An experimental research program was designed to study laminar flows through and over models of porous media with or without inertial effects. The models used were made up of circular or square rods arranged to cover solid volume fraction ϕ ranging from 0.03 to 0.49, and filling fraction h / H ranging from 0.34 to 1 of the test channel. In this way, the ratios of the depth of the test section to the porous medium pore H / l ranged from 5.75 to 18.25. Three types of model porous media were tested: (1) two-dimensional ‘horizontal’ models, having rod axes aligned along the span of the channel in a staggered or non-staggered fashion; (2) three-dimensional ‘vertical’ models with rod axes aligned in the transverse direction; and (3) three-dimensional ‘mesh’ models with rod axes aligned along both transverse and spanwise directions. Using a pressure-driven viscous fluid, the bulk Reynolds number Rebulk was varied from 0.1 to 10.3. Velocity measurements were obtained using particle image velocimetry at various streamwise-transverse planes of the test section. Differential pressure measurements were also obtained using electronic transducers. These measurements were used to determine relevant governing equations for the flow through the porous media; to characterize the effects of ϕ rod shape and arrangement, h / H, H / l, porous media dimensionality, and Rebulk on the flow; and to predict the flow at the porous medium-free flow interface. The Izbash and quadratic Forchheimer equations were respectively found to describe well the flow through two- and three-dimensional porous media. Penetration of the free flow into the porous medium varied with ϕ and rod arrangement, but was nearly independent of the rod shape. At the interface between the porous medium and the free flow, h / H and H / l effects were found to be counteractive. Penetration was highest for the vertical models compared with the mesh and horizontal models. Inertial dependence of interfacial flow was weak when porous medium conditions were considered. The interfacial flow was found to follow a dose response formulation with a predictable slip coefficient.

An experimental research program was designed to study laminar flows through and over models of porous media with or without inertial effects. The models used were made up of circular or square rods arranged to cover solid volume fraction ϕ ranging from 0.03 to 0.49, and filling fraction h / H ranging from 0.34 to 1 of the test channel. In this way, the ratios of the depth of the test section to the porous medium pore H / l ranged from 5.75 to 18.25. Three types of model porous media were tested: (1) two-dimensional ‘horizontal’ models, having rod axes aligned along the span of the channel in a staggered or non-staggered fashion; (2) three-dimensional ‘vertical’ models with rod axes aligned in the transverse direction; and (3) three-dimensional ‘mesh’ models with rod axes aligned along both transverse and spanwise directions. Using a pressure-driven viscous fluid, the bulk Reynolds number Rebulk was varied from 0.1 to 10.3. Velocity measurements were obtained using particle image velocimetry at various streamwise-transverse planes of the test section. Differential pressure measurements were also obtained using electronic transducers. These measurements were used to determine relevant governing equations for the flow through the porous media; to characterize the effects of ϕ rod shape and arrangement, h / H, H / l, porous media dimensionality, and Rebulk on the flow; and to predict the flow at the porous medium-free flow interface. The Izbash and quadratic Forchheimer equations were respectively found to describe well the flow through two- and three-dimensional porous media. Penetration of the free flow into the porous medium varied with ϕ and rod arrangement, but was nearly independent of the rod shape. At the interface between the porous medium and the free flow, h / H and H / l effects were found to be counteractive. Penetration was highest for the vertical models compared with the mesh and horizontal models. Inertial dependence of interfacial flow was weak when porous medium conditions were considered. The interfacial flow was found to follow a dose response formulation with a predictable slip coefficient.

Orientador: Milton Dall'Aglio Sobrinho / Banca: Fernando Braz Tangerino Hernandez / Banca: Paulo Kroeff de Souza / Resumo: Este trabalho teve o objetivo de avaliar os medidores de vazão com uma ou múltiplas tomadas de pressão em sistemas de água. Esses medidores de vazão são de fácil construção, utilizando materiais de baixo custo, podem ser instalados em locais que apresentem perfis de velocidades axialmente assimétricos em decorrência da existência de singularidades e/ou incrustações internas. Este estudo também foi idealizado para auxiliar os programas de redução de perdas físicas de água, uma vez que existe uma demanda reprimida na instalação de medidores de vazão em redes públicas de abastecimento. O trabalho foi desenvolvido em escala real nas instalações da ETA de Presidente Prudente-SP que abastece a zona de distribuição denominada de Alto ETA. Como padrão de medição foi utilizado um tubo de Pitot do tipo Cole, calibrado em túnel de vento pelo IPT. Além da aferição em diversos perfis de velocidade, medidores de múltiplos furos foram instalados em vários locais da rede, o que proporcionou uma verificação do comportamento do medidor em relação à variação do tipo de materiais e diâmetros das redes de abastecimento e uma avaliação geral do seu emprego em condições reais de uso em sistemas de abastecimento público. Os resultados demonstram que o medidor multifuros foi menos sensível à variação do perfil de velocidades, ou seja, a utilização da curva de calibragem obtida em condições ideais numa situação de perfil assimétrico levou a erros de medição menores que os obtidos com medidor de tomada única. A possibilidade de contar com um medidor de vazão adequado às condições brasileiras, de baixo custo e facilidade de construção, abre perspectivas para alavancar os programas de redução de perdas físicas de água, uma vez que existe uma grande demanda reprimida na instalação de medidores de vazão em redes de abastecimento público. / Abstract: This work had the objective of evaluating the flow meters with one or multiple orifices in water supply systems. Those flow meters are of easy construction, using inexpensive materials, and can be installed in places that present asymmetric velocity profiles as a consequence the existence of singularities and internal incrustations. This study was also conceived to aid the programs of reduction of physical losses of water, since a repressed demand for flow meters exists in water distribution systems. The work was developed in real scale in the Water Treatment Station - ETA of Presidente Prudente city-SP, that provisions the zone of distribution denominated High ETA. The measurement standard was a Pitot-Cole meter calibrated in wind tunnel by IPT. Besides calibration in several velocity profiles, meters of multiple orifices were installed at several places of the net, that provided a verification of the behavior of the meter related to the variation of the type of material and diameters of water distribution systems and a general evaluation of its employment in real conditions of use in public supply systems. The results demonstrate that the multi-port meter was less sensitive to the variation of the velocity profiles, in other words, the use of the calibration curve obtained in ideal conditions in a situation of asymmetric velocity profiles, led to smaller measurement errors than that obtained with a meter of only one orifice. The possibility to count on a flow meter adequate to the Brazilian conditions, inexpensive and easily constructed, opens perspectives for support the programs of reduction of physical losses of water, since there is a great unsatisfied demand for flow meters in water public supply systems. / Mestre

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The first part of this study describes the synthesis of new porous materials from basic building blocks. Five structurally related ligands namely: N,N'-bis(3-pyridylmethyl)-naphthalene diimide (L1), N,N'-bis(4-pyridylmethyl)-naphthalene diimide (L2), N,N'-bis(4-pyridylmethyl)- pyromellitic diimide (L3), N,N'-bis(3-pyridylmethyl)-pyromellitic diimide (L4) and 2-(pyridin-4- ylmethyl)-benzene tricarboxylic anhydride (L5) were synthesised. Ligands L1 and L2 were reacted with metal nitrates and carboxylates as co-ligands in a systematic manner with a view to obtaining potentially porous 3–D coordination polymers. Ten structurally diverse coordination polymers were obtained and they were characterised by single-crystal X-ray diffraction, powder X-ray diffraction and thermogravimetric analysis. Four of these compounds absorb moderate amounts of CO2 and, in addition, show sorption selectivity towards CO2 over N2. The reaction of L3 and L4 with transition metal halides yielded two 1–D chains, while the reaction of L5 with transition metal nitrates yielded seven coordination polymers of which four are 2–D and three are 1–D. Of the 2–D structures three are isostructural. The second part of this work describes a variable pressure study of a flexible metal-organic framework [Zn2(BDC)2(BPY)] (BPY = 4,4 -bipyridine and BDC = 1,4-benzene dicarboxylic acid). [Zn2(BDC)2(BPY)] is one of the few examples of a flexible metal-organic framework that undergoes phase transformations in response to gas pressure. The high pressure sorption recorded for this metal-organic framework displays two inflection steps in the pressure range 0 to 30 bar, possibly indicating two phase transformations. The gas-loaded structures for each phase transformation were determined by means of single-crystal X-ray diffraction. High-pressure differential scanning calorimetry was also carried out on the system in order to determine accurate gate-opening pressures, as well as the energies involved with each phase transformation. The results correlate with those obtained from single-crystal X-ray diffraction and high-pressure sorption. The final section reports the mechanochemical synthesis of two Werner complexes [NiCl2(4- PhPy)4] (1), [CoCl2(4-PhPy)4] (2) and their corresponding solid solution [Ni0.5Co0.5Cl2(4-PhPy)4] (3) (PhPy = phenyl pyridine). The solid solution could only be formed by mechanochemical synthesis and not by conventional solution crystallisation methods. The solid solution exhibits sorption properties that differ from those of the pure compounds. / AFRIKAANSE OPSOMMING: Die eerste deel van hierdie studie beskryf die sintese van nuwe poreuse stowwe uit basiese boublokke. Vyf struktureel verwante ligande naamlik: N,N'-bis(3-piridielmetiel)-naftaleen diimied (L1), N,N'-bis(4-piridielmetiel)-naftaleen diimied (L2), N,N'-bis(4-piridielmetiel)- piromellitien diimied (L3), N,N'-bis(3-piridielmetiel)-piromellitien diimied (L4) en 2-(piridiel-4- ielmetiel)benseen trianhidried (L5) is gesintetiseer. Ligande L1 en L2 is gereageer met metaal nitrate en karboksielsure as mede-ligande in 'n sistematiese wyse met 'n oog op die verkryging van potensieel poreuse 3–D koördinasie polimere. Tien struktureel diverse koördinasie polimere is verkry en hulle is gekarakteriseer deur enkel-kristal X-straal-diffraksie, poeier X-straal diffraksie en termo-analise (thermal analysis). Vier van hierdie verbindings het matige hoeveelhede CO2 geabsorbeer en, bykomend, wys sorpsie selektiwiteit van CO2 oor N2. Die reaksie van L3 en L4 met oorgangsmetaalhaliede het twee 1–D kettings gevorm, terwyl die reaksie van L5 met oorgangsmetaal nitrate sewe koördinasie polimere opgelewer het, waarvan vier 2–D en drie 1–D polimere is. Van die 2–D polimere het drie vergelykbare strukture. Die tweede deel van hierdie werk beskryf 'n veranderlike druk studie van 'n buigsame metaalorganiese raamwerk [Zn2(BDC)2(BPY)] (BPY = 4,4-bipiridien en BDC = 1,4-benseen dikarboksielsuur). [Zn2(BDC)2(BPY)] is een van die min voorbeelde van 'n buigsame metaalorganiese raamwerk wat fase transformasies (phase transformations) ondergaan in respons op ‘n verandering in gas druk. Die hoë-druk sorpsie aangeteken vir hierdie metaal-organiese raamwerk vertoon twee infleksie stappe in die gebestudeerde druk gebied (0 tot 30 bar), wat moontlik op twee fase transformasies dui. Die gas-gelaaide strukture vir elke fase transformasie is bepaal deur middel van enkel-kristal X-straal-diffraksie. Hoë-druk differensiële skandeer kalorimetrie (differential scanning calorimetry) is ook uitgevoer op die stelsel ten einde dié akkurate hekopenings druk, sowel as die energie betrokke by elke fase transformasie te bepaal. Die resultate stem ooreen met dié verkry vanaf enkel-kristal X-straal diffraksie en hoë-druk sorpsie. Die finale afdeling bespreek die meganochemiese sintese van twee Werner komplekse [NiCl2(4-PhPy)4] (1) en [COCl2(4-PhPy)4] (2) en hul ooreenstemmende vaste oplossing (solid solution) [Ni0.5Co0.5Cl2(4-PhPy)4] (3). Die vaste oplossing kan slegs gevorm word deur meganochemiese sintese en nie deur konvensionele oplossing kristallisasie metodes. Die vaste oplossing vertoon sorpsie eienskappe wat verskil van dié van die suiwer verbindings.

