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Anderås, Emil. "Advanced MEMS Pressure Sensors Operating in Fluids." Doctoral thesis, Uppsala universitet, Fasta tillståndets elektronik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-173182.
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Today’s MEMS technology allows manufacturing of miniaturized, low power sensors that sometimes exceeds the performance of conventional sensors. The pressure sensor market today is dominated by MEMS pressure sensors. In this thesis two different pressure sensor techniques are studied. The first concerns ways to improve the sensitivity in the most commonly occurring pressure sensor, namely such based on the piezoresistive technique. Since the giant piezoresistive effect was observed in silicon nanowires, it was assumed that a similar effect could be expected in nano-thin silicon films. However, it turned out that the conductivity was extremely sensitive to substrate bias and could therefore be controlled by varying the backside potential. Another important parameter was the resistivity time drift. Long time measurements showed a drastic variation in the resistance. Not even after several hours of measurement was steady state reached. The drift is explained by hole injection into the buried oxide as well as existence of mobile charges. The piezoresistive effect was studied and shown to be of the same magnitude as in bulk silicon. Later research has shown the existence of such an effect where the film thickness has to be less than around 20 nm. The second area that has been studied is the pressure sensitivity of in acoustic resonators. Aluminium nitride thin film plate acoustic resonators (FPAR) operating at the lowest-order symmetric (S0), the first-order asymmetric (A1) as well as the first-order symmetric (S1) Lamb modes have been theoretically and experimentally studied in a comparative manner. The S0 Lamb mode is identified as the most pressure sensitive FPAR mode. The theoretical predictions were found to be in good agreement with the experiments. Additionally, the Lamb modes have been tested for their sensitivities to mass loading and their ability to operate in liquids, where the S0 mode showed good results. Finally, the pressure sensitivity in aluminium nitride thin film bulk wave resonators employing c- and tilted c-axis texture has been studied. The c-axis tilted FBAR demonstrates a substantially higher pressure sensitivity compared to its c-axis oriented counterpart.
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Suleiman, Norhidayah. "High pressure phase equilibria applications involving supercritical fluids." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/35580/.
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This thesis describes the investigation of phase behaviour of binary and ternary mixtures at high pressure. The particular applications chosen to be explored in this phase behaviour investigation were supercritical fluid electrodeposition (SCFED) and carbon capture and storage (CCS). Chapter 1 introduces the phase behaviour of mixtures. Chapter 2 describes the equipment and analytical techniques used throughout this thesis including the high-pressure variable-volume view cell, electrical conductivity cell, high pressure FTIR cell, and high-pressure optical fiber phase analyser. Chapter 3 details the solubility and conductivity investigation of several supporting electrolytes in difluoromethane (CH2F2), which provided an electrochemical bath with sufficient conductivity for electrodeposition in supercritical fluids. The most effective supporting electrolyte amongst the eight ionic compounds tested was [N(nC4H9)4][Al(OC(CF3)3)4] which was found to give a moderate solubility and the highest conductivity (222 Scm2mol-1) in CH2F2. [N(nC4H9)4][Al(OC(CF3)3)4] was followed by [N(nC4H9)4][FAP] and [N(nCH3)4][FAP], , making all of them to be satisfactory potential supporting electrolytes for SCFED. Chapter 4 describes the investigation of water solubility in CO2/N2 mixtures relevant to the CCS process. The scope of the investigation covers a wide pressure range and two levels of N2 (xN2= 0.05 and xN2= 0.10). This experimental study was conducted by using the FTIR technique as described in further detail in Chapter 2. It was found that the presence of N2 in CO2 lowered the solubility of H2O in supercritical CO2 with N2 compared to pure CO2. The solubility of water also decreases significantly when the concentration of N2 is increased from 5% to 10%. Chapter 5 further explores the role of phase behaviour in the application of CCS with the investigation of the phase envelope of the ternary mixtures of CO2 and permanent gases (Ar, N2, and H2). Three ternary mixtures were measured (90% CO2 + 5% N2 + 5% Ar, 98% CO2 + 1% N2 + 1% Ar, and 95% CO2 + 3% H2 + 2% Ar) by using the fiber optic reflectometer, as described in further detail in Chapter 2. The experimental data presented in this part also have been used to validate the equation of state for the CCS applications. It was found that the phase envelope of CO2 shifted to a higher pressure and the two-phase region become broader with the presence of permanent gases. Overall, both GERG-2004 and gSAFT provide a good agreement between the predicted and experimental data for all the ternary mixtures investigated, with the exception of the bubble-point line for the 3%H2 + 2%Ar + 95% CO2 mixture. Finally, Chapter 6 summarises the research that was conducted in this thesis. It also evaluates the progress made towards achieving the aims initially set-up in Chapter 1.
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Palmer, Sheila Carmody. "Dual-pressure absorption cycles : the second law and working fluids." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/18389.
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Laghaei, Rozita. "Calculation of phase equilibria of quantum fluids at high pressure." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968311326.
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Verma, Prashant K. "Experimental and theoretical determination of nonlinear pressure fields in biological fluids." Thesis, University of Bath, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760667.
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Yuen, David J. (David Joseph). "Measurement of high frequency dielectric constant and conductivity of fluids and fluid-saturated rocks at high pressure." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/84199.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1990.Title as it appears in the M.I.T. Graduate List, June 1990: High-frequency dielectric constant and conductivity of fluids and fluid-saturated rocks at high pressure.
Includes bibliographical references (leaves 124-127).
by David J. Yuen.
M.S.
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Ntamba, Ntamba Butteur Mulumba. "Non-Newtonian pressure loss and discharge coefficients for short square-edged orifices plates." Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/1252.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2011.Despite the extensive research work carried out on flow through short square-edged orifice plates over the last century (e.g. Johansen, 1930; Benedict, 1977; Alvi et al., 1978; Swamee, 2005; ESDU, 2007), gaps in the engineering data still exist for certain ranges of flow conditions and geometries. The majority of data available in the literature are for Newtonian fluids in the turbulent flow regime (ESDU, 2007). Insufficient data have been observed for the orifice with pipe diameter ratio, β = 0.2, in the laminar flow regime. There are no experimental data for β = 0.3 and 0.57. The objective of this thesis was to conduct wide-ranging experimental studies of the flow in orifice plates, which included those geometrical configurations, by measuring pressure loss coefficients and discharge coefficients across the orifice plates using both Newtonian fluids and non-Newtonian fluids in both laminar and turbulent flow regimes. The test work was conducted on the valve test rig at the Cape Peninsula University of Technology. Four classical circular short square-edged orifice plates having, β = 0.2, 0.3, 0.57 and 0.7, were tested. In addition, two generation 0 Von Koch orifice plates (Von Koch, 1904), with equivalent cross sectional area were also tested for β = 0.57. Water was used as Newtonian fluid to obtain turbulent regime data and also for calibration purposes to ensure measurement accuracy and carboxymethyl cellulose, bentonite and kaolin slurries were used at different concentrations to obtain laminar and transitional loss coefficient data. The hydraulic grade line method was used to evaluate pressure loss coefficients (Edwards et al., 1985), while the flange tap arrangement method was used to determine the discharge coefficients (ESDU, 2007). A tube viscometer with three different pipe diameters was used to obtain the rheological properties of the fluids. The results for each test are presented in the form of pressure loss coefficient (kor) and discharge coefficient (Cd) against pipe Reynolds number (Re)
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Schaeffer, Steven T. "Extraction and isolation of monocrotaline from Crotalaria spectabilis using supercritical fluids." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/10234.
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Bohra, Lalit Kumar. "Flow and Pressure Drop of Highly Viscous Fluids in Small Aperture Orifices." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7269.
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A study of the pressure drop characteristics of the flow of highly viscous fluids through small diameter orifices was conducted to obtain a better understanding of hydraulic fluid flow loops in vehicles. Pressure drops were measured for each of nine orifices, including orifices of nominal diameter 0.5, 1 and 3 mm, and three thicknesses (nominally 1, 2 and 3 mm), and over a wide range of flow rates (2.86x10sup-7/sup Q 3.33x10sup-4/sup msup3/sup/s). The fluid under consideration exhibits steep dependence of the properties (changes of several orders of magnitude) as a function of temperature and pressure, and is also non-Newtonian at the lower temperatures. The data were non-dimensionalized to obtain Euler numbers and Reynolds numbers using non-Newtonian treatment. It was found that at small values of Reynolds numbers, an increase in aspect ratio (length/diameter ratio of the orifice) causes an increase in Euler number. It was also found that at extremely low Reynolds numbers, the Euler number was very strongly influenced by the Reynolds number, while the dependence becomes weaker as the Reynolds number increases toward the turbulent regime, and the Euler number tends to assume a constant value determined by the aspect ratio and the diameter ratio. A two-region (based on Reynolds number) model was developed to predict Euler number as a function of diameter ratio, aspect ratio, viscosity ratio and generalized Reynolds number. This model also includes data at higher temperatures (20 and le; T and le; 50supo/supC) obtained by Mincks (2002). It was shown that for such highly viscous fluids with non-Newtonian behavior at some conditions, accounting for the shear rate through the generalized Reynolds number resulted in a considerable improvement in the predictive capabilities of the model. Over the laminar, transition and turbulent regions, the model predicts 86% of the data within and plusmn25% for 0.32 l/d (orifice thickness/diameter ratio) 5.72, 0.023 and beta; (orifice/pipe diameter ratio) 0.137, 0.09 Resubge/sub 9677, and 0.0194 and mu;subge/sub 9.589 (kg/m-s)
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Namuq, Mohammed Ali. "Simulation and modeling of pressure pulse propagation in fluids inside drill strings." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2013. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-107969.
