Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 198-204). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 198-204). Also available on the Internet.

No description available.

Thesis (M.S. in environmental engineering)--Washington State University, May 2009. / Title from PDF title page (viewed on June 19, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 58-61).

The process of vapor extraction (VAPEX) is a recovery process which targets the heavy oil and bitumen resources. Owing to high viscosity values for these unconventional types of oil, the recovery processes in such reserves are still challenging. The unconventional oil recovery processes usually include a mechanism for reducing the oil viscosity by means of heat, solvent, or both. The process of VAPEX utilizes the injection of a light hydrocarbon solvent into a reservoir for recovering the viscous oil in place by diffusing into the oil and by providing sufficient mobility to the oil upon dilution. Although this process offers a variety of advantages over the alternative thermal recovery processes such as SAGD or CSS, it suffers from two major drawbacks. First, the oil production rates obtained in the VAPEX process are considerably lower than those obtained in the thermal processes. Second, the solvent cost is considerably high. We tried to tackle these two problems during this research and we searched for potentials for an improved VAPEX process. Three potentially improved occurrences of a VAPEX project were found when: 1) the injected solvent was superheated, 2) the wettability of media was altered to oil-wet, and 3) the vugs were distributed in the porous media. Warm VAPEX process is introduced in which the VAPEX process is thermally augmented through superheating the solvent vapor. An attractive feature of this process is the capability of the solvent in being able to condense at the bitumen-solvent interface, which provides the opportunity for the bitumen to be upgraded in-situ through asphaltene precipitation. The asphaltene precipitation was not observed during the conventional vapor extraction process and was only observed during the warm VAPEX process. Upon a moderate level of superheating, the production rate of bitumen was sufficiently improved while the solvent content of the produced oil was significantly decreased as a result of decreased solubility of solvent in the oil at elevated temperatures. Therefore, more oil was produced at lower costs. The warm VAPEX experiments were conducted at 4 temperature levels in high and low permeability media using Cold Lake bitumen and Lloydminster heavy oil blend, n-pentane was used as solvent. The warm VAPEX process was found to be more effective for Cold Lake bitumen and for less permeable media. The potential of in-situ upgrading decreased when the level of superheating increased. The second potential for an improved VAPEX process obtained when the wettability of porous medium was altered to oil-wet conditions. Although this wettability condition is harmful to steam-based recovery processes, such as SAGD, it becomes beneficial to VAPEX. For the application of VAPEX process in fractionally wet media the wettability of glass beads was altered to oil-wet conditions through silylation process, and the VAPEX experiments were conducted in a random packing of water-wet and oil-wet beads of similar size at 7 different compositions. A substantial increase in the oil production rate was observed in a completely oil-wet medium, compared to the water-wet medium. By increasing the fraction of oil-wet beads in the packing up to a critical composition, the production rate of live oil increased linearly with the increase in the fraction of oil-wet beads in the packing during the vapor extraction process. Beyond this critical composition, however, the production rate of live oil did not change significantly with further increase in the fraction of the oil-wet beads in the randomly packed medium. Vugs were also found to be beneficial to the production performance of the VAPEX process. The presence of vugs was investigated in synthesized vugular media at 4 different levels of vuggy-to-total pore volume ratios. The performance of vugular media was compared to that of the homogeneous sintered media. The vugs facilitated the production of oil during the VAPEX process by providing flow communication between the vugs and the surrounding matrix, and therefore, by providing a local high permeability pathways towards the production well. A peak in the oil production rate was observed whenever a series of vugs were simultaneously invaded by the solvent vapor. The overall production rate of oil was higher in vuggy media compared to a homogeneous media at the same overall porosity and permeability. Furthermore, the magnitude of residual oil saturation left behind was also slightly lower in vuggy medium because the vugs were perfectly drained. Finally, a constant rate air injection (CRAI) porosimetry method was developed for characterization of vugs in a vugular media. This method was successfully tested in different synthetic vugular media, and the results illustrated higher accuracy in CRAI porosimetry method compared to constant rate mercury porosimetry. CRAI porosimetry method was also employed for identification of higher permeability regions embedded in a matrix of lower permeability. The analysis of a typical porosimetry signal was also modified.

