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Polymeric Hollow Fiber Heat Exchanger Design / Polymeric Hollow Fiber Heat Exchanger DesignAstrouski, Ilya January 2016 (has links)
This Ph.D. thesis is focused on theory and experimental investigations developing of new knowledge about polymeric hollow fiber heat exchanger (PHFHE). The state-of-the-art study of plastic heat exchangers shows that their usage is limited by several niches where their advantages significantly dominates, or where the use of non-plastic competitors is not impossible. On the other hand, plastic heat exchangers (and PHFHEs in particular) are devices of increasing interest. It is shown that use of small tubes (fibers) allows PHFHEs to be more competitive than conventional plastic heat exchangers. Small hydraulic diameter of a fiber causes high heat transfer coefficients, reduces thermal resistance of plastic wall and allows it to create light and compact design. Detailed study of fluid flow and heat transfer inside the hollow fiber showed that conventional approaches for single-phase laminar flow can be utilized. Poiseuille number equal to 64 and Nussel number about 4 are recommended to be used to predict pressure drops and heat transfer coefficient, respectively. Additional attention should be paid to careful determination of fiber diameter and liquid properties (viscosity). Scaling effects, such as axial heat conduction, thermal entrance region and viscous dissipation can be neglected. The study of outside heat transfer showed that heat transfer on fiber bunches are intense and are competitive to contemporary compact finned-tube heat exchangers. The Grimson approach showed clear correlation with experimental results and, thus is recommended to predict heat transfer coefficients on fiber bunches. Two types of fouling (particulate- and biofouling) of outer fiber surface were experimentally studied. It was found that particulate fouling by titanium oxide particles is not intense and deposits can be removed relatively easy. However, fouling is much more intense when it is associated with biofouling caused by wastewater. In this case, smooth and low-adhesive surface of plastic is not sufficient precaution to prevent deposit formation.
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An Investigation into the Impact of Cell Metabolic Activity on Biofilm Formation and Flux Decline during Cross-flow Filtration of Cellulose Acetate Ultrafiltration MembranesMohaghegh Motlagh, Seyed Amir H. January 2011 (has links)
No description available.
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Characterization of Ultrafiltration Membranes and Effect of Biofouling on Their Water Treatment PerformanceZaky, Amr M. 09 June 2011 (has links)
No description available.
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Optical Module studies for underwater neutrino telescopes / Etudes de modules optiques pour les télescopes à neutrinos sous-marinsAvgitas, Theodoros 15 December 2017 (has links)
Un banc test, composé d’ une cuve à eau et d’ un hodoscope, a été optimisé et utilisé pour la caractérisation des Modules Optiques (OMs) des expériences ANTARES et KM3NeT. La comparaison entre le flux attendu de muons atmosphériques et le flux mesuré a permis l’ estimation de l’ efficacité de l’ hodoscope.Dans un premier temps, des mesures effectuées avec un OM ANTARES ont permis de valider le système d’ acquisition et de caractériser l’ étalonnage temporel du banc test. Un Module Optique Digital (DOM) a ensuite pu être installé dans la cuve pour être testé. De nombreux points cruciaux pour les télescopes sous-marins à neutrino ont été mentionnés et une description détaillée de l’ étalonnage en charge et du réglage du détecteur a été présentée. La dégradation, observée expérimentalement, de l’ efficacité de détection des OMs ANTARES a été confrontée aux résultats obtenus en simulant la formation d’ une couche de sédimentation. L’ impact de différents profils de sédimentation a été étudié et les résultats de l’ analyse Monte Carlo ont été détaillés. Ce travail a permis de rejeter certains profils de sédimentation en désaccord avec les données. / A test bench, comprised of a water tank and a hodoscope, was optimized and operated for the characterization of ANTARES and KM3NeT OpticalModules (OMs). A calculation of the expected atmospheric muon flux and the comparisonto the detected flux is made for the evaluation of the hodoscope efficiency.Measurements were initially made with an ANTARES OM for the evaluation of thetest bench potential and the consequent time correlation analysis. The results wereconsidered satisfying for proceeding to the characterization of a KM3NeT DigitalOM (DOM). This was the first time a DOM was investigated with known muontracks and the analysis lead to original and insightful results. Many key aspectsfor an undersea neutrino telescope are outlined and a detailed description of chargecalibration and the tuning sequence for the ANTARES detector are presented. Theobservation that the OM efficiencies for ANTARES are deteriorating in the courseof time has been compared to simulations of a sedimentation layer on the OMÕsglass sphere. Different profiles for this sedimentation impact are considered and thecombined analysis of monte carlo results with detector data is described. This workpermitted to reject extreme cases of biofouling profiles that are inconsistent withthe data
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Selected Experiments with Proteins at Solid-Liquid InterfacesTeichroeb, Jonathan January 2008 (has links)
This thesis describes a number of novel experiments contributing to the understanding of protein adsorption from both a fundamental and applied perspective.
