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Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 77-78). Also available on the World Wide Web.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1980.

Buildings are responsible for over a third of the energy consumption in the United States annually. This energy consumption contributes to some of the most pressing problems facing our society. Modeling of buildings and their systems is an integral part of most strategies for reduction of energy use in buildings. Modeling allows for informed building designs, optimization of systems, and greater market acceptance of new energy-saving technologies. This work addresses two particular modeling applications concerned with reduction of energy usage in buildings: convective heat transfer modeling in perimeter zones, and liquid desiccant dehumidification modeling. The first objective of this work is concerned with modeling convective transport in buildings and creation of inputs for energy modeling programs and passive pollutant removal calculations. This is accomplished through four investigations. In the first investigation, the influence of floor diffusers on convection heat transfer at perimeter zone windows in commercial buildings is measured. In the second, the impact of blinds on convection under a variety of circumstances is quantified. In the third, movement of air jets issuing from floor diffusers is predicted, and the effect of buoyancy on convective heat transfer at perimeter zone surfaces is analyzed. In the fourth investigation, convective mass transfer at indoor surfaces is investigated. Full scale experiments were conducted in support of these four investigations and semi-empirical correlations vii consistent with theory are given to predict jet movement and convective transport under a variety of circumstances. The second objective of this dissertation is concerned with modeling and analysis of liquid desiccant dehumidification systems and is pursued through three additional investigations. The first is concerned with modeling small-scale transport within the channels of a liquid desiccant absorber and regenerator. Physical and empirical models are developed which agree well with laboratory data. During the second investigation, a dynamic model of a liquid desiccant dehumidification system is developed and integrated into a full-building energy simulation. This is used to assess the potential applicability of the system in supermarkets in various climates. The models developed are used to optimize the system and develop a procedure to size components in the final investigation. / text

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The phenomenology of vertical two phase flow was examined / Thesis (Ph.D.)-University of Natal, Durban, 1984.

The industrial application of gas-liquid contactors has made effective design and optimisation of these processes a very important topic. In order to sustain a competitive advantage, rate limiting steps must be clearly understood. Hydrodynamics, heat transfer and mass transfer are complicated features of gas-liquid contactors and require a fundamental understanding. The mechanism of mass transfer in the presence of a small concentration of solid micro particles has been the subject of debate. The adsorption of gas by solid particles ("shuttle mechanism") is the traditional explanation. Recent experimental evidence suggests that the introduction of micro particles removes trace surface active impurities from the system and allows the true mass transfer coefficient to be measured. The objective of this study was to confirm the surfactant removal theory. Mass transfer is a field characterised by imprecise empirical relationships and difficult to obtain experimental parameters. This puts into context the significant challenge posed in preparing the careful set of measurements and analyses presented in this study to lend support to the surfactant removal mechanism. The study began with a review of mass transfer models. These models are based on concepts such as surface renewal and idealised turbulence. It is, however, difficult to choose between the models as they predict similar values despite being based on different mechanisms. The overall mass transfer coefficient is composed of the gas-phase coefficient (kGa) and liquid-phase coefficient (kLa). As the values of the coefficients are comparable and the solubility of oxygen or hydrogen is very Iow, the overall mass transfer coefficient is approximately equal to the liquid side coefficient. The relationship of kL with the diffusion coefficient (D) is one of the limited ways of choosing between the models. Mass transfer models predict k j • u:. D" . n is predicted to be % for a rigid surface (contaminated interface region) and Y2 for a mobile surface (clean interface region). If the surfactant removal mechanism applies, the introduction of solid particles will be accompanied by a reduction of n from % to 1/2. The effect of particles on n can be calculated from precise measurement of kL of gases with significantly different diffusion coefficients. A review of experimental methods was made to find precise methods to characterise mass transfer in the presence of solid micro particles. The chemical sulphite, gas-interchange and pressure step methods were identified as appropriate methods. These were implemented in a stirred cell (0.5 !) and an agitated tank (6 I). The chemical sulphite measurements were used to confirm that the enhancement of kLa is due to an enhancement of kL and not the specific interfacial area (a). Flat surface experiments were made using water and 0.8 M sodium sulphate batches. The reduction of n from % to Y2 was confirmed in both apparatuses after the addition of solid particles. The data were very well correlated and the dependence of kr on the energy dissipation rate per unit volume (e) is similar to the theoretically predicted value of 114 for the exponent. Observation of the reduction of n from % to Y2 was extended to agitated dispersions. The stirred cell kLa data were measured by the gas interchange method and are of excellent quality. The agitated tank results were measured by pressure step methods. The pressure dependence of the polarographic probes affected the precision of the results and the effect was within the experimental uncertainty. The effect of particles on n could not, therefore, be conclusively confirmed in the agitated tank. By relating precisely measured mass transfer coefficients to the diffusion coefficients; the surfactant removal theory is confirmed. The result is valid for a flat mass transfer area as well as for agitated dispersion where the nature of the interface region changes with time due to the accumulation of surfactants on an initially clean interface. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2008.

Atherogenesis is the leading cause of death in the developed world, and is putting considerable monetary pressure on health systems the world over. Although the risk factors are well understood, unfortunately, the initiation and development of this disease still remains relatively poorly understood, but it is becoming increasingly identifiable as a dysfunction of the endothelial cells that line the walls of arteries. The prevailing haemodynamic environment plays an important role in the focal nature of atherosclerosis to very specific regions of the human vasculature. Disturbed haemodynamics lead to very low wall shear stress, and inhibit the transport of important blood borne chemicals. The present study models, both computationally and mathematically, the transport and hydrolysis of important blood borne adneosine nucleotides in physiologically relevant arterial geometries. In depth analysis into the factors that affect the transport of these low diffusion coefficient species is undertaken. A mathematical model of the complex underlying endothelial cell dynamics is utilised to model production of key intracellular molecules that have been implicated into the complex initiation processes of atherosclerosis; hence regions of the vasculature can be identified as being 'hot spots' for atherogenesis. This model is linked into CFD software allowing for the assessment of how 3D low yields and mass transfer affect the underlying cell signalling. Three studies are undertaken to further understand nucleotide variations at the endothelium and to understand factors involved in determining the underlying cell dynamics. The major focus of the first two studies is geometric variations. This is primarily due to the plethora of evidence implicating the geometry of the human vasculature, hence the haemodynamics, as an influential factor in atherosclerosis initiation. The final model looks at a physiologically realistic geometry to provide a more realistic reproduction of the in vivo environment.

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