Dissertations / Theses on the topic 'Physical properties of the fluid'

Comprendre et connaitre les propriétés physiques et le comportement mécanique de l'andésite est important pour des applications industrielles comme la géothermie ou le stockage de CO2 mais aussi pour comprendre différents processus naturels. Tout d'abord, les effets de la fissuration thermique sur les propriétés physiques et les processus de rupture de l'andésite ont été étudiés via des expériences triaxiales à taux de déformation constant et à température ambiante. Deuxièmement, nous avons effectué des recherches sur les effets de l'altération sur le comportement physique et la minéralogie. Enfin, une série d'expériences a été réalisée afin d'étudier l'effet de la variation de la pression du fluide i) sur le comportement mécanique des échantillons d'andésite et ii) sur les activités d'émissions acoustiques
The physical properties and mechanical behavior of andesite are of interest in the context of geothermal reservoir, CO2 sequestration and for several natural processes. The effects of thermal crack damage on the physical properties and rupture processes of andesite were investigated under triaxial deformation at room temperature. Secondly we did research on the effect of alteration on physical behavior and mineralogy. At last a series of experiments were performed in order to investigate the effect of fluid pressure variation i) on the mechanical behavior of andesite samples and ii) on acoustic emissions activities

"Composites of nanoparticles with complex fluids represent a unique physical system where thermal physical properties of the components partially or fully mix and new behavior can emerge. Traditional composites are relatively well understood as the superposition, weighted by volume or mass, of the components properties and the interfacial interactions play the role of holding the composite together. As the filler component, nanoparticle, decreases in size, the surface area begins to dominate, leading to unique behavior of the nanocomposites. The richness of the nanocomposites that can be designed by coupling various nanoparticles and complex fluid materials opens a wide field of active research. This dissertation presents a series of experimental studies on various nanocomposites using modulated differential scanning calorimetry, spectroscopic ellipsometry, dielectric spectroscopy, polarizing microscopy, and conductivity measurements of nanoparticles such as multi-wall carbon nanotubes and quantum dots on the phase transitions of several liquid crystals and polymers. The liquid crystals (LCs) and liquid crystalline polymer (LCP) of interest are: negative dielectric anisotropy alkoxyphenylbenzoate (9OO4), octylcyanobiphenyl (8CB), decylcyanobiphenyl (10CB), and isotactic polypropylene (iPP) which can form smectic liquid crystal (LC) phase. Studies have been carried out as a function of concentration and temperature spanning through various ordered phases. The results indicate a mixture of ordering and disordering effects of the nanoparticles on the phases of the complex fluids. In 9OO4/CNT system, dipole moment of liquid crystal and graphene like surface can allow a random dispersion of CNT to promote both orientational and positional order. For nCB/CNT, nCB/Quantum dot (QD) systems, nanoparticles induce net disordering effect in LC media. The effect of QDs on LC depends on the anchoring conditions and the QDs size. The results clearly demonstrate that the nematic phase imposes self-assembly on QDs to form one dimensional arrays. This leads to net disordering effect. The thermal/electrical conductivity changes in thin films of iPP/CNT sheared/un-sheared samples and it also varies with temperature for the purpose of inducing anisotropy of those properties in parallel and perpendicular to average orientation. The percolation threshold is clearly pronounced in both conductivities due to pressing and shearing treatment of the films. This will further our abilities to nano-engineer material for many important applications."

Thesis (MEng) -- Stellenbosch University, 2014.
ENGLISH ABSTRACT: Distillation is one of the most widely used processes for the separation of fluids with different volatilities. Due to the popularity of this process it is often assumed that the hydrodynamic behaviour inside distillation columns is well-defined. However, this is not always the case and this study therefore endeavoured to provide additional insight into the topic through a systematic investigation into the hydrodynamics and the capacity limitations of a sieve tray distillation column. The objective of the study was to measure and evaluate the effects of the following variables on entrainment and weeping: - Fluid flow rate (gas and liquid). - Plate geometry (i.e. hole diameter and fractional hole area). - Liquid properties (i.e. surface tension, viscosity and density). - Gas properties (i.e. viscosity and density). The hydrodynamic effects were evaluated at zero mass transfer in a pilot-scale tray column, by passing pure liquids and gases in counter current configuration. The pilot column was rectangular in shape with internal dimensions of 175 mm by 635 mm. A chimney tray was used to capture the weeping liquid, while a de-entrainment tray was used in combination with a mist eliminator pad to capture the entrained liquid. The fractional hole areas for the sieve trays under investigation were 7%, 11% and 15% and the hole diameters were 3.2 mm (⅛ in.), 6.4 mm (¼ in.) and 12.7 mm (½ in.). The experimental liquids were ethylene glycol, butanol, water and silicone oil, while the gases were air and carbon dioxide (CO2). These experimental measurements produced over 10 000 data points for entrainment and over 7 000 data points of weeping. The results were repeatable and the entrainment values compared reasonably well with previous data produced by Nutter (1971) and Uys (2012). The differences between entrainment for the different liquids were more significant in the spray regime than in the froth regime, and butanol was entrained more readily than silicone oil, ethylene glycol and water. Fluids that caused a larger spray layer in the dispersion zone produced more entrainment. Entrainment increased with decreasing liquid density, decreasing liquid surface tension and decreasing liquid viscosity. The more unstable the dispersion layer, the higher the entrainment. The liquid density strongly influenced weeping, i.e. weeping increased with increasing liquid density. On the other hand, gases with higher densities – and thus with a higher mass flow rates at similar volumetric flow rates through the sieve tray – displayed less weeping and more entrainment than less dense gases, because of an increased upward drag force on the fluids. When considering tray geometry and when operating in the spray regime, the magnitude of entrainment increased with decreasing fractional hole area, while the dependency of entrainment on fractional hole area was more prominent at lower fractional hole areas. When operating in the froth regime – typically above 23 m3/(h.m) – the fractional hole area had a relatively small influence on the magnitude of entrainment, while the cross-flowing liquid rate dominated related effects. In the spray regime, i.e. typically below 23 m3/(h.m), the entrainment increased with increasing sieve tray hole diameter, while hole diameter had a relatively small influence on entrainment at higher liquid flow rates between 23 and 60 m3/(h.m). However, at even higher liquid flow rates in the froth regime, i.e. above 60 m3/(h.m), the effect of hole diameter on the entrainment became more prominent again, with increased entrainment for smaller hole diameters. The effect of hole diameter on weeping differed with changing fluid combinations and the 12.7 mm hole size caused notably less weeping than the 3.2 mm and 6.4 mm trays at higher liquid flow rates. It is believed that weeping occurred preferentially at so-called localised high pressure zones on the sieve tray. At high gas and liquid flow rates, the resultant extended dispersion layer allows minimal intimate contact between the plate and the liquid (minimising such localized high-pressure zones). In effect, the liquid ‘jumps’ over the entire flow path length in the test rig, thus resulting in low weeping rates at high gas and liquid rates. The effects of fractional hole area and hole diameter on entrainment and weeping can be correlated with combinations of well-known hydrodynamic dimensionless numbers, such as the Weber number (We), Froude number (Fr) and Reynolds number (Re). Within the limitations of this study, the flow-Froude number was shown to be the most useful dimensionless number, since it displayed a monotonic relationship with magnitude of entrainment for different combinations of fluid systems and tray configurations. Furthermore, both the construction number and fluid density ratio could be used in a sensible manner to correlate some of the effects of tray geometry on entrainment.
AFRIKAANSE OPSOMMING: Distillasie word wêreldwyd op groot en klein skaal toegepas as ʼn metode om chemiese komponente van mekaar te skei, gebasseer op hul verskil in vlugtigheid. Die hidrodinamiese gedrag van vloeistowwe en hul damp binne ʼn distillasiekolom beïnvloed die effektiwiteit van die skeidingsproses. Hierdie studie beoog dus om bykomende insig te verskaf tot die hidrodinamika en kapasiteitsbeperkings van ʼn plaat-distilleerkolom. Die doelwit van die studie was om die invloed van die volgende veranderlikes op die meesleuring en deurdripping van vloeistowwe te ondersoek: - Gas- en vloeistof vloeitempo. - Plaatgeometrie (i.e. gatdeursnit en fraksionele deurvloei-area). - Vloeistofeienskappe (i.e. oppervlakspanning, viskositeit en digtheid). - Gaseienskappe (i.e. viskositeit en digtheid). Die hidrodinamiese studie is uitgevoer in ʼn reghoekige plaatkolom met interne afmetings van 175 mm x 635 mm. Die vloeistof en gasfases is in kontak gebring op ʼn teenstroom basis, met geen massa-oordrag wat plaasvind nie. ʼn Skoorsteenplaat het die vloeistof opgevang wat deurdrip terwyl ʼn ekstra plaat aan die bokant van die kolom die meegesleurde vloeistof opgevang het. Hierdie ekstra plaat is gebruik tesame met ʼn mis-elimineerder om al die meegesleurde vloeistof op te vang. Plate met verskillende deurvloei-areas (7%, 11% en 15%) en gat deursnitte (3.2 mm, 6.4 mm en 12.7 mm) is gebruik in die ondersoek. Die vloeistowwe wat gebruik is, sluit in etileen glikol, butanol, water en silikon olie. Lug en koolstofdioksied is as gasse gebruik. Die eksperimentele data het goeie herhaalbaarheid getoon en is vergelykbaar met die gepubliseerde data van Nutter (1971) en Uys (2012). Meer as 10 000 data punte is gemeet vir vloeistofmeesleuring en meer as 7 000 vir deurdripping. Die verskil in hoeveelheid meesleuring tussen die vloeistowwe, soos ondersoek in hierdie studie, was mees beduidend in die spoei-regime. Butanol is die meeste meegesleur, gevolg deur silikon olie en dan etileen glikol. Water is die minste meegesleur is. Vloeistowwe wat ʼn groter sproeivolume in die dispersielaag bo die plaat gevorm het, is die meeste meegesleur. Meesleuring het toegeneem met ʼn afname in digtheid, oppervlakspanning en viskositeit van die vloeistof. ʼn Onstabiele dispersielaag bo die plaat het meer meesleuring tot gevolg gehad. Vloeistofdeurdripping is sterk beïnvloed deur vloeistofdigtheid, i.e. deurdripping het sterk toegeneem met digtheid. Gasse met ʼn hoër digtheid veroorsaak weer ʼn afname in deurdripping a.g.v. die hoër opwaartse sleurkragte wat ʼn gas met hoë digtheid op die vloeistof uitoefen. In die sproei-regime (tipies by vloeistofvloeitempos laer as 23 m3/(h.m) is gevind dat meesleuring toeneem met ʼn afname in fraksionele deurvloei-area. Meesleuring se afhanklikheid van fraksionele deurvloei-area was meer beduidend by laer fraksionele deurvloei-areas. In die skuim-regime (tipies by vloeistofvloeitempos hoër as 23 m3/(h.m)) was die afhanklikheid van meesleuring op fraksionele deurvloei-area relatief klein. In die sproei-regime is gevind dat meesleuring toeneem met ʼn toename in gat deursnit, terwyl dieselfde veranderlike ʼn minder beduidende invloed op meesleuring getoon het by hoër vloeistofvloeitempos (tussen 23 en 60 m3/(h.m)). By vloeitempos hoër as 60 m3/(h.m) het meesleuring weer begin toeneem met ʼn afname in gat deursnit. By hoë vloeistofvloeitempos het die plaat met 12.7 mm gat deursnit aansienlik minder deurdripping getoon as plate met 3.2 mm en 6.4 mm deursnitte. Daar word vermoed dat deurdripping hoofsaaklik plaasvind by lokale hoëdruk gebiede op die plaat. By hoër vloeistof- en gasvloeitempos beslaan die dispersielaag ʼn groter volume en is daar dus minder gebiede van digte vloeistofkontak met die plaat, wat ʼn afname in die lokale drukgebiede veroorsaak. Dit lei tot ʼn afname in deurdripping by hoër gas- en vloeistofvloeitempos. Die invloed van fraksionele deurvloei-area en gatdeursnit op meesleuring en deurdripping korreleer goed met kombinasies van welbekende hidrodinamiese dimensielose getalle, i.e. die Webergetal (We), die Froudegetal (Fr) en die Reynoldsgetal (Re). Die vloei-Froudegetal is mees bruikbaar om die invloed van vloeistof-en-gas kombinasies en kolomuitleg op meesleuring te korreleer. Die konstruksiegetal asook die digtheidsverhoudings tussen vloeistof en gas kan op ʼn sinvolle manier aangewend word om van die invloede van plaatgeometrie op meesleuring te beskryf.

In this thesis we describe numerical simulations performed in one- and two-dimensions of a theoretical granular model called the Random Force Model. The properties of non-equilibrium steady state granular media, which this model is a simple example of, are still hotly debated. We begin by observing that the one-dimensional Random Force Model manifest multi-scaling behaviour brought on by the clustering of particles within the system. For high dissipation we find that the distribution of nearest neighbour distances are approximately renormalisable and devise a geometrical method that accounts for some of the structural features seen in these systems. We next study two-dimensional systems. The structure factor, S(k), is known to vary, for small k, as a power-law with an exponent D_f, referred to as the fractal dimension. We show that the value of the D_f is unchanged with respect to both dissipation and particle density and that the power-law is different from that given in any previous study. These structural features influence the long distance behaviour of individual particles by affecting the distances travelled by particles between consecutive collision. The velocity distribution, P(v), is known to strongly deviate away from Maxwell-Boltzmann statistics and we advocate that the velocity distributions have asymptotic shape which is universal over a range of dissipation and particle densities. This invariance in behaviour of the large-scale structure and velocity properties of the two-dimensional Random Force Model leads us to develop a new self-consistent model based around the motion of single high velocity particles. The background mass of low velocity particles are considered to be arrange as a fractal whereby the high velocity particles move independently in ballistic trajectories between collisions. We use this description to construct the high velocity tail of P(v), which we find to be approximately exponential. Finally we propose a method of structure formation for these systems that builds self-similarity into the system by consecutively fracturing the system into smaller parts.

