[No abstract available] / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

This thesis examines the reactions of hydrocarbons exposed to chlorosulfonic acid in order to establish the reaction rate and associated molecular structure of each compound.

NMR methods have been designed and employed in studying ofcomplex liquids and solids formed by surfactants. PGSE NMRexperiments are easily biased by convection; this artifact canbe avoided by changing the sample holder and by usingconvection-compensated pulse sequences. The temperaturedistribution within samples was controlled using thetemperature dependent order parameter for CBr2H2dissolved in a thermotropic nematic solvent.Electronic ringing that often spoils accurate NMR experimentsfor broad lines was removed by the using composite pulses andquadrupole echo sequences with appropriate phase cycles. Field-dependent81Br and35Cl NMR relaxation studies in micellar solutions ofC16TAX surfactants showed that the structure ordynamics of the hydration shell is more influenced by thesurfactant cation for bromide than for chloride, in agreementwith their position in the Hoffmeister series. The presence ofa small but significant frequency-dependent relaxation showedthat the lateral self diffusion of the anions may be reduced ascompared to its bulk value in diluted solutions but only with afactor of 1.0 - 2.5. The ions are clearly not "bound" to thesurface. A field-dependent2H NMR relaxation study on the CTABr-α-d2and benzene-d6showed an initial one-dimensional micellargrowth followed by the appearance of microemulsion droplets onaddition of benzene. The local mobility of the benzene wasreduced when solubilized in small amounts, consistent with aninitial average location of benzene at the micellar interface.The surfactant diffusion coefficients fromconvection-compensated PGSE NMR experiments in the C12E8-D2O system showed monotonous growth of the micellesupon increasing temperature. Emulsion droplets in the C12E5-decane-D2O system where shown to coarsen according to theOstwald ripening theory after being brought out of equilibriumby a temperature drop. X-ray scattering and2H NMR line-shape and relaxation experimentssuggested that complex solids formed by a partly-sulfatedpolysaccharide and CnTAB exhibit regular ordering at both microscopicand mesoscopic length scales. <b>Keywords</b>: CTAB, CTAC, C12E8, C12E5, decane, benzene, CBr2H2, polysaccharide, micelle, microemulsion, emulsion,Ostwald ripening, NMR,81Br,35Cl,2H, field- dependent spin relaxation, PGSE, selfdiffusion, convection, ringing, thermometer, generalized Blochequations, EXORCYCLE, quadrupole echo, SAXS, WAXS, cryo-TEM.

<p>NMR methods have been designed and employed in studying ofcomplex liquids and solids formed by surfactants. PGSE NMRexperiments are easily biased by convection; this artifact canbe avoided by changing the sample holder and by usingconvection-compensated pulse sequences. The temperaturedistribution within samples was controlled using thetemperature dependent order parameter for CBr₂H₂dissolved in a thermotropic nematic solvent.Electronic ringing that often spoils accurate NMR experimentsfor broad lines was removed by the using composite pulses andquadrupole echo sequences with appropriate phase cycles.</p><p>Field-dependent⁸¹Br and³⁵Cl NMR relaxation studies in micellar solutions ofC₁₆TAX surfactants showed that the structure ordynamics of the hydration shell is more influenced by thesurfactant cation for bromide than for chloride, in agreementwith their position in the Hoffmeister series. The presence ofa small but significant frequency-dependent relaxation showedthat the lateral self diffusion of the anions may be reduced ascompared to its bulk value in diluted solutions but only with afactor of 1.0 - 2.5. The ions are clearly not "bound" to thesurface. A field-dependent²H NMR relaxation study on the CTABr-α-<i>d</i><i>2</i>and benzene-<i>d</i><i>6</i>showed an initial one-dimensional micellargrowth followed by the appearance of microemulsion droplets onaddition of benzene. The local mobility of the benzene wasreduced when solubilized in small amounts, consistent with aninitial average location of benzene at the micellar interface.The surfactant diffusion coefficients fromconvection-compensated PGSE NMR experiments in the C₁₂E₈-D₂O system showed monotonous growth of the micellesupon increasing temperature. Emulsion droplets in the C₁₂E₅-decane-D₂O system where shown to coarsen according to theOstwald ripening theory after being brought out of equilibriumby a temperature drop. X-ray scattering and²H NMR line-shape and relaxation experimentssuggested that complex solids formed by a partly-sulfatedpolysaccharide and C_nTAB exhibit regular ordering at both microscopicand mesoscopic length scales.</p><p><b>Keywords</b>: CTAB, CTAC, C₁₂E₈, C₁₂E₅, decane, benzene, CBr₂H₂, polysaccharide, micelle, microemulsion, emulsion,Ostwald ripening, NMR,⁸¹Br,³⁵Cl,²H, field- dependent spin relaxation, PGSE, selfdiffusion, convection, ringing, thermometer, generalized Blochequations, EXORCYCLE, quadrupole echo, SAXS, WAXS, cryo-TEM.</p>