The first three papers involve the use of the localized surface plasmon resonance of gold nanospheres to measure protein conformational dependencies during heat and acid denaturation. Thermal denaturation of BSA is shown to proceed differently depending on the size of nanosphere to which it is conjugated. Activation energies are extracted for thermal denaturing on nanoparticles. These energies decrease with decreasing radius of curvature. Under pH perturbation in the acid region, the multiple transition states of bulk BSA are suppressed, and only one apparent transition around pH 4 is evident. Smaller spheres (diameter < 20nm) do not exhibit any transition. A significant finding of all three studies is that the state and stability of BSA depends strongly upon local curvature.
The last two papers investigate protein adsorption relevant to the biomaterial field. Investigation of protein adsorption to polyHEMA hydrogels is carried out using a quartz crystal microbalance. Single and mixed protein adsorption kinetics for BSA, lysozyme and lactoferrin are extracted and interpreted. Selected commercial cleaning solutions are shown to be no more effective than simple buffer solution.
Examination of commercial lenses indicates that the morphology of adsorption is material dependent and that siloxane-based hydrogels only deposit low levels of protein. A unique fibril-like morphology is identified on galyfilcon A. Protein morphology is discussed in terms of bare lens morphology, roughness, and surface composition.
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Selected Experiments with Proteins at Solid-Liquid InterfacesTeichroeb, Jonathan January 2008 (has links)
This thesis describes a number of novel experiments contributing to the understanding of protein adsorption from both a fundamental and applied perspective.
The first three papers involve the use of the localized surface plasmon resonance of gold nanospheres to measure protein conformational dependencies during heat and acid denaturation. Thermal denaturation of BSA is shown to proceed differently depending on the size of nanosphere to which it is conjugated. Activation energies are extracted for thermal denaturing on nanoparticles. These energies decrease with decreasing radius of curvature. Under pH perturbation in the acid region, the multiple transition states of bulk BSA are suppressed, and only one apparent transition around pH 4 is evident. Smaller spheres (diameter < 20nm) do not exhibit any transition. A significant finding of all three studies is that the state and stability of BSA depends strongly upon local curvature.
The last two papers investigate protein adsorption relevant to the biomaterial field. Investigation of protein adsorption to polyHEMA hydrogels is carried out using a quartz crystal microbalance. Single and mixed protein adsorption kinetics for BSA, lysozyme and lactoferrin are extracted and interpreted. Selected commercial cleaning solutions are shown to be no more effective than simple buffer solution.
Examination of commercial lenses indicates that the morphology of adsorption is material dependent and that siloxane-based hydrogels only deposit low levels of protein. A unique fibril-like morphology is identified on galyfilcon A. Protein morphology is discussed in terms of bare lens morphology, roughness, and surface composition.
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A reverse osmosis treatment process for produced water: optimization, process control, and renewable energy applicationMareth, Brett 02 June 2009 (has links)
Fresh water resources in many of the world's oil producing regions, such as
western Texas, are scarce, while produced water from oil wells is plentiful, though unfit
for most applications due to high salinity and other contamination. Disposing of this
water is a great expense to oil producers. This research seeks to advance a technology
developed to treat produced water by reverse osmosis and other means to render it
suitable for agricultural or industrial use, while simultaneously reducing disposal costs.
Pilot testing of the process thus far has demonstrated the technology's capability to
produce good-quality water, but process optimization and control were yet to be fully
addressed and are focuses of this work. Also, the use of renewable resources (wind and
solar) are analyzed as potential power sources for the process, and an overview of
reverse osmosis membrane fouling is presented.
A computer model of the process was created using a dynamic simulator, Aspen
Dynamics, to determine energy consumption of various process design alternatives, and
to test control strategies. By preserving the mechanical energy of the concentrate stream
of the reverse osmosis membrane, process energy requirements can be reduced several
fold from that of the current configuration. Process control schemes utilizing basic
feedback control methods with proportional-integral (PI) controllers are proposed, with
the feasibility of the strategy for the most complex process design verified by successful
dynamic simulation. A macro-driven spreadsheet was created to allow for quick and
easy cost comparisons of renewable energy sources in a variety of locations. Using this
tool, wind and solar costs were compared for cities in regions throughout Texas. The
renewable energy resource showing the greatest potential was wind power, with the
analysis showing that in windy regions such as the Texas Panhandle, wind-generated
power costs are approximately equal to those generated with diesel fuel.