In this study, we have investigated the effects of structural anisotropy of porous media on the permeation of fluids. The motivation for the work was an increased understanding of the permeation of inks into paper coatings, which often contain platey or needle-like particles, which have been aligned during the coating process. However, the findings are also relevant to other systems, such as the sub-terranean migration of fluids, including pollutants, within shale that contains particles of high aspect ratio. Mineral pigments, comprising mainly of calcium carbonate or clay, are often are applied to the surface of paper to improve optical and printing properties. For a high quality image to be achieved, the coating should have sufficient capillarity to allow the ink film to set within the time-scale of a modern printing press. The permeation of fluids into a range of different coating formulations has been investigated, with its main focus on the following samples: Speswhite and Amazon90 SD, which belong to the Kaolin (day) mineral group, and OpacarbA40 and Albaglos, which belong to the Precipitated Calcium Carbonate (PCC) mineral group. The permeation was measured by five different techniques, including a novel use of the Ink Surface Interaction Tester. The results were modelled using a modified version of the software package ‘Pore-Cor’, which simulated both permeability and capillary absorption of a wetting liquid into porous media containing anisotropic voids, and allowed the effects of anisotropy to be isolated from other closely related pore properties. The model generated a simplified three-dimensional void network having pores with a rectangular cross-section and throats with an elliptic cross-section. From visual inspection of the modelled structures, the effect of anisotropy revealed advance wetting in the narrow features of Speswhite-CL and OpacarbA40-CL. Overall, to gain a clear understanding of the permeation of anisotropic structures both inertia and surface throat density is needed to be included in the Pore-Cor model. Once these factors were applied to the model, it was able to predict the permeation of fluids more successfully than those predicted by the Kozeny and aligned cylinders models. The insights gained from this study have allowed conclusions to be drawn about the nature of fluid permeation; they have therefore opened the way to more sophisticated modelling and the engineering of high performance coating structures.

Master of Science
Department of Food Science
Karen A. Schmidt
This research sets out to determine how varying factors such as electromagnetic fluid conditioning (EFC) and varying protein and sugar contents can influence yogurt and skim milks overall quality. EFC uses magnets to alter the chemical and physical properties of skim milk in these studies. EFC has many different treatment parameters to optimize before this new processing technology can be industrialized. Treatment parameters include voltage, exposure time, flow rate, and magnetic field direction, as studied in this research. Voltage was altered 10 and 30 V for 2 and 10 minutes. This study showed that at 2 minutes that skim milk was not altered, but at both voltages at 10 minutes some changes occurred to surface tension and color properties (L* and a* values) of skim milk. For both voltages at 10 minutes, it was always the negative direction that experienced the most changes. A separate EFC experiment was done that set out to determine if pretreating skim milk with EFC, would have an effect on yogurt’s quality post fermentation throughout storage. Results indicated that EFC does alter the yogurt’s properties, but not in a desirable manner. Results were undesirable changes to the product’s firmness and syneresis when compared to the control sample. Dielectric spectroscopy is a rapid method to determine if varying protein and sugar contents has compromised yogurt’s quality. In the dielectric spectroscopy study, this research wanted to determine if varying protein and sugar contents influenced dielectric properties enough to where a model could be developed to predict yogurt’s firmness. Both of these methods, EFC and dielectric spectroscopy, are novel technologies to the dairy industry where, both have been very minimally tested on yogurt. This research proved to be a stepping stone to open further doors to research in these areas due to results indicating changes but not pin-pointing exactly what is going on due to these technologies.