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Modern bottom-hole assemblies are equipped with various sensors which measure the geological and directional information of the borehole while drilling. It is very crucial to get the measured downhole information to the surface in real time in order to be able to monitor, steer and optimize the drilling process while drilling. The transmission of the information to the surface is most commonly carried out by coded pressure pulses (the technology called mud pulse telemetry) which propagate through the drilling mud inside the drill string towards the surface. However, hardly any specific experimental research on the hydraulic data transmission can be found in the literature. Moreover, it is essential to use a reliable model/simulation tool which can more accurately simulate the pressure pulse propagation in fluids inside drill strings under various drilling operation conditions in order to improve the performance of the data transmission process. The aims of this study are to develop and test a laboratory experimental setup, a simulation model and a novel method for detecting and decoding of measurement while drilling pressure pulse propagation in fluids inside drill strings.
This thesis presents a laboratory experimental setup for investigating the process of data transmission in boreholes by mud pulse telemetry. The test facility includes a flow loop, a centrifugal pump, a positive mud pulser or alternatively a mud siren, pressure transducers at four different locations along the flow loop and a data collection system. Moreover, it includes an “actuator system” for the simulation of typical noise patterns created by the common duplex or triplex mud pumps. This laboratory setup with great capabilities opens the way for testing and developing new concepts for data transmission.
A theoretical model using ANSYS CFX11 (Computational Fluid Dynamics (CFD) commercial code) was successfully developed to simulate dynamic pressure pulse transmission behavior in the fluid inside the flow loop. The collected laboratory data which simulate various data transmission processes in boreholes were used to verify and calibrate the theoretical method. A pretty good agreement is achieved between the predicted and measured pressure pulses at different locations along the flow loop for positive pulses with various durations using different flow rates and for continuous pressure pulses using different carrier frequencies.
A novel approach (continuous wavelet transformation) for detecting and decoding the received continuous pressure pulses in a noisy environment was applied to various simulated drilling operation conditions for data transmission in boreholes in the laboratory. The concept was registered at the German Patent and Trade Mark Office (DPMA) for a patent in 2011. The results indicate that the continuous wavelet transformation can be used to clearly identify and better detect the continuous pressure pulse periods, frequencies and discontinuity positions in the time domain compared to the conventional method (Fourier transformation). This method will contribute to the possibility of transmitting the data at higher rates and over longer distances.
A concept for developing an innovative pulser using electrical discharge or acoustic sources for inducing pulses keeping the drill strings fully open (eliminating the problem of plugging the pulser by pumped lost circulation materials) and without any mechanical moving parts (eliminating the failure related to the pulser moving parts) was also registered at the German Patent and Trade Mark Office (DPMA) for a patent in 2012. With this pulser, it is expected that it would be possible to transmit the data over longer distances and at higher rates. Realizing the concept of the new pulser and using continuous wavelet transformation for detecting and decoding the pulser signal are recommended for future work.
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Ndiaye, Serigne Ndiaga. "Ultimate behavior of confined fluids under very high pressure and shear stress." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI104/document.
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L’étude du frottement dans les contacts lubrifiés fortement chargés est un sujet complexe. En effet, le frottement dépend fortement du comportement rhéologique du lubrifiant dans le centre du contact et, celui-ci n'est pas bien connu à pression et taux de cisaillement élevé. Diverses méthodes expérimentales ont été développées pour expliquer le comportement plateau dans les courbes de frottement, associé à l’existence d’une contrainte limite de cisaillement, mais aucune d'elles n'a fourni une image complète des mécanismes réels impliqués. Dans la continuité de ces efforts, des études sont présentées dans ce mémoire. Le premier défi dans ce travail est d'effectuer des mesures de frottement dans des conditions isothermes nominales, ce qui signifie que même si des effets thermiques doivent se produire dans toute mesure de frottement, il est possible de les minimiser et de rendre les résultats insensibles à une faible dissipation d'énergie dans le volume expérimental d'intérêt. La minimisation de l’échauffement du lubrifiant aide à se focaliser sur l’origine mécanique de la contrainte limite de cisaillement et de mieux caractériser sa dépendance à la pression et à la température. C'est pourquoi, tout d'abord, une série d'expériences a été réalisée sur deux lubrifiants, un diester pur (benzyl benzoate) et une huile minérale de turbine (Shell T9) avec des vitesses d'entraînement variables. Cela nous permet d'abord d'observer directement l'influence des effets thermiques sur les valeurs de la contrainte limite de cisaillement et ensuite, de déterminer les conditions expérimentales qui limitent ces effets tout en assurant un régime en film complet. Le deuxième objectif est de caractériser le comportement en frottement des lubrifiants sous conditions isothermes nominales et sur une large gamme de pression (jusqu'à 3 GPa) et de température (jusqu’à 80°C) afin d'établir un nouveau modèle découplé permettant de décrire la dépendance à la température et à la pression de la contrainte limite sous fortes charges. Enfin, l'étude se focalise sur la compréhension du comportement microscopique des lubrifiants dans des conditions extrêmes de cisaillement et de pression. Des mesures in situ de spectroscopie Raman et Brillouin ont été également effectuées sous conditions statiques, afin d'étudier le changement de phase du lubrifiantFriction in highly loaded lubricated contacts is a complex issue. Indeed, it highly depends on the lubricant rheological behaviour in the Hertzian region, which is not well known under such high pressure and high shear stress. Various experimental methods have been developed to explain the plateau-like behaviour in friction curves referred to as the limiting shear stress (LSS), but none of them provided a full picture of the real mechanisms involved. In a continuation of these efforts, some investigations are presented in this manuscript. The first challenge in this work is to carry out friction measurements under nominal isothermal conditions, meaning that even if thermal effects must occur in any friction measurement, it is possible to minimize them and to make the results almost insensitive to a weak energy dissipation within the experimental volume of interest. Minimizing shear heating of the lubricant help us to focus on the mechanical origin of the LSS and to better characterize its dependence to pressure and temperature. That’s why, first of all, a series of experiments was performed on two lubricants, a pure diester fluid (benzyl benzoate), and a commercial turbine mineral oil (Shell T9) with varying entrainment velocities. This allow us first to directly observe the influence of the lubricant shear heating on the LSS values and then to determine the experimental conditions which limit this thermal effect while ensuring a full film regime. The second objective is to characterize the frictional behavior of both lubricants under nominal isothermal conditions and over a wide range of pressure (up to 3 GPa) and temperature (up to 80°C) in order to establish a new uncoupled model to describe the temperature and pressure dependence of the limiting shear stress under highly loaded conditions. Finally, the study focuses on the understanding of the microscopic behavior of lubricants under extreme shear and pressure conditions. In situ Raman and Brillouin spectroscopy investigations were also conducted under static conditions, in order to study the lubricant phase changes under various pressure and temperature conditions
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Liu, Kun. "Miscibility, Viscosity, Density, and Formation of Polymers in High-Pressure Dense Fluids." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/29787.
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This thesis is an experimental investigation of the phase behavior, volumetric properties, and viscosity of poly (methyl methacrylate) (PMMA), poly (ε-caprolactone) (PCL) and their blends. Homopolymerization and copolymerizations of methyl methacrylate (MMA) and 2-methylene-1,3-dioxepane (MDO) in mixtures of acetone + CO2 have also been explored.
The viscosities and densities of acetone + CO2 mixtures were measured in the temperature range 323-398 K at pressures up to 35 MPa. This is the first study in which viscosity of acetone + CO2 mixtures have been measured and the mixtures have been evaluated as solvents for PCL. It is shown that PCL can be readily dissolved in these fluid mixtures at modest pressures even at high carbon dioxide levels. Investigations have been conducted over a temperature range from 323 to 398 K at pressures up to 50 MPa for polymer concentrations up to 20 wt %, and CO2 concentrations up to 60 wt %. It is shown that in these mixtures PCL is dissolved at pressures that are much lower than the pressures reported for miscibility in the mixtures of carbon dioxide with other organic solvents. It is shown that PMMA also readily dissolves at modest pressures. Blends of PMMA and PCL require higher pressures than for the individual polymers for complete miscibility.