The process of vapor extraction (VAPEX) is a recovery process which targets the heavy oil and bitumen resources. Owing to high viscosity values for these unconventional types of oil, the recovery processes in such reserves are still challenging. The unconventional oil recovery processes usually include a mechanism for reducing the oil viscosity by means of heat, solvent, or both. The process of VAPEX utilizes the injection of a light hydrocarbon solvent into a reservoir for recovering the viscous oil in place by diffusing into the oil and by providing sufficient mobility to the oil upon dilution. Although this process offers a variety of advantages over the alternative thermal recovery processes such as SAGD or CSS, it suffers from two major drawbacks. First, the oil production rates obtained in the VAPEX process are considerably lower than those obtained in the thermal processes. Second, the solvent cost is considerably high. We tried to tackle these two problems during this research and we searched for potentials for an improved VAPEX process. Three potentially improved occurrences of a VAPEX project were found when: 1) the injected solvent was superheated, 2) the wettability of media was altered to oil-wet, and 3) the vugs were distributed in the porous media. Warm VAPEX process is introduced in which the VAPEX process is thermally augmented through superheating the solvent vapor. An attractive feature of this process is the capability of the solvent in being able to condense at the bitumen-solvent interface, which provides the opportunity for the bitumen to be upgraded in-situ through asphaltene precipitation. The asphaltene precipitation was not observed during the conventional vapor extraction process and was only observed during the warm VAPEX process. Upon a moderate level of superheating, the production rate of bitumen was sufficiently improved while the solvent content of the produced oil was significantly decreased as a result of decreased solubility of solvent in the oil at elevated temperatures. Therefore, more oil was produced at lower costs. The warm VAPEX experiments were conducted at 4 temperature levels in high and low permeability media using Cold Lake bitumen and Lloydminster heavy oil blend, n-pentane was used as solvent. The warm VAPEX process was found to be more effective for Cold Lake bitumen and for less permeable media. The potential of in-situ upgrading decreased when the level of superheating increased. The second potential for an improved VAPEX process obtained when the wettability of porous medium was altered to oil-wet conditions. Although this wettability condition is harmful to steam-based recovery processes, such as SAGD, it becomes beneficial to VAPEX. For the application of VAPEX process in fractionally wet media the wettability of glass beads was altered to oil-wet conditions through silylation process, and the VAPEX experiments were conducted in a random packing of water-wet and oil-wet beads of similar size at 7 different compositions. A substantial increase in the oil production rate was observed in a completely oil-wet medium, compared to the water-wet medium. By increasing the fraction of oil-wet beads in the packing up to a critical composition, the production rate of live oil increased linearly with the increase in the fraction of oil-wet beads in the packing during the vapor extraction process. Beyond this critical composition, however, the production rate of live oil did not change significantly with further increase in the fraction of the oil-wet beads in the randomly packed medium. Vugs were also found to be beneficial to the production performance of the VAPEX process. The presence of vugs was investigated in synthesized vugular media at 4 different levels of vuggy-to-total pore volume ratios. The performance of vugular media was compared to that of the homogeneous sintered media. The vugs facilitated the production of oil during the VAPEX process by providing flow communication between the vugs and the surrounding matrix, and therefore, by providing a local high permeability pathways towards the production well. A peak in the oil production rate was observed whenever a series of vugs were simultaneously invaded by the solvent vapor. The overall production rate of oil was higher in vuggy media compared to a homogeneous media at the same overall porosity and permeability. Furthermore, the magnitude of residual oil saturation left behind was also slightly lower in vuggy medium because the vugs were perfectly drained. Finally, a constant rate air injection (CRAI) porosimetry method was developed for characterization of vugs in a vugular media. This method was successfully tested in different synthetic vugular media, and the results illustrated higher accuracy in CRAI porosimetry method compared to constant rate mercury porosimetry. CRAI porosimetry method was also employed for identification of higher permeability regions embedded in a matrix of lower permeability. The analysis of a typical porosimetry signal was also modified.

Understanding the gas phase flow and transport of volatile organic compounds (VOCs) in unsaturated zones is indispensable to develop effective environmental remediation strategies, to create precautions for fresh water protection, and to provide guidance for land and water resources management. Atmospheric pressure and water table fluctuations are two important natural processes at the upper and lower boundaries of the unsaturated zone, respectively. However, their significance has been neglected in previous studies. This dissertation systematically investigates their influence on the gas phase flow and transport of VOCs in soil and ground water remediation processes using analytically and numerically mathematical modeling. New semi-analytical and numerical solutions are developed to calculate the subsurface gas flow field and the gas phase transport of VOCs in active soil vapor extraction (SVE), barometric pumping (BP) and natural attenuation taking into account the atmospheric pressure and the water table fluctuations. The accuracy of the developed solutions are checked by comparing with published analytical solutions under extreme conditions, newly developed numerical solutions in COMSOL Multiphysics and field measured data. Results indicate that both the atmospheric pressure and the tidal-induced water table fluctuations significantly change the gas flow field in active SVE, especially when the vertical gas permeability is small (less than 0.4 Darcy). The tidal-induced downward moving water table increases the depth-averaged radius of influence (ROI) for the gas pumping well. However, this downward moving water table leads to a greater vertical pore gas velocity away from the gas pumping well, which is unfavorable for removing VOCs. The gas flow rate to/from the barometric pumping well can be accurately calculated by our newly developed solutions in both homogeneous and multi-layered unsaturated zones. Under natural unsaturated zone conditions, the time-averaged advective flux of the gas phase VOCs induced by the atmospheric pressure and water table fluctuations is one to three orders of magnitude less than the diffusive flux. The time-averaged advective flux is comparable with the diffusive flux only when the gas-filled porosity is very small (less than 0.05). The density-driven flux is negligible.