The phase behaviour of reservoir fluids under the addition of carbon dioxide (CO2) were studied at elevated pressures and temperatures similar to those encountered in enhanced oil recovery (EOR) and carbon storage processes. The principal focus of the work presented in this thesis is the experimental investigation of the phase behaviour of these CO2 mixtures with hydrocarbon reservoir fluids. For this purpose, a new high-pressure high-temperature apparatus was designed and constructed. The apparatus consisted of a thermostated variable-volume view cell driven by a computer-controlled servo motor system. The maximum operating pressure and temperature were 40 MPa and 473.15 K, respectively. Measurements were then made over a wide range of pressure and temperature conditions for two representative CO2-hydrocarbon systems: (CO2 + n-heptane + methylbenzene) and (CO2 + synthetic crude oil). The vapour-liquid phase behaviour of the former system was studied, under CO2 addition and various molar ratios of n-heptane to methylbenzene, along different isotherms at temperatures between (298 and 473) K and at pressures up to approximately 16 MPa. In the latter, the synthetic oil contained a total of 17 components while solution gas (methane, ethane and propane) was added to obtain live synthetic crudes with gas-oil ratios of either 58 or 160. Phase equilibrium and density measurements were then made for the ‘dead’ oil and the two ‘live’ oils under the addition of CO2. The measurements were carried out at temperatures between (298.15 and 423.15) K and at pressures up to 36 MPa, and included vapour-liquid, liquid-liquid and vapour-liquid-liquid equilibrium conditions. The phase equilibria of (carbon dioxide + n-heptane + water) and (carbon dioxide + methane + water) mixtures were also studied using a high pressure quasi-static analytical apparatus with on-line compositional analysis by gas chromatography. The former system was studied under conditions of three-phase equilibria along five isotherms at temperatures from (323.15 to 413.15) K and at pressures up to the upper critical end point (UCEP). In the latter system, compositions of three coexisting fluid phases have been obtained along eight isotherms at temperatures from (285.15 to 303.5) K and at pressures up to either the UCEP or up to the hydrate formation locus. Compositions of coexisting vapour and liquid phases have been obtained along three isotherms at temperatures from (323.15 to 423.15) K and pressures up to 20 MPa for mixtures containing nearly equal overall mole fractions of CH4 and CO2. The quadruple curve along which hydrate coexists with the three fluid phases was also measured. A detailed study of these ternary mixtures was carried out based on comparison with available ternary data of the type (CO2 + n-alkane + water) and available data for the constituent binary subsystems. In this way, we analyze the observed effects on the solubility when the n-alkane component was changed or a third component was added. The experimental data for the (CO2 + hydrocarbon) systems have been compared with results calculated with two predictive models, PPR78 and PR2SRK, based on Peng-Robinson 78 (PR78) and Soave-Redlich-Kwong (SRK) cubic equations of state (EoS) with group-contribution formula for the binary interaction parameters and with the use of different alpha functions. Careful attention was paid to the critical constants and acentric factor of high molar-mass components. The use of the Boston-Mathias modification of the PR78 and SRK equations was also investigated. The experimental data obtained for the (CO2 + n-heptane + methylbenzene) mixture were also compared with the predictions made using SAFT-Gamma-Mie, a group-contribution version of the Statistical Associating Fluid Theory (SAFT), which was implemented with the generalized Mie potential to represent segment-segment interactions. Detailed assessment of the predictive capability of these models concluded that the agreement between the experimental data and prediction from these methods, while not perfect, is very good, especially on the bubble curve. The results suggest that there is merit in the approach of combining these methods with a group-contribution scheme. Comparison between these approaches concluded that they all have comparable accuracies regarding VLE calculations. The experimental data obtained for the ternary mixtures (CO2 + n-alkane + water) have been compared with the predictions of SAFT for potentials of variable range (SAFT-VR), implemented with the square-well (SW) potential using parameters fitted to experimental pure-component and binary-mixture data. A good performance of the SAFT-VR equation in predicting the phase behaviour at different temperatures was observed even with the use of temperature-independent binary interaction parameters. It was also observed that an accurate prediction of phase behaviour at conditions close to criticality cannot be accomplished by mean-field based theories, such as the models used in this work, that do not incorporate long-range density fluctuations. Density measurements on a variety of brines (both single-salt and mixed) were studied in the present work within the context of CO2 storage processes in saline aquifers. Densities of MgCl2(aq), CaCl2(aq), KI(aq), NaCl(aq), KCl(aq), AlCl3(aq), SrCl2(aq), Na2SO4(aq), NaHCO3(aq) , the mixed salt system [(1 – x) NaCl + xKCl](aq) and the synthetic reservoir brine system [x1NaCl + x2KCl + x3MgCl2 + x4CaCl2 + x5SrCl2 + x6Na2SO4 + x7NaHCO3](aq), where x denotes mole fraction, were studied at temperatures between (283 and 473) K and pressures up to 68.5 MPa. The measurements were performed with a vibrating-tube densimeter calibrated under vacuum and with pure water over the full ranges of pressure and temperature investigated. It was observed that careful attention needs to be paid to the type of calibration method selected. An empirical correlation is reported that represents the density for each brine system as a function of temperature, pressure and molality with absolute average relative deviations (%AAD) of approximately 0.02 %. Comparing the model with a large database of results from the literature suggested that the model is in good agreement with most of the available data. The model can be used to calculate density, apparent molar volume and isothermal compressibility of single component salt solutions over the full ranges of temperature, pressure and molality studied. An ideal mixing rule for the density of a mixed electrolyte solution was tested against our mixed salts data and was found to offer good predictions at all conditions studied with an absolute average relative deviation of 0.05 %. The present work was carried out as part of the Qatar Carbonates and Carbon Storage Research Centre (QCCSRC) program. It covered a wide range of phase behaviour and density measurements at conditions relevant to oil and gas fields’ applications, and explored the predictive capabilities of some available models, in particular predictive cubic EoS, SAFT-VR and SAFT-Gamma-Mie. The research and data collected represents a good step in enabling the direct design and optimisation of CO2-EOR and carbon storage processes. An example is the validation of the predictive models and the determination of the miscibility pressure which is essential for effective recovery of the heavy hydrocarbons. Areas in which the research might be extended, both through further experimental studies and improved modelling, have been identified.

A newly designed Langmuir probe has been evaluated and was used to map the plasma potential near the powered electrode of a plasma etch chamber in 2 dimensions. Various electrode materials and geometries were used in order to investigate the relationship between electrode design and the presence of localized regions of elevated plasma potential. These regions of elevated plasma potential were known to be responsible for the presence of particle clouds suspended in the plasma during operation. A relationship was established between sharp edges on the powered electrode, insulating materials on the electrode and localized elevation in plasma potential. A thin layer of raised plasma potential has also been discovered at the plasma-sheath boundary. Suggestions for electrode design to reduce the presence of particles suspended in the plasma are made.

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Capes
O presente trabalho teve como objetivo analisar a influência da saturação fluida nas propriedades elásticas de rochas carbonáticas, bem como a eficácia dos modelos de substituição de fluidos e de simulação computacional. Foram estudadas 9 amostras de rochas carbonáticas, sendo dois calcários laminados e sete tufas. As medições de velocidade foram realizadas em amostras secas, saturadas com água ou com óleo, sob diferentes pressões efetivas. A simulação de propagação de ondas foi feita no COMSOL Multiphysics 5.1, utilizando o Avizo Fire 8.1 para a criação das amostras digitais. Análise por difração de raios X (DRX) foi realizada para determinar a composição das amostras de rocha. Os resultados obtidos nos ensaios laboratoriais e nas simulações computacionais foram comparados com as estimativas dos modelos de substituição de fluidosGassmann, Biot e Brown & Korringa. Foi observado que a saturação das amostras com agua ou óleo geraram aumentos nas velocidades de propagação de onda P, porém sem apresentar um comportamento padrão. Para o caso das ondas S, a saturação por óleo predominantemente gerou aumentos nas velocidades, com exceção para os casos em que as amostras possuíam porosidade secundária do tipo vugular, devido à pouca influência que o óleo oferece para o módulo de cisalhamento nestes casos. A saturação por água resultou em diminuições das velocidades de propagação de onda S devido ao aumento da densidade total. Também foi constatado que o modelo de Gassmann foi o mais efetivo na estimativa de velocidades de onda P e S, enquanto que o de Biot mostrou-se eficaz apenas para a estimativa de velocidades de ondas S, sendo ineficiente para a estimativa de velocidades de ondas P, com erros de até 20%. A simulação computacional gerou resultados superdimensionados, porém que evidenciam que um aperfeiçoamento da metodologia, tal como o aumento do número de pontos de leitura pode gerar resultados mais próximos dos obtidos laboratorialmente e de maior confiabilidade.
This research aimed to analyze the influence of the saturating fluid in carbonate rocks, as well as verify the effectiveness of the fluid substitution models and computational simulations of wave propagation. To do so, nine carbonate rock samples were analyzed, which two of them were laminated limestones and seven were carbonate tufas. The measurement of velocities were made in dry, water saturated and oil saturated samples, under different effective pressures. The wave propagation simulations were made in COMSOL Multiphysics 5.1 using Avizo Fire 8.1 to generate the digital rock samples. The results obtained in lab procedures and in computer simulations were compared with the estimated velocities of the fluid substitution models of Gassmann, Biot and Brown & Korringa. It was observed that the saturation of the samples with water or oil resulted in an increasing of P-wave velocities, however without a pattern. The saturation with oil resulted in most cases in an increasing of S-wave velocities, the exceptions occurred in samples which had vugular porosity, due to the small influence of the oil in the shear modulus in this cases. T he saturation with water resulted in a decreasing of S-wave velocities due to the increment of the bulk density. It was found that the Gassmann’s model was more effective than the other two models in estimating P-wave and S-wave velocities. Biot’s model generated unsatisfying results to P-wave velocities, with errors up to 20%. However, this model had a good accuracy in estimating S-wave velocities. The computer simulations produced mainly overestimated results, though it was shown that an optimization of methodology, such as and addition in the number of the measure points, could improve the quality of the data, providing more representative results.

