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1
Wibawa, Martin Sulaiman. "Vorticity transfer through rapid area change". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62791.
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Thesis (S.M. in Naval Architecture and Marine Engineering)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 77-81).
Extensive studies have been conducted on the use of biomimetic foils for propulsion and maneuvering of vehicles. These studies, however, mostly focuses on the use of sinusoidal motion similar to bird flapping or fish swimming to generate the necessary forces. Few studies have been conducted to investigate the generation of maneuvering forces by using rapid vorticity transfer into the fluid through a rapid motion as observed in some animals. In this study a NACA 0012 foil was towed steadily at Reynolds number of 14000, then the foil is rapidly accelerated in the transverse direction. Two different cases were tested: One where the area decreases and one where it increases, referred to as vanishing foil and emerging foil, respectively. Various angle of attacks were tested, and in all the cases the circulation is conserved. The method of Particle Image Velocimetry and flow visualization were used to map out the three-dimensional vortical structure after the rapid motion. In the emerging foil experiment the flow structure is similar to the case of accelerating wing. From the vanishing foil experiment, however, we managed to discover a phenomenon called global separation, where separation happens instantaneously over the entire surface of the body. This global separation allows a more effective and rapid transfer of vorticity, at about one order of magnitude faster than vorticity transfer through conventional means.
by Martin Sulaiman Wibawa.
S.M.in Naval Architecture and Marine Engineering
2
Gilbert, Myrna. "Technological change as a knowledge transfer process". Thesis, Cranfield University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307571.
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Forber, Kirsty Jessica. "The phosphorus transfer continuum under climate change". Thesis, Lancaster University, 2018. http://eprints.lancs.ac.uk/125606/.
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Phosphorus (P) is a key nutrient in governing crop growth, and its fate and behaviour in the environment is critical to water quality. Climatic changes such as hotter, drier summers and warmer, wetter winters will cause changes to the movement of P across the land-water continuum yielding potentially detrimental impacts to water quality which underpin many ecosystem services. This thesis uses the ‘P transfer continuum’ as a framework to discuss and explore the possible impacts of climate change to P in the environment. I use the three National Demonstration Test Catchment (DTC) platforms (Eden, Cumbria; Wensum, Norfolk; and Avon, Hampshire) which are representative of typical catchment typologies and agricultural activities in the UK to frame this work. Potential changes to the P transfer continuum are essential to consider and react to if we are to improve water quality in order to preserve ecosystem services into an ever uncertain future. Estimations of dry period characteristics (duration and temperature) under current and predicted climate (determined using data from the UK Climate Projections (UKCP09) Weather Generator tool) were used to design a laboratory experiment to examine whether changes in the future patterns of drying/re-wetting will affect the amount of soluble reactive phosphorus (SRP) solubilised from soil. This study is focused on the second tier of the P transfer continuum: mobilisation via solubilisation. For three UK soils critical breakpoints (6.9-14.5 d) of drying duration have been identified; before the breakpoint an increase in SRP loss with the number of dry days was observed; after this point the amount of SRP lost decreased or stayed fairly constant. It is likely that longer periods of dry days followed by rapid re-wetting events will not yield more SRP via solubilisation than at the breakpoint. However, because the frequency of longer dry periods will increase under climate change, the solubilisation of SRP from soil (-1 to +13%) will also change. Using the Hydrological Predictions in the Environment (HYPE) model for three distinct UK DTC catchments, and Extended End-Member Mixing Analysis (EEMMA), I explore how climate change (UKCP09 scenarios) might impinge on catchment total phosphorus (TP) retention and sensitivity, which is determined by catchment characteristics to P input pressures. This study encompasses the all tiers of the P transfer continuum: source, mobilisation, transfer (or delivery), and impact. Under a high emissions scenario (2080s), an increase of catchment TP retention was predicted in three UK catchments. I conclude that catchment sensitivity to climate change should be accounted for in determining appropriate water quality targets that can be effectively delivered via catchment stakeholders and government. I use the Newby Beck (Eden DTC) sub-catchment as a critical example of how anthropogenic point sources of P can alter the retention of P even at the headwater scale where agricultural diffuse sources dominate. I use bi-weekly sampling of P, chloride (Cl- ) and flow (Q), load apportionment modelling (LAM) and mass balance, alongside sediment sampling to investigate retention at the headwater scale. I found that although diffuse sources contributed to more of the TP load, point sources dominate more frequently and are therefore proportionally perhaps more important in terms of continuous downstream water quality. Under climate change the transfer of diffuse sources is likely to increase, therefore it might be hypothesised that climate change will yield extremes between nutrient quality in summer (high concentrations, low flows) and winter (high loads, high flows). This calls for policy and regulation to reflect the urgency of the impacts of climate change on the riparian health in rural headwater communities. I conclude by discussing the implications of climate change on the P transfer continuum. I highlight the possible risks of climate change exacerbating, rather than changing, the processes described in the P transfer continuum for the Newby Beck catchment. My findings, in addition to those from the NUTCAT team, call for climate change to be taken seriously in forming new effective policies which preserve the health of UK water bodies, the sustainability and profitability of UK agriculture, the enjoyment and amenity value of our water courses, and avoid large financial costs into the future. I therefore provide a new framework which can be used to aid the challenges which surround the preservation of water quality into the future.
4
Kiehl, Janet K. "Learning to Change: Organizational Learning and Knowledge Transfer". online version, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1080608710.
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Taetz, Christoph [Verfasser]. "Laminar Heat Transfer of Phase Change Dispersions / Christoph Taetz". Aachen : Shaker, 2014. http://d-nb.info/1053903332/34.
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Parayil, Govindan. "Conceptualizing technological change : technology transfer in the green revolution /". Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-08232007-112133/.
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Tetlow, David. "Heat transfer enhancement in integrated phase change drywall system". Thesis, Nottingham Trent University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446610.
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Wittneben, Bettina Beata Friederike. "Institutional change in the transfer of climate-friendly technology". Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615151.
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Uddin, Mahatab. "Climate Change and Requirement of Transfer of Environmentally Sound Technology". Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-160461.
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Technology and policy play a twofold role in international environmental laws. Stronger environmental policies encourage new green technologies and likewise, better technologies make it easier to regulate. “Technology transfer” refers to the transfer from one party, an association or institution that developed the technology, to another that adopts, adapts, and uses it. As different kinds of threats posed by climate change are continuously increasing all over the world the issue of “technology transfer” especially the transfer of environmentally sound technologies has become one of the key topics of international environmental debates. This thesis addresses, firstly, the possible methods of technology transfer and secondly, how current international environmental laws play its role to facilitate the transfer. Accordingly, I have focused on the concerned provisions of Kyoto Protocol and its subsequent implementation measures. I have also taken in to account the decisions of the annual meetings of the Conference of the parties (COPs) of the UNFCCC. The thesis has also made a brief comparative discussion between the provisions of international environmental laws and the provisions of intellectual property rights in terms of technology transfer. However, at the last stage of the thesis, some potential recommendations are mentioned and briefly discussed in view to come up with a sustainable solution. In addition to the international environmental law, I have also tried to figure out some other international or multinational instruments which concern the transfer of environmentally sound technologies.
