaz purs et de mélanges, permettant de visualiser simultanément l'échantillon au moyen d'une caméra fixée près de la fenêtre en saphir de la cellule de mesure. Tout d'abord, l'adsorption de gaz purs à haute pression (jusqu'à 7 MPa) (CO2, CH4 & N2) dans le (FeNi[CN]4.Pz) a été réalisée à différentes températures et les résultats ont montré une flexibilité structurelle intéressante de ce MOF lors de l'adsorption du CO2, quel que soit son état de spin initial. Ces transitions structurelles lors de l'adsorption de CO2 ont ensuite été observées à l'aide de techniques de spectroscopie vibrationnelle in-situ : FTIR et Raman. En outre, il a été démontré que la propriété SCO de ce matériau est bien associée aux changements de couleur de l'échantillon lui-même, ce qui montre que la technique combinée d'adsorption et d'analyse d'images est un outil utile pour étudier le changement SCO dû à l'adsorption pour ce type d’adsorbant.La mesure de l'adsorption de mélanges gazeux a pu être réalisée en utilisant le même dispositif manométrique couplé à un analyseur de gaz infrarouge. Les données expérimentales ont démontré que le (FeNi[CN]4.Pz) adsorbe préférentiellement le CO2 par rapport au CH4, ce qui en fait un candidat approprié pour la séparation CO2/CH4 dans certaines conditions. Il a été montré que cette adsorption préférentielle du CO2 est renforcée par la flexibilité du matériau.En plus de ces résultats expérimentaux, une modélisation de l'adsorption à l'équilibre, de la cinétique d'adsorption et de la sélectivité a été réalisée et comparée aux propriétés mesurées.En résumé, cette thèse présente une étude du (FeNi[CN]4.Pz), mettant en évidence sa synthèse, sa caractérisation, sa flexibilité et ses performances exceptionnelles dans les séparations CO2/CH4 et CO2/N2, grâce à des approches à la fois expérimentales et théoriquesMetal Organic Frameworks (MOFs) have been identified in recent years as advanced alternatives for gas storage, molecular separations, sensing or catalysis, thanks to their remarkable host-guest properties and versatility. More recently, the combination of the ferrous spin-crossover (SCO) with MOFs has made it possible to obtain switchable porous architectures where the electron spin of the iron(II) metal centers can be controlled by different stimuli. This work focuses on one of these SCO MOFs, also called Hofmann clathrates, (FeNi[CN]4.Pyrazine) with a switchable property that is studied here for its gas storage and separation properties.This material is first synthesized using an environmentally friendly mixing of reagents, employing iron and nickel salts with pyrazine as the organic linker. The resulting microcrystalline powder is then characterized via different experimental techniques including nitrogen and argon porosimetry, thermogravimetry analysis (TGA), X-ray diffraction, scanning electron microscopy (SEM), and IR spectroscopy, thus confirming the successful synthesis of this material.One of the aims of this research was to design and construct a novel homemade volumetric setup to study the high-pressure adsorption of pure gases and mixtures allowing to simultaneously visualize the sample by means of a camera attached near the sapphire window of the measuring cell. First, high pressure (up to 7 MPa) pure gases (CO2, CH4 & N2) adsorption in (FeNi[CN]4.Pz) were conducted at various temperatures and results have shown an interesting structural flexibility of this MOF during CO2 adsorption, whatever the initial spin state of the material. These structural transitions upon CO2 adsorption were then observed using in-situ vibrational spectroscopy techniques: FTIR and Raman spectroscopy. Moreover, it was shown that the SCO property of this material is well associated with the changes in color of the sample itself showing that the combined adsorption/image analysis technique is a useful tool to investigate the SCO change due to adsorption for this type of material.The adsorption measurement of gas mixtures could be achieved by utilizing the same homemade manometric setup coupled with an IR gas analyzer. Experimental data demonstrated that (FeNi[CN]4.Pz) has a preferential adsorption for CO2 over CH4, making it a suitable candidate for CO2/CH4 separation in some conditions. It was shown that this preferential adsorption of CO2 is enhanced by the structural flexibility of the material.In addition to these experimental results, modeling of both equilibrium adsorption, kinetics of adsorption and selectivity was performed and compared to the measured properties.In summary, this thesis presents a comprehensive study of (FeNi[CN]4.Pz), highlighting its synthesis, characterization, structural flexibility, and exceptional performance in CO2/CH4 as well as CO2/N2 separations, highlighted by both experimental and theoretical approaches
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Ngeleka, Tholakele Prisca. "Sulphur dioxide capture under fluidized bed combustion conditions / Tholakele Prisca Ngeleka." Thesis, North-West University, 2005. http://hdl.handle.net/10394/1416.
Full textAbstract:
An investigation was undertaken to determine the feasibility of increasing the hydrogen
production rate by coupling the water gas shift (WGS) process to the hybrid sulphur process
(HyS). This investigation also involved the technical and economical analysis of the water gas
shift and the H2 separation by means of Pressure swing adsorption (PSA) process. A technical
analysis of the water gas shift reaction was determined under the operating conditions selected
on the basis of some information available in the literature. The high temperature system (HTS)
and low temperature system (LTS) reactors were assumed to be operated at temperatures of
350ºC and 200ºC, respectively. The operating pressure for both reactors was assumed to be 30
atmospheres. The H2 production rate of the partial oxidation (POX) and the WGS processes was
242T/D, which is approximately two times the amount produced by the HyS process alone. The
PSA was used for the purification process leading to a hydrogen product with a purity of
99.99%. From the total H2 produced by the POX and the WGS processes only 90 percent of H2
is recovered in the PSA. The unrecovered H2 leaves the PSA as a purge gas together with CO2
and traces of CH4, CO, and saturated H2O. The estimated capital cost of the WGS plant with
PSA is about US$50 million. The production cost is highly dependent on the cost of all of the
required raw materials and utilities involved. The production cost obtained was US $1.41/kg H2
based on the input cost of synthesis gas as produced by the POX process. In this case the
production cost of synthesis gas based on US $6/GJ for natural gas and US $0/Ton for oxygen
was estimated to be US $0.154/kg. By increasing the oxygen and natural gas cost, the
corresponding increase in synthesis gas has resulted in an increase in H2 production cost of US $1.84/kg.Thesis (M.Sc. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2006.