Ce travail consacre à l'étude des transferts de l'uranium aux différents stades hydrothermaux dans le massif de saint sylvestre (NW du M. C. F. ), et aux caractéristiques des perturbations d'ordre géochimique, minéralogique et structural qui leur sont associées, a été réalisée grâce à une approche pluridisciplinaire. Il a permis de connaitre: (1) la remobilisation tardive d'uranium hors du gisement et son ampleur; (2) les relations entre les différentes phases d'altération et la minéralisation primaire qui se traduisent par des marqueurs spécifiques et des orientations de réseaux de micro à macro-fracturation; (3) les conditions et la géométrie de développement des différents stades d'altération grâce à l'étude des fluides liées à ces stades. L'étude simultanée des circulations fluides, de la microfissuration et des altérations associées, a permis de: (1) envisager un développement des pièges d'uranium episyenite dans un système de fractures e-w, par un mécanisme de condensation de fluide aqueux type VW dont les caractéristiques sont, une faible salinité (<2% pds eq. Nacl) et une température élevée (350 a 400c); (2) définir les caractéristiques physicochimiques des fluides associes aux stades précoces à tardifs par rapport a la minéralisation uranifère. En effet, les stades précoces, sont caractérises par des fluides aquo-carboniques assez comparables (300 a 350c, salinité comprise entre 6 et 14% pds eq. Nacl) et par différents stades de piégeages de fluides aqueux

Ce travail étudie comment la mesure des forces hydrodynamiques exercées par un liquide confiné entre une sphère et une surface d'intérêt permet de sonder à distance et sans contact les propriétés mécaniques de cette surface. Nous présentons tout d'abord le principe de cette technique originale de sonde fluide et la machine à forces de surface dynamique que nous utilisons pour mettre en oeuvre ces expériences de nano-rhéologie. Puis nous nous intéressons à deux applications que nous avons plus particulièrement étudiées. D'une part, l'étude des propriétés de friction des bicouches lipidiques. Nous mettons en évidence une très faible friction mesurée sur certaines bicouches fluides et son potentiel rôle pour la bio-lubrification. D'autre part l'étude des propriétés élastiques de couche mince d'élastomère. Nous développons pour cela une théorie de l'élasto-hydrodynamique à géométrie sphère-plan en mode dynamique et présentons des résultats expérimentaux en très bon accord. Nous sommes capables de mesurer le module d'Young de films mince de PDMS d'épaisseur allant jusqu'à 600~nm. Enfin, nous présentons les développements instrumentaux réalisés pour optimiser les performances de la machine à forces de surfaces comme sonde fluide.

This thesis consists of two main parts. The first part is a theoretical analysis, or a literary research, it is focused on the physical properties of the fluid, which have direct impact on the decompression. The aim of the second part is to evaluate the measurement of the forging valve and subsequently simulate the issue by means of CFD. The first simulations were performed for the maximal valve stroke and used for the CFD solver setup calibration. The subsequent analyses dealt with possible openings of the valve. In the final chapter the theoretical impact of the liquid compressibility and of the undissolved air is discussed. The results of the thesis can prove useful for the new valve setting in hydraulic circuit or for possible geometry modification.

Optical techniques were used to study the critical behaviour of the pure fluids CHF₃, CCIF₃ and Xe, and binary mixtures He-Xe and nicotine + water. We find that for all these substances, the order parameter is described by a power law in the reduced temperature t = (Tc - T)/Tc with a leading exponent β = 0.327 ± 0.002. Also, we determine the first correction to scaling exponent to be Δ = 0.43 ± 0.02 for the pure fluids and Δ = 0.50 ± 0.02 for the He-Xe system. The coexistence curve diameter in CHF₃ and CCIF₃ exhibits a deviation from rectilinear diameter, in agreement with a modern theory which interprets this behaviour as resulting from three-body effects. In contrast, no such deviation is observed in Xe where, according to that theory, it should be more pronounced than in other substances. In the polar fluid CHF₃, the order parameter, isothermal compressibility and the chemical potential along the critical isotherm were simultaneously measured in the same experiment in an effort to ensure self-consistency of the results. From the data, two amplitude ratios which are predicted to be universal are determined: Γ+⃘ /Γ-⃘= 4.8 ± 0.6 and D⃘Γ+⃘B⃘δ-₁ = 1.66 ± 0.14. In the binary liquid system nicotine + water, the diffusivity was measured both by light scattering and by interferometry. The results agree qualitatively, but differ by a factor of ≈ 2. From the light scattering data, the critical exponent of the viscosity is found to be zη = 0.044 ± 0.008. The interferometric experiments on Xe and He-Xe furnish a direct way to maesure the effects of wetting: From the data, the exponent of the surface tension is found to be n = 1.24 ± 0.06. The similarity of the order parameter and compressibility in Xe and a He-Xe mixture containing 5% He indicate that the phase transition in this He-Xe mixture is of the liquid-gas type rather than the binary liquid type.
Science, Faculty of
Physics and Astronomy, Department of
Graduate

This thesis contains details of experiments involving the use of supercritical fluids (SCF) and high pressure liquids acting as antisolvents and transport media. The thesis is divided into six Chapters, each detailing different aspects of SCF technology. Chapter 1: Provides the reader with general information concerning the properties of supercritical fluids. Information is given concerning the use of SCFs as solvents and antisolvents. Reviews of the PCA and GAS processes are also provided. Chapter 2: Describes the initial study of the preparation of C60(gas) intercalation compounds. PCA generates compounds of C₂H₄, C₂H₆, C₃H₆ and C₃H₈, which were characterised by JR. A novel GAS technique is used to allow collection of PXD, SEM and MAS ¹³C NMR data of these compounds. Chapter 3: Details a novel supercritical antisolvent technique which allows the generation of macroscopic crystals of intercalate species C60(C₂H₄) and C60(C₂H₆). Crystallographic data on these compounds is presented. Datasets for the intercalates C60(CO₂), C70(C₂H₆) and C70(CO₂) were also collected. Chapter 4 Contains preliminary information on the formation of ‘nanopeapods', that is, carbon nanotubes filled with C60. A new route to the formation of these materials at room temperature is shown. Chapter 5: Describes the impregnation of mesoporous silica with aluminium containing species using SCF as a solvent. Materials display unprecedented stability to steaming with high retention of structural ordering and surface area. Chapter 6: Describes the extraction of template molecules from mesoporous silica. The possibility of complete removal of surfactant using a SCF is shown. The effect of temperature and pressure effects are also measured. Appendices are available at the back of the thesis to describe the equipment, analytical techniques and some safety principles for use of SCF.

Les zones de failles concentrent la migration de fluides et la déformation dans la croûte supérieure. Les propriétés hydrauliques des formations argileuses en font des excellents sites de stockage et des roches mères performants. Les zones de failles peuvent jouer deux rôles contraires dans la circulation de fluides, soit elles s’expriment sous forme de drains, soit elles constituent une barrière, et souvent les deux rôles sont combinés au sein d’une même zone de failles. Les processus de migration des fluides dans les zones de failles affectant les argiles sont peu connus. Cette étude s’est focalisée sur la structure, les paléo-circulations, les circulations actuelles lors de tests d’injection et les propriétés pétro-physiques de la zone de failles présente dans le laboratoire de recherche souterrain de Tournemire dans les argilites Toarciennes. La structure de la zone de failles a été caractérisée par des forages et reconstituée en 3D par modélisation numérique, permettant de définir des faciès de déformation. L’architecture de la zone de failles se caractérise par une imbrication de facies de déformations plus ou moins intenses sans claire organisation en cœur et zone endommagée comme observée dans les roches plus dures. Les zones intactes, fracturées et les brèches sont respectivement caractérisées par des porosités matricielles comprises entre 9.5-13.5, 10-15 et 13-21%. La circulation de fluide se concentrant aux limites de la brèche et au niveau des zones de failles «immatures» ou secondaires comprises dans les zones fracturées. Lors de son activité, la zone de failles a déjà été affectée par au moins deux phases de circulations de fluides
Fault zones concentrate fluids migration and deformations in the upper crust. The shale hydraulic properties make them excellent storage sites and hydrocarbon reservoirs/source rocks. Fault zones can play two roles in the fluid circulation; drains or barriers, in general, both roles are combined within the same fault zone. What are the conditions that promote the fluid circulation along the fault zones in shales and what are the fault zone impacts on the formation properties are relatively poorly explored key questions. This study focused on characterizing the relationships between fault architecture, paleo-fluid as well as current fluid circulations through the analysis of fault calcite mineralization, injection tests and petrophysical properties conducted on a fault zone outcropping underground in the Tournemire research laboratory nested in the Toarcian shale. The fault zone structure was characterized using boreholes data and reconstructed in 3D through modeling to define different deformation facies. No clear facies organization is observed, a fault core and a fault damage zone being difficult to define as it is in hard rocks. The intact, fractured and breccia facies are characterized by a porosity of 9.5-13.5, 10-15 and 13-21%. Large fluid flowrate concentrated along a few “channels” located at the breccia boundaries and in the secondary fault zones that displayed fractured facies and limited breccia fillings. Detailed microstructural and geochemical analysis at the breccia/fractured zones interface revealed that fluids circulated out of the main shear zones, in micro-more or less inherited fractures highlighting a decoupling between fault slip and fluid migrations

Soliton solutions of Einstein's field equations for space–times with two non-null, commuting Killing Vectors are exact solutions obtained using the solution-generating techniques that resemble the well-known Inverse Scattering Methods that have been widely used m the solution of certain nonlinear PDE's such as Korteweg–de Vries, Sine–Gordon, non-linear Schrödinger. There exist two main soliton techniques in General Relativity. The Belinski–Zakharov technique allows for purely gravitational solutions. The Alekseev technique allows for solutions of the Einstein–Maxwell equations. In both techniques, solitons arise in connection with the poles of a certain so-called "dressing matrix".

This thesis examines the dynamics and physical properties of the rough hard sphere fluid (RHSF). The RHSF model consists of spherical particles with well-defined radii that exchange linear and angular momenta upon collision. The simplicity of this model allows for a precise theoretical description that provides a basis for studying fluid properties on the most fundamental level. Extensive molecular dynamics calculations were made of transport properties as functions of density, tracer particle size, and degree of rotational-translational coupling. Results were compared with the smooth hard sphere case and it was found that transport coefficients change significantly due to rotational-translational coupling, becoming stronger with an increase in coupling. Tracer diffusion coefficients were examined for a range of tracer sizes and at various densities. As tracer particles become larger, their diffusion coefficient moves from an Enskog (molecular) to a Stokes-Einstein (hydrodynamic) functional form; the latter depends upon the boundary condition at the surface of the tracer. These boundary conditions for the RHSF are directly proportional to the degree of rotational-translational energy exchange, and can be tuned from "slip" to "stick" values. The validity of several kinetic theory equations have been examined as functions of density and translational-rotational coupling. At very low densities, Boltzmann theory was accurate even at low order except for describing the dependence upon rotational-translational coupling, where low order expansions are less accurate. Enskog theory performed well at low and moderate densities but deviated at larger densities, as expected. For thermal conductivity as a function of translational-rotational coupling even the qualitative behavior was incorrect. The Enskog predictions for diffusion were also found to be quite poor at low order. Finally, motivated by the results of the thesis, experimental diffusion coefficient data were analyzed, especially for nanoparticles. It was shown that defining the correct radius is crucial for describing such systems. In addition, a new formula for predicting tracer diffusion was tested.

Tight gas-condensate reservoirs contain large reserves, but can be extremely costly to develop. Understanding the fundamental controls on the fluid flow behaviour of tight gas and gas-condensate reservoirs has the potential to result in more cost-effective reservoir development and help increase the world's producible reserves. Therefore, the principal objective of the thesis is to improve understanding of multiphase flow within tight gas-condensate reservoirs. In order to achieve this objective a series of pore-to-core scale experiments under controlled conditions were performed, followed by numerical simulation. Three methodologies were used in this study: First, pore-scale experiments in glass micromodels with liquid-liquid systems were performed to improve understanding of the phase separation and flow mechanisms at pore level. Second, coreflood experiments were performed while in-situ saturation was monitored using an X-ray C'I' -scanner. A newly developed liquid-liquid system was used in these experiments. Flow through tight gas sandstones allowed the determination of relative penneabilities as well as determining their dependence on absolute permeability and capillary number. Third, production simulation modelling has been conducted to investigate the implications of the results. The micromodel experiments have proved extremely useful for characterizing the flow behaviour . of condensate systems. The results showed that the flow mechanisms and phases' distributions were affected largely by interfacial tension, pore structure and wettability.