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The effect of natural organic matter on ultrafiltration and reverse osmosis membrane performance at Komati Power StationDladla, Zanele January 2013 (has links)
Komati Power Station has installed a membrane plant consisting of ultrafiltration, double
pass reverse osmosis and continuous electro-deionisation to treat cooling tower
blowdowns in order to produce demineralised water and to conduct sidestream chemistry
control of the cooling water circuit. This plant has replaced the existing ion-exchange
plant that was used for the production of demineralised water and thus serves to reduce
the loading of mobile salts in the ash dam (90% reduction) by eliminating regeneration effluent from the ion-exchange plant.
Due to oil contamination in the cooling water circuit (when oil from oil coolers leaks into
the cooling water), the membrane plant was also designed to operate on raw water from
either the Nooigdedacht or the Vygeboom Dam or a blend of both dams. This is
considered to be an emergency intervention under abnormal conditions to prevent
possible irreversible fouling of the membranes due to oil in the cooling water. The
Nooigtedach Dam water contains high concentrations of organic matter and is also
enriched with nutrients due to raw sewage influent into the Dam water. This poses a
challenge with regard to treatment of the high fouling feed water on the membrane plant.
Natural organic matter in water has the ability to foul reverse osmosis membranes. This
adversely affects the operation of the reverse osmosis process. However, very little
information is available regarding the fouling characteristics of natural organic material in
the raw and cooling water at Komati Power Station for the reverse osmosis membranes.
Therefore, a pilot study was undertaken to determine the influence of natural organic
matter on membrane fouling, to optimise the process for the removal of natural organic
matter and to assess the ability of two different reverse osmosis membranes to
effectively treat the high fouling feed water at Komati Power Station. The ability of a polyethersulphone hollow-fibre ultrafiltration membrane system was first
evaluated to remove natural organic matter in the feedwater, by conducting pilot tests,
initially without coagulation of the raw water and thereafter with in-line coagulation for
organics removal. Jar tests were conducted in the laboratory to determine the most
suitable coagulant and dosage for turbidity and natural organic matter removal. Various
coagulants were tested and, based on the results of the jar tests, a coagulant (U3000)
was identified based on optimal removal of both total organic carbon and turbidity at a
dosing level of 20 mg/L. During the operation of the ultrafiltration pilot plant, permeate flow; feed pressure and
feed temperature were monitored. Performance of the ultrafiltration membrane was
monitored in terms of flux versus time for operation with and without a coagulation
process. The results indicated that there was very little total organic carbon removal
(maximum removal of 4%) without coagulation and a slight decrease in flux. The flux
declined as a result of fouling but could be recovered by performing hydraulic
backwashes and CEB procedures. Permeate flux, however, could be maintained at
about 90 Lmh (from 642 hours of operation). Since most of the organics passed through
the ultrafiltration membrane, it was concluded that the loss in flux was due to colloidal
fouling of the membrane. This was observed when the operation was carried out using
raw water as feed as well as when cooling water was used.
The total organic carbon removal increased to 30% when the plant was operated with inline
coagulation. The flux remained relatively stable during the first 600 hours of
operation and only decreased significantly during the last 200 hours of operation as a
result of fouling. The reduction in flux prior to cleaning was less than the 15% (maximum
flux decline of 9.9% during the test period) which is acceptable according to the industry
norm of 15%. It appeared that flux could be maintained at around 90 Lmh which was
about the same as when no coagulant was applied. The 30% total organic carbon
reduction that was obtained was not sufficient to reduce the organics to the level of 6mg/L dissolved organic carbon that was specified by the membrane manufacturer for the
standard brackish water reverse osmosis membrane.
Two reverse osmosis membranes – the standard brackish water reverse osmosis
membrane (BW30-2540) and the extra-low-fouling membrane (BW30XFR-2540) – were
assessed in terms of their ability to remove dissolved organic carbon, ease of cleaning of
the membrane and the ability to recover flux after cleaning. This was done to establish
which membrane is more suited to Komati’s high-fouling feedwater.