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Busby, Michael. "Ultrafast studies on photoisomerisation and change transfer in organometallic complexes". Thesis, Queen Mary, University of London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407978.
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Chu, Kuang-Han Ph D. Massachusetts Institute of Technology. "Micro and nanostructured surfaces for enhanced phase change heat transfer". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79311.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 61-65).
Two-phase microchannel heat sinks are of significant interest for thermal management applications, where the latent heat of vaporization offers an efficient method to dissipate large heat fluxes in a compact device. However, a significant challenge for the implementation of microchannel heat sinks is associated with flow instabilities due to insufficient bubble removal, leading to liquid dry-out which severely limits the heat removal efficiency. To address this challenge, we propose to incorporate micro/nanostructures to stabilize and enhance two-phase microchannel flows. Towards this goal, this thesis focuses on fundamental understanding of micro/nanostructures to manipulate liquid and vapor bubble dynamics, and to improve overall microchannel heat transfer performance. We first investigated the role of micro/nanostructure geometry on liquid transport behavior. We designed and fabricated asymmetric nanostructured surfaces where nanopillars are deflected with angles ranging from 7 -52'. Uni-directional liquid spreading was demonstrated where the liquid propagates in a single preferred direction and pins in all others. Through experiments and modeling, we determined that the spreading characteristic is dependent on the degree of nanostructure asymmetry, height-to-spacing ratio of the nanostructures, and intrinsic contact angle. The theory, based on an energy argument, provides excellent agreement with experimental data. This work shows a promising method to manipulate liquid spreading with structured surfaces, which potentially can also be used to manipulate vapor bubble dynamics. We subsequently investigated the effect of micro/nanostructured surface design on vapor bubble dynamics and pool boiling heat transfer. We fabricated micro-, nano-, and hierarchically-structured surfaces with a wide range of well-defined surface roughness factors and measured the heat transfer characteristics. The maximum critical heat flux (CHF) was ~250 W/cm2 with a roughness factor of~-13.3. We also developed a force-balance based model, which shows excellent agreement with the experiments. The results demonstrate the significant effect of surface roughness at capillary length scales on enhancing CHF. This work is an important step towards demonstrating the promising role of surface design for enhanced two-phase heat transfer. Finally, we investigated the heat transfer performance of microstructured surfaces incorporated in microchannel devices with integrated heaters and temperature sensors. We fabricated silicon micropillars with heights of 25 [mu]m, diameters of 5-10 [mu]m and spacings of 5- 10 [mu]m in microchannels of 500 [mu]m x 500 [mu]m. We characterized the performance of the microchannels with a custom closed loop test setup. This thesis provides improved fundamental understanding of the role of micro/nanostructures on liquid spreading and bubble dynamics as well as the practical implementation of such structures in microchannels for enhanced heat transfer. This work serves as an important step towards realizing high flux two-phase microchannel heat sinks for various thermal management applications.
by Kuang-Han Chu.
Ph.D.
12
Khan, Javaid Rabbani. "Heat transfer on a rotating surface with and without phase change". Thesis, University of Newcastle Upon Tyne, 1986. http://hdl.handle.net/10443/670.
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This study is concerned with heat transfer to liquid films flowing across the surface of a rotating disc. Two cases of heat transfer have been considered, the first dealing with sensible heating of the liquid film, the second with heating and evaporation from the surface of the film. In both cases the heating medium was condensing steam. A model for the thermal performance of such devices, has been constructed and compared with experimental data for water and methanol. Values of the temperature of the liquid leaving the disc periphery have been measured for a wide range of liquid flow rates and disc speeds. These results compare very favourably with the temperatures predicted by the proposed model. Similar comparisons have been made for the rates of evaporation measured when methanol is heated on such discs. Again predictions compare well with measured values, except in conditions of flow where film breakdown is known to occur. If the flow on a disc surface, rotating at constant speed, is gradually reduced, a flow will occur at which the surface is no longer completely wetted. Increasing the flow rate will produce rewetting of the surface at some slightly higher value of the flow rate. This mechanism of rewetting has been studied in some detail and a theoretical model has been developed. The model has been tested under a wide range of operating conditions and comparison between measured and predicted minimum rewetting rates is quite good. Power dissipation associated with the flow of liquid film across a disc has also been considered.
13
Hakimian, M. H. "Structural change and labour transfer in Iran's economic developoment, 1900-79". Thesis, University of Sussex, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378263.
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Mahdavi, Nejad Alireza. "Numerical Study of Heat and Mass Transfer Using Phase Change Materials". Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-dissertations/500.
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Phase Change Materials (PCM) absorb and release heat at preset temperatures. Due to their relatively high values of latent heat, they are capable of storing and releasing large amounts of energy during phase change. When a PCM is in its solid phase, it will absorb heat as the external temperature rises. The temperature of the PCM will mirror the external temperature until the melting point of PCM is reached. At this stage, the PCM will begin to melt with almost no change in its temperature. PCM plays an opposite role when the external temperature drops. It releases the stored energy back while going through phase change from liquid phase to solid phase.
The present work is a numerical study towards fundamental understanding of the impact of using PCM on enhancement of heat and mass transfer in several scenarios. A numerical analysis has been carried out to determine the impact of presence of PCM on the insulating characteristics of paper board packaging. Two different cases of a layered PCM and uniformly dispersed PCM within the packaging wall are considered. The numerical results illustrate significant reduction in exchange of heat between the exterior and the interior of the packaging.
Specifically, the unique concept of utilizing PCM in drying of paper is proposed and a numerical investigation is performed to determine the corresponding transport characteristics. The results indicate that the PCM acts as a heat source and a heat sink alternatingly throughout the conventional paper drying process, enhancing the drying energy efficiency. This study also included presence of gas-fired infrared emitters in the drying process as well for which the spectral absorption coefficient of PCM was measured and incorporated into the theoretical model.
Finally, the impact of the presence of PCM in convective air-drying of moist paper is numerically investigated. The hot air ow is generated by an in-line jet nozzle. The air impinges on the exposed surface of the moist paper while the other side is considered to be perfectly insulated. The results provide the corresponding air flow field as well as air temperature distribution in between the nozzle exit and the surface of the moist paper. The results also reveal the enhancement of drying rates with PCM, fundamentally confirming the role of PCM on enhancing the energy efficiency of convective drying of moist paper.
15
Zhang, Xi. "Climate-change-related technology transfer to China in the TRIPS era". Thesis, University of Portsmouth, 2018. https://researchportal.port.ac.uk/portal/en/theses/climatechangerelated-technology-transfer-to-china-in-the-trips-era(80a6480f-83cc-4645-9345-7f6cd595fa18).html.