Free-radical polymerizations of MMA in acetone at 343 K were followed using in-situ measurements of viscosity and density at different pressures from 7- 42 MPa. This is the first time viscosity has been used as a real-time probe of high pressure polymerizations. Two distinct kinetic regimes were identified. Homopolymerizations of MDO were conducted in carbon dioxide at 323 and 343 K at pressures up to 42 MPa. For the first time it is shown that high molecular weight PCL can be produced from MDO in high pressure CO2. Ring-opening free-radical copolymerizations of MDO with MMA, styrene and acrylonitrile were conducted for the first time in carbon dioxide and have been shown to lead to polymers with high molecular weights.Ph. D.
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Logan, Barry Kerr. "The analysis of drugs in biological fluids by high pressure liquid chromatography." Thesis, University of Glasgow, 1986. http://theses.gla.ac.uk/3217/.
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Slegr, Helen Tania. "A study of the behaviour of viscoelastic fluids in constant pressure filtration." Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/7870.
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A filtration theory for constant pressure filtration in viscoelastic media is presented. The theory is based on the linearized capillary hybrid model for flow in a porous medium. The main filtration equation is quite similar to that for non-Newtonian filtration except for the parameter $v\sb{me}$ representing a sum of two terms: one term characterizing the viscous (Newtonian) nature of the flow, and the second term portraying the elastic contribution to the flow. Constant pressure filtration experiments are performed using slurries of calcium carbonate in aqueous solutions of high molecular weight polyacrylamide (viscoelastic slurries) and slurries of calcium carbonate and water (Newtonian slurries). Three pressure drops are employed: 345 kPa, 517 kPa, and 689 kPa. The filtration theory provides a means to compile the experimental data, wherein filter cake and filter medium resistances are computed and compared. It is found that the filter cake resistances of the viscoelastic filtrations were considerably lower than those of the Newtonian filtrations. Furthermore, the filter medium resistances of the viscoelastic filtrations were, in general, higher than those of the Newtonian filtrations.
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Childress, Beverly Bibera. "Nitric oxide metabolites in wound fluids from pressure ulcers on v.a.c.(tm) therapy." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0005140.
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Thesis (Ph.D.)--University of Florida, 2004.Typescript. Title from title page of source document. Document formatted into pages; contains 84 pages. Includes Vita. Includes bibliographical references.
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Amouroux-Berthe, Solange Claire. "Pressure driven transport of non-wetting fluids in membranes used in composite processing." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 254 p, 2009. http://proquest.umi.com/pqdweb?did=1885755801&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Gouw, Myrna Aphrael. "Poly(Methyl Methacrylate) swelling in carbon dioxide at high pressure." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/11106.
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Hartt, William H. "Flow of viscoelastic fluids through banks of cylinders : an experimental and numerical investigation /." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-06062008-164249/.
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Ilunga, Luc Mwamba. "Performance of a symmetrical converging-diverging tube differential pressure flow meter." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1029.
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Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Civil Engineering
in the Faculty of Engineering
at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY
2014The current problems of orifice, nozzle and Venturi flow meters are that they are limited to turbulent flow and the permanent pressure drop produced in the pipeline. To improve these inadequacies, converging-diverging (C-D) tubes were manufactured, consisting of symmetrical converging and diverging cones, where the throat is the annular section between the two cones, with various angles and diameter ratios to improve the permanent pressure loss and flow measurement range. The objective of this study was firstly to evaluate the permanent pressure loss, secondly to determine the discharge coefficient values for various C-D tubes and compare them with the existing differential pressure flow meter using Newtonian and non-Newtonian fluids, and finally to assess the performance of these differential pressure flow meters. The tests were conducted on the multipurpose test rig in the slurry laboratory at the Cape Peninsula University of Technology. Newtonian and non-Newtonian fluids were used to conduct experiments in five different C-D tube flow meters with diameter ratios (β) of 0.5, 0.6 and 0.7, and with angles of the wall to the axis of the tube (θ) of 15°, 30° and 45°. The results for each test are presented firstly in the form of static pressure at different flow rates. It was observed that the permanent pressure loss decreases with the flow rate and the length of the C-D tube. Secondly, the results are presented in terms of discharge coefficient versus Reynolds number. It was found that the Cd values at 15° drop earlier than at 30° and 45°; when viscous forces become predominant, the Cd increases with increasing beta ratio. The Cd was found to be independent of the Reynolds number for Re>2000 and also a function of angle and beta ratio. Preamble Performance of a symmetrical converging-diverging tube differential pressure flow meter Finally, the error analyses of discharge coefficients were assessed to determine the performance criteria. The standard variation was found to increase when the Reynolds number decreases. The average discharge coefficient values and their uncertainties were determined to select the most promising C-D tube geometry. An average Cd of 0.96, with an uncertainty of ±0.5 % for a range of Reynolds numbers greater than 2,000 was found. The comparison between C-D tubes 0.6(15-15) and classical Venturi flow meters reveals that C-D 0.6(15-15) performs well in turbulent range and shows only a slight inaccuracy in laminar. This thesis provides a simple geometrical differential pressure flow meter with a constant Cd value over a Reynolds number range of 2000 to 150 000.
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Chang, Chiehming James. "Recrystallization of organic compounds from supercritical fluids and high-pressure gas-expanded liquid solvents." Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/185083.
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The precipitation of organic particles from supercritical fluids (SF) by expansion (SFX) has become an interesting alternative to milling without thermal decomposition. Through the rapid-expansion process, a dramatic change of the solute supersaturation ratio is created causing subsequent precipitation with a narrow particle size distribution. It was found that β-carotene precipitates from SF ethylene and ethane have the feed material crystallinity. However, SF CO₂ reacted with β -carotene and did not give characteristic β -carotene X-ray spectra. The mean particle sizes of these precipitates were in the submicron range (ca. 0.3 μm). Increased solubility was obtained by addition of toluene as co-solvent in SF ethylene. It was found that the mean size of β -carotene particles, generally remained unchanged if the toluene concentration was less than one and one-half mole percent. The GAS (Gas Anti-Solvent) process, wherein a high pressure gas is dissolved in a liquid solvent, thus precipitating a solid, has successfully been applied to recrystallize some difficult-to-comminute materials. It is essential to obtain the experimental solubility of the high pressure gas in the liquid solvent in order to model the GAS recrystallization process. A new method to measure compressed gas solubility and solvent expansion behavior was developed using a high precision densitometer. Theoretical predictions of phase equilibria and solubility of the compressed gas dissolved in the liquid solvent for three binary asymmetric systems was done in this study. Solids precipitation from liquid solvents, using dissolution of high pressure CO₂ as an anti-solvent to create supersaturation, is a potentially attractive crystallization process. Separation and purification of β -carotene mixtures was done in this study by this anti-solvent salting out technique. It was found that total carotene was successfully separated from epoxy oxides, as well as trans β -carotene from cis isomers. The separation can be carried out in batch or continuous modes. It is suggested that the purification (or fractionation) of an isomer mixture might be done using a mixed solvent if the desired compound dissolves in a highly expanded solvent and the undesired compound dissolves in a less expanded solvent.
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Maråk, Knut Arild. "Condensation Heat Transfer and Pressure Drop for Methane and Binary Methane Fluids in Small Channels." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-5702.
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A conventional heat exchanger consists of fluid channels with diameter larger than approximately 3 mm. Here, the phenomena around heat transfer and pressure drop are more or less well understood and can be well predicted. Newer and more compact heat exchangers use channels with smaller diameter which gives multiple advantages; they occupy less volume, are lighter, may be modular and can be faster and cheaper to produce. However, it is uncertain whether the phenomena affecting heat transfer and pressure drop are the same as in the larger channels. Clarifying this with respect to possible usage in the LNG-industry has been the main purpose of this work. An experimental set-up designed by Dr. Steffen Grohmann has been used in these investigations. A total of 749 measurements in tubes with diameter 1 mm, 0.5 mm and 0.25 mm have been done. Both single and two-phase flow measurements of pure methane, methane/ethane- and methane/nitrogenmixtures have been carried out. The measurements were done over a broad range with respect to pressure, vapour fraction, mass flux and heat flux. Also the pressure drop was measured. The conclusion is that the models concerning heat transfer and pressure drop in conventional channels also can be used in tubes with diameter 1 mm and 0.5 mm. The results from the 0.25 mm tube are burdened with too high uncertainty to be used in the conclusion. The results can also be relevant for non-circular diameters in microscale, e.g. for plate-fin heat exchangers.Konvensjonelle varmevekslarar nyttar kanalar med diameter ned til omlag 3 mm. I desse er fenomena kring varmeovergang og trykktap i stor grad kjende. Nyare og meir kompakte varmevekslarar har kanalar med mindre diameter som inneber ei rekkje fordelar; dei tek mindre plass, er lettare og kan vere raskare og billigare å produsere. Det herskar imidlertid uvisse om fenomena kring varmeovergang og trykktap er dei same som i konvensjonelle kanalar. Å få dette avklart i høve til mogleg bruk i LNG-industrien har vore hovudføremålet med arbeidet. Eit eksperimentelt oppsett designa av Steffen Grohmann vart brukt i undersøkjingane. Tilsaman 749 m˚alingar i røyr med diameter 1 mm, 0.5 mm og 0.25 mm vart utført. Både einfase kjøling og kondensasjon av metan og blandingar av metan/etan og metan/nitrogen vart gjort. Målingane varierte over eit stort omr˚ade med omsyn til trykk, dampfraksjon, massefluks og varmefluks. Ogs˚a trykkfall gjennom røyra vart målt. Resultata viser at varmeovergang i einfase veske kan forutseiast med eksisterande modellar i 1 mm og 0.5 mm røyra. Trykkfallsmålingane for 1 mm royret er som forventa utifr˚a konvensjonelle modellar. For 0.5 mm røyret er trykkfallet høgare enn forventa. For 0.25-mm røyret er uvissa for stor til at resultata kan brukast i ein konklusjon. For kondensering av rein metan kan varmeovergangen i 1 mm-røyret forutseiast med konvensjonelle modellar. I 0.5 mm røyret er varmeovergangen høgare enn berekna. For kondensering av binære blandingar kan varmeovergangen bereknast med konvensjonelle modellar for både 1 mm og0.5 mm royret. For tofasemålingar i 1 mm-røyret er den gjennomsnittlege uvissa for varmeovergang rundt 10 % og hovudsakleg knytt til temperatursensorane. For 0.5 mm røyret er uvissa for kondensering av rein metan litt over 20 %, medan den er rundt 10 % for kondensering av binarblandingane. For 0.5 mm-royet og sarskilt for 0.25 mm-røyret er massestraumsmålaren ei mykje viktigare kjelde til uvisse.
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Hariharan, Prasanna. "Peristaltic Pressure-Flow Relationship of Non-Newtonian Fluids in Distensible Tubes with Limiting Wave Forms." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1123687109.
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Gaiaschi, Pietro. "Enhanced models for mixtures of fluids in chemical equilibrium at high pressures." Master's thesis, Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-11052008-195907.
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Mönicke, K. Annett. "Fluids in systems of natural rock composition at ultra-high pressure metamorphic conditions an experimental approach /." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=971472327.
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Herring, Adam Russell. "Computer Simulation Studies of Inhomogeneous Fluids: The Depletion Force and the Disjoining Pressure of Colloidal Physics." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491650.
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Investigations have been carried out via Monte Carlo simulation of simple, inhomogeneous fluids into two important quantities of colloidal systems; the depletion force and the disjoin'': ing pressure. Simulations of a hard-sphere solvent confined to the annular wedge formed between a spherical hard colloid and a planar hard wall were performed in order to shed light on the recently discovered disagreement of several results for the depletion force in the nanD-colloidal regime at solvent density pa3 > 0.6. Emphasis is placed on attempting to understand the limits of validity in terms of colloid size for the Derjaguin approximation applied to depletion forces and fundamental-measures-theory density functional theory (FMT-DFT), and the manner in which the depletion force scales between these two results at intermediate colloid sizes. The depletion force was evaluated via an exact statistical mechanical sum rule requiring only knowledge of the integral of the one-body density of solvent at the planar hard wall from the apex of the wedge to a large distance from the colloid. Simulations were performed for a colloid/solvent size ratio of 8 = 20 for several colloid-wall separations, h, between physical contact and the hard-sphere solvent diameter, a, at pa3 = 0.764, the results for the depletion force appearing to be consistent with a recently proposed theoretic model suggesting a (curiously non-analytic) 8-1/ 2 correction to the linear scaling behaviour of the depletion force with colloid size between the FMT-DFT and Derjaguin results, with the Derjaguin result valid in the large colloidal limit 8 --t 00 and FMT-DFT only as colloid size approaches solvent size. Further simulations, restricted to h = a for 8 = 10, 30, 50 and 100 though reveal that at least for this special separation 8-1/ 2 scaling does not hold, suggesting that to confirm scaling behaviour requires simulations over the entire range 0 ~ h ~ a for several values of 8. The disjoining pressure profile has been simulated through the three-phase contact line formed between the liquid-vapour interface of a square-well fluid at bulk liquid-vapour coexistence and a planar, square-well wall for three different depths of the wall-fluid potential. The disjoining pressure is found to follow a smooth, downward curve across the contact line that is well fit by a Gaussian. The simulation method used to make these disjoining pressure measurements has been validated using a statistical mechanical sum rule linking the integral of the disjoining pres- . . sure across the contact line to the liquid-vapour surface tension and macroscopic Young's contact angle, both measured from the interface far from three-phase contact.
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Teca, Dário Bokiló Machado. "Correction of the anisotropy in resistivity: application to pore pressure prediction." Master's thesis, Faculdade de Ciências e Tecnologia, 2014. http://hdl.handle.net/10362/13132.
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Dissertação para obtenção do Grau de Mestre em
Engenharia Geológica (Georrecursos)This dissertation is based on a curricular training period done at company Total EP Angola between July and December 2013. The data presented relate to a real case study of an exploration block, which for reasons of confidentiality is designated by Block Michocho. The fluids pressure measurement in the geological formations can be inferred from the formation resistivity log. In not perpendicular wells to the layers, resistivity curves show higher values than the expected due to the anisotropic effect of the formation thus the inference of the pressure of fluids from resistivity logs can lead to unrealistic values. Most of the developments wells drilled on Block Michocho in Angola are highly deviated, if not sub-horizontal, in the reservoir section. The objective of this work is to correct the anisotropic effect of the resistivity of Block Michocho due to non-perpendicularity of the wells when intersect the geological formations. In this study, the correction of the resistivity is based on the formula proposed by Moran and Gianzero in 1979 and involves the dipping angle of the induction logging tool and the coefficient of anisotropy of the rock formation. Prior to application of this formula for the corrections of resistivity of the Block Michocho wells logs, a set of validation tests were made. Due to lack of data on development wells (highly inclined wells) the validation test was carried out in five exploration wells where resistivity is available in the two principal directions. It was assumed that the formula would be approved for resistivity corrections if the horizontal resistivity obtained by the formula had a good correspondence with the horizontal resistivity obtained by the induction logging tool. After this validation step, the coefficient of anisotropy to be used in the formula was calibrated as well as the correction of the curves of resistivity of the remaining development wells, those much more diverted regarding the rock layers. The corrected resistivity can be applied for pore pressure prediction in low permeability rock formations, in which the main objective is to identify regions where fluid pressure is higher than normal pressure, i.e. overpressure regions. For illustration purposes, a resistivity curve from an exploration well was chosen and the pressure of the fluids in low permeability rocks was computed by using the formula proposed by Eaton in 1975. With this well data, a potential overpressure region was identified and should be avoided in drilling activities.
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Zoporowski, Anna [Verfasser]. "Dynamical and Mechanistic Effects of High Pressure Fluids in the Earth's Crust / Anna Zoporowski. Mathematisch-Naturwissenschaftliche Fakultät." Bonn : Universitäts- und Landesbibliothek Bonn, 2012. http://d-nb.info/1021444855/34.
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Dindar, Cigdem. "High-pressure viscosity and density of polymer solutions at the critical polymer concentration in near-critical and supercritical fluids." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/35720.
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The motivation for the determination of the viscosity of polymer solutions in dense fluids at the critical polymer concentration stems from the need to understand the factors that influence the time scale of phase separation in systems that undergo spinodal decomposition upon a pressure quench. In a recent investigation of PDMS + CO2 and PE + n-pentane where molecular weights of the polymers and the critical polymer concentrations were comparable, significant differences were observed in the time evolution of new phase growth. Among the reasons that contribute to the difference in phase separation kinetics is the viscosity of the solutions.
This thesis has been carried out to experimentally demonstrate the differences in viscosities of solutions at their critical polymer concentration. Specifically, the thesis focused on the high-pressure density and viscosity of solutions of poly(dimethylsiloxane) (Mw = 93,700, Mw/Mn = 2.99) in supercritical carbon dioxide and of polyethylene (Mw = 121,000, Mw/Mn = 4.3) in near-critical n-pentane. The measurements have been carried out at the critical polymer concentrations, which is 5.5 wt % for solution of PDMS in CO2 and 5.75 wt % for solution of PE in n-pentane. For PDMS + CO2 system, the measurements were conducted at 55, 70, 85 and 100 oC and pressures up to 50 MPa. For PE + n-pentane system, the measurements were conducted at 140 and 150 oC and again up to 50 MPa. All measurements were conducted in the one-phase homogenous regions. At these temperatures and pressures, the viscosities were observed to be in the range from 0.14 mPa.s to 0.22 mPa.s for PDMS + CO2, and from 2.3 mPa.s to 4.6 mPa.s for PE + n-pentane systems. In both systems the viscosities increase with pressure and decrease with temperature. The temperature and pressure dependence could be described by Arrhenius type relationships in terms of flow activation energy (E#) and flow activation volume (V#) parameters. The flow activation energies in PDMS + CO2 system were about 7 kJ/mol compared to about 18 kJ/mol for the PE + n-pentane system. The activation volumes were in the range 40-64 cm3/mol for PDMS + CO2 system and 65-75 cm3/mol for the PE + n-pentane solution. The higher values of E# and V# represent the higher sensitivity of viscosity to temperature and pressure changes in the PE + n-pentane system. The viscosity data could also be correlated in terms of density using free-volume based Doolittle type equations. Density is shown to be an effective scaling parameter to describe T/P dependency of viscosity. The closed packed volumes suggested from density correlations were found to be around 0.33 cm3/g for the PDMS and 0.48 cm3/g for the PE systems. Comparison of the viscosity data in these systems with the data on the kinetics of pressure-induced phase separation confirms that the slower kinetics in the PE + n-pentane stems from the higher viscosity in this solution compared to the PDMS + CO2 system, despite the similarity in the molecular weight of the polymer and the critical polymer concentrations.
These viscosity and density measurements were conducted in a special falling-body type viscometer. In the course of this thesis a more reliable procedure for determining the terminal velocity of the falling sinker was implemented. This is based on the precise and more complete description of the position of the sinker with time with the aid of a set of linear variable differential transformers (LVDTs). The design of the new arrangement and procedure for terminal velocity determination and calibration procedures for the viscometer are also presented. The densities and viscosities are determined with an accuracy of ± 1 % and ± 5 % or better, respectively.Master of Science
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Thamanavat, Kanrakot. "High Pressure Phase Equilibria in the Carbon Dioxide + Pyrrole System." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4919.
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The objectives of this work are to measure phase equilibria in the carbon dioxide + pyrrole system and to correlate and predict the phase behavior of this system with a thermodynamic model. This binary system is of interest due to the growing applications of supercritical carbon dioxide as a solvent or reaction medium for pyrrole. Polypyrrole is an electrically conducting polymer of interest in a number of applications such as anti-static coatings. Pyrrole has also been used as a reactant in enzymatic reaction. Knowledge of the phase behavior of carbon dioxide + pyrrole system is therefore necessary for evaluating optimal conditions and feasibility of such applications.
Phase equilibria in the carbon dioxide + pyrrole system were measured at 313 K, 323 K, and 333 K using a synthetic method. Liquid-vapor (LV) phase behavior and liquid-liquid (LL) phase behavior were observed. The pressure in the experiments ranged from 84 to 151.1 bar. The Patel-Teja equation of state and the Mathias-Klotz-Prausnitz mixing rule with two temperature independent parameters was able to correlate the phase equilibrium data satisfactorily and was used to predict the phase behavior at other temperatures. A pressure-temperature diagram was then constructed from these calculations and suggests that the carbon dioxide + pyrrole system exhibit type IV phase behavior in the classification of Scott and van Konynenburg.
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Combs, Michael T. "Optimal Analysis of Sulfonamides From Biological Matrices Using Supercritical Fluids." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30564.
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The objective of this research was to develop new sample preparation procedures for the isolation of sulfonamides, as well as, to determine the applicability of employing on-line nitrogen selective and mass spectrometric detection methods.
The first phase of this research investigated the effect of temperature and pressure on the supercritical fluid extraction (SFE) of sulfonamides from a spiked sand matrix. Temperature effects were either positive or negative with respect to extraction rate and total recovery, depending on the pressure and extraction fluid employed.
The second portion of this research compared trifluoromethane (CHF3) and carbon dioxide (CO2) as fluids for the extraction of sulfonamides from spiked non-fat dry milk, beef liver, and egg yolk were found to be more selective using CHF3 than CO2. The polar trifluoromethane improved the extraction efficiency of the polar sulfonamides from the biological matrices and also reduced the amount of co-extractives.
The next phase of this research considered the effect of organic modifier and CO2 in the SFE of sulfonamides from chicken liver, beef liver and egg yolk. Methanol, ethanol, acetone, acetonitrile were compared to determine optimum conditions. A SFE method employing 20% acetonitrile modified CO2 yielded quantitative recovery of sulfonamides from chicken liver, but 20% acetone modified CO2 was required to obtain quantitative recovery from beef liver. Either 20% acetone or 20% acetonitrile yielded quantitative recovery from egg yolk.
The last phase of this research focused on the evaluation of selective detection methods for sulfonamide analysis. Chemiluminescence nitrogen detection (CLND) parameters were optimized for use with packed column supercritical fluid chromatography (SFC) yielding a minimum detectable quantity (MDQ) of 5 ng of sulfamethazine, on column. Improvements in the detector design decreased the MDQ to 0.5 ng, while, decreasing the column diameter further reduced the MDQ to 125 pg. The second part of this phase evaluated PLC/Atmospheric pressure chemical ionization (APCI) mass spectrometry for the detection of sulfonamides. Sensitivity in selective ion mode was found to be as low as 50 pg on column for sulfamethazine. Supercritical fluid extracts of sulfonamides spiked at 100μg/kg in chicken liver were found to be readily detected by this method.Ph. D.
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Kanjanasakul, Chanisa. "Analysis of the optical properties of droplets of different fluids in high-pressure environments by rainbow optical diagnostic." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMIR22/document.
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La caractérisation des propriétés optiques de gouttes de combustible aux alentours de la pression critique est un défi. L’objectif de la thèse est de mesurer la taille et l’indice de réfraction de fluides dans des conditions de pression élevée proche du point critique. A cet effet, une installation expérimentale d’injection de gouttes à haute pression a été conçue. La réfractométrie d’arc-en-ciel a été développée et adaptée pour travailler d’abord sur des gouttelettes d’eau et d’éthanol dans le domaine de pression 1 - 40 bar. Des évolutions de leur indice de réfraction avec la pression ont été obtenues. Pour les mesures se rapprochant d’un fluide proche du point critique, l’éthane a été sélectionné car son point critique est à 48,7 bar et 32,2°C. Des mesures de réfraction d’index sur des gouttes liquides d’éthane ont ensuite été réalisées dans le domaine 40 - 46 bar et 18 - 25°C. Une mesure de l’indice de réfraction de gouttes d’éthane donne alors une valeur de 1,255 ± 0.002The characterization of the optical properties of fuel drops around the critical pressure is a challenge. The aim of the thesis is to measure the size and the refractive index of fluids under high pressure conditions close to the critical point. For this purpose, an experimental installation of injection of high-pressure drops has been designed. Rainbow refractometry has been developed and adapted to work first on water and ethanol droplets in the pressure range 1 - 40 bar. Evolutions of their index of refraction with the pressure were obtained. For measurements approaching a fluid near the critical point, ethane was selected because its critical point is 48.7 bar and 32.2 ° C. Index refractive measurements on liquid drops of ethane were then carried out in the range 40 - 46 bar and 18 - 25 ° C. A measurement of the refractive index of ethane drops then gives a value of 1.255 ± 0.002
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Relvas, Frederico Miguel Horta de Albuquerque Moura. "Kinetic study of biomass hydrolysis under high pressure conditions." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/13848.
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Mestrado em Engenharia QuímicaThis study was focused on the kinetics of lignocellulosic biomass pre-treatment, in particular CO2-assisted autohydrolysis. The temperature was fixed at 180 ºC, varying pressure from 0 (CO2-free autohydrolysis), 20, 35 to 50 bar. For every pressure, a set of isothermal reactions was performed for various reaction times from 0 and 45 minutes. The pre-treatment resulted in a liquid, solid and gas phases, which were analyzed by HPLC. The liquid phase is essentially composed by sugars both in oligomer and monomer forms, mainly from xylan, also containing acetic acid and degradation products such as furfural and formic acid. In turn, there was an improvement of lignin and glucan’s fraction in the solid residue, being more pronounced for longer treatments. Regarding gas phase collected during depressurization, no traces of products from biomass hydrolysis were found. Basing on the literature and experimental results, 4 kinetic models were developed to predict the behavior of the biomass hydrolysis. Models for xylan, arabinoxylan, glucan and another for acetyl groups were presented. According to the results, the use of CO2 is beneficial for the selective fractionation of biomass, including hemicellulose and amorphous cellulose fractions. Beside, CO2 favors the production of xylooligosaccharides (XOS) achieving a maximum concentration of 14.76 g·L-1 at 50 bar assay vs 13.62 g·L-1 in case of autohydrolysis. Furthermore the conversion of oligomers to monomers is directly proportional to pressure and is enhanced by CO2 presence. With respect to the developed kinetic models, all showed good correlation with experimental data, with R2 as high as 0.9986. In the worst case, the R2 was 0.7865 what considering the so complex multistep analysis process can be acknowledge as a good result. Despite kinetic constants showed an increase of hydrolysis rate of xylan and arabinan in the presence of CO2, they decreases for higher pressures used. In turn, the model for acetyl groups also shows very consistent results with the lowest R2 of 0.9491. The removal of acetyl groups seems to be impaired by the carbon dioxide presence. With respect to glucan, the obtained data shows that reactions are close to zero order as they are independent on the products’ concentrations.
O presente trabalho focou-se no estudo cinético do pré-tratamento de biomassa lignocelulósica, em particular no processo de autohidrólise assistido com dióxido de carbono. O estudo foi feito fixando a temperatura em 180 ºC, variando a pressão entre 0 (ausência de CO2), 20, 35 e 50 bar. Para todas as gamas de pressão foram feitos ensaios isotérmicos entre 0 e 45 minutos. Os pré-tratamentos resultaram em 3 fases, líquida, sólida e gasosa, que foram analisadas por HPLC. A fase líquida é consituída essencialmente por açúcares (monómeros e oligómeros) provenientes maioritariamente do xilana, encontrando-se também ácido acético e produtos de degradação, tais como furfural e ácido fórmico. Por sua vez, as fracções de lignina e celulose na fase sólida aumentaram, sendo mais evidente para tratamentos mais longos. Em relação à fase gasosa, não foram encontrados quaisquer produtos de hidrólise da biomassa. Com base na literatura e nos resultados experimentais, foram desenvolvidos 4 modelos cinéticos para prever o comportamento da hidrólise da biomassa, correspondentes à fracção de xilana, arabinoxilana, celulose e grupos acetilo. De acordo com os resultados obtidos, concluiu-se que o uso de CO2 é útil para fraccionamento selectivo da biomassa, nomeadamente da fracção de hemicelulose e de celulose amorfa, apresentando também melhores resultados do que a autohidrólise na produção de xilooligossacarídeos (XOS), com um máximo de concentração de 14.76 g·L-1 para 50 bar vs. 13.62 g·L-1 na autohidrólise. Além disso, a conversão de oligomeros em monómeros é proporcional à pressão e favorecida pela presença de CO2. Quanto aos modelos cinéticos apresentam uma boa correlação com os dados experimentais, com um R2 mais alto de 0.9986. No pior caso, o R2 foi de 0.7865 que, tratando-se de uma reacção complexa, pode ser considerado um boa resultado. Apesar das constantes cinéticas mostrarem um aumento da hidrólise de xilana e arabinana na presença de CO2, estas decrescem em pressões mais elevadas. Por sua vez, os grupos acetilo também mostram resultados bastante consistentes, com o R2 mais baixo de 0.9491. A remoção de ácido acético parece ser prejudicada pela presença de CO2, enquanto os resultados da hidrólise de glucano sugerem uma cinética de ordem zero, uma vez que a concentração dos produtos aparenta ser independente da concentração dos diferentes produtos.
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Zhang, Wei. "Phase Behavior and Phase Separation Kinetics in Polymer Solutions under High Pressure." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/26963.
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The phase behavior and phase separation kinetics in polymer solutions in binary mixtures of supercritical carbon dioxide (CO2) and organic solvents were studied for two systems. Solutions of polyethylene (PE) in CO2 + n-pentane were selected as one model system to study both the solid-fluid (S-F) and liquid-liquid (L-L) phase transitions as well as the interplay of these two types of phase separations on the final morphological and thermal properties of PE crystals. Solutions of polysulfone (PSF) in CO2 + tetrahydrofuran (THF) were selected as another model system because of the technological importance of this membrane forming polymer and because of the broad interest in developing new solvent/non-solvent systems for forming microporous materials. These phase boundaries were determined using a high-pressure view-cell and optical techniques over a temperature range of 90-165 oC and pressures up to 55 MPa for PE/n-pentane/CO2 system, and over a temperature range of 25 to 155 oC and pressures up to 70 MPa for PSF/THF/CO2 system.
For PE solutions, it has been found that the addition of CO2 to the PE/n-pentane system shifts the L-L phase boundary to significantly higher pressures, but moves the S-F phase boundary only slightly to higher temperatures. The S-F phase boundary which represents the crystallization/melting process in the polymer solution was about 10 oC lower than the crystallization/melting temperatures of the neat polyethylene samples determined by differential scanning calorimetry (DSC). It was further found that the S-F phase boundary in n-pentane displays a unique sensitivity to the pressure-temperature conditions and moves to lower temperatures in the pressure range from 38 to 42 MPa. This effect even though not as augmented remains also for the S-F boundary in the solutions in CO2 + n-pentane mixtures.
The miscibility of PSF in THF + CO2 was investigated at CO2 levels up to 14 wt %. This system shows lower critical solution temperature (LCST)-type phase behavior at low CO2 content, which is shifted to upper critical solution temperature (UCST)-type at higher CO2 levels along with an increase in the miscibility pressures. In contrast to the PE system, this system was found to display multiple miscibility windows. A â Uâ -shaped phase boundary in 92 % THF + 8 % CO2 mixture was observed to transfer to a â Wâ -shaped phase boundary at 10 wt % CO2, which was further separated into a double â Uâ -shaped phase boundary at 13 wt % CO2. The specific volume of the polysulfone solutions were found to display a variation parallel to this changing pattern in the phase boundaries, with reduced miscibility being accompanied with an increase in the specific volume.
The phase separation kinetics in these two polymer solutions were investigated using time- and angle-resolved light scattering techniques. With the PE solutions, the focus was on the kinetics of S-F phase separation (crystallization) and miscibility and (melting) in n-pentane. Experiments were conducted with relatively dilute solutions at concentrations up to 2.3 wt %. The results show that the crystallization which was induced by cooling at constant pressure is dominated by a nucleation and growth process. In the majority of the experiments the particle growth process was observed to last for about 1 minute with a slight dependence on the crystallization pressure.
The phase separation kinetics in PSF solutions were conducted only in a solvent mixture containing 90 wt % THF and 10 wt % CO2. Polymer concentrations were varied up to 3.3 wt %. This system was also observed to undergo phase separation by only nucleation and growth mechanism under these conditions upon reducing the pressure at constant temperature. Several experiments were conducted using a multiple rapid pressure drop technique to identify the depth of the metastable region.
PE crystals that were produced by crossing the S-F boundary by different paths were collected and characterized by field emission scanning electron microscopy (FESEM) and DSC. Crystallization was carried out either by cooling at constant pressure, or by cooling without pressure adjustment, or by first crossing the L-L boundary via pressure reduction at a constant temperature followed by cooling. For crystal recovery, the system was depressurized to ambient conditions irrespective of the path. It was found that all of the crystals formed from these solutions show multiple melting peaks in their first DSC heating scans, which however collapse into one crystallization peak in the cooling scans and one melting peak in the second heating scans. The temperatures corresponding to the multiple melting peaks were lower than the single melting temperature of the original PE sample and the melting temperature observed in the second heating scans for all samples. The multiple melting peaks were attributed to the presence of different lamellar thickness that are formed in the crystallization, final depressurization and sample collection stages. Depending upon the crystallization path some differences were noted. The crystals formed by first going through L-L phase separation displayed predominately double melting peaks in the first DSC scan. It was observed that the overall crystallinity is increased by more than 10 % to about 75 % compared to the crystallinity of the original PE sample, which is about 63 %.
FESEM characterization showed that the prevailing morphology is composed of plate-like lamellae that show different level of agglomeration depending on the crystallization conditions. The overall structures of the particles were ellipsoid for crystals formed from dilute solutions. For crystals formed from the 1% PE solution, crystal sizes ranged from 4 mm ´ 10 mm for crystals formed at 14 MPa to 30 mm ´ 45 mm at 45 MPa. The crystals formed from 5 wt % solutions in n-pentane at pressures in the range of 38-54 MPa showed different morphologies with features of shish-kebab like structures which were however absent in crystals formed from n-pentane + CO2 solutions. The crystals that were formed from first crossing the L-L phase boundary followed by cooling showed two distinct particle size ranges that were attributed to crystals formed from the polymer-rich and polymer-lean phases that evolve when the L-L phase boundary is crossed.Ph. D.
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Ibeh, Chijioke Stanley. "Investigation on the effects of ultra-high pressure and temperature on the rheological properties of oil-based drilling fluids." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2569.
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Zhang, Gengxin. "Geomicrobial Processes and Diversity in Ultra-High Pressure Metamorphic Rocks and Deep Fluids from Chinese Continental Scientific Deep Drilling." Miami University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=miami1165003593.
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Bamgbade, Babatunde A. "MEASUREMENTS AND MODELING OF HYDROCARBON MIXTURE FLUID PROPERTIES UNDER EXTREME TEMPERATURE AND PRESSURE CONDITIONS." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/3967.
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Knowledge of thermodynamic fluid properties, such as density and phase behavior, is important for the design, operation, and safety of several processes including drilling, extraction, transportation, and separation that are required in the petroleum. The knowledge is even more critical at extreme temperature and pressure conditions as the search for more crude oil reserves lead to harsher conditions. Currently, there is dearth of experimental data at these conditions and as such, the predictive capability of the existing modeling tools are unproven. The objective of this research is to develop a fundamental understanding of the impact of molecular architecture on fluid phase behavior at temperatures to 523 K (250 °C) and pressures to 275 MPa (40,000 psi). These high-temperature and high-pressure (HTHP) conditions are typical of operating conditions often encountered in petroleum exploration and recovery from ultra-deep wells that are encountered in the Gulf of Mexico.