The evaluation of the performance of the two reverse osmosis membranes was
conducted using pre-treated water (filtered water after in-line coagulation, anti-scalant
and biocide dosing) as well as using water that was not pre-treated. During operation
(under both conditions), the normalised permeate flux, conductivity, dissolved organic
carbon and organics absorbing at UV254 were monitored.
It was established that in terms of flux decline that the extra low-fouling membrane gave
slightly superior performance to that of the standard membrane, achieving longer
production runs (up to 5 days compared with 3 days achieved by the standard brackish
water membrane) without requiring chemical cleaning. The low fouling membrane
achieved better CWF recovery after the cleaning cycles (81.26% Lmh of the virgin
membrane on the occasions when there was flux loss) compared to the standard
membrane (restored to 77.35% of CWF of the virgin membrane) when using untreated
feed water. This performance improved when pre-treated feed water was used and the
low fouling membrane’s CWF regained after the CIP was 95.89% which was within the
industry norm of a flux recovery of 95%, indicating that the CIP had been effective. It was
determined that the TOC rejection of the low-fouling membrane was higher (average
TOC rejection of 97%, maximum TOC rejection of 99%) than that of the standard
membrane (average TOC rejection of 95.3%, maximum TOC rejection of 97%).
Preliminary efforts to optimize the pre-treatment for organics removal in order to reduce
organic loading for the RO membranes confirmed that the use of granular activated
carbon and use of an organic scavenger resin might not be economically feasible due to
the relatively quick TOC breakthrough (8910BV, approximately 18000BV and less than
18000BV for the Filtrasorb 300, Filtrasorb 400 and organic scavenger resin,
respectively). Although further investigations should still be conducted, the preliminary
results indicate that it would be beneficial to also identify other options that can be further
investigated for optimization of organics removal at Komati Power Station.
Decline in the normalised flux as well as the evidence of biofouling were witnessed
during the pilot operation suggesting that the membranes were fouled. Autopsies were
performed on both membranes to identify foulants responsible for the decline in flux that
was observed during the pilot study. The results did not indicate an organic foulant on the
membrane surface. Biofouling should however, be monitored in the main plant as this
was suspected to have resulted in the flux decline during the pilot study.
The low fouling membrane demonstrated a better capability to treat the Komati raw and
cooling water and would be expected to achieve lower operating costs for the plant (CIP
costs and membrane replacement costs) while achieving better organics removal and it
is therefore recommended that the low-fouling membranes be used at Komati Power
Station as they are superior to the standard membrane and the cost of the low-fouling
membranes is comparable to that of the standard membrane. While this would provide
somewhat better performance than that obtained with the standard brackish water
membranes, it is proposed that further investigation into pre-treatment optimization for
organics removal as well as more efficient cleaning solutions be investigated to improve
the performance and economics of the main water treatment plant at Komati power
Station. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Chemical Engineering / unrestricted
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[en] METROLOGICAL VALIDATION OF NEW METHOD FOR FOULING MITIGATION IN HEAT EXCHANGERS / [pt] VALIDAÇÃO METROLÓGICA DE ALTERNATIVA TECNOLÓGICA PARA MITIGAÇÃO DE INCRUSTAÇÃO EM TROCADORES DE CALORVELFE HOLLANDINO DE OLIVEIRA JÚNIOR 17 May 2016 (has links)
[pt] Problemas com incrustações em equipamentos são frequentes em
equipamentos de resfriamento de mancais de turbinas hidráulicas e
hidrogeradores, drasticamente comprometendo a sua eficiência de operação.
Pesquisas aplicadas buscam a eficiência térmica dos trocadores de calor por meio
da mitigação do fouling formado nesses equipamentos. Esta dissertação de
mestrado tem por objetivo avaliar a eficácia de uma alternativa tecnológica de
limpeza dos tubos do trocador de calor que faz uso de esferas abrasivas para
mitigar indesejáveis incrustações em trocadores de calor utilizados no
arrefecimento de hidrogeradores. A motivação da pesquisa deu-se no contexto do
projeto de PeD Light-Aneel Ref.: 07/2011, Proposição de solução inovadora
para o sistema de resfriamento dos hidrogeradores da Usina Fontes Nova,
desenvolvido pelo Programa de Pós-graduação em Metrologia da PUC-Rio.
Superando o desafio de oferecer um método de limpeza que evita a raspagem
mecânica e o uso de produtos químicos, o trabalho construiu um equipamento e
validou uma alternativa tecnológica de limpeza, que opera on-line, portanto sem a
necessidade de parada técnica da usina para realizar a manutenção. A metodologia
utilizada fundamenta-se na análise do desempenho hidrodinâmico e térmico do
trocador de calor quando assistido pelo sistema proposto. Dentre os resultados,
destacam-se (i) o caráter prático da alternativa de limpeza proposta, que realiza a
limpeza sem a necessidade de interromper a geração e (ii) o estudo da velocidade
ótima das esferas para assegurar eficácia do processo de desobstrução dos
trocadores. Os resultados favoráveis dos testes de desempenho realizados em
laboratório e no campo consubstanciam a conclusão do trabalho, permitindo
validar a técnica e o protótipo de equipamento construído para ser utilizado nas
condições reais de operação da usina. / [en] Formation and deposit of fouling is a common problem encountered in heat
exchangers, bearings of hydraulic and hydro turbines, drastically reducing their
operation efficiency. Applied research continuously seeks for gains in thermal
efficiency by encouraging fouling mitigation in the internal passages of heat
exchangers. This dissertation aims to evaluate the effectiveness of a technological
alternative for cleaning heat exchanger tubes by the use of abrasive spheres to
mitigate undesirable fouling in heat exchangers used in hydro generators cooling.
The motivation of the research took place in the context of the ReD project Light-
Aneel 07/2011, entitled Innovative solution for fouling mitigation of heat
exchangers used in the cooling system of the Fontes Nova Power Plant, developed
by the postgraduate Metrology Programme of Catholic University of Rio de
Janeiro, financed under a Brazilian government regulated R&D Programme.
Overcoming the challenge of providing a cleaning method that prevents the
mechanical scraping and the use of chemicals, a prototype of an equipment was
built and validated as a technological alternative cleaning tool, which operates
online, therefore without the need to shutdown the power plant to perform the heat
exchanger maintenance. The methodology is based on the analysis of
hydrodynamic and thermal performance of the heat exchanger when assisted by
the envisioned system. Among the results achieved, the work highlights (i) the
practical character of the cleaning alternative proposed, which performs the
cleaning without the need to interrupt the electrical energy generation and (ii) the
study of the optimum speed that must be imposed to the abrasive spheres to ensure
effectiveness of the unclogging process of the exchangers. The favourable results
emerged from the performance tests carried out in the laboratory and in the field
environments substantiate the conclusion of the work, validating the technical
method and the prototype of the equipment to operate in the real conditions of the
power plant.
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ANTI-BIOFOULING IMPLANTABLE CATHETER USING THIN-FILM MAGNETIC MICROACTUATORSQi Yang (7104800) 12 October 2021 (has links)
<p>Hydrocephalus is a neurological disease characterized by abnormal accumulation of cerebral spinal fluid (CSF) in ventricle of brain. 1 in 1000 newborns are affected each year and it is life-threatening if left untreated. The golden standard of treatment is to surgically implant a shunt that divert excessive CSF away from ventricle to alleviate intraventricular pressure (ICP) in patient. Unfortunately, shunt failure rate is notoriously high because of obstruction of catheter intake pore. The obstruction is primary caused by normal and inflammatory tissue (biofilm) buildup over time. Shunt replacement surgery is typically required after only 1 year of implantation for 40% of patients. To prolong the lifespan of hydrocephalus shunt, we previously proposed and designed magnetic micro-actuators platform to remove biofilm mechanically. Removal of muscle cells and microbeads were demonstrated from wafer level devices on bench-top.</p><p> </p><p>To examine device efficacy in ventricular catheter, I developed magnetic actuator on polymer substrate. First, polyimide based flexible thin-film devices were microfabricated and integrated into a single-pore silicone catheter. A proof-of-concept self-clearing smart catheter was presented. Removal of microscopic biofilm was evaluated against bovine serum protein (BSA). Detachment of BSA up to 95% was achieved by shear stress from magnetic actuation. Next, I developed resistive deflection sensing using a metallic strain gauge, allowing device alignment with magnetic field for maximum energy delivery. In addition, auxiliary functionalities such as occlusion detection and flow rate measurement were demonstrated on catheter. Moreover, a new serpentine cantilever geometry with increased magnetic volume was proposed for improved delivery of torque and deflection. In a benchtop evaluation, we showed prolonged catheter drainage (7x) in a dynamic fluid environment containing macroscopic blood clots. Finally, using an intraventricular hemorrhage (IVH) porcine model, we observed that self-clearing catheter had longer survival than control catheter (80% vs. 0%) over the course of 6 weeks. Animals treated with magnetic actuation had significantly smaller ventricle size after 1 week of implantation.</p>
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