PINHEIRO, Érika Sousa. Avaliação dos aspectos sensoriais, físico-químicos e minerais do suco de uva da variedade benitaka(Vitis vinìfera L.). 2008. 105 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Tecnologia de Alimentos, Fortaleza-CE, 2008 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-06-03T12:40:29Z No. of bitstreams: 1 2008_dis_espinheiro.pdf: 907413 bytes, checksum: 6cc1d45e191919db3c2814281a2ad765 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-06-03T12:40:43Z (GMT) No. of bitstreams: 1 2008_dis_espinheiro.pdf: 907413 bytes, checksum: 6cc1d45e191919db3c2814281a2ad765 (MD5) / Made available in DSpace on 2016-06-03T12:40:43Z (GMT). No. of bitstreams: 1 2008_dis_espinheiro.pdf: 907413 bytes, checksum: 6cc1d45e191919db3c2814281a2ad765 (MD5) Previous issue date: 2008 / The Brazilian market of table grapes is one of the markets fruit and vegetable that more it grew at the country. The grape is one of the fruits that presents considerable value nutritional, being rich in minerals, vitamins and phenolic compounds, it is also considered an energy food, in reason of the presence of sugars. There is an increase tendency in the production and in the consumption of due grape juice the several ones cultivate obtained and, also, due to the consumer's concern with the health. This work had as objective evaluates the stability of the grape juice obtained by the extraction process through vapor with relationships to the aspects chemical, physic-chemical and sensory, during a period of 210 days of storage at ambient temperature. We performed analyses of water activity, dry residue (%), pH, titrable acidity, soluble solids, color, total phenolics, total anthocyanins, sugars (reducers and total), minerals (K, Na, Ca, Cu, Mg, Mn, Fe and Zn) and sensory tests of acceptance of the grape juice. The results for water activity, dry residue, pH, total phenolics and total anthocyanins showed significant difference with the time of storage (p ≤ 0,05). With relationship to the analysis of minerals, the same ones came stable during the studied period. For the sensory attributes evaluated, only the acceptance of the color and appearance did not vary significantly with the time. The flavor, general impression, intensity of sweetness and natural flavor of grape, besides the purchase intention, they presented significant difference (p > 0,05). / O mercado brasileiro de uvas de mesa é um dos mercados hortifrutícolas que mais crescem no país. A uva é um dos frutos que apresenta considerável valor nutricional, sendo rico em minerais, vitaminas e compostos fenólicos, é também considerado um alimento energético, em razão da presença de açúcares. Há uma tendência de aumento na produção e no consumo de suco de uva devido a diversas cultivares obtidas e, também, devido à preocupação do consumidor com a saúde. Este trabalho teve como objetivo avaliar a estabilidade do suco de uva obtido pelo processo de extração por meio de vapor, quanto aos aspectos químicos, físicoquímicos e sensoriais, durante um período de 210 dias de armazenamento em temperatura ambiente. Foram realizadas análises de atividade água, resíduo seco (%), pH, acidez titulável, sólidos solúveis, cor, fenólicos totais, antocianinas totais, açúcares (redutores e totais), minerais (K, Na, Ca, Cu, Mg, Mn, Fe e Zn) e testes sensoriais de aceitação do suco de uva. Os resultados para atividade água, resíduo seco, pH, fenólicos totais e antocianinas totais apresentaram diferença significativa com o tempo de armazenamento (p ≤ 0,05). Com relação à análise de minerais, os mesmos apresentaram-se estáveis durante o período estudado. Para os atributos sensoriais avaliados, apenas a aceitação da cor e da aparência não variaram significativamente com o tempo. O sabor, impressão geral, intensidade de doçura e sabor natural de uva, além da intenção de compra, apresentaram diferença significativa (p > 0,05).