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Ngeleka, Tholakele Prisca. "An investigation into the feasibility of applying the watergas shift process to increase hydrogen production rate of the hybrid sulphur process / T.P. Ngeleka." Thesis, North-West University, 2008. http://hdl.handle.net/10394/4108.
Full textAbstract:
An investigation was undertaken to determine the feasibility of increasing the hydrogen production rate by coupling the water gas shift (WGS) process to the hybrid sulphur process (HyS). This investigation also involved the technical and economical analysis of the water gas shift and the H2 separation by means of Pressure swing adsorption (PSA) process. A technical analysis of the water gas shift reaction was determined under the operating conditions selected on the basis of some information available in the literature. The high temperature system (HTS) and low temperature system (LTS) reactors were assumed to be operated at temperatures of 350°C and 200°C, respectively. The operating pressure for both reactors was assumed to be 30 atmospheres. The H2 production rate of the partial oxidation (POX) and the WGS processes was 242T/D, which is approximately two times the amount produced by the HyS process alone. The PSA was used for the purification process leading to a hydrogen product with a purity of 99.99%. From the total H2 produced by the POX and the WGS processes only 90 percent of H2 is recovered in the PSA. The unrecovered H2 leaves the PSA as a purge gas together with C02 and traces of CH4, CO, and saturated H20. The estimated capital cost of the WGS plant with PSA is about US$50 million. The production cost is highly dependent on the cost of all of the required raw materials and utilities involved. The production cost obtained was US $1.41/kg H2 based on the input cost of synthesis gas as produced by the POX process. In this case the production cost of synthesis gas based on US $6/GJ for natural gas and US $0/Ton for oxygen was estimated to be US $0.154/kg. By increasing the oxygen and natural gas cost, the corresponding increase in synthesis gas has resulted in an increase in H2 production cost of US $1.84/kg.Thesis (M.Sc. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2009.
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Mutasim, Z. Z. "Separation of gas mixtures by pressure swing adsorption." Thesis, Swansea University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379811.
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Zone, Ian Robert. "Dynamics and control of a pressure swing adsorption process." Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/762/.
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Mallardeau, Catherine. "L'hydrogène atomique polarisé : interaction avec les films d'Helium : expérience de compression." Paris 6, 1986. http://www.theses.fr/1986PA066186.
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Etude expérimentale de certains mécanismes de recombinaison de H| afin de comprendre les limites à l'obtention de la condensation de Bose Einstein. Mesure de l'énergie d'adsorption de H sur une couche mince 4He en fonction de l'épaisseur de la couche, paramètre qui donne les limites de stabilisation de H à basse température; obtention de la stabilisation sur des couches biomoléculaires. Construction d'un dispositif expérimental pour comprimer le gaz H| en champ magnétique de 20t, pour étudier le taux de recombinaison à 3 corps de H à haute densité et en champ magnétique intense.
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Liow, Daniel Ann Keng. "The modelling of diffusion controlled Pressure Wing Adsorption." Thesis, University of Surrey, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332279.
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Bestfather, Chris. "Upgrading landfill gas to natural gas quality: Bulk separation by pressure swing adsorption." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28403.
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Equilibrium adsorption properties are studied on zeolites for the application of upgrading biogas from landfills. Pure adsorption isotherms of carbon dioxide (CO2) and methane (CH4) measured with a constant volume apparatus. The Henry's Law constant and the heat of adsorption for NaLSX is also determined. The adiabatic working capacity and selectivity of four adsorbents is compared. NaLSX showed the highest capacity for CO2 at elevated temperatures.
The binary equilibrium of CO2/CH4 on NaLSX is measured in a modified gas chromatograph at total mixture pressures of 1 and 3.3 atmospheres. The adsorbed phase is dominated by CO2 with a selectivity of 20 to 100 for the separation of CO2 and CH4. The increase in total pressure resulted in an increase in adsorbent capacity and a decrease in selectivity. Finally, an economic analysis relates landfill size to PSA operational costs and returns.
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Manolis, Ionnis Georgios. "High pressure gas-liquid slug flow." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633654.
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McNaught, Robert John. "Gas permeation of high pressure polymeric pipe." Thesis, University of Newcastle Upon Tyne, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417721.
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Lei, Pan. "High pressure three-phase (gas/liquid/liquid) flow." Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/7204.
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Kimambo, Cuthbert Z. M. "Modelling of linebreak in high-pressure gas pipes." Thesis, City University London, 1996. http://openaccess.city.ac.uk/7934/.