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This thesis attempts to look at the practical impacts that the Agreement on Trade-related Aspects of Intellectual Property Rights has on the international transfer of technology,especially to China, and in relation to climate change technology, which is provided for by international agreements such as the United Nations Framework Convention on Climate Change and the Kyoto Protocol. The author takes the perspective of a developing country,China, focusing on both international and national regulations in order to study the operational situation of the “pull” side of technology transfer. On the one hand, the research addresses the positive and negative effect of the Agreement on Trade-related Aspects of Intellectual Property Rights by looking into the interpretation of its provisions; and on the other hand it examines how individual transactions, or potential transactions, of climate change technology have been affected by intellectual rights and surrounding issues, especially in projects coordinated by the Clean Development Mechanism. The transactions examined are focused upon China, which is a large and rapidly growing developing country, because it possesses certain features that make the transfer of technology both desirable (major climate change and related problems, e.g. severe air pollution) and at times problematic (e.g. its capacity to become a major manufacturer of climate change technology, putting at risk the IP rights of the transferor). This thesis attempts to look at the outlined subject by employing a social-legal methodology to acquire information through an interview survey and to examine empirical data while discussing literatures and laws. It provides a specific and original angle from which to look at the dynamic of renewable energy technology being transferred to China. This has enabled this research to provide a relatively up-to-date insight into whether intellectual property laws hinder, or are not conductive to, technology transfer as well as the efficiency of mechanisms available under the Kyoto Protocol. The results of the research show that although the patent data indicates a positive technology growth in China, there are still considerable difficulties in the climate change technology-transfer process. Nevertheless, importing and absorbing such technologies could be crucial to the objective of protecting the global environment. Recognizing this, the Chinese government has played a critical role in promoting technology transfer in a much more effective manner than intellectual property law amendments required by the Agreement on Trade-related Aspects of Intellectual Property Rights. In the future, governments in both the developed and developing world should put effort into establishing a financially practical framework to facilitate technology beyond expediency. The establishment of such should enable developing countries like China to address their need for environmental technologies and to play an active role as a transferor. Given the significant differences in circumstances, and the various needs of nations, reforms towards a more environmental-enabling intellectual property legal system should be conducted in several stages, before any substantial amendments are made to the current international agreements.
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Karl, Ralph. "Technical college transfer students at UW-Stout a description and study of change /". Menomonie, WI : University of Wisconsin--Stout, 2005. http://www.uwstout.edu/lib/thesis/2005/2005karlr.pdf.
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Karlsson, Benny, i Philip Kappen. "International Inter-Organizational Knowledge Transfer : A case study of conformity and change". Thesis, Uppsala University, Department of Business Studies, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7519.
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Gong, Zhen-Xiang. "Time-dependent melting and freezing heat transfer in multiple phase change materials". Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=42043.
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Based on an analysis of the causes of non-convergence in the effective heat capacity methods a new conservative effective heat capacity method is developed for general phase change heat transfer problems. Numerical experiments verified the accuracy and efficiency of the new method.A multi-layer phase change material (PCM) heat transfer module is proposed for latent heat energy storage. Cyclic heat transfer in the module was modelled using the finite element technique. A parametric study was performed to investigate the energy charge/discharge rates for the new design.
A second-law thermodynamic analysis was carried out for thermal energy storage using multiple PCMs. The exergy efficiency of energy storage units using two, three as well as five different PCMs was analyzed and compared with that using a single PCM.
A novel cone-cylinder design configuration is proposed for a shell-and-tube latent heat energy storage exchanger. A finite element model was developed to simulate the coupled convection and cyclic melting/freezing phase change heat transfer occurring outside the tube. The advantages of the new configuration are examined and discussed with the help of numerical experiments. Following the new design configuration a novel multi-exchanger energy storage system is proposed. Finite element simulation results validated and extended the thermodynamic analytical results.
A new solar thermal storage unit using multiple PCMs was proposed and analyzed by a finite element model. A parametric study was carried out to investigate the advantages of the new design when compared with conventional single PCM designs.
Finally, a finite element model for melting and freezing heat transfer including free convection in the melt region was developed. The streamline upwind/Petrov-Galerkin method was employed to enhance both the stability and accuracy of the numerical solution. Using this finite element model simulations were carried out for melting of a PCM in a rectangular cavity heated from below. Flow patterns and local heat flux distributions at the heating surface are presented and discussed. In addition, melting of a PCM in a rectangular cavity with an isothermal vertical wall was simulated. To enhance the heat transfer rate during the last stage of the melting process, inverting the PCM container is shown to be an effective technique; this idea was examined with a parametric study.
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Gong, Zhen-Xiang. "Time-dependent melting and freezing heat transfer in multiple phase change materials". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ29948.pdf.
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Xiao, Rong Ph D. Massachusetts Institute of Technology. "Wetting and phase-change phenomena on micro/nanostructures for enhanced heat transfer". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/79285.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, February 2013.Page 76 blank. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 71-75).
Micro/nanostructures have been extensively studied to amplify the intrinsic wettability of materials to create superhydrophilic or superhydrophobic surfaces. Such extreme wetting properties can influence the heat transfer performance during phase-change which is of great importance in a wide range of applications including thermal management, building environment, water harvesting and power production. In particular, superhydrophilic surfaces have been of interest to achieve thin film evaporation with high heat fluxes. Meanwhile, superhydrophobic surfaces with dropwise condensation promises higher heat transfer coefficients than typical filmwise condensation. My thesis work aims at improving fundamental understanding as well as demonstrating practical enhancements in these two areas. A key challenge to realizing thin film evaporation is the ability to achieve efficient fluid transport using superhydrophilic surfaces. Accordingly, we developed a semi-analytical model based on the balance between capillary pressure and viscous resistance to predict the propagation rates in micropillar arrays with high aspect ratios. Our experimental results showed good agreement with the model, and design guidelines for optimal propagation rates were proposed. For micropillar arrays with low aspect ratio and large spacing between pillars, however, we identified that the microscopic sweeping of the liquid front becomes important. We studied this phenomenon, explained the effect of such microscale dynamics on the overall propagation behavior, and proposed a strategy to account for these dynamics. While these propagation studies provide a means to deliver liquid to high heat flux regions, we investigated a different configuration using nanoporous membrane that decouples capillarity from the viscous resistance to demonstrate the potential heat dissipation capability. With nanoporous membranes with average pore diameters of 150 nm and thicknesses of 50 [mu]m, we achieved interfacial heat fluxes as high as 96 W/cm2 via evaporation with isopropyl alcohol. The effect of membrane thickness was studied to offer designs that promise dissipation of 1000 W/cm 2 . Meanwhile, we developed new metrology to measure transient heat transfer coefficients with a temporal resolution of 0.2 seconds during the evaporation process. Such a technique offers insight into the relationship between liquid morphology and heat transfer behavior. Finally, for enhanced condensation, we demonstrated immersion condensation using a composite surface fabricated by infusing hydrophobic oil into micro/nanostructures with a heterogeneous coating. With this approach, three key attributes to maximize heat transfer coefficient, low departure radii, low contact angle, and high nucleation density, were achieved simultaneously. We specifically elucidated the mechanism for the increase in nucleation density and attribute it to the combined effect of reduced water-oil interfacial energy and local high surface energy sites. As a result, we demonstrated approximately 100% enhancement in heat transfer coefficient over state-of-the-art superhydrophobic surfaces with the presence of non-condensable gases. This thesis presents improved fundamental understanding of wetting, evaporation, and condensation processes on micro/nanostructures as well as practical implementation of these structures for enhanced heat transfer. The insights gained demonstrate the potential of new nanostructure engineering approaches to improve the performance of various thermal management and energy production applications.
by Rong Xiao.