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / RESUMO O mercado brasileiro de uvas de mesa à um dos mercados hortifrutÃcolas que mais crescem no paÃs. A uva à um dos frutos que apresenta considerÃvel valor nutricional, sendo rico em minerais, vitaminas e compostos fenÃlicos, à tambÃm considerado um alimento energÃtico, em razÃo da presenÃa de aÃÃcares. Hà uma tendÃncia de aumento na produÃÃo e no consumo de suco de uva devido a diversas cultivares obtidas e, tambÃm, devido à preocupaÃÃo do consumidor com a saÃde. Este trabalho teve como objetivo avaliar a estabilidade do suco de uva obtido pelo processo de extraÃÃo por meio de vapor, quanto aos aspectos quÃmicos, fÃsicoquÃmicos e sensoriais, durante um perÃodo de 210 dias de armazenamento em temperatura ambiente. Foram realizadas anÃlises de atividade Ãgua, resÃduo seco (%), pH, acidez titulÃvel, sÃlidos solÃveis, cor, fenÃlicos totais, antocianinas totais, aÃÃcares (redutores e totais), minerais (K, Na, Ca, Cu, Mg, Mn, Fe e Zn) e testes sensoriais de aceitaÃÃo do suco de uva. Os resultados para atividade Ãgua, resÃduo seco, pH, fenÃlicos totais e antocianinas totais apresentaram diferenÃa significativa com o tempo de armazenamento (p ≤ 0,05). Com relaÃÃo à anÃlise de minerais, os mesmos apresentaram-se estÃveis durante o perÃodo estudado. Para os atributos sensoriais avaliados, apenas a aceitaÃÃo da cor e da aparÃncia nÃo variaram significativamente com o tempo. O sabor, impressÃo geral, intensidade de doÃura e sabor natural de uva, alÃm da intenÃÃo de compra, apresentaram diferenÃa significativa (p > 0,05). / ABSTRACT The Brazilian market of table grapes is one of the markets fruit and vegetable that more it grew at the country. The grape is one of the fruits that presents considerable value nutritional, being rich in minerals, vitamins and phenolic compounds, it is also considered an energy food, in reason of the presence of sugars. There is an increase tendency in the production and in the consumption of due grape juice the several ones cultivate obtained and, also, due to the consumer's concern with the health. This work had as objective evaluates the stability of the grape juice obtained by the extraction process through vapor with relationships to the aspects chemical, physic-chemical and sensory, during a period of 210 days of storage at ambient temperature. We performed analyses of water activity, dry residue (%), pH, titrable acidity, soluble solids, color, total phenolics, total anthocyanins, sugars (reducers and total), minerals (K, Na, Ca, Cu, Mg, Mn, Fe and Zn) and sensory tests of acceptance of the grape juice. The results for water activity, dry residue, pH, total phenolics and total anthocyanins showed significant difference with the time of storage (p ≤ 0,05). With relationship to the analysis of minerals, the same ones came stable during the studied period. For the sensory attributes evaluated, only the acceptance of the color and appearance did not vary significantly with the time. The flavor, general impression, intensity of sweetness and natural flavor of grape, besides the purchase intention, they presented significant difference (p > 0,05).

With continued development of the electronic industry, the demand for highly efficient heat removal solutions requires innovative cooling technologies. A computational fluid dynamic (CFD) study, including heat transfer, is performed for an axisymmetric, confined jet impingement experiencing boiling and coupled with vapor extraction. Boiling occurs at the target surface while extraction occurs at the wall confining the radial flow. The region between the target and confining wall is defined as a confined gap. Extraction is employed to enhance heat transfer and to minimize the potential negative influence of flow instabilities resulting from two-phase flow within a confined region. A three-dimensional sector of the confined jet is employed in the simulation. A single circular impinging jet with a constant jet diameter (4 mm) and variable gap height (0.5, 1.0 and 1.5 mm), also known as nozzle-to-target spacing, is considered. The effect of mass flux at the confined gap entrance is also investigated (200, 400 and 800 kg/m²-s) for a range of heat flux (5 to 50 W/cm²). Fluid flow and heat transfer are simulated using the Volume of Fluid (VOF) model and the wall-boiling sub-model within the Multiphase Segregated Flow (MSF) model. The boiling sub-model in the VOF model applies the Rohsenow boiling correlation, while in the MSF model, the Kurul-Podowski boiling sub-model is used. Also, vapor extraction is realized by different mechanisms for these two models. For the VOF model, a specific phase "wall porosity" can be assigned to a wall to make it porous. Over a range of pressure differentials across this porous wall such that the inertial transport influence is negligible, vapor transport should agree with Darcy's law. For the MSF model, a wall can be made permeability to one substance or phase while remaining impermeable to the other substance or phase. However, a portion of the substance or phase reaching the boundary allowed to pass through the surface must be specified. A pressure drop cannot be applied across the wall, thereby prohibiting Darcy flow modeling. The solutions of both models are at steady state. The boiling curves without vapor extraction from both models are provided and compared to experiments. Simulations matching experimental wall temperatures under-predict theoretical vapor generation and those matching vapor generation over-estimate wall superheat. For cases with no extraction, local temperature and velocity profiles from the VOF model are provided at several radial locations within the confined gap. Scalar temperature and pressure distributions and velocity vectors are presented to explain observations in profiles. / Graduation date: 2013