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Although there are many computer codes available for analysis of fluid transients, only. a few are known to be applicable to line break situations and their scope is limited. There is therefore,s till a big potential for development work in the subject. Discrepancies between different models which have been developed have mainly centred on the assumptions used in developing the basic partial differential equations of flow, and subsequent simplifications; the thermophysical model used; representation of various terms in the equations such as the friction term; and the numerical method of solution of the basic partial differential equations. A previous model developed by Tiley (1989), overestimated the actual wave speeds and had problems of instability of the solution. A new approach, in which the three basic partial differential equation of flow are derived, based on the assumption of an unsteady quasi-one-dimensional flow of a real gas through a rigid constant cross-section area pipe, and using the Gamma Delta method is used. No further simplification is made on the basic equations. Significant improvements have been made on the type of equation of state, thermodynamic model, heat transfer approximation and friction factor representation. The QUANT software for thermodynamic and transport properties of real gases is used. A flow dependent explicit equation of Chen (1979) is used to calculate the frictional force and heat transfer is calculated using the concept of recovery factor and adiabatic wall temperature. Numerical solution of the basic equations is performed using the third-order Warming- Kutler-Lomax method, the second-order MacCormack method and the method of characteristics. A pc based computer coding with the C language is used. The QUANT software has successfully been incorporated with the programme. The full benefits of the software could not be realised with linebreak problems due to limitation of the range within which it gives output at present, but satisfactory results have nevertheless been attained. An improved and more accurate way of calculating the break boundary condition has been used. A non-uniform grid spacing has been used, which allow fine grid spacing in the vicinity of the break in order to enable accurate modelling of the rapid transients occurring in that part. Two different models for calculating the heat transfer i. e. one for the case of pipes exposed to the atmosphere and buried pipes have been incorporated with the model. Experimental data from full-scale pipeline tests is used to validate the computer models. Results from the computer model simulations show good agreement with the experimental data. The MacCormack method has been found to be unsuitable for modelling transient flow following linebreak in high-pressure gas pipelines. The method of characteristics has proved to be the method of solution for such applications. A better understanding of the flow following a break in high-pressure gas pipes is achieved, especially the decompression behaviour at the break boundary. Data gathered from feasibility studies conducted in the late 1980's for a pipeline in Tanzania is used to validate the steady state analysis model and to simulate a linebreak in the pipeline. Results of the computer simulation are discussed and recommendations made on the suitability the pipeline design. Additional work is recommended on refining and further testing of the computer programmes and using the Gamdeleps method which covers all the three phases region i.e. gas, liquid and gas/liquid.
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Abercrombie, Matthew G. "Acoustic microsensor with optical detection for high-temperature, high-pressure environments." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/19467.
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Gobbi, David G. "A high-pressure gas microstrip detector for digital radiography." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ27049.pdf.
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Bocian, Artur. "Gas-loading apparatus for large-volume high-pressure cell." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/6235.
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The Paris-Edinburgh cell (PEC) is a widely used opposed-anvil device for neutron scattering. Since its development, it has been used to study a number of samples loaded as solids or liquids. However, studying gases at room temperature has not yet been possible. Up until now only a few gases could be loaded as liquids, in cryogenic conditions. Thus, it was impossible to study many gases and gas mixtures and also it was difficult to use gases as pressure-transmitting media (PTM). In order to overcome these limitations, a technique that would enable loading of gases into the PEC was required. The work described in this thesis was focused on the design and use of a gas-loading system for the PEC. The challenge of designing such a system comes from the fact that the gases need to be loaded into the gasket at sufficient density in order to achieve any significant pressure during further compression in the cell. This can be achieved by using a separate pressure vessel. Because the whole PEC is too large to be placed inside the vessel, a technique of loading gas into the anvils separated from the rest of the cell had to be devised. Designing the holder for the anvils, which would make this possible, presented a major challenge as it should allow the anvils to be transferred between the vessel and the PEC, with the gasket filled with high-pressure gas. Then it needs to allow further compression of the gasket inside the PEC. The developed system consists of a pressure vessel and a locking clamp for the anvils. The pressure vessel is a closed-end thick-walled cylinder with a top cover which has an opening for a piston. The vessel is placed on the table of a hydraulic press and the piston, sealed by a high-pressure reciprocating seal, is used to transmit the force from hydraulic ram onto the anvils which are held by the clamp and placed inside the vessel. One of the anvils is fixed to the clamp and the other one is supported by spring-loaded latches - the latches engage when the anvils are pushed towards each other. Thus, when the force is applied onto the anvils to compress the gasket, latches lock the anvils in their positions stopping them from retracting and maintaining the gasket compressed after the force is released. The clamp allows the gasket to be filled with the gas and then deformed to seal the compressed gas. The locking mechanism keeps the gasket compressed, which enables the clamp to be transferred from the vessel to the PEC. After the system was built and tested, it was installed at ISIS neutron source (Oxfordshire, UK), where it has been used in several experiments. The first experiment prepared with the gas-loading system was a neutron diffraction study of nitrogen at high pressure. Nitrogen was chosen as a sample material because its high-pressure structural phase diagram is well established. Nitrogen was loaded into the gasket using the gas loader and then it was compressed in increments to 6 GPa in the PEC. β and δ phases of solid nitrogen were clearly seen in the collected neutron diffraction data. The experiment proved the usability of the gas-loading system and verified its expected performance. The second experiment utilizing the gas-loading system was to study singlecrystal and powder samples of sodium chloride (NaCl) and squaric acid (H2C4O4). For these studies argon was used as a PTM, replacing the conventionally used methanol-ethanol mixture (ME). Up until this experiment the highest pressure reported in single-crystal neutron-scattering experiments was 12 GPa. This limit was set by the solidi cation pressure of ME. With argon as the PTM, the samples were compressed to 15 GPa without any damage to the crystals. Another advantage of replacing ME with argon is improved hydrostaticity. The highest pressure that ME remain hydrostatic to is 11 GPa. Compressing beyond this point causes sheer stress acting on the sample which affects the quality of the neutron scattering data manifested in the appearance of peak-broadening in the diffraction patterns. With use of argon, the powder samples have been compressed to 18 GPa while maintaining quasi-hydrostatic pressure conditions, resulting in clean and sharp diffraction patterns without any noticeable peak-broadening.
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Abbassian, F. "Long-running ductile fracture of high pressure gas pipelines." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372872.
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Alhajeri, Hamad. "Heat removal in axial flow high pressure gas turbine." Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/11465.
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The demand for high power in aircraft gas turbine engines as well as
industrial gas turbine prime mover promotes increasing the turbine entry
temperature, the mass flow rate and the overall pressure ratio. High
turbine entry temperature is however the most convenient way to increase
the thrust without requiring a large change in the engine size.
This research is focused on improving the internal cooling of high pressure
turbine blade by investigating a range of solutions that can contribute to
the more effective removal of heat when compared with existing
configuration. The role played by the shape of the internal blade passages
is investigated with numerical methods. In addition, the application of mist
air as a means of enhanced heat removal is studied.