Ph.D.
21
Klyn, de Novelo Jessica. "The impact of intercultural differences in change agentry interventions in technology transfer". Scholarly Commons, 2012. https://scholarlycommons.pacific.edu/uop_etds/833.
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This qualitative study explored the effects of intercultural differences on technology transfer interventions. More specifically, the emphasis was on key differences between the worldviews of change agents and clients that impact such change agentry attempts. Utilizing frameworks taken from intercultural relations, change agentry, and diffusion of innovations research, the study examined a single case of change agentry-the distribution of cookstoves to a rural community in Peru-in an attempt to answer the following question: How do intercultural differences help shape the results of change agentry interventions in technology transfer attempts?
The focus of this study was the distribution of "improved cookstoves" in rural Andean, Peru, by a rural aid organization based at a university in Lima, Peru. Individuals from both the aid organization and the community were interviewed regarding their experience, including the engineering and technical team responsible for diffusing the technology, as well as community members who adopted the technology, others who did not, and a third group trained by the aid organization to be local "experts" in the use of cookstoves.
The research contributes to a deeper understanding of the relationships between change agents and client recipients by contributing a,n intercultural perspective to discussions of the diffusion of innovations and development interventions.
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Ali, Rashid. "Phase Change Phenomena During Fluid Flow in Microchannels". Doctoral thesis, KTH, Tillämpad termodynamik och kylteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-26796.
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Phase change phenomena of a fluid flowing in a micro channel may be exploited to make the heat exchangers more compact and energy efficient. Compact heat exchangers offer several advantages such as light weight, low cost, energy efficiency, capability of removing high heat fluxes and charge reduction are a few to mention. Phase change phenomena in macro or conventional channels have been investigated since long but in case of micro channels, fewer studies of phase change have been conducted and underlying phenomena during two-phase flow in micro channels are not yet fully understood. It is clear from the literature that the two-phase flow models developed for conventional channels do not perform well when extrapolated to micro scale. In the current thesis, the experimental flow boiling results for micro channels are reported. Experiments were conducted in circular, stainless steel and quartz tubes in both horizontal and vertical orientations. The internal diameters of steel tubes tested were 1.70 mm, 1.224 mm and the diameter of quartz tube tested was 0.781 mm. The quartz tube was coated with a thin, electrically conductive, transparent layer of Indium-Tin-Oxide (ITO) making simultaneous heating and visualization possible. Test tubes were heated electrically using DC power supply. Two refrigerants R134a and R245fa were used as working fluids during the tests. Experiments were conducted at a wide variety of operating conditions. Flow visualization results obtained with quartz tube clearly showed the presence of confinement effects and consequently an early transition to annular flow for micro channels. Several flow pattern images were captured during flow boiling of R134a in quartz tube. Flow patterns recorded during the experiments were presented in the form of Reynolds number versus vapour quality and superficial liquid velocity versus superficial gas velocity plots. Experimental flow pattern maps so obtained were also compared with the other flow pattern maps available in the literature showing a poor agreement. Flow boiling heat transfer results for quartz and steel tubes indicate that the heat transfer coefficient increases with heat flux and system pressure but is independent on mass flux and vapour quality. Experimental flow boiling heat transfer coefficient results were compared with those obtained using different correlations from the literature. Heat transfer experiments with steel tubes were continued up to dryout condition and it was observed that dryout conditions always started close to the exit of the tube. The dryout heat flux increased with mass flux and decreased with exit vapour quality. The dryout data were compared with some well known CHF correlations available in the literature. Two-phase frictional pressure drop for the quartz tube was also obtained under different operating conditions. As expected, two-phase frictional pressure drop increased with mass flux and exit vapour quality.QC 20101206
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Yudiarsah, Efta. "Change transport through molecules structural and dynamical effects /". Ohio : Ohio University, 2008. http://www.ohiolink.edu/etd/view.cgi?ohiou1219343872.
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Washington, Christopher L. "The relationships among learning transfer climate, transfer self-efficacy, goal commitment, and sales performance in an organization undergoing planned change /". The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486402544592042.
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Trejo, Peimbert Esli. "Dynamics and Transfers in two phase flows with phase change in normal and microgravity conditions". Phd thesis, Toulouse, INPT, 2018. http://oatao.univ-toulouse.fr/23986/1/Trejo_Esli.pdf.
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Two-phase flows with or without phase change are present in terrestrial and space applications like thermal control of satellites, propellant supply for launchers, and waste water treatment for space exploration missions. Flow boiling experiment with HFE7000 were conducted in a heated tube in vertical upward flow on ground and in microgravity conditions to collect data on flow patterns, pressure drops, heat transfers, void fraction. Void fraction measurements allowed to measure mean gas velocity and the liquid film thickness in annular flow. In microgravity condition, the liquid film thickness and the interfacial shear stress are significantly lower than in normal gravity. A detail analysis of the film structure was performed by image processing. The impact of gravity and liquid and vapour superficial velocities on the disturbance waves velocities and frequencies was investigated. Two different measurement techniques were used and compared to determine the heat transfer coefficient. For quality values greater than 0.2, HTC is not sensitive to gravity and is in good agreement with classical correlations of the literature. For qualities smaller than 0.1, in the subcooled nucleate boiling regime HTC is significantly smaller in microgravityconditions.
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Chiu, Justin NingWei. "Heat Transfer Aspects of Using Phase Change Material in Thermal Energy Storage Applications". Licentiate thesis, KTH, Kraft- och värmeteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-34263.
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Innovative methods for providing sustainable heating and cooling through thermal energy storage (TES) have gained increasing attention as heating and cooling demands in the built environment continue to climb. As energy prices continue to soar and systems reach their maximal capacity, there is an urgent need for alternatives to alleviate peak energy use. TES systems allow decoupling of energy production from energy utilization, both in location and in time. It is shown in this thesis that successful implementation of TES in the built environment alleviates peak energy load and reduces network expansion as well as the marginal energy production cost. This thesis analyzes phase change material (PCM) based TES systems in terms of material property characterization, numerical modeling and validation of thermal storage, as well as case specific techno-economic feasibility studies of system integration. The difficulties identified in latent heat TES design, such as heat transfer aspects, subcooling and identification of phase separation, have been analyzed through Temperature-History mapping and TES numerical modeling with experimental validation. This work focuses on the interdependency between resource availability, thermal charge/discharge power and storage capacity. In a situation where resource availability is limited, e.g. when using free cooling, waste heat or off-peak storage, the thermal power and storage capacity are strongly interrelated and should always be considered in unison to reach an acceptable techno-economic solution. Furthermore, when considering TES integration into an existing thermal energy distribution network, three adverse aspects are revealed in the Swedish case study: the single tariff system, the low-return temperature penalty, and the low storage utilization rate. These issues can be overcome through better adapted policies and optimized storage control strategies. Finally, despite the currently unfavorable conditions in the Swedish energy system, it is shown that TES has the potential to mitigate climate change through greenhouse gas emission reduction by displacing fossil-fuel based marginal thermal energy production.QC 20110629
Cold Thermal Energy Storage
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Scott, David A. 1972. "Heat transfer in pipes conveying slurries of microencapsulated phase-change materials in water". Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102169.
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Complementary computational and experimental investigations of steady, laminar, mixed convection in a heated vertical pipe, with slurries of a microencapsulated phase-change material (MCPCM) suspended in distilled water as the working fluid, are presented in this thesis.The MCPCM consists of particles composed of a core of phase-change material (PCM) surrounded by a solid shell: The effective diameter of the particles is 2.5 mum; the melting and freezing temperatures of the PCM in the particles are in the ranges 27°C to 31°C (mean value 29.94°C) and 12°C to 16°C (mean value of 14.64°C), respectively; the latent heat of fusion during melting is 131.8 kJ/kg. Experimental apparatus and procedures for measurements of the effective density, the effective viscosity, the effective thermal conductivity, and the effective specific heat of the MCPCM slurries are presented along with results and correlations that apply to temperatures in the range 5ºC to 60ºC.
In the presentation of the computational investigation, a homogenous mathematical model is shown to be applicable and proposed; procedures for incorporation of correlations for the effective properties of the MCPCM slurries are discussed; difficulties with the standard definition of bulk temperature when the specific heat of the fluid changes significantly with temperature are elaborated; a modified bulk temperature that overcomes these difficulties is proposed; a finite volume method is described; and its validation and use in the computer simulations are discussed.
An apparatus that was designed, constructed, benchmarked, and used in the mixed-convection experiments is described. Details of this experimental investigation, conducted with slurries of mass concentration 0% (pure distilled water), 5%, 10%, 15%, and 20%, temperatures in the range 20°C to 60°C, and volume flow rates in the range 1.78 mL/s to 2.69 mL/s, are presented.
The experimental and numerical results are presented, compared, and discussed. They show that the proposed homogenous model, with input of correlations that give the variation of the effective properties of the MCPCM slurries with temperature, provides a cost-effective and accurate foundation for computer simulations of the problems of interest.
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Griffin, Karen. "Transfer track versus workforce development : implications for policy change in Florida community colleges". [Tampa, Fla] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0001908.
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Brink, Barend. "Managing change to enable the transfer and sharing of knowledge and best practices". Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52331.
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Thesis (MBA)--Stellenbosch University, 2001.ENGLISH ABSTRACT: This study project investigates the implementation of a Management Information System (MIS) in Telkom S.A. Ltd. With any implementation process, the affected company and its employees go through a change process. This report discusses knowledge management theory and the transfer of best practices theory, and how the implementation of these principles can improve the acceptance and use of the new software system. Following is a description and explanation of the structure and content of the report. Chapter 1 defines the research problem in detail. It also defines and briefly discusses the terms Management Information System, knowledge management and change management. Chapter 2, the literature review, consists of five sections. The five sections discuss; knowledge management concepts, knowledge management models, the comparison between models, knowledge management technology and the implementation of knowledge management. Section one, knowledge management concepts, discusses the basic theory on knowledge and learning. It looks at the basic differences between Western and Eastern philosophy and theories about learning. Concepts such as tacit knowledge, explicit knowledge and intellectual capital are introduced. A brief explanation of the start of knowledge management is offered. The four models that are discussed in section two are; The Knowledge Spiral, Best Practices Transfer, The Four Elements of Knowledge Management and The Tactical and Strategic Activities in Knowledge Management. The models discuss methods of identifying and capturing knowledge, ways in which innovation takes place in an organisation as well as identifying where a company is heading and finding ways to invest in intellectual capital to prepare for the future needs of the company. Section three compares all of the models discussed in section two. A comparison is made between the different approaches and the main focus of each model is highlighted. Technology, information management and knowledge management cannot be separated. Section four discusses the importance of technology in knowledge management, the technology backbone and applications of knowledge management. The reality of the implementation of knowledge management is discussed in section 5. The effect of knowledge management on the organisation as a whole, change management and knowledge management enablers are the topics discussed. Chapter three discusses the implementation environment, that is the business units affected by the implementation. It also gives an explanation of the design and workings of the MIS that was implemented. It is possible to read the study without reading chapter three and without background on the implementation environment and the product. The implementation of the MIS was reviewed one month and again two months after implementation. Chapter four discusses the review procedure and the main findings of the reviews. Chapter five ends the report with an evaluation on the implementation of the MIS and knowledge management practices.
AFRIKAANSE OPSOMMING: Hierdie studieprojek ondersoek die implementering van 'n Bestuurs Informasiestelsel in Telkom S.A. Bpk. Gedurende die implementeringsproses van enige nuwe stelsel, gaan die personeel, asook die maatskappy deur 'n veranderingsproses. Hierdie verslag bespreek kennisbestuur teorie, oordrag van beste praktyke teorie, en hoe die implementering van hierdie beginsels , die aanvaarding en gebruik van die nuwe sagtewaresisteem kan bevorder. Vervolgens 'n beskrywing van die struktuur en die inhoud van die verslag. Hoofstuk 1 definieer die probleemstelling in meer besonderhede. Die terme, Bestuurs Informasiestelsel, kennisbestuur en die bestuur van verandering word gedefineer en kortiks bespreek. Hoofstuk 2 bevat die literatuurstudie en bestaan uit 5 seksies. Die 5 seksies bespreek; kennisbestuur konsepte, kennisbestuur modelle, 'n vergelyking tussend die modelle, kennisbestuur-tegnologie asook die implementering van kennisbestuur. Die eerste seksie wat handel oor kennisbestuur konsepte, bespreek die basies begrippe van kennis en die leerporses. Die seksie kyk onder andere na die verskillende sienswyses tussen die Westerse en Oosterse filisofie oor kennis en die leerproses. Die konsepte, interne/eie-kennis, ekplisiete/eksterne kennis en intellektuelekapitaal word bespreek. Die seksie eindig met 'n kort weergawe van die ontstaan van kennisbestuur. Die vier kennisbestuurmodelle wat in die tweede seksie bespreek word is; "The Knowledge Spiral", "Best Practices Transfer", "The Four Elements of Knowledge Management" en "The Tactical and Strategic Activities in Knowledge Management". Verskillende metodes hoe om kennis vas te vang, maniere hoe innovasie plaasvind in maatskappy verband, asook vroegtydige identifisering van die maatskappy se toekomstige intellektuelekapitaalbehoeftes word deur die verskillende modelle voorgestel. Die modelle wat in seksie twee bespreek is, word vergelyk in die derde seksie. Die modelle word bespreek op grond van die verskille tussen die modelle, asook die hooffokus van elke model. Informasiebestuur, kennisbestuur en tegnologie kan nie van mekaar geskei word nie. Die vierde seksie bespreek die belangrikheid van tegnolgie in kennisbestuur, asook die toepassings as boublokke op die tegnologiebasis in kennisbestuur. Die realiteit wanneer kennisbestuur geimplementeer word, word bespreek in seksie 5. Daar word gekyk na die effek wat die implementering van kennisbestuur op die organisasie het. Faktore wat die implementering van kennisbestuur en verandering vergemaklik, word bespreek. Hoofstuk 3 verskaf inliging oor die omgewing waar die sagteware geimplementeer is. Agtergrond word verskaf oor die besigheidseenheid, asook die verskillende Iynseksies. Die Bestuursinligtingsprogram wat geimplementeer is, word in meer detail bespreek. Dit is moontlik om die studieprojek te lees sonder die agtergrond wat in hoofstuk 3 bespreek word. 'n Evaluasie is gehou 1 maand en weer 2 maande na die implementering van die sagteware. Die evalusieprosedure, asook die belangrikste gevolgtrekkings word bespreek in hoofstuk 4. Die verslag einding met 'n bespreking van die implementering van die sagteware asook kennisbestuur praktyke in hoofstuk 5.
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Shaw, Jonathan. "Pragmatic dualism : socio-economic change, teachers and knowledge transfer to Vietnamese university curricula". Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394255.
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Kuo, Long-Sheng 1969. "Non-equilibrium energy transfer and phase change during intense picosecond laser-metal interactions". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/34346.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.Includes bibliographical references (leaves 55-57).
Laser interactions with metals involve absorption of photon energy by electrons, energy coupling between electrons and the lattice, and energy transport by diffusion of electrons and lattice vibrations. During picosecond laser irradiation of metal films, electrons and the lattice are not in thermal equilibrium. On the other hand, rapid laser heating produces a large degree of superheating and undercooling during melting and solidification. First, this work investigates experimentally non-equilibrium heating processes during intense picosecond laser heating of metal films. Results show excellent agreement with predictions of the two-step radiation heating model. Second, this work develops a general model to characterize both non-equilibrium energy deposition and phase change processes. The predictions show that the non-equilibrium heating processes significantly increase the laser melting threshold, enlarge the thermal-affected region, reduce the lattice temperature rise, prolong the phase change duration, and reduce the solidification speed. These results are important for materials processing using ultrashort pulsed lasers.
by Long-Sheng Kuo.
S.M.
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Shapiro, Andrew P. "Steady and unsteady heat and mass transfer through porous media with phase change". Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/31004.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1987.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Bibliography: leaves 138-139.
by Andrew P. Shapiro.
M.S.
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De, Lima e. Silva Waldyr. "A front-tracking boundary element formulation for heat transfer problems with phase change". Thesis, University of Portsmouth, 1994. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386081.
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Tawfik, Victor, i Fredrik Marstorp. "Investigating underlying factors influencing transfer of training and behavioral change in organizational settings". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235921.
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The aim of the master thesis was to investigate the factors influencing transfer of training and behavioral change in organizational settings. Two research questions were formulated for this master thesis. Two models are presented and tested both qualitatively and quantitatively through literature research, interviews, and surveys. One is a conceptualized model based on existing literature that displays the factors influencing transfer of training. The other is a framework called the Reasoned Action Approach that explains the factors influencing behavioral change. Three firms that underwent training and development workshops participated in the study. Based on the results, it can be concluded that transfer of training was found to be predicted by motivation to transfer, which, in turn was predicted by job congruence and supervisor support. Learning, which was hypothesized to predict transfer of training, was found to be a factor parallel to transfer of training, it was found to be predicted by training motivation, which, in turn was found to be predicted by reaction to training and organizational commitment. It is concluded that these factors need to be taken into consideration when designing training and development programs for organizations. The Reasoned Action Approach have been proven to be a model fit for training and development programs to understand the underlying factors affecting behavioral change in an organizational context. The model aims to understand which of the three factors attitude, perceived norm, and perceived behavioral control are the strongest predictor of the intention to perform abehavior. Targeting these predictors in a training and development program, and measuring the result allows for determining if the intended changes have been made.Syftet med detta masterexamensarbete var att undersöka faktorerna som påverkar tillämpningav lärande och beteendeförändring i organisatoriska sammanhang; för detta arbete formulerades två forskningsfrågor. Två modeller har presenteras och testats både kvalitativt och kvantitativt genom befintlig forskning på ämnet, intervjuer, och enkäter. Den ena modellen är en konceptmodell baserat på befintlig forskning som kartlägger faktorerna som påverkar tillämpning av lärande. Den andra modellen är ett ramverk, ”The Reasoned Action Approach” som förklarar faktorerna som påverkar beteendeförändring. Tre företag som undergick utvecklingsworkshops deltog i studien. Resultatet visade att tillämpning av lärande föregås av motivation till att tillämpa lärande, som i sin tur föregås av jobbkongruens och support från chef. Lärande som hypotiserades att förutspå tillämpning av lärande upptäcktes istället vara en faktor som är parallell till tillämpande av lärande. Resultatet visade att lärande föregås av motivation till att lära sig, som i sin tur föregås av reaktion till träning och engagemang för organisationen. Slutsatsen som därmed dras är att dessa faktorer bör tas hänsyn till när utvecklingsprogram tas fram för organisationer. The Reasoned Action Approach har visat sig vara en modell som passar utvecklingsprogram för att förstå vilka faktorer som påverkar beteendeförändring i organisatoriska sammanhang. Modellens syfte är att förstå vilka av de tre faktorerna attityd, uppfattad norm, och uppfattad kontroll som starkast kan förutspå intentionen av att utföra ett beteende. Fokusering på dessa antecedenter och mätning efter workshop kan visa om önskade förändringar har skett.
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Al, Hashimi Husain. "Local Measurement and Characterization via Fluorescing Materials for Phase Change Heat Transfer Applications". Thesis, University of Maryland, College Park, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10624676.
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Better understanding of phase change phenomena can be obtained through local measurements of the heat transfer process, which cannot be attained by traditional thermocouple point measurements. Infrared (IR) technology, which has been used by many researchers in the past, cannot be used under certain circumstances due to spectral transparency issues present in some materials. In the current study, the optical properties of fluorescing materials are proposed as a novel tool for heat transfer measurements. Two fluorescing materials were examined within the framework of the current dissertation: Namely Quantum dots and Ruthenium based temperature sensitive paint, which tend to fluoresce upon excitation by blue or Ultraviolet (UV) light. The light intensity emitted by those fluorescing materials tends to drop with temperature, which can be utilized to obtain the surface temperature distribution at a pixel resolution, for a given monochromic camera. Advantages of the fluorescing materials include feasibility, applicability to various surface geometries, and the ability to resolve submicron features. The main objective behind the current research work was to develop and assess the optical measurement technique of fluorescing materials, where phase change heat transfer applications, including ethanol drop evaporation and pool boiling, were used to quantify the advantages and limitations of the current temperature measurement technique. Furthermore, a thermofluid study was conducted in order to examine the mechanism of rapid vapor patch formation near critical heat flux (CHF) conditions. Results from the current research work show a correlation between the fluid velocity gradient near the wall and surface heat flux, where both tend to follow similar trend with surface super heat. Thus, it’s believed that the incomplete wetting of previous vapor patches near CHF is associated with restricted capillary motion near the surface, where the wetting liquid fails to reach the dry areas with the increased bubble generation activity, due to the local heating caused by the mushroom bubble ebullition.