This PhD study focuses on the fluid phase behavior of a low molecular weight compound, two moderately high molecular weight compounds, three asymmetric binary mixtures of a light gas and a heavy hydrocarbon compound with varying molecular size. The compounds are selected to represent the family of saturated compounds found in typical crude oils. Furthermore, this study reports experimental data for two "dead" crude oil samples obtained from the Gulf of Mexico and their mixtures with methane from ambient to HTHP conditions. A variable-volume view cell coupled with a linear variable differential transformer is used to experimentally measure the high-pressure properties of these compounds and mixtures. The reported density data compare well to the limited available data in the literature with deviations that are less than 0.9%, which is the experimental uncertainty of the density data reported in this study.
The phase behavior and density data obtained in this study are modeled using the Peng-Robinson (PR), the volume-translated (VT) PR, and the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equations of state (EoS). The EoS pure component parameters, typically obtained from the open literature, are derived from fitting the particular EoS to, critical point, or to vapor pressure and saturated liquid density data, or to HTHP density data. For the density data reported here, the PREoS provided the worst predictions, while the VT-PREoS gives an improved performance as compared to the PREoS. However, the PC-SAFT EoS provided the best HTHP density predictions especially when using HTHP pure component parameters. The situation is however reversed in the modeling performance for the phase behavior data whereby the PC-SAFT EoS with HTHP parameters provided the worst vapor-liquid equilibria predictions. Better predictions are obtained with the PC-SAFT EoS when using parameters obtained from fit of the vapor pressure data and is comparable to the PREoS predictions. This reversal in performance is not surprising since the phase behavior data occur at moderately low pressures. The performance of the PC-SAFT EoS is extended to the experimental density data reported for the dead crude oil samples and their mixtures with methane. The PC-SAFT EoS with either set of pure component parameters yield similar predictions that are within 3% of the reported crude oil density data. However, when using the HTHP parameters, the PC-SAFT gives a good representation of the slope of experimental data, which is crucial in the calculation of second-derivative properties such has isothermal compressibility.
The PC-SAFT EoS is also employed to model the crude oil HTHP density data for both the dead crude oils and their mixtures with methane using correlations for both the Low-P parameters and the HTHP parameters. The Low-P parameters are derived from fitting the PC-SAFT EoS to pure compound vapor pressure and saturated liquid density data, while the HTHP parameters are obtained from fitting the PC-SAFT EoS to pure compound HTHP liquid density data. Interestingly, the PC-SAFT EoS with the Low-P parameters provided better HTHP density predictions that are within 1.5% of the experimental data for the dead oils than the HTHP parameters that are within 2 to 4% of the data. Density predictions for the dead oil mixtures with methane are however comparable for both sets of parameters and are within 1% on average. However, the PC-SAFT EoS with HTHP parameters clearly provided better representation of the isothermal property, a derivative property obtained from density data, within 10% while predictions with the Low-P parameters can be as high as 37%.
The successful completion of the thesis work expands the current knowledge base of fluid phase behavior at the extreme operating conditions encountered by engineers in the petroleum industries. Furthermore, the reported HTHP experimental data also provide a means to scientists and researchers for the development, improvement, and validation of equations with improved modeling performance.
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Wingert, Maxwell. "Carbon dioxide foaming and High-pressure rheology of polystyrene and polystyrene/organoclay nanocomposites." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1167770881.
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Wright, Darrel W. "Pressure losses experienced by liquid flow through straight PDMS microchannels of varying diameters." Honors in the Major Thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1527.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Engineering and Computer Science
Mechanical Engineering
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Yazdi, Nezhad Simin [Verfasser], and Ulrich [Akademischer Betreuer] Deiters. "Calculation of entropy-dependent thermodynamic properties of fluids at high pressure with computer simulation / Simin Yazdi Nezhad. Gutachter: Ulrich Deiters." Köln : Universitäts- und Stadtbibliothek Köln, 2016. http://d-nb.info/1095765876/34.
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Rambaks, Andris, Filipp Kratschun, Carsten Flake, Maren Messirek, Katharina Schmitz, and Hubertus Murrenhoff. "Computational approach to the experimental determination of diffusion coefficients for oxygen and nitrogen in hydraulic fluids using the pressure-decay method." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71099.
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In the presented paper, the applicability of pressure-decay methods to determine the diffusivities of gases in hydraulic fluids is analysed. First, the method is described in detail and compared to other measurement methods. Secondly, the thermodynamics and the mass transfer process of the system are studied. This results in four different thermodynamic models of the gaseous phase in combination with two diffusion models. Thirdly, the influence of the models on the pressure-decay method is evaluated computationally by examining the diffusion process of air in water as all system parameters are available from literature. It is shown that ordinary pressure-decay methods are not applicable to gas mixtures like air and therefore a new method for calculating the diffusivities is suggested.
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Mittempergher, Silvia. "Processus physiques et chimiques en failles sismiques : exemples de failles actives et exhumées." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00767252.
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Les processus physiques et chimiques activés pendant le cycle sismique déterminent l'évolution des propriétés mécaniques des failles, à court terme (pendant un séisme) comme à long terme (la récupération des propretés élastiques des roches de faille après un seisme). L'étude des roches de faille naturelles est un moyen pour identifier les processus actives pendant les diverses phases des cycle séismique. En cette thèse, échantillons prévenants de deux failles séismiques sont étudiés: la Faille de San Andreas (California, USA), une faille séismique active, et la faille de Gole Larghe (Alpes Méridionales, Italie), une faille séismique exhumée. La Faille de San Andreas a été forée jusqu'à 2.7km de profondeur. Les échantillons montrent une superposition de: pression-dissolution - hydrofracturation - pression dissolution. La succession des évents est compatible avec la formation de sacs de fluides dans zones de basse perméabilité dans la faille, ou la pression de fluides augmente à cause de le progressif compactage de le gouge de faille, jusqu'à la nucléation de une rupture. La faille de Gole Larghe est une faille exhumée, qui a préservé des pseudotachylytes (roches fondues par le chaleur de friction pendant une frottement séismique) formées à 9 - 11 km de profondeur il y a 30 millions d'années. Deux argumentes sont traités: (i) l'évolution des microstructures des cataclasites associées à les pseudotachylytes, pour identifier les processus qui peuvent porter à la formation de instabilités frictionnelles pendant les premières phases de croissance de une faille. (ii) L'origine des fluides en failles séismiques et pendant la fusion pour friction. La formation de un système de failles à cataclasites permit la percolation de un fluide aqueux de profondeur. La composition isotopique des pseudotachylytes (calculé sans la component de hydratation) est proche à celle des pseudotachylytes reproduites en expériences du laboratoire (sans fluides). La principale source de fluides pendant la fusion pour friction est donc la déshydratation des minéraux hydraté des roches autour de la faille.
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Castro, Nicholas D. "Numerical Modeling of Synthetic Jets in Quiescent Air with Moving Boundary Conditions." VCU Scholars Compass, 2005. http://scholarscompass.vcu.edu/etd/1466.
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Flow control is a key factor in optimizing the performance of any vehicle moving through fluids. Particularly, in aerodynamics there are many potential benefits for implementing synthetic jets to achieve aircraft designs with less moving parts, uper- maneuverability, and separation control for fuel economy. Piezoelectric synthetic jets are of special interest because of their lightweight and low power consumption. Numerous publications on such jets are available. Actuator properties and boundary conditions relevant to this particular application however are often overlooked. The focus of this project is to numerically model synthetic jets in quiescent air to study the influence of cavity geometry and boundary conditions of the piezoelectric diaphragm on jet velocity. Numerical simulation is performed for two synthetic jet cavities of different height and orifice diameter. The numerical modeling utilizes a turbulent RNG κ ε model and a moving boundary condition with two oscillating deflection profiles, parabolic and logarithmic, applied to the diaphragm. The actuators modeled are typical Bimorph and Thunder piezoelectric actuators. The initial conditions for the actuators are obtained experimentally resulting in 0.396mm and 0.07mm respectively when driven with a sinusoidal wave input at 1524 V/m and 4064 V/m. Although the velocity boundary numerical model gave overall better results than the current moving-boundary numerical model, the moving-boundary model is more accurate since it better approximates the movement of the diaphragm. From an optimizing viewpoint the moving boundary is more suitable to attempt to optimize the design because displacement magnitude of the diaphragm can be measured directly from experiments. For the higher displacement Bimorph actuator, a logarithmic profile matches the experimental results, whereas the parabolic profile provided better results for the relatively small displacement Thunder actuator. It is thus hypothesized that both tested actuators, Bimorph and Thunder, oscillate according to the specified logarithmic and parabolic profile respectively. Cavity height was briefly investigated for the Bimorph actuator. Results show that cavity height did not make a difference in the centerline velocity for the numerical model. The model fails to consider the important effect of the dynamic coupling of the actuator displacement and the pressure that develops inside the cavity. The pressure values obtained are comparable to the theoretical blocking pressure for the Bimorph in the cavity. The results of this study show that jet formation and development has unique characteristics for each actuator and cavity configuration. The smaller orifice cavity configuration produced a faster, longer, thinner jet with larger vortices than the bigger orifice. During max expulsion, t = 0.25T, and max ingestion, t = 0.75T, a low-pressure area localized at the corners of the orifice, inlet and exit respectively, were observed. All cavity configurations passed all three known jet formation criterions that include, Lo/Do>1, Re > 50, and Re/S2 > 0.16.