The phase and volumetric behaviour of reservoir fluid properties, referred to as pressure-volumetemperature (PVT) properties, involve the thermodynamic studies of the fluid with respect to pressure, temperature and its volumetric compositions. PVT properties are usually determined by laboratory experiments performed on the actual samples of the reservoir fluid. Failing that, these fluid properties have been evaluated by some other methods such as equations of state, empirical correlations and recently, machine learning models. Machine learning is basically the prediction of the future with, (supervised learning), or without, (unsupervised learning), prior knowledge of the past. A common problem for the standalone machine learning technique is local minimum. In view of this, ensemble systems and hybrid techniques have been developed successfully for improvement in different fields. This work introduces two different ensemble methods based on support vector regression and regression trees where both ensemble approaches utilise a novel concept tagged "Tying Ranking" in selection of the base models. Also, a hybrid system for reservoir fluid characterisation with a novel way of grouping petroleum fluid properties using intelligent method was developed. The hybrid system uses K-Means clustering for the intuitive grouping along with functional networks for the prediction. The performance and generalisation of the developed models are compared against their standalone and selected empirical models using some statistical measures which are commonly used for performance evaluation in the petroleum industry. In the first category of experimentation, the impact and effect of training the machine learning models with more diverse and bigger data set is shown. Effects of using different functional forms to predict dead oil, saturated and undersaturated viscosity are also explored. In addition, impacts of different statistical measures on the predicted outputs and wrong interpretations of results in the literature are examined. The main statistical measures that are used for comparison are root mean squared errors, average absolute percentage relative error and maximum absolute percentage relative error. For each of the reservoir fluid properties considered in this work, at least one or more of the developed machine learning models have better overall and average performance than all the compared correlations in each category. The superiority of the three developed machine learning models is visible in the trend analysis as they show less deviations in results compared to the empirical correlations and their standalone methods in most cases for all the considered reservoir fluid properties.

'Fluid gel' consists of gel particles in a non-gelling medium and its particles are able to mimic fat globules and their bulk rheological behavior in emulsions based food products. The formation of single single polysaccharide fluid gel structure has been well described in the literature. However, mixed fluid gels have a potential of greater control over texture and in use performance but mechanisms governing their structure formation are not very well understood yet. This research aims to contribute to this understanding by investigation of structure formation of mixed fluid gels formed from various red algal polysaccharides, starch and its derivatives. A combination of rheological, calorimetric and optical microscopy analysis were used to investigate how presence of an additional co-solute and manipulation of process parameters during gelation (shear rate and the cooling rate) impact on final structure and rheological properties. It was observed that mixed fluid gel structures were formed as a result of physical entrapment of additional co solute. If gelation of the red algal polysaccharide occurred, the size of formed aggregates decreased with a decrease in red algal polysaccharide charge density. Applied shear rate was more effective structure modifier in mixtures with starch, whereas cooling rate in mixtures containing maltodextrin.

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 90-92).
We explore a non-contact method to measure changes in fluid properties by analyzing refractive motion in high speed video. We present a method of extracting fluid properties by performing video motion analysis using an automated wavelength matching filter followed by fitting of the measurements to theoretical capillary-gravity wave dispersion equations. This method requires an understanding of how field of view, refraction, and parallax affect measurements. We tested the method by analyzing trends in the surface tension to density ratio for cooling water, and for water versus glycerol.
by Victoria Allyce Gunning.
M. Eng.

A requirement for thermophysical property data of diesel fuels at conditions removed from ambient was identified. A series of measurements of the pressure-volume-temperature relations of diesel fuels was undertaken using a Micro-PVT apparatus at pressures to 300MPa in the temperature range 25 to 75°C. A new calibration procedure for this instrument was devised to enable measurements of high accuracy to be made. Viscosity measurements of diesel fuels over a range of temperature and pressure were made using the National Engineering Laboratory high pressure viscometer to pressures of 460MPa in the temperature range 25 to 100°C.Corresponding states theory was applied for compressed liquid density prediction. Improvement in density prediction in this region was found through use of iso-octane and heptadecane as reference fluids. Compressibility factors of these were represented by Tait-style equations. An iterative solution technique was developed to allow the corresponding states method to be applied to diesel fuelsusing limited density measurement and a guess value of boiling point as inputs. Densities predicted from this method agreed well with measurements made using the Micro-PVT apparatus. Hard sphere theory was applied as a method for viscosity prediction. Despite the complexity of the diesel fuel mixture, reasonable estimates of viscosity were made with limited measurement input at higher temperatures. At lower temperatures, an additional simple empirical correction term was required. A method of viscosity estimation of complex hydrocarbon mixtures based upon composition is presented. Further development of this would require additional measurements and greater characterisation of the fuel.

Quantification of the fluid flow properties of the Earth's crust is an essential precursor to the understanding of a wide range of geological processes, including earthquake generation and crustal strength, and the recovery of natural resources. Faults playa key role in the migration of fluids around the ;Earth's crust, and therefore the fluid flow properties of fractured rocks and how these properties evolve with time are of major importance. This thesis aims to improve our understanding of the hydraulic transport properties of large fault zones by presenting a large dataset of detailed field and microstructural observations and results from a suite of laboratory experiments to provide a basis for studying the distribution, and fluid flow properties, of damage surrounding large natural fault zones. Damage surrounding the core of faults is represented by both microfracturing of the rock matrix and by macroscopic fracture networks. Microfracture and macrofracture densities and orientations have been analysed on strike slip faults with displacements ranging over 3 orders of magnitude (~O.l2 m - 5000 m). These faults cut crystalline rock within the excellently exposed Atacama Fault Zone, Northern Chile. All faults consist of a fault core and associated damage zone. Damage zone width as defined by macrofractures and microfractures scale with displacement and fault length. Both microfractures (specifically fluid inclusion planes) and macrofractures within the damage zone show a log-linear .decrease in fracture density with perpendicular distance from the fault core. An empirical equation for microfracture density distribution based on the evolution of displacement has been derived for these faults. Preferred microfracture orientations in the damage zone suggest that this damage may predominantly be due to early processes related to enhanced stress at fault tips, in addition to cumulative wear processes from the juxtaposition of geometrical irregularities on the fault plane and damage from dynamic rupture. Fault core widths scale with displacement, with the largest displacement fault showing a wide multiple core zone. Detailed experimental studies of the development of permeability of crustal rock during deformation are essential in helping to understand fault mechanics and constrain larger scale models that predict bulk fluid flow within the crust. The strength, permeability and pore fluid volume evolution of initially intact crystalline rock under increasing differential load leading to macroscopic failure has been determined at water pore pressures of 50 MPa and varying effective pressures from 10 to 50 MPa. Permeability is seen to increase by, up to, and over two orders of magnitude prior to macroscopic failure, with the greatest increase seen at lowest effective pressures. Post-failure permeability is shown to be over three orders of magnitude higher than initial intact permeabilities and approaches the lower the limit of measurements of in situ bulk crustal permeabilities. Increasing amplitude cyclic loading tests show permeabilitystress hysteresis with high permeabilities maintained as differential stress is reduced and the greatest permeability increases are seen between 90-99% of the failure stress. Under hydrothermal conditions without further loading, it is suggested that much of this permeability can be recovered by healing and sealing, and pre-macroscopic failure fracture damage may heal relatively faster than post-failure macroscopic fractures. Pre-failure permeabilities are nearly seven to nine orders of magnitude lower than that predicted by some high pressure diffusive models suggesting that microfracture matrix flow cannot dominate, and agrees with inferences that bulk fluid flow and dilatancy must be dominated by larger scale structures, such as macrofractures. It is suggested that the permeability of a highly stressed fault tip process zone in low-permeability crystalline rocks could increase by more than 2 orders of magnitude, while stress drops related to fracture propagation close damage zone cracks, and some permeability is maintained due to hysteresis from permanent microfracture damage. Future work should aim to quantify experimentally-induced microfractures and. associated permeability measurements, and by relating the fracture densities surrounding natural fault zones with densities seen in experimental deformed samples with known permeabilities, modelling techniques can then be applied to gain estimates of bulk fluid flow of the fracture networks. This will provide a basis for predicting the influence of pore fluid pressures on important geological issues, such as crustal strength.