Carbon capture and sequestration are considered to be a temporary fix to the climate change global crisis. Following the noble gas tracers injection field experiment at Salt Creek in the state of Wyoming, USA, these tracers may be used to characterise the reservoir as a potential geological sequestration site for carbon dioxide. This study aims to investigate various thermodynamics properties of the five noble gases (Xe, Kr, Ar, Ne, and He) in n-decane at reservoir conditions (340 K – 460 K and 10 MPa – 200 MPa). The study utilises the SKS force field to describe n-decane and both Gibbs Ensemble Monte Carlo and molecular dynamics simulations were used to investigate the solubility, diffusivity, and vapour-liquid equilibrium of the five binary mixtures. The size of the noble gases was found to be important in these nonpolar mixtures where typical interactions are weak and short-ranged. The enthalpies of solvation were calculated and found to be directly correlated to the size of the solute where the energy required for the formation of a cavity to accommodate the solute is compensated by the nature of the intermolecular interaction between solvent and solute. The mixture of Ar + n-decane is of interest particularly because the sigma value for Ar is very similar to that of the CH3 group, resulting in the overall non-mononicity of several thermodynamics properties. Additionally, maxima in enthalpies of solvation were observed in Xe and Kr in n-decane solution at 200 MPa. While these maxima were observed in two different species at similar conditions, they are accommodated by unusually high uncertainties - further investigation is required before definitive conclusions can be drawn. The results from the vapour-liquid equilibrium study of the five noble gas + n-decane binary mixtures were in good agreement with the Peng-Robinson equation of state predictions. What is more, the diffusion coefficient ratios amongst the five noble gases in n-decane were investigated in light of Stoke-Einstein’s relation and Enskog’s hard-sphere relation. Three different radii of solute-solvent interaction were investigated and the best fit was observed when R =radius of solute + radius of gyration of n-decane. Additionally, the diffusion coefficients were utilised in the reservoir simulation to investigate the role of diffusion within the reservoir.

This study investigates the factors that affect the lifetime and popping location of surface bubbles. The experiment was conducted using three different liquids (water, Sodium Dodecyl Sulfate, and Decane) with varying bubble sizes, using three different needle sizes. Each setup was tested 50 times. For pure water bubbles, the foot of the bubble is the most critical location because it typically has the highest temperature gradient, which creates a localized Marangoni flow that thins the film and eventually leads to the bubble bursting at the foot. When SDS was added to water, the bubble lifetime increased significantly. This is because the Marangoni stresses were reduced, and the bubble film thinned mainly due to curvature-driven drainage flow. The lifetime of the SDS bubble had a positive correlation with increasing bubble size. For Decane bubbles, the volatility of the liquid plays a significant role in the lifetime and popping location of the bubble. When the Decane was heated to 40°C, the lifetime of the bubbles increased significantly from 0-20 seconds to 8-12 minutes. This is because the high volatility of the Decane caused rapid evaporation of the bubble cap at the interface, which cooled the surface of the liquid. This temperature difference creates a difference in surface tension, which causes the liquid to flow from the bulk liquid into the apex of the bubble, thickening the cap film until it cools down. Then, it pops from the top due to the curvature-driven drainage.

No description available.