Uncoated defects in hot dip metal-coated steel products result from non-wetting of the steel surface by the molten alloy. The occurrence of uncoated defects is highly detrimental to product quality and production efficiency; uncoated defects compromise the appearance and anti-corrosion performance of hot dip metal-coated steel products and causes time delays in the application of subsequent surface treatments. Although many studies have been directed towards evaluating the effect of steel pre-heat temperature and oxidation on the formation of uncoated defects, fewer investigations have analysed how oil-derived residues remaining on steel surface following the cold rolling and furnace cleaning processes impact upon hot dip metallic coating quality. Furthermore, although a considerable amount of research has focussed on the process of deposit formation in lubricants used in other applications, the composition of oily residues remaining after the continuous annealing process, and the origins of these residues in the original rolling oil formulation, are poorly understood. The primary focus of the present work has been to gain an improved understanding of relationships between cold rolling oil composition, oil residue-formation characteristics and the occurrence of uncoated defects in 55Al-43.4Zn-1.6Si hot dip metallic coatings. Several key classes of rolling oil ingredients which decompose to leave high levels of thermally-stable residue have been identified. The thermal decomposition processes undergone by a variety ingredients within these classes have been studied under both oxidising and reducing conditions using Thermogravimetric Analysis (TGA) and Pressure Differential Scanning Calorimetry (PDSC) techniques, with chemical characterisation of the decomposition process and the resultant thermally-stable residue by infrared spectroscopy. Model blends of each ingredient in a typical cold rolling oil base ester have also been evaluated by TGA and PDSC to identify the impact of ingredient concentration and chemical structure on the amount of oily residue formed. The results of these investigations have been related to the impact of the ingredients on 55Al-43.4Zn-1.6Si hot dip metallic coating quality through the performance of industrial-scale hot dipping trials and hot dip simulation studies. In order to translate these results into a context more closely aligned with industrial conditions, the effect of processing variables, including furnace atmosphere and the availability/concentration of iron in contact with the rolling oil at the steel surface, on the decomposition process of a fully-formulated commercial cold rolling oil has also been investigated. The information gained can potentially be used to tailor operating conditions within the cold rolling/continuous hot dip metallic coating processes to enhance steel surface cleanliness. Finally, the deposit-forming tendencies of an array of different commercial cold rolling oils have been evaluated, leading to the development of a thermal analysis-based test for screening cold rolling oils with respect to their likely impact upon 55Al-43.4Zn-1.6Si hot dip metallic coating quality. This test, together with the understanding obtained on the effect of different rolling oil ingredients on hot dip metallic coating quality, can be used within the industry to formulate improved cold rolling oils.

This thesis was concerned with the proof of concept for mid-grade, 250-500oC, industrial waste heat recovery using a thermally regenerative electrochemical system. Proposed thermally regenerative electrochemical systems are limited to high operating temperatures (> 900oC) and suffer from poor conversion efficiencies (< 20%). As such, a single chamber design that is free of moving parts was presented in this work. The concept for this novel regenerative system relies on gravity and a liquid medium to convey dissolved sodium hydride in a hydride-borohydride solution from cold to hot regions in a continuous circuit. Such a liquid transport medium could allow for operation below 500oC while stabilizing the hydride from thermal decomposition. Investigations on this system were carried out using a custom pressure differential thermal analyzer that was able to operate above temperatures of 700oC and pressures of 2.2MPa. The results of the experiments provided valuable information concerning the phase diagrams of various hydride-borohydride mixtures. The eutectic composition of the NaH-KBH4 system was found to be 43 mole% NaH. The corresponding eutectic temperature (503oC) was determined using the differential cooling curves. Appreciable NaH decomposition was noticed in mixtures above 59.0 mole% NaH. Mixtures up to 42.5 mole% KH in KBH4 were also investigated. The eutectic composition of the KH-KBH4 binary system was determined by extrapolating the liquidus curve to intersect the solidus curve. The KH-KBH4 eutectic temperature was found to be 390oC at 66 mole% KH. The experimental work successfully demonstrates that thermally unstable hydrides can be obtained in the liquid phase below their melting points, under moderate pressures, when mixed with alkali borohydrides. This significantly lowers the achievable operating temperature of the thermally regenerative electrochemical systems currently proposed. The use of the single chamber design with a hydride-borohydride liquid medium offers numerous advantages including: reduced maintenance, reduced operating temperature, reduced system weight, reduced parasitic losses, increased voltage, and increased reliability. The viability for mid-grade industrial waste heat recovery requires construction of a prototype which optimizes power outputs and explores the hydrodynamic transport of material. / Thesis (Master, Mining Engineering) -- Queen's University, 2009-09-24 14:33:22.627