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McLean, Bronwyn. "Implementing Sustainability Locally : A Case Study of Policy Mobilities and Transfer". Thesis, Stockholms universitet, Kulturgeografiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-91922.
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Glavin, Nicholas R. "Photonically Enhanced and Controlled Pool Boiling Heat Transfer". University of Dayton / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1343401685.
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Cusack, Stephen. "Development of a radiative transfer parameterisation based on correlated k-distribution theory for use in climate studies". Thesis, Glasgow Caledonian University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320069.
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Li, Yichen. "Phase-field Modeling of Phase Change Phenomena". Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/99148.
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The phase-field method has become a popular numerical tool for moving boundary problems in recent years. In this method, the interface is intrinsically diffuse and stores a mixing energy that is equivalent to surface tension. The major advantage of this method is its energy formulation which makes it easy to incorporate different physics. Meanwhile, the energy decay property can be used to guide the design of energy stable numerical schemes.
In this dissertation, we investigate the application of the Allen-Cahn model, a member of the phase-field family, in the simulation of phase change problems. Because phase change is usually accompanied with latent heat, heat transfer also needs to be considered. Firstly, we go through different theoretical aspects of the Allen-Cahn model for nonconserved interfacial dynamics. We derive the equilibrium interface profile and the connection between surface tension and mixing energy. We also discuss the well-known convex splitting algorithm, which is linear and unconditionally energy stable. Secondly, by modifying the free energy functional, we give the Allen-Cahn model for isothermal phase transformation. In particular, we explain how the Gibbs-Thomson effect and the kinetic effect are recovered. Thirdly, we couple the Allen-Chan and heat transfer equations in a way that the whole system has the energy decay property. We also propose a convex-splitting-based numerical scheme that satisfies a similar discrete energy law. The equations are solved by a finite-element method using the deal.ii library. Finally, we present numerical results on the evolution of a liquid drop in isothermal and non-isothermal settings. The numerical results agree well with theoretical analysis.Master of Science
Phase change phenomena, such as freezing and melting, are ubiquitous in our everyday life. Mathematically, this is a moving boundary problem where the phase front evolves based on the local temperature. The phase change is usually accompanied with the release or absorption of latent heat, which in turn affects the temperature. In this work, we develop a phase-field model, where the phase front is treated as a diffuse interface, to simulate the liquid-solid transition. This model is consistent with the second law of thermodynamics. Our finite-element simulations successfully capture the solidification and melting processes including the interesting phenomenon of recalescence.
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Kovacevic, Ljubinka, i Erika Kovács. "Change of Employer and Preservation of Employment: Serbian Experience in Light of European Law". University of Belgrade Faculty of Law, 2019. http://dx.doi.org/10.5937/AnaliPFB1902107K.
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Protection of employees in the event of a change of employer in Serbia was
first regulated by the Labour Act (2005). This was a result of the harmonization of
Serbian legislation with Council Directive 2001/23/EC, while the effect of the European
Court of Justice jurisprudence was negligible. Protection is guaranteed regardless
of whether the company identity has been preserved or not, thereby making it more
favourable than the European concept of transfer of undertaking. Nevertheless, the
relevant provisions of the Labour Act have often been evaded in practice, especially
when it comes to the application of the principle of preservation of employment. This
was facilitated by the content of certain legal provisions. There is a notable need for
their improvements, in order to enable employees to continue to work for the transferee
under the same working conditions and be protected from dismissals exclusively
or predominantly motivated by the change of employer.
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Thompson, Clarissa Ann. "The Representational Alignment Hypothesis of Transfer of Numerical Representations". The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1211376719.
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Saad, Mohammed. "The transfer and the management of new technology : the case of two firms in Algeria". Thesis, University of Brighton, 1991. https://research.brighton.ac.uk/en/studentTheses/6db7bc94-48e8-47a0-ad54-db1076af0ecd.
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Bhansali, Anil P. "Heat transfer resulting from a turbulent, submerged jet impinging on a phase change material". Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/19568.
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Khakpour, Yasmin. "Numerical and Experimental Study of Heat and Mass Transfer Enhancement using Phase Change Materials". Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-dissertations/241.
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Conventional heat transfer enhancement methods have focused on the surface characteristics of the heat-exchanger. The enhancement of heat transfer through altering the characteristics of the working fluid has become a new subject of interest. Micro-encapsulated phase change material (MEPCM) slurries show improved heat transfer abilities compared to single phase heat transfer fluids such as water due to their higher specific heat values in their phase change temperature range. The present work is a numerical and experimental study towards fundamental understanding of the impact of using PCM on thermal and fluid flow characteristics of different single-phase and two-phase heat transfer applications. The mathematical formulation to represent the presence of single and multi-component MEPCM is developed and incorporated into the numerical model for single-phase and two-phase fluid flow systems. In particular, the use of PCM in its encapsulated form for heat transfer enhancement of liquid flow in the presence of evaporation is explored. In addition, an experimental study is conducted to validate the numerical model in a setting of natural convection flow. Finally, the application of PCM in its layered form on the effectiveness of drying of moist porous materials (e.g. paper) is investigated.
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Xing, Keqiang. "Numerical Investigation on the Heat Transfer Enhancement Using Micro/Nano Phase-Change Particulate Flow". FIU Digital Commons, 2007. http://digitalcommons.fiu.edu/etd/28.
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The introduction of phase change material fluid and nanofluid in micro-channel heat sink design can significantly increase the cooling capacity of the heat sink because of the unique features of these two kinds of fluids. To better assist the design of a high performance micro-channel heat sink using phase change fluid and nanofluid, the heat transfer enhancement mechanism behind the flow with such fluids must be completely understood. A detailed parametric study is conducted to further investigate the heat transfer enhancement of the phase change material particle suspension flow, by using the two-phase non-thermal-equilibrium model developed by Hao and Tao (2004). The parametric study is conducted under normal conditions with Reynolds numbers of Re=600-900 and phase change material particle concentrations ¡Ü0.25 , as well as extreme conditions of very low Reynolds numbers (Re < 50) and high phase change material particle concentration (0.5-0.7) slurry flow. By using the two newly-defined parameters, named effectiveness factor and performance index, respectively, it is found that there exists an optimal relation between the channel design parameters, particle volume fraction, Reynolds number, and the wall heat flux. The influence of the particle volume fraction, particle size, and the particle viscosity, to the phase change material suspension flow, are investigated and discussed. The model was validated by available experimental data. The conclusions will assist designers in making their decisions that relate to the design or selection of a micro-pump suitable for micro or mini scale heat transfer devices. To understand the heat transfer enhancement mechanism of the nanofluid flow from the particle level, the lattice Boltzmann method is used because of its mesoscopic feature and its many numerical advantages. By using a two-component lattice Boltzmann model, the heat transfer enhancement of the nanofluid is analyzed, through incorporating the different forces acting on the nanoparticles to the two-component lattice Boltzmann model. It is found that the nanofluid has better heat transfer enhancement at low Reynolds numbers, and the Brownian motion effect of the nanoparticles will be weakened by the increase of flow speed.
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Martinez, Christian David. "Heat transfer enhancement of spray cooling with nanofluids". [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003237.
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Patel, Shinel. "Implementing change in practice following staff in-service training on attachment and resilience : an action research study". Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/13925.
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This two phase study investigated the role of Educational Psychologists (EPs), in supporting school staff to transfer learning, from training about attachment and resilience into their practice. Of the various types of action research, this study focused on practical action research, using a responsive model design (Schmuck, 2006). Therefore findings from paper 1 informed the actions in paper 2. The researcher adopted a process consultancy role (Kemmis, 2007), which supported staff to identify and address concerns related to training transfer. The two papers view knowledge in terms of its usefulness for developing practice and therefore operate on the principles of a pragmatic approach. Using a mixed methods approach, the first paper and phase of the research examined the views of staff working in schools on their experiences of how training transfers to practice. In particular, paper 1 aims were to: 1) Determine if (and how) staff have changed their practice following the Multi Agency Attachment and Resilience Group (MAARG) training. 2) Identify what the supporting factors and barriers are perceived to be relevant to implementing or transferring the knowledge gained from the MAARG training, in their daily practice with children and young people. Key findings showed workplace factors such as communication and staff support, to influence staff’s experiences of training transfer. Barriers to implementation were also identified by staff (e.g. time constraints). These findings informed the second phase of the research, where staff were supported to develop capacity, and plan and implement actions to facilitate change. A case study approach was used to develop and evaluate a group intervention for school staff in two schools. This phase had three main aims: 1) To develop a programme which would further support staff to apply relevant knowledge learnt through training, to solve real life problems in their work. 2) To evaluate the processes of the programme of support, in terms of the fidelity of implementation, knowledge use, staff engagement and method acceptability (i.e. the 7 degree to which staff perceive the structure and processes of the programme to be suitable). 3) To evaluate the effectiveness of the programme of support, in terms of immediate outcomes. Process and outcome evaluations were carried out using a mixed methods approach. Key findings showed staff benefited from the intervention programme. The structured group consultation process enabled staff to work efficiently, share responsibilities whilst problem solving, and agree and implement actions with colleagues. Staff applied practical and experiential knowledge when solving problems, with little explicit links to training or research knowledge. Both papers reflect on the role of EPs within the contexts of training implementation. Sections 4 and 5 draw on the findings from both papers, and discuss implications for EP practice.
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Wang, Dianshuang, Yuanting Xu i Xiaochun Li. "Environment and Labor Transfer of Skilled Labor and Unskilled Labor between Sectors". 名古屋大学大学院経済学研究科附属国際経済政策研究センター, 2013. http://hdl.handle.net/2237/17817.
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Smart, Martin James. "Deglaciation dynamics of the Feegletscher Nord, Switzerland : implications for glacio-fluvial sediment transfer". Thesis, University of Hertfordshire, 2015. http://hdl.handle.net/2299/17094.
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Understanding of the processes of sediment transfer within, and from, glaciated catchments is of fundamental importance in order to establish rates of sediment transfer and resultant landscape evolution. Rates of glacio-fluvial sediment transfer are strongly controlled by glacier meltwater runoff and the availability of sediments for entrainment. However, it is becoming apparent that recently deglaciated forefields can modify the patterns of suspended sediment transfer. Glacier shrinkage exposes areas of unstable glacigenic sediments that can be subject to reworking and redistribution, and, as these environments become ice-free, heightened levels of geomorphological activity (so-called 'paraglacial' activity) are also likely to have a significant impact on both sediment and water yields from deglaciating catchments. Consequently, questions are raised as to the impacts of deglaciation upon contemporary and future rates of suspended sediment transfer, and the resultant fluvial sediments loads and rates of landscape adjustment. Therefore, the aim of this research was to present an integrated study of how sediment transfer in a glaciated catchment functions during, and is responding to, deglaciation. A variety of techniques were employed to examine the hydrological functioning of an Alpine glacier, the Feegletscher Nord, Switzerland, and the resultant temporal and spatial patterns of sediment transfer in light of catchment hydrology, ablation processes and forefield geomorphology. Data was collected over two field campaigns in 2010 and 2012 to capture the inputs, throughputs and outputs of meltwater and sediment. This research found that patterns of sediment transfer were modified within the proglacial zone, reinforcing previous findings that the location of proglacial monitoring is important in determining the observed patterns of sediment transfer. These patterns of sediment transfer were attributed to variations in forefield sediment availability, which appeared to demonstrate marked spatial variability. This variability was hypothesised to be influenced by the geomorphological characteristics of the forefield, including rock fall debris that appeared to limit sediment availability, and glacigenic sediment deposits that enhanced the availability of in-channel and channel-marginal sediments. These findings suggest that the investigation of rates of sediment transfer and paraglacial sedimentation may be complicated in catchments that have experienced complex geomorphological responses to deglaciation. In addition, the investigation of sediment transfer processes and the development of a glacier runoff model enabled the exploration of future suspended sediment loads with progressive deglaciation and a changing climate. Suspended sediment loads were predicted to experience rapid declines until the end of the 21st Century due to reductions in meltwater runoff as glacier extent is reduced. However, it is suggested that uncertainties in future sediment availability limit the usefulness of such forecasts. Consequently, this research highlights how the understanding of both sedimentary and hydrological processes in glaciated catchments may be enhanced by consideration of the changes that can occur in these environments associated with glacier shrinkage and a changing climate.
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Hasselström, Linus. "The monetary value of marine environmental change". Doctoral thesis, KTH, Miljöstrategisk analys (fms), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193727.
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The marine ecosystems are fundamental for human welfare. A number of current environmental pressures need attention, and the formulation of management strategies requires information from a variety of analytical dimensions. The linkage between environmental change and resulting implications for human welfare is one such dimension. This thesis presents studies on welfare implications from hypothetical future policies which improve the state of the marine environment. The method for these studies is economic valuation. The studied scenarios concern eutrophication in the Baltic Sea (including the Kattegat) and oil spill risk from shipping in the Lofoten-Vesterålen area in the Arctic Barents Sea. The thesis shows that the economic benefits from undertaking policies to improve or protect the marine environment in these cases are substantial and exceed the costs of taking measures. In addition to providing new monetary estimates, the thesis also provides new insights concerning 1) what type of scenario to use when valuing an environmental improvement and 2) whether there may exist trade-offs between precision in estimates and the level of ambition with respect to survey instrument complexity and econometric models when conducting valuation studies. The findings suggest an end of an era for studies in which the environmental change is unspecified or based on a single environmental indicator while the actual consequences of the suggested measures are more multifaceted. In contrast, relevant scenarios to study are well-specified and holistic. The thesis further reveals that it might not always be worth the effort to go for the most advanced scenario presentation or statistically best-fitting model specifications. This is something that needs to be further discussed among practitioners in order to allocate valuation resources wisely and not waste resources on unnecessarily elegant valuation studies.QC 20161011