The research covers three main area of investigation. The first one is
concerned with the supply of mist on to the coolant flow as a mean to
enhancing heat transfer. The second area of investigation is the
manipulation of the secondary flow through cross-section variation as a
means to augment heat transfer. Lastly a combination of a number of
geometrical features in the passage is investigated.
A promising technique to significantly improve heat transfer is to inject
liquid droplets into the coolant flow. The droplets which will evaporate after
travelling a certain distance, act as a cooling sink which consequently
promote added heat removal. Due to the promising results of mist cooling
in the literature, this research investigated its effect on a roughened
cooling passage with five levels of mist mass percentages.
In order to validate the numerical model, two stages were carried out.
First, one single-phase flow case was validated against experimental
results available in the open literature. Analysing the effect of the rotational
force, on both flow physics and heat transfer, on the ribbed channel was
the main concern of this investigation. Furthermore, the computational results using mist injection were also validated against the experimental
results available in the literature.
Injection of mist in the coolant flow helped achieve up to a 300% increase
in the average flow temperature of the stream, therefore in extracting
significantly more heat from the wall. The Nusselt number increased by
97% for the rotating leading edge at 5% mist injection.
In the case of air only, the heat transfers decrease in the second passage,
while in the mist case, the heat transfer tends to increase in the second
passage. Heat transfer increases quasi linearly with the increase of the
mist percentage when there is no rotation. However, in the presence of
rotation, the heat transfers increase with an increase in mist content up to
4%, thereafter the heat transfer whilst still rising does so more gradually.
The second part of this research studies the effect of non-uniform cross-
section on the secondary flow and heat transfer in order to identify a
preferential design for the blade cooling internal passage. Four different
cross-sections were investigated. All cases start with square cross-section
which then change all the way until it reaches the 180 degree turn before it
changes back to square cross-section at the outlet. All cases were
simulated at four different speeds. At low speeds the rectangle and
trapezoidal cross-section achieved high heat transfer. At high speed the
pentagonal and rectangular cross-sections achieved high heat transfer.
Pressure loss is accounted for while making use of the thermal
performance factor parameter which accounts for both heat transfer and
pressure loss. The pentagonal cross-section showed high potential in
terms of the thermal performance factor with a value over 0.8 and higher
by 33% when compared to the rectangular case.
In the final section multiple enhancement techniques are combined in the
sudden expansion case, such as, ribs, slots and ribbed slot. The maximum
heat enhancement is achieved once all previous techniques are used
together. Under these circumstances the Nusselt number increased by
60% in the proposed new design.
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Gobbi, David G. (David Gregory) Carleton University Dissertation Physics. "A High-pressure gas microstrip detector for digital radiography." Ottawa, 1997.
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Amin, Abdul Malek. "A study of hydrogen purification from the refinery fuel gas by pressure swing adsorption." Online version, 1996. http://bibpurl.oclc.org/web/23945.
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Arvanitis, Antonios. "High Temperature High Pressure Water Gas Shift Reaction in Zeolite Membrane Reactors." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563872266361549.
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Brigadeau, Alexandre H. M. "Modeling and Numerical Investigation of High Pressure Gas-Liquid Separation." Doctoral thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1756.
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In this Ph.D. thesis, a model for the study of the efficiency of high-pressure liquid/gas industrial separators has been developed. The model is a three fluid model (gas phase, droplet phase and film phase) and is entirely Eulerian. For the gas phase, a κ - ε model extended to multiphase flows has been used. The turbulent kinetic energy of the dispersed phase, the turbulent dispersion coefficient and the momentum equation of the liquid film were closed algebraicly. The total deposition velocity was determined by turbulent dispersion and a near-wall deposition velocity. The latter was the sum of a non-diffusive term (due to the mean convection of the flow and gravity) and a diffusive term. This diffusive term accounted for the diffusion-impaction deposition regime and the inertia-moderated deposition regime. The gas/liquid film interfacial shear stress was calculated from the local value of the turbulent kinetic energy of the gas. The film acted on the gas as a steady rough wall. An experimental entrainment rate correlation was chosen. The model was implemented in a finite-volume commercial code (Fluent 6.2). The model is based on local closure relations so that it can be further developed for complex industrial geometries.
The results were first compared with experiments from the literature. Deposition rates and film heights were in agreement with the data of the literature. However, the calculated pressure drops were higher and the calculated entrainment rates were lower than the experimental values. The present work pinpoints the reasons of these inaccuracies and corrections to the original model are proposed. The model was finally applied to calculate the efficiency of a vane-pack demister. At atmospheric pressure with air and water the efficiency of the demister was 99.7%. This value agrees with the prediction of a former model from the literature. At high pressure with natural gas and condensate the efficiency of the separator was 0%. The deposition rate was lower, the entrainment rate very high and the liquid layer vanished.
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Hosking, Lee. "Reactive transport modelling of high pressure gas flow in coal." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/61446/.
Full textAbstract:
This thesis describes a study of reactive transport processes in fractured rock in response to high pressure gas injection and displacement. This is achieved through the development and application of a theoretical and numerical modelling platform. A dual porosity, dual permeability framework has been formulated based on a mechanistic approach, which considers the coupled hydraulic, gas/chemical and deformation behaviour of fractured rock. The fracture network and porous rock matrix were treated as overlapping continua with distinct transport and storage properties. Flow in each continuum was considered by advection, diffusion and dispersion mechanisms, and a sink/source term was included for the kinetically controlled sorption of multicomponent gas. A mass exchange term was introduced to couple the continua and allow pressure and concentration differences to develop. The transport properties of non-ideal gas mixtures at high pressure were characterised by appropriate constitutive relationships. The developed model has been incorporated in an existing coupled thermal, hydraulic, chemical and mechanical framework. A numerical solution was obtained using the finite element method for spatial discretisation and the finite difference method for temporal discretisation. Verification of the approach proposed has been addressed via a series of benchmark tests. The results obtained provide confidence in the accuracy of the numerical implementation of the dual porosity governing equations, including a time splitting approach used to couple the transport module with the mass exchange and geochemical reaction modules. Key theoretical features have been included to enhance the model capabilities and enable application of the model to study species dependent coal-gas behaviour, especially in relation to carbon dioxide sequestration in coal and enhanced coal bed methane displacement. The development of constitutive relationships describing the feedback of dual porosity physico- and chemo-mechanical deformation on gas transport in coal was considered in detail. Furthermore, a combination of two first-order rate models was used to include the specific gas sorption behaviour in coal. A detailed validation of the model using high resolution experimental data on gas interactions, transport and displacement in coal has been included. The theoretical models developed for coal-gas interactions were first evaluated, providing a platform to facilitate numerical simulations of gas injection and displacement experiments, performed on intact samples of anthracite coal from the South Wales coalfield. Under the conditions considered and for two injection scenarios, namely, nitrogen and subcritical carbon dioxide injection, it was demonstrated that the model is capable of simulating the salient physical and chemical phenomena involved in gas transport and methane displacement in coal. More advanced simulations have been performed to study the behaviour for a larger sample size and different gas injection pressures and compositions. The injection of supercritical carbon dioxide and two carbon dioxide-rich gas mixtures at high pressure was considered. It is claimed that a substantive insight has been gained into the coupled behaviour of the material at the laboratory scale. Overall, the analysis carried out in this research indicated that species dependent chemo-mechanical deformation was the dominant factor in smaller core samples. Fracture-matrix exchange and preferential methane desorption by carbon dioxide only became more apparent in larger samples. An appreciation of the effects of sample size on the behaviour observed is therefore important when interpreting experimental data, and implies that due care must be taken in interpreting laboratory scale results towards larger scale applications. In this work, the capabilities of the new model have been showcased with regards to the study of coal-gas systems. Importantly, the developments presented are more generally relevant and thus enable the study of a broad new range of applications involving multiphase, multicomponent gas/chemical transport in fractured rock.
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Barton, David Alan. "Particle Discrimination Using a High-Pressure Xenon Gas Scintillation Detector." Diss., Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/179369.
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PhysicsPh.D.
This work presents results on the study of the scintillation of high-pressure Xenon gas irradiated by various sources. Noble gases such as Xenon give off characteristic scintillation light when irradiated. The goal of the study was to develop a characteristic based on the scintillation time response of Xenon gas that would reliably discriminate between events from different types of primary radiation (neutron or gamma). A reliable discrimination characteristic would enable the development of room temperature, gas phase detectors for use in the search for Galactic Dark Matter. The surprising result of the present work was that a reliable discrimination characteristic existed for distinguishing x-ray, gamma ray, and alpha particle events. Results for neutrons were negative. This was due to several factors: Ionization tracks in xenon generally form two roughly cylindrical regions. A region near the center of the track, called the core, has very dense ionization. An outer region, called the penumbra, has sparse ionization. In Xenon, recombination of ions and the subsequent scintillation from the penumbra region happens slowly and can be easily distinguished from scintillation that happens in the core region. Nuclear recoils resulting from neutron collisions that give recoil energies in the same range as that predicted for WIMP-nuclear collisions are of such low energy that they do not produce a significant penumbra region in Xenon gas. As such, the scintillation time response for these events is similar to that of high-energy gamma rays. Other results of the present work include: The amount of energy deposited in the gas needed to produce a scintillation photon was measured for gamma rays and was found to be in agreement with results from other experiments. Low-energy gamma rays appeared to produce more scintillation photons for an equal amount of energy deposited than high-energy gamma rays. The decay of the singlet and triplet molecular states of xenon was observed and the lifetimes of these states were measured. The singlet state lifetime was found to be independent of pressure while the triplet state lifetime was dependent on pressure. The lifetimes were measured and compared to previous results. A better understanding of the ionization, recombination, and scintillation processes of gaseous Xenon was achieved. Argon gas has been proposed as an alternative to Xenon gas for use in a high-pressure gas scintillation detector due to its lower mass and its property of forming a core ionization region that is much less dense than the core region of xenon. This substitution may allow for a reliable discrimination characteristic to be developed.
Temple University--Theses
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Romero, Sandra. "Crystallization Study Of Polymers Under High Pressure Gas / Supercritical Fluid." ScholarWorks @ UVM, 2018. https://scholarworks.uvm.edu/graddis/953.
Full textAbstract:
The global demand for polymers especially Polypropylene (PP) foams is increasing rapidly. Foam structures can be very beneficial for producing structural components which can be significantly larger than the raw material formed by volume expansion. In this context, the objective of this work is to develop uniform fine-cell and low-density polymer foams with improved mechanical properties.
In order to promote a deeper understanding of the low-density (<0.1 g/cc) and microcellular structure (10^8 cells/cm^3), a novel foaming-visualization system was developed. This novel custom-made system captures in situ crystallization-induced foaming behaviors of polymers. The shear effect on bubble and crystal growth processes were investigated independently in an isolated manner.
Based on data observed from the visualization system, a two-dimensional model of the foam nucleation process was developed. The model was extended to account for the simultaneous cell nucleation, growth, and collapse processes of the foaming bubbles. By means of connection among neighboring bubbles, secondary nucleation behaviors emerged from multi-bubble interactions were attempted in simulations. Finally, the effects of gas pressure, temperature, additive content, and shear stress were thoroughly investigated for the sake of optimizing the processing conditions and foamed products.
Potential applications from these researches lie in the analysis of the resulting micro-/nano-cellular structures and the development of innovative plastic foaming technologies and foams.
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Popović, Ivan. "Aerothermal investigation of hub leakage flows in high-pressure turbines." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608563.
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El-Usta, Shaaban. "High pressure combustion tube studies of medium and light oil." Thesis, University of Bath, 1998. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242524.
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Bessho, Naoki. "Advanced pressure swing adsorption system with fiber sorbents for hydrogen recovery." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42822.
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A new concept of a "fiber sorbent" has been investigated. The fiber sorbent is produced as a pseudo-monolithic material comprising polymer (cellulose acetate, CA) and zeolite (NaY) by applying hollow fiber spinning technology. Phase separation of the polymer solution provides an appropriately porous structure throughout the fiber matrix. In addition, the zeolite crystals are homogeneously dispersed in the polymer matrix with high loading. The zeolite is the main contributor to sorption capacity of the fiber sorbent. Mass transfer processes in the fiber sorbent module are analyzed for hydrogen recovery and compared with results for an equivalent size packed bed with identical diameter and length. The model indicates advantageous cases for application of fiber sorbent module over packed bed technology that allows system downsizing and energy saving by changing the outer and bore diameters to maintain or even reduce the pressure drop. The CA-NaY fiber sorbent was spun successfully with highly porous structure and high CO2 sorption capacity. The fiber sorbent enables the shell-side void space for thermal moderation to heat of adsorption, while this cannot be applied to the packed bed. The poly(vinyl alcohol) coated CA-NaY demonstrated the thermal moderation with paraffin wax, which was carefully selected and melt at slightly above operating temperature, in the shell-side in a rapidly cycled pressure swing adsorption. So this new approach is attractive for some hydrogen recovery applications as an alternative to traditional zeolite pellets.
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Chanut, Nicolas. "Using external factors to improve gas adsorption in nanoporous materials : control of humidity and mechanical pressure." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4743.
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L'augmentation du niveau de CO2 atmosphérique est un sujet de préoccupation publique notoire. Afin d'atténuer son impact sur l'environnement, il est urgent de réduire les émissions de CO2 d’origines anthropiques. Une méthode considérée comme viable est la capture de CO2 par des procédés d’adsorption en utilisant une classe émergente de matériaux, les Metal-Organic Frameworks (MOFs). A ce jour, l’évaluation des MOFs s’est principalement axée sur leurs performances de séparation (capacité, sélectivité et régénération). Cependant, des facteurs externes peuvent influer sur les performances globales des procédés. L’objectif de cette thèse est d’évaluer trois d’entre eux : la présence de vapeur d’eau dans les effluents gazeux, l’effet de la mise en forme des matériaux et l’effet d’une pression mécanique externe sur les performances d’adsorption de gaz. Il est montré que ces facteurs externes peuvent être utilisés pour améliorer les performances des procédés dans des conditions spécifiquesThe increase in atmospheric CO2 level is a notorious matter of public concern. To mitigate its impact on the environment, it is urgent to reduce emissions of anthropogenic CO2. A method considered by many as a viable option is CO2 capture by adsorption using an emerging class of materials, the Metal-Organic Frameworks (MOFs). To date, evaluation of MOFs has been mainly focused on the separation performance of the material looking at the capacity, selectivity and regeneration capability. However external factors can influence the overall performances of processes turning to industrial applications. The purpose of this thesis was to evaluate three of them: the presence of water vapor in post-combustion flue gases, the effect of shaping powders into pellets form and the effect of an external mechanical pressure on gas adsorption performance. Unexpectedly, it is shown that these external factors could be used to improve process performances under specific conditions
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Kim, Sangil. "High Permeability/High Diffusivity Mixed Matrix Membranes For Gas Separations." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/26649.
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The vast majority of commercial gas separation membrane systems are polymeric because of processing feasibility and cost. However, polymeric membranes designed for gas separations have been known to have a trade-off between permeability and selectivity as shown in Robeson's upper bound curves. The search for membrane materials that transcend Robeson's upper bound has been the critical issue in research focused on membranes for gas separation in the past decade. To that end, many researchers have explored the idea of mixed matrix membranes (MMMs). These membranes combine a polymer matrix with inorganic molecular sieves such as zeolites. The ideal filler material in MMMs should have excellent properties as a gas adsorbent or a molecular sieve, good dispersion properties in the polymer matrix of submicron thickness, and should form high quality interfaces with the polymer matrix.
In order to increase gas permeance and selectivity of polymeric membranes by fabricating MMMs, we have fabricated mixed matrix membranes using carbon nanotubes (CNTs) and nano-sized mesoporous silica. Mixed matrix membranes containing randomly oriented CNTs showed that addition of nanotubes to a polymer matrix could improve its selectivity properties as well as permeability by increasing diffusivity. Overall increases in permeance and diffusivity for all tested gases suggested that carbon nanotubes can provide high diffusivity tunnels in the CNT within the polymer matrix. This result agreed well with molecular simulation estimations. In order to prepare ordered CNTs membranes, we have developed a simple, fast, commercially attractive, and scalable orientation method. The oriented CNT membrane sample showed higher permeability by one order of magnitude than the value predicted by a Knudsen model. This CNT membrane showed higher selectivities for CO₂ over other gas molecules because of preferential interaction of CO₂ with the amine functionalized nanotubes, demonstrating practical applications in gas separations.
Recently, mesoporous molecular sieves have been used in MMMs to enhance permeability or selectivity. However, due to their micrometer scale in particle size, the composite membrane was extremely brittle and tended to crack at higher silica loading. In this study, we have developed fabrication techniques to prepare MMMs containing mesoporous MCM-41 nanoparticles on the order of ~50 nm in size. This smaller nanoparticle lead to higher polymer/particle interfacial area and provides opportunity to synthesize higher loading of molecular sieves in polymer matrix up to ~80 vol%. At 80 vol% of nano-sized MCM-41 silica loading, the permeability of the membrane increased dramatically by 300 %. Despite these increases in permeability, the separation factor of the MMMs changed only slightly. Therefore, these nanoscale molecular sieves are more suitable for commercialization of MMMs with very thin selective layers than are micro-sized zeolites or molecular sieves.Ph. D.
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Lau, Wai Man. "Hydrodynamics and mass transfer studies in high pressure gas-liquid and gas-liquid-solid fluidization." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1070295869.
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Lau, Wai Man R. "Hydrodynamics and mass transfer studies in high pressure gas-liquid and gas-liquid-solid fluidization." Connect to this title online, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1070295869.
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Thesis (Ph. D.)--Ohio State University, 2003.Title from first page of PDF file. Document formatted into pages; contains xix, 168 p.; also includes graphics (some col.) Includes bibliographical references (p. 159-168). Available online via OhioLINK's ETD Center
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Sandvik, Peter. "High-Pressure Natural Gas to Syngas Chemical Looping: Thermodynamic Modeling, Gas-to-Liquid Plant Integration, and Variable Reducer-Combustor Operating Pressure." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1553858544883504.
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Mathew, Denny. "Discharge instabilities in high-pressure fluorine based excimer laser gas mixtures." Enschede : University of Twente [Host], 2007. http://doc.utwente.nl/57860.
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Clinch, Michael. "The thermomechanical processing of aluminium alloys for high pressure gas cylinders." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326551.
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Jayasuriya, Jeevan. "Experimental Investigations of High Pressure Catalytic Combustion for Gas Turbine Applications." Doctoral thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134445.
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This work is devoted to generate knowledge and high quality experimental data of catalytic combustion at operational gas turbine conditions. The initial task of the thesis work was to design and construct a high pressure combustion test facility, where the catalytic combustion experiments can be performed at real gas turbine conditions. With this in mind, a highly advanced combustion test facility has been designed, constructed and tested. This test facility is capable of simulating combustion conditions relevant to a wide range of operating gas turbine conditions and different kinds of fuel gases. The shape of the combustor (test section) is similar to a “can” type gas turbine combustor, but with significant differences in its type of operation. The test combustor is expected to operate at near adiabatic combustion conditions and there will be no additions of cooling, dilution or secondary supply of air into the combustion process. The geometry of the combustor consists of three main zones such as air/fuel mixing zone, catalytic reaction zone and downstream gas phase reaction zone with no difference of the mass flow at inlet and exit. The maximum capacity of the test facility is 100 kW (fuel power) and the maximum air flow rate is 100g/s. The significant features of the test facility are counted as its operational pressure range (1 – 35 atm), air inlet temperatures (100 – 650 °C), fuel flexibility (LHV 4 - 40 MJ/m3) and air humidity (0 – 30% kg/kg of air). Given these features, combustion could be performed at any desired pressure up to 35 bars while controlling other parameters independently. Fuel flexibility of the applications was also taken into consideration in the design phase and proper measures have been taken in order to utilize two types of targeted fuels, methane and gasified biomass. Experimental results presented in this thesis are the operational performances of highly active precious metal catalysts (also called as ignition catalysts) and combinations of precious metal, perovskites and hexaaluminate catalysts (also called as fully catalytic configuration). Experiments were performed on different catalytic combustor configurations of various types of catalysts with methane and simulated gasified biomass over the full range of pressure. The types of catalysts considered on the combustor configurations are palladium on alumina (Pd/AL2O3), palladium lanthanum hexaaluminate (PdLaAl11O19), platinum on alumina (Pt/AL2O3),and palladium:platinum bi-metal on alumina (Pd:Pt/AL2O3). The influence of pressure, inlet temperature, flow velocity and air fuel ratio on the ignition, combustion stability and emission generation on the catalytic system were investigated and presented. Combustion catalysts were developed and provided mainly by the project partner, the Division of Chemical Technology, KTH. Division of Chemical Reaction Technology, KTH and Istituto di Ricerche sulla Combustione (CNR) Italy were also collaborated with some of the experimental investigations by providing specific types of catalysts developed by them for the specific conditions of gas turbine requirements.QC 20131125
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Mori, Hideo, Tomohide Niimi, Madoka Hirako, and Hiroyuki Uenishi. "Pressure Sensitive Paint Suitable to High Knudsen Number Regime." IOP, 2006. http://hdl.handle.net/2237/6960.
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Perryman, Adrian Colin. "An investigation of catalyst preparative methods and a study of high pressure CO adsorption." Thesis, Brunel University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333030.
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Gardner, Nicola Jane. "The development of a high efficiency centrifugal separator for gas/liquid mixtures at high pressure." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337168.
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Hu, Jianbing. "Modeling and simulation of high pressure composite cylinders for hydrogen storage." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Hu_09007dcc805d8846.pdf.
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Thesis (Ph. D.)--Missouri University of Science and Technology, 2009.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 9, 2009) Includes bibliographical references.
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Sheldrake, C. D. "Unsteady effects in the high pressure stage of a model gas turbine." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242794.
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Tuema, Fadhil A. "Methods of improving the pulse repetition frequency of high pressure gas switches." Thesis, University of Strathclyde, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418736.
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Teeratchanan, Pattanasak. "First-principles studies of gas hydrates and clathrates under pressure." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31359.