Experimental investigation of phase equilibria at supercritical fluid conditions was carried out for four binary mixtures and two ternary mixtures consisting of supercritical carbon dioxide and aromatic compounds (naphthalene, biphenyl, m-terphenyl and phenanthrene). A new technique, the first freezing point method, was developed in this study to determine the pressure-temperature (P-T) projection of the solid-liquid-gas (S-L-G) three-phase coexistence curves for binary and ternary mixtures at supercritical fluid conditions. In addition, the equilibrium liquid compositions along the three-phase coexistence curves were also determined. A temperature minimum in the P-T projection of the three-phase coexistence curve was observed for each of the binary mixtures. The liquid-gas (L = G) critical loci of two binary mixtures consisting of super-critical carbon dioxide and a solid (naphthalene or biphenyl) were determined. The bubble-point pressures along three isotherms as well as the solubilities of carbon dioxide in liquid naphthalene and biphenyl were also measured. By means of the intersection method, the upper critical end points (UCEP) were established to be 333.4 K, 25.9 MPa and 0.16 mole fraction of naphthalene for naphthalene-carbon dioxide mixture and 328.5 K, 48.5 MPa and 0.18 mole fraction of biphenyl for biphenyl-carbon dioxide mixture. A "crossover region" was found in the study of isothermal solubilities of super-critical CO$\sb2$ in liquid biphenyl at a pressure of about 36 MPa. Below the crossover region pressure, an increase in temperature caused a decrease in solubility of carbon dioxide in the liquid phase, while above the crossover region pressure the opposite effect occurs. A rational explanation was given. The P-T projection of the solid 1-solid 2-liquid gas (S$\sb1$-S$\sb2$-L-G) four-phase coexistence curve of two ternary mixtures--naphthalene-biphenyl-carbon dioxide and naphthalene-phenanthrene-carbon dioxide--were determined. The results indicate that the assumption of an unchanged eutectic composition of the solids with pressure may lead to a not negligible error in the measurements. The freezing point depression of the solid under the pressure of a supercritical solvent and the solubility behaviour in the vicinity of the lower critical end point (LCEP) and the UCEP were explored and discussed. The slopes of the depression curves at the triple points of the solids were predicted. Two different approaches, based respectively on the compressed gas model (equation of state) and the expanded liquid model (activity coefficient model), were developed to describe the S-L-G three-phase equilibria and the solubilities of supercritical carbon dioxide in the melted solids. Using the Peng-Robinson equation of state with the modified correction factors, $\alpha$, together with the composition-dependent mixing rules, the correlations of the experimental results were accomplished with satisfactory accuracy. The merits of these two approaches in the representation of the S-L-G three-phase equilibria were compared.

The magnetic particle inspection (MPI) method is a widely used non destructive testing (NDT) technique for ferrous structures. Magnetic inks used in MPI are suspensions of fine ferro/ferrimagnetic particles which, when applied to a magnetized test specimen, delineate surface flaws. This work is an investigation of some of the properties of magnetic ink systems and some aspects of their interaction with defect leakage flux. Reviews of magnetism, the MPI method and leakage flux at defects are given. The construction, characterization and automation of a 1.2 T electromagnet vibrating sample magnetometer, used for magnetic measurements on the inks, is described. The instrument has a resolution of better than l0(^-9) JT(^-1) . A 2D model of indication formation in MPI, based upon the simulation of many particles in the neighbourhood of a defect, is presented. Results of the role of several of the model parameters are given. Results indicate that carrier coefficients of viscosity at the lower end of the range investigated (η = 0.3 mPas) are optimum. The size and contrast of an indication increases with defect size. The contrast and rate of formation of contrast increase with defect aspect ratio. The effect of the contrast paint layer thickness indicates that the recommendation of the British Standard, BS 5044 (1973), is qualitatively correct. Experimental observations of particles in field gradients reveals a discrepancy between theoretical and observed behaviour which is attributed, in particular, to unobservable voids in the particles. Detailed characterization of the particles shows them to be aggregates of 20 - 200 nm crystallites which are probably single domain particles. The morphology of larger aggregates is related to measurements of the low field susceptibility. Evidence from intensive magnetic measurements supports the relationship between magnetic properties and aggregate characteristics. A 'In t' magnetic viscosity effect is reported. At 77 K, the coefficient of magnetic viscosity has a maximum near the coercivity field.

Water is a fundamental part of life as we know it, and by that also a fundamental for biology, chemistry, and parts of physics. Understanding how water behaves and interacts is key in many fields of all these three branches of science. Numerical simulation using molecular dynamics can aid in building insight in the behavior and interactions of water. In this thesis molecular dynamics is used to simulate common rigid 3 point water models to see how well they replicate certain physical and chemical properties as functions of temperature. This is done with molecular dynamics program GROMACS which offers a complete set of tools to run simulations and analyze results. Everything has been automated to work with a python script and a file of input parameters. Most of the models follow the same trends and are valid within a limited temperature range.
Vatten är en av de fundamentala byggstenarna för liv, därmed är det även fundamentalt för biologi, kemi och delar av fysiken. Att förstå hur vatten beter sig och interagerar är en stor fråga inom dessa tre grenar av vetenskap. Med molekyldynamik går det att utföra numeriska simuleringar som kan användas som hjälpmedel för att bygga en djupare förståelse för riktigt vatten. I den här uppsatsen så har molekyldynamik använts till att simulera vanliga rigida 3 punkts parametiseringar av vatten för att se hur bra de kan replikera vissa egenskaper som funktioner av temperatur. Simuleringen är gjord med hjälp av molekyldynamik programet GROMACS som ger en fullständig uppsättning verktyg för att simulera och analysera molekylsystem. Alla simuleringar och analys är automatiserat med ett pythonprogram och en fil för parametrar. De allra flesta modeller följer liknande trender och är giltiga inom små temperaturintervall.