Pour répondre aux défis environnementaux actuels, des solutions en rupture par rapport aux turbomachines existantes sont actuellement encours de développement. Elles s’appuient sur des cycles thermodynamiques plus efficients.L’objectif de ces travaux de thèse est d’étudier expérimentalement les mécanismes de transition de régime de combustion pour ce type d'applications en utilisant un surrogate de kérosène, le n-décane. Pour cela, une déflagration est initiée dans une enceinte fermée et comprime les gaz frais. La pression et la température de ces derniers augmentent jusqu’à atteindre les conditions propices à l’apparition de l’autoinflammation.3 régimes de combustion successifs sont caractérisés dans la chambre de combustion au moyen de diagnostics optiques rapides. Un premier dégagement de chaleur associé à la flamme froide pré-oxyde les gaz frais, il est suivi du dégagement de chaleur principal (Main Heat Release,MHR). Pour les températures initiales de mélange les plus élevées, une détonation est observée à la fin du processus. Deux chemins de transition différents sont mis en évidence : la transition Déflagration-Auto-inflammation (DAIT) et la transition Déflagration-Auto-inflammation-Détonation (DAIDT). La sensibilité des transitions de régime aux conditions initiales de pression, de température et de richesse a été caractérisée au moyen de plusieurs études paramétriques. Dans ce but, les conditions de température, de pression et de composition du mélange sont calculées aux instants d’apparition des différents fronts réactifs (flamme froide, MHR et détonation). Il a notamment été observé que les dégagements de chaleur successifs de l’auto-inflammation se déroulaient aux mêmes températures (740 K pour la flamme froide et 1050 K pour le MHR)quelles que soient les conditions initiales. L’étude s’est concentrée ensuite sur l’analyse d’un point de fonctionnement particulier. L’étude de ce point de fonctionnement, différents vitesses de front d’auto-inflammation ont été observées, mettant en évidence le mécanisme de SWACER lors de la transition.Un critère de transition de régime depuis l’auto-inflammation proposé de Zander et al., dans le cadre d’études numériques, a été testé dans notre configuration expérimentale. Un critère modifié a été développé en lui adjoignant la notion d’effets de compressibilité dans l’écoulement réactif. L’application de ce critère à l’ensemble des essais permet de prédire l’apparition de la détonation dans les conditions où 0 et 100 % de DAIDT sont observés. Les différents domaines de transition de régime ont également été positionnés sur le diagramme de Bradley (ξ, ϵ). Les modes de combustion prédits par le diagramme sont consistants avec ceux qui sont atteints dans la chambre.L’influence de la distribution initiale de température sur les modes de combustion atteignables dans la chambre a été étudiée. Trois topologies d’auto-inflammation ont été mises en évidence pour trois distributions de température dans la chambre. Ces topologies sont séparées en deux catégories, celles privilégiant une direction particulière lors de l’auto-inflammation séquentielle et celle présentant un comportement tridimensionnel.Les essais ayant un comportement tridimensionnel présentent une très forte propension à la DAIDT mais une propagation lente des fronts d’auto-inflammation. Dans ce cas, un autre mécanisme de transition vers la détonation est mis en évidence : l’auto-inflammation d’une poche homogène de gaz génère des ondes de choc et déclenchent des auto-inflammations successives pendant leur propagation. Le couplage choc/front réactif entraine la formation de la détonation.Différents mécanismes de transition vers la détonation ont été observés et étudiés sur une large plage de conditions de pression, température,richesse et gradient thermique. Les résultats obtenus permettront d’appuyer les études numériques réalisées sur le sujet, manquant jusque-là de données expérimentales en conditions académiques. / To meet the current environmental challenges, breakthrough solutions compared to existing turbomachines are currently under development.They rely on the use of more efficient thermodynamic cycles.The objective of this thesis is to study experimentally the mechanisms of transition of combustion regime using a kerosene surrogate, n-decane.For this purpose, a deflagration is initiated in a closed chamber and compresses the fresh gases. The pressure and the temperature of the endgas increase until reaching the conditions favorable to the appearance of the autoignition in the chamber.3 successive combustion regimes are characterized in the combustion chamber by means of fast optical diagnostics. A first heat release,associated with the cool flame phenomenon, pre-oxidizes the fresh gases, it is followed by the Main Heat Release (MHR). For the highest initial temperatures, a detonation is observed at the end of the process. Two different transition paths are highlighted: the Deflagration-Autoignition Transition (DAIT) and the Deflagration-Autoignition-Detonation Transition (DAIDT).The sensitivity of regime transitions to the initial conditions of pressure, temperature and mixture composition was characterized by means of several parametric studies. For this purpose, the conditions of temperature, pressure and composition of the mixture are calculated at the onset of the different reactive fronts (cool flame, MHR and detonation). In particular, it has been observed that the successive heat releases of theauto-ignition start at the same temperatures (740 K for the cool flame and 1050 K for the MHR) whatever the initial conditions. The study, then, focused on the analysis of a particular operating point. During the study of this operating point different self-ignition front velocities were observed, highlighting the mechanism of SWACER during the transition.A regime transition criterion proposed by Zander et al. based on numerical studies has been tested in our experimental setup. A modified criterion has been developed to take into account compressibility effects in the reactive flow. The application of this criterion to all the dataset makes possible to predict the appearance of the detonation under the conditions where 0 and 100% of DAIDT are observed. The different regime transition domains have also been positioned on the Bradley diagram (ξ, ε). The modes of combustion predicted by the diagram are consistent with those reached in the chamber.The influence of the initial temperature distribution on the combustion modes achievable in the chamber has been studied. Three topologies of autoignition have been demonstrated for three initial temperature distributions in the chamber. These topologies are separated into two categories, those favoring a particular direction during sequential self-ignition and that exhibiting a three-dimensional behavior.Three-dimensional tests show a very high propensity for DAIDT but a slow spread of autoignition fronts. In this case, another mechanism of transition to detonation is evidenced: the self-ignition of an homogeneous gas pocket generates shock waves and triggers successive autoinflammations during their propagation. The shock coupling / reactive front causes the formation of the detonation. Different transition mechanisms to detonation have been observed and studied over a wide range of pressure, temperature, equivalence ratio and thermal gradient conditions. The obtained results will be useful to support the numerical studies carried out on the subject, which lacks experimental data in academic conditions.