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The sample used for evaporative cooling system is Fabric defender 750 with Shelltite finish. From the experimental data and equations we have diffusion coefficient of 20.9 ± 3.71 x 10-6 m2/s for fabric with one layer with 17%-20% fluctuations from the theory, 27.8 ± 4.5 x 10-6 m2/s for fabric with two layers with 6%-14% fluctuations from the theory and 24.9 ± 4.1 x 10-6 m2/s for fabric with three layers with 13%-16% fluctuations from the theory. Since the thickness of the fabric increases so the mass transport rate decreases so the mass transport resistance should be increases. The intrinsic mass resistances of Fabri-1L, Fabri-2L and Fabri-3L are respectively 104 ± 10.2 s/m, 154 ± 23 s/m and 206 ± 26 s/m from the experiment.

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A detailed design was developed of an apparatus to measure moisture transfer in porous materials. The apparatus is to be used to collect data to aid in the development of mathematical models which accurately describe this phenomena. The apparatus consists of dual environmental chambers between which a specimen material is sealed. The temperature of each chamber is controlled separately allowing nonisothermal test conditions. The relative humidity is maintained without the use of saturated salt solutions. The moisture transfer rate is measured by periodically weighing a desiccant column used to absorb moisture as result of diffusion across the specimen. The apparatus was built and used to verify a heat transfer model written to predict its thermal characteristics. The chamber temperature capabilities are 5°C to 60°C with up to a 20°C temperature difference across the specimen. The relative humidity limits are based on the heat transfer into or out of the system. High relative humidities (75 to 85 percent) are possible at chamber temperatures close to ambient, but decrease sharply at the extremely high or low temperatures and during nonisothermal operation. The apparatus maintains a constant temperature within ±0.4°C of the setpoint when subjected to varying ambient temperatures. The spatial temperature variation close to the sample (within 25 mm) is within approximately ​​​​±1°C of the average chamber temperature. The relative humidity can be manually controlled to within ±.7 percent RH. Automated control, complicated by a response lag, was within ±1 percent RH. / Master of Science

Non-dilute salt strength solutions occur in many near surface geologic environments. In order to better understand the occurrence and movement of the water and salt, mathematical models for this non-ideal fluid need to be developed. Initial boundary value problems may then be solved to predict behavior for comparison with observations. Using the principles of equilibrium reversible and irreversible thermodynamics, relationships describing the thermo-physics of non-dilute saline solutions in variably saturated porous media are investigated. Each of four central chapters investigates a particular aspect of the flow of saline solutions through porous media. The first chapter derives the general relationships describing the effects of salt on the vapor content in the gas phase and also on the liquid pressure. The second chapter summarizes an example using the new theory for sodium chloride (NaCl) from zero to saturated strength. Additional terms beyond the dilute approximation are shown to be more important in very dry, fine textured soils with significant salt content. The third chapter derives the salt corrections for Darcy-type flow laws for variably saturated porous media, and an example for NaCl is given. Agreement between theory and experimental data is good, though there appear to be some unaccounted for effects. These effects may be the result of ionic interaction of the salt with the loamy sand used, and/or the effect of hysteresis of the water content-pressure relationship. The final chapter investigates two fundamental assumptions commonly used in process thermodynamics when considering mixtures described by porous media, saline water, and moist air. The first assumption is that temperature is the generalized intensive variable associated with entropy. The second assumption is that the form of the differential of total energy is known a-priori. It is shown that the first assumption is suspect under some circumstances, and a generalized notion of how to select extensive variables for a given system is introduced for comparison with the second assumption. Examples comparing the "usual" and new theories are accomplished for ideal gases and for isotropic Newtonian liquids, with results being favorable except possibly for the Gibbs-Duhem Relation of the Newtonian liquid for the "usual" theory. / Graduation date: 2005

Pulse tube cryocoolers (PTC) are a class of rugged and high-endurance refrigeration systems that operate without moving parts at their low temperature ends, and are capable of reaching temperatures down to and below 123 K. PTCs are particularly suitable for applications in space, guiding systems, cryosurgery, medicine preservation, superconducting electronics, magnetic resonance imaging, weather observation, and liquefaction of gases. Applications of these cryocoolers span across many industries including defense, aerospace, biomedical, energy, and high tech. Among the challenges facing the PTC research community is the improvement of system efficiency, which is a direct function of the regenerator component performance. A PTC implements the theory of oscillatory compression and expansion of the gas within a closed volume to achieve desired refrigeration. An important deficiency with respect to the state of art models dealing with PTCs is the limited understanding of the hydrodynamic and thermal transport parameters associated with periodic flow of a cryogenic fluid in micro-porous structures. In view of the above, the goals of this investigation include: 1) experimentally measuring and correlating the steady and periodic flow Darcy permeability and Forchheimer’s inertial hydrodynamic parameters for available rare-Earth ErPr regenerator filler; 2) employing a CFD-assisted methodology for the unambiguous quantification of the Darcy permeability and Forchheimer’s inertial hydrodynamic parameters, based on experimentally measured steady and periodic flow pressure drops in porous structures representing recently developed regenerator fillers; and 3) performing a direct numerical pore-level investigation for steady and periodic flows in a generic porous medium in order to elucidate the flow and transport processes, and quantify the solid-fluid hydrodynamic and heat transfer parameters. These hydrodynamic resistances parameters were found to be significantly different for steady and oscillatory flows.