Made available in DSpace on 2014-06-11T19:29:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-11-27Bitstream added on 2014-06-13T20:59:27Z : No. of bitstreams: 1 camapumfilho_na_me_ilha.pdf: 1741621 bytes, checksum: 8d03cd3c15e2515c463152711b059b6c (MD5) / PROPG / Este trabalho teve o objetivo de avaliar os medidores de vazão com uma ou múltiplas tomadas de pressão em sistemas de água. Esses medidores de vazão são de fácil construção, utilizando materiais de baixo custo, podem ser instalados em locais que apresentem perfis de velocidades axialmente assimétricos em decorrência da existência de singularidades e/ou incrustações internas. Este estudo também foi idealizado para auxiliar os programas de redução de perdas físicas de água, uma vez que existe uma demanda reprimida na instalação de medidores de vazão em redes públicas de abastecimento. O trabalho foi desenvolvido em escala real nas instalações da ETA de Presidente Prudente-SP que abastece a zona de distribuição denominada de Alto ETA. Como padrão de medição foi utilizado um tubo de Pitot do tipo Cole, calibrado em túnel de vento pelo IPT. Além da aferição em diversos perfis de velocidade, medidores de múltiplos furos foram instalados em vários locais da rede, o que proporcionou uma verificação do comportamento do medidor em relação à variação do tipo de materiais e diâmetros das redes de abastecimento e uma avaliação geral do seu emprego em condições reais de uso em sistemas de abastecimento público. Os resultados demonstram que o medidor multifuros foi menos sensível à variação do perfil de velocidades, ou seja, a utilização da curva de calibragem obtida em condições ideais numa situação de perfil assimétrico levou a erros de medição menores que os obtidos com medidor de tomada única. A possibilidade de contar com um medidor de vazão adequado às condições brasileiras, de baixo custo e facilidade de construção, abre perspectivas para alavancar os programas de redução de perdas físicas de água, uma vez que existe uma grande demanda reprimida na instalação de medidores de vazão em redes de abastecimento público. / This work had the objective of evaluating the flow meters with one or multiple orifices in water supply systems. Those flow meters are of easy construction, using inexpensive materials, and can be installed in places that present asymmetric velocity profiles as a consequence the existence of singularities and internal incrustations. This study was also conceived to aid the programs of reduction of physical losses of water, since a repressed demand for flow meters exists in water distribution systems. The work was developed in real scale in the Water Treatment Station - ETA of Presidente Prudente city-SP, that provisions the zone of distribution denominated High ETA. The measurement standard was a Pitot-Cole meter calibrated in wind tunnel by IPT. Besides calibration in several velocity profiles, meters of multiple orifices were installed at several places of the net, that provided a verification of the behavior of the meter related to the variation of the type of material and diameters of water distribution systems and a general evaluation of its employment in real conditions of use in public supply systems. The results demonstrate that the multi-port meter was less sensitive to the variation of the velocity profiles, in other words, the use of the calibration curve obtained in ideal conditions in a situation of asymmetric velocity profiles, led to smaller measurement errors than that obtained with a meter of only one orifice. The possibility to count on a flow meter adequate to the Brazilian conditions, inexpensive and easily constructed, opens perspectives for support the programs of reduction of physical losses of water, since there is a great unsatisfied demand for flow meters in water public supply systems.

This work describes the modeling, synthesis, integration and characterization of a novel nanostructure embedded thermoresponsive material for microfluidic applications. The innumerable applications of thermoresponsive surfaces in the recent years have necessitated the development of a rigorous mathematical treatment for these surfaces to understand and improve their behavior. An analytical model is proposed to describe the transfer characteristic (variation of contact angle versus temperature) of a unique switchable, nanostructured, thermoresponsive surface consisting of silica nanoparticles and the thermoresponsive polymer, Poly(N-isopropylacrylamide ) (PNIPAAm) which changes its wetting angle upon heating. Important metrics such as the absolute lower critical solution temperature, threshold & saturation temperatures and gain are modeled and quantified by mathematical expressions. Based on the modeling, a heat source for the thermoresponsive surface was integrated on the glass substrate itself to create a fully functional smart surface. The design and fabrication of a smart platform consisting of the switchable, nanostructured, thermoresponsive surface with an integrated gold microheater for wettability control and its time response analysis was conducted. The insight gained into the behavior of the thermoresponsive surface by using the analytical model, aided the effort in the effective integration of the surface into a microfluidic channel for flow regulation applications. The implementations of novel microfluidic flow regulator concepts were tested. The aim is to integrate a regulator function to a channel surface utilizing the layer-by-layer (LBL) deposition technique. The characterization and pressure differential study of the microfluidic regulators was carried out on simple straight microchannels which were selectively coated with the thermoresponsive surface. Theoretical and experimental studies were performed to determine the important characteristic parameters including capillary, Weber and Reynolds numbers. The pressure differential data was used to develop critical operating specifications. This work lays out a new microfluidic device concept consisting of a channel with a built-in regulatory function.

No description available.