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Gas hydrates are molecular host-guest mixtures where guest gas species are encapsulated in host water networks. They play an important role in gas storage in aqueous environments at relatively low pressures, and their stabilities are determined by weak interactions of the guest species with their respective host water frameworks. Thus, the size and the amount of the guest species vary, depending on the size of the empty space provided by the host water structures. The systems studied here are noble gas (He, Ne, Ar) and diatomic (H2) hydrates. Because of the similarity of the guests' sizes between the noble gases and the di-atomic gases, the noble gas hydrates act as simple models for the di-atomic gas hydrates. For example, He, Ne and H2 have approximately the same size. Density functional theory calculations are used to obtain the ground state formation enthalpies of each gas hydrate, as a function of host network, guest stoichiometry, and pressure. Dispersion effects are investigated by comparing various dispersion corrections in the exchange-correlation functionals (semi-local PBE, semi-empirical D2 pair correction, and non-local density functionals i.e. vdW-DF family). Results show that the predicted stability ranges of various phases agree qualitatively, although having quantitative difference, irrespective of the methods of the dispersion corrections in the exchange-correlation functionals. Additionally, it is shown in gas-water dimer interaction calculations that all DFT dispersion-corrected functionals overbind significantly than the interaction acquired by the coupled-cluster calculations, at the CCSD(T) level, which is commonly accepted to provide the most accurate estimation of the actual interaction energy. This could lead to an overestimation of the stability of the hydrate mixtures. Further study in the gas-water cluster indicates that less overbinding effect is found in the cluster than in the dimer. This implies that the overbinding energy caused by DFT might become less pronounce in the solid phase. Graph invariant topology and a program based on a graph theory are used to assign protons based on the 'ice rule' to fulfill the incomplete experimental structural data such as unknown/unclear positions of protons in the host water lattices. These methods help constructing host water networks for computational calculations. Several configurations of the host water structures are tested. Those configurations having lowest enthalpies are used as the host water networks in this research. Furthermore, the enthalpic spread between the configurations having the highest and the lowest enthalpy in the pure water ice network is very small (about 10 meV per water molecule). Nevertheless, it is still unclear to conclude that this protonic effect is also trivial in the gas-water compound. Therefore, this study also calculates the enthalpies of the gas-water mixtures having various proton configurations in the host water networks. Results indicate that very small enthalpic distributions among the proton configurations are found in the compounds as well. Furthermore, the enthalpic spread is almost constant as pressure increases. This suggests there is no pressure effect in the enthalpy gap amoung the proton distributions in both pure water ice and the gas-water compounds. Predicted stable phases for the noble gas compound systems are based on four host water networks, namely, ice Ih, II and Ic, and the novel host water network S!. The He-water system adopts ice Ih, II and Ic network upon increasing pressure. In the Ne-water system, a phase sequence of Sx/ice-Ih, II and Ic with a competitive hydrate phase in the S! host network at very low pressure is found. This is similar to the phase evolution of the H2-water system. For the Ar-water mixture, only a partially occupied hydrate in the Sx host network is found stable. This Sx phase becomes metastable if taking the traditional clathrates (sI and sII) into account. This result agrees very well with the experiment suggesting only two-third filling is found the large guest gases i.e. CO2. For the diatomic guest gas compound systems, the traditional clathrate structure (sII) that found to be existed experimentally in the H2-H2O system is also included in this study together with those four host water networks. Predicted phase stability sequence as elevated pressure is as follows: Sx, ice-Ih, II and Ic. This computationally prediction agrees very well with experiment. Results in this work suggest that the compound based on the traditional clathrate structure II (sII) host water framework is found to be metastable with respect to the decomposition constituents - in this case, they are pure water ice and the S!. The metastability of the hydrogen hydrates based on the sII structure might due to zero-point motions or other dynamic/entropic mechanisms uncovered in this research. Dynamic studies concerning the transition states of the hydrogen guest molecules in three competitive phases at very low pressure (less than 10 kbar), based on Sx, ice-Ih, and ice-II host water network, are considered. The energy barriers required by the hydrogen guest molecules in those three host frameworks are calculated by using Nudged Elastic Band (NEB) method. Results suggest that the hydrogen molecules are more mobile in the Sx than the other two host structures significantly. In the S! host water network, the energy barrier is about 25 meV/hydrogen molecule. This energy is about the room temperature suggesting that the hydrogen guest molecules are easily mobile in the Sx host water network if there is an empty site adjacent to them.
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Patychuk, Bronson David. "Particulate matter emission characterization from a natural-gas high-pressure direct-injection engine." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44341.
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Stringent regulations have been enacted to reduce particulate matter (PM) emissions from heavy-duty compression-ignition (CI) engines. New regulations (Euro VI) restrict PM mass and particle number concentration. To help meet these regulations, a greater understanding of the physical and chemical characteristics of the PM is desired. This thesis is concerned with the mobility, morphology (by electron microscopy), mass (filter sampling), light scattering and semivolatile content of the particles.
Natural gas has become an increasingly attractive transportation fuel for both environmental and economic reasons. One technology to utilize gaseous fuels in heavy-duty engines is Westport Innovations Inc.’s High Pressure Direct Injection (HPDI™) system. This is a system where the natural gas is directly injected late in the compression stroke and ignition of the natural gas is provided by a diesel pilot.
PM emissions were characterized from a heavy-duty Cummins ISX engine converted to single cylinder operation and operating under HPDI™ fueling. Tests were performed to observe the effects of speed and load combinations, the effects of operating parameter variations (Injection timing, equivalence ratio, gas supply pressure, EGR % and diesel injection mass) and the effects of fuel premixing on the PM emissions.
Engine load was more important than speed for qualitatively grouping the PM emission characteristics (mass, number, semi-volatile fraction). The exception is at low engine speeds where low mass and number concentrations were observed, along with nearly constant particle sizes, across different loads.
The effects of the input parameter variations were analyzed with response surface methods. The PM emissions were more sensitive to changes in the input parameters than the gaseous emissions. Equivalence ratio, engine power and injection pressure were the most important parameters for PM mass emissions. Overall, the PM emissions varied monotonically with the input parameters and no local PM emission minima were observed.
Partially premixing some of the natural gas before ignition can reduce PM emissions by over 80% at some conditions at the expense of cycle-to-cycle variability and pressure rise rates. Some optimized equivalence ratios and EGR percentages were developed to improve the stability of combustion.
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Arora, Deepali. "High-Pressure Microfluidic Crystallization of Active Pharmaceutical Ingredients Using a Gas Antisolvent Process." Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/86251.
Full textAbstract:
The work focused on the development of a novel microfluidic platform that enables continuous pharmaceutical crystallization in an efficient and reproducible manner using pressurized carbon dioxide. Excellent control over the pharmaceutical crystal shape, size and structure was achieved. This is a step forward in the process intensification of existing crystallization methods. It combines greener processes and flexible microtechnology to improve the bioavailability and therapeutic efficiency of pharmaceutical products.