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Razavi, Seyed Mostafa. "OPTIMIZATION OF A TRANSFERABLE SHIFTED FORCE FIELD FOR INTERFACES AND INHOMOGENEOUS FLUIDS USING THERMODYNAMIC INTEGRATION." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1481881698375321.
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Sorgun, Mehmet. "Modeling Of Newtonian Fluids And Cuttings Transport Analysis In High Inclination Wellbores With Pipe Rotation." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12612385/index.pdf.
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This study aims to investigate hydraulics and the flow characteristics of drilling fluids inside annulus and to understand the mechanism of cuttings transport in horizontal and deviated wellbores. For this purpose, initially, extensive experimental studies have been conducted at Middle East Technical University, Petroleum &Natural Gas Engineering Flow Loop using water and numerous drilling fluids for hole inclinations from horizontal to 60 degrees, flow velocities from 0.64 m/s to 3.05 m/s, rate of penetrations from 0.00127 to 0.0038 m/s, and pipe rotations from 0 to 120 rpm. Pressure loss within the test section and stationary and/or moving bed thickness are recorded. New friction factor charts and correlations as a function of Reynolds number and cuttings bed thickness with the presence of pipe rotation for water and drilling fluids in horizontal and deviated wellbores are developed by using experimental data. Meanwhile empirical correlations that can be used easily at the field are proposed for predicting stationary bed thickness and frictional pressure loss using dimensional analysis and the effect of the drilling parameters on hole cleaning is discussed. It has been observed that, the major variable influencing cuttings transport is fluid velocity. Moreover, pipe rotation drastically decreases the critical fluid velocity that is required to prevent the stationary cuttings bed development, especially if the pipe is making an orbital motion. A decrease in the pressure loss is observed due to the bed erosion while rotating the pipe. Cuttings transport in horizontal annulus is modeled using a CFD software for different fluid velocities, pipe rotation speeds and rate of penetrations. The CFD model is verified by using cuttings transport experiments. A mathematical model is also proposed to predict the flow characteristics of Newtonian fluids in concentric horizontal annulus with drillpipe rotation. The Navier-Stokes equations of turbulent flow are numerically solved using finite differences technique. A computer code is developed in Matlab 2007b for the proposed model. The performance of the proposed model is compared with the experimental data which were available in the literature and gathered at METU-PETE Flow Loop as well as Computational Fluids Dynamics (CFD) software. The results showed that the mechanistic model accurately predicts the frictional pressure loss and the velocity profile inside the annuli. The model&rsquo
s frictional pressure loss estimations are within an error range of ±
10%.
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Baskaya, Fadime Suhan. "Phase equilibrium at supercritical (SC) conditions: solubility analysis of curcumin in supercritical carbon dioxide and co-solvent mixtures, and phase equilibrium analysis of cis-1,4-(poly)isoprene in propane and co-solvent mixtures." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1133980672.
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Bouainouche, Mokrane. "Etude de l'interaction entre un jet plan à grande vitesse et un film liquide." valenciennes, 1995. https://ged.uphf.fr/nuxeo/site/esupversions/2f38b9a7-3e25-4c6f-968e-e4d2d3c14d4a.
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La première partie de l'étude s'intéresse à la modélisation de l'impact d'un jet de gaz plan et mince sur une paroi plane en vue d'en déduire les distributions de pression et de contrainte de cisaillement sur la paroi. Dans la deuxième partie, ces résultats sont utilisés pour étudier le comportement d'un film liquide visqueux entraîné par le déplacement vertical d'une bande et soumis à l'action d'un jet. Les actions du jet sur la surface sont déterminées par un calcul numérique en utilisant un schéma de type volume fini. L’écoulement d'un jet bidimensionnel, turbulent et compressible sur une plaque plane est modélisé en utilisant le modèle de turbulence k- avec des fonctions de paroi. Pour réduire l'influence du maillage près de la paroi sur le calcul de la contrainte de cisaillement pariétale, une loi de paroi hybride est proposée en utilisant simultanément la loi de paroi logarithmique et sa forme généralisée. Les distributions de pression et de contrainte de cisaillement sont calculées et validées par des mesures expérimentales. L’équation du mouvement du film liquide est écrite en considérant le terme d'accélération, négligé dans les études précédentes. Le modèle est appliqué a un processus de galvanisation et validé par des résultats expérimentaux obtenus dans des conditions diversesThe first part of this study deals with the modelling of the impact of a thin plane gas jet a flat plate in order to define the pressure and shear stress distributions on the wall. In the second part, these results are used to study the behavior of viscous film liquid on the strip moving upward and submitted to the jet action. The jet actions are determined by a numerical computation based on finite volume scheme. The impingement of a plane two dimensional turbulent and compressible jet is modelised using the k-ɛ model combined to the wall functions. In order to reduce the near wall gnd influence on the shear stress calculation, a hybrid wall law is proposed resulting from simultaneous use of the logarithmic law and generalized one. Pressure and shear stress distributions on the flat plane are calculated and validated by experimental data. The motion of liquid coating is modelised by taking into account the inertia terms, neglected in the previous studies. This model is applied to the galvanization process and compared with measurements obtained in various conditions
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Namuq, Mohammed Ali [Verfasser], Matthias [Akademischer Betreuer] Reich, Matthias [Gutachter] Reich, Gerhard [Gutachter] Thonhauser, and Joachim [Gutachter] Oppelt. "Simulation and modeling of pressure pulse propagation in fluids inside drill strings / Mohammed Ali Namuq ; Gutachter: Matthias Reich, Gerhard Thonhauser, Joachim Oppelt ; Betreuer: Matthias Reich." Freiberg : Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2013. http://d-nb.info/1220911534/34.
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Wilson, Raymond Gary. "A Numerical Analysis of the Influence of Korteweg Stresses on the Flow and Mixing of Miscible Fluids." Cleveland, Ohio : Case Western Reserve University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1081283678.
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Thesis (Ph.D.)--Case Western Reserve University, 2004Title from PDF (viewed on 01 October 2009) Department of Mechanical Engineering Includes abstract Includes bibliographical references Available online via the OhioLINK ETD Center
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Clausen, Jonathan Ryan. "The effect of particle deformation on the rheology and microstructure of noncolloidal suspensions." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34680.
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In order to study suspensions of deformable particles, a hybrid numerical technique was developed that combined a lattice-Boltzmann (LB) fluid solver with a finite element (FE) solid-phase solver. The LB method accurately recovered Navier-Stokes hydrodynamics, while the linear FE method accurately modeled deformation of fluid-filled elastic capsules for moderate levels of deformation. The LB/FE technique was extended using the Message Passing Interface (MPI) to allow scalable simulations on leading-class distributed memory supercomputers.
An extensive series of validations were conducted using model problems, and the LB/FE method was found to accurately capture proper capsule dynamics and fluid hydrodynamics. The dilute-limit rheology was studied, and the individual normal stresses were accurately measured. An extension to the analytical theory for viscoelastic spheres [R. Roscoe. J. Fluid Mech., 28(02):273-93, 1967] was proposed that included the isotropic pressure disturbance. Single-body deformation was found to have a small negative (tensile) effect on the particle pressure.
Next, the rheology and microstructure of dense suspensions of elastic capsules were probed in detail. As elastic deformation was introduced to the capsules, the rheology exhibited rapid changes. Moderate amounts of shear thinning were observed, and the first normal stress difference showed a rapid increase from a negative value for the rigid case, to a positive value for moderate levels of deformation. The particle pressure also demonstrated a decrease in compressive stresses as deformation increased. The corresponding changes in microstructure were quantified. Changes in particle self-diffusivity were also noted.
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Herdegen, Volker. "Hochdruckextraktion von Naturstoffen mit nahe-/ überkritischen Fluiden unter Einbindung eines Membranverfahrens." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2014. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-153234.
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Die vorliegende Arbeit beschäftigt sich mit dem Einsatz eines Membranverfahrens zur Extraktabtrennung unter Hochdruckbedingungen. Die in einem zu koppelnden Prozess extrahierten Naturstoffsubstanzen sollen dabei ohne große Energieverluste, wie sie bei der herkömmlichen Methode der Druckentspannung entstehen, in nahezu isobarer und isothermer Fahrweise aus dem verdichteten Lösungsmittel gewonnen werden. Für den Einsatz oxid-keramischer, integral-asymmetrisch aufgebauter Einkanal-Rohrmembranen wurden vor allem grundlegende Daten zum Transportverhalten hinsichtlich der beiden eingesetzten Gase CO2 und dem Frigen Tetrafluorethan ermittelt. Dies geschah für zwei Nanofiltrationsmembranen mit trennaktiven Schichten aus TiO2 und SiO2. Die Filtrationsleistung der Membranen wurde für drei beispielhafte Wertstoffe (Koffein, Aescin, Inulin), deren Extraktionsverhalten im Vorfeld untersucht wurde, u.a. anhand von Rückhalt und Deckschichtbildung bewertet.