Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 28 for “"maldistribution"”.
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Steam temperature and flow maldistribution in superheater headers
… thermal stresses due to temperature and flow maldistribution at full and partial boiler load operations. The purpose of this project is to develop process models of the outlet stubbox header of a final superheater (FSH) heat exchanger in a 620MW coal-fired drum type boiler. The process models …
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Global surgery - socioeconomic and geographic maldistribution of surgical resources
Surgery is an indispensable part of any health system and improving access to safe surgery remains a challenge in the developing world. Surgery is emerging as a priority in global health, unfortunately information around the burden of surgical diseases or the available surgical resources is …
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Investigation of local velocities and phase holdups, and flow regimes and maldistribution identification in a trickle bed reactor
… technique to identify flow regime, gross maldistribution and liquid distribution. The GRD technique was able to identify trickle and pulse flow regime and their transition. The findings have been consistent with what have been reported in the literature. The measurement of these techniques …
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Two phase flow distribution in parallel flow heat exchangers -- experimentally verified model
Maldistribution of refrigerant is a problem in parallel microchannel heat exchangers that lowers their potential effectiveness, especially when controlled by superheat. This paper describes modeling and numerical simulation of two phase mass flow distribution in a microchannel evaporator, on the …
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Untersuchungen zur Neuverteilung der Rücklaufflüssigkeit in Packungskolonnen
… mit geordneten Packungen eingesetzt. Die Maldistribution, ein bislang ungelöstes Problem in Füllkörperkolonnen, wirkt sich negativ auf die Stoffaustauschleistung aus. Zur Verringerung der Maldistribution wird zwischen den Packungssektionen mehrfach die Rücklaufflüssigkeit gesammelt und …
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Gas distribution in shallow large diameter packed beds
… previous work has been done in this field. A gas maldistribution number, F, was defined, based on point to point velocity variations in the gas emerging from the top of packed beds. f has a minimum value for a uniformly distributed flow and much larger values for maldistributed flows. A method of …
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Flow distribution in brazed plate heat exchangers
… coefficient. However, they suffer from the flow maldistribution among parallel plate channels. Especially when they are used as evaporators, the non-uniform distribution of two-phase refrigerant creates an unwanted superheated region, which has a lower heat transfer coefficient and a smaller …
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Continous annular chromatography for the separation of carbohydrate mixtures
… and built to determine the cause of liquid maldistribution around the annulus. The problem was caused by the porous bed support media becoming clogged with fines being introduced by eluent flows and off the resin. An outer ring was constructed to house the bed support which could be quickly …
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Intermediate vapor bypass: A novel design for mobile heat pump at low ambient temperature
… model was developed and validated. Refrigerant maldistribution in the outdoor heat exchanger in heating mode was modeled with a given liquid refrigerant flow rate distribution profile. Without considering maldistribution, the outdoor heat exchanger capacity in heating mode was overestimated by …
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Global Surgery - A review of the paediatric surgical workforce in South Africa
… marked indicating geographic and socioeconomic maldistribution of paediatric surgeons. The public sector paediatric surgeon density (per million population under 14 years) was 2.4 which fell below the private sector paediatric surgeon density of 9.4. These numbers fell far below developed …
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Refrigerant flow distribution in vertical headers of reversible microchannel heat exchangers
… it functions as an evaporator and refrigerant maldistribution among parallel microchannel tubes creates unwanted superheated region, which lowers the heat transfer between refrigerant and air. This thesis presents the experimental and modeling study of refrigerant distribution in the vertical …
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Non-intrusive two-phase flow regime identification and transport characterization in microchannels subject to uniform and non-uniform heat input
… during the experiments. It is observed that flow maldistribution must be taken into account in the model for heating profiles that are prone to flow maldistribution in order to improve the match to experimental data. ^ Another experimental investigation is performed to measure the critical heat …
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Instability of flow boiling in parallel microchannels
… encounters important problems related to flow maldistribution and instabilities in parallel-channels flow. The thermal and hydrodynamic performance of a microchannel evaporator can drastically decrease, due to the presence of instabilities, and maintaining a set point for operational parameters …
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The values of global citizenship education and implications for social justice
… of the injustices of misrepresentation and maldistribution, compounding a lack of participatory parity. I conclude that UNESCO must afford recognition to alternative values and ways of doing global citizenship such that global citizenship education becomes more socially just.
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Control of flash gas bypass mac system with emphasis on start-ups and transients
… has the benefits of eliminating refrigerant maldistribution and reducing refrigerant pressure drop across the evaporator. Most of the previous research on flash gas bypass focused on performance improvement in steady state and demonstrated that compared to direct expansion mode (DX), FGB mode …
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Flash gas bypass - a way to improve distribution of adiabatic two-phase refrigerant flow in headers of microchannel evaporators
… vapor and header pressure drop induced flow maldistribution on heat transfer performance of microchannel evaporators; 3) periodic reverse vapor flow in microchannel evaporators used in A/C systems. These three issues were part of a project to improve distribution by separation of vapor prior …
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Carbon dioxide transfer in membrane oxygenators and associated membranes
… rates stipulated. Effects of blood and gas flow maldistribution were also studied in the TMO and CAPIOX II units respectively. Non-uniform blood flow was not a major factor contributing to the decline in CO₂ transfer performance compared with theory. This was confirmed in experiments with a …
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Design, Modeling and Characterization of a Multiscale Heat Exchanger for High-Temperature, High-Pressure Applications
… to minimize both pressure loss and flow maldistribution of the working fluids. To evaluate prototypes of our design, we constructed a test setup and experimentally quantified the performance of initial heat exchanger core components. Our design offers a practical solution to address the …
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Analysis of Flow and Heat Transfer in the U.S. EPR Heavy Reflector
… cooling channels was calculated to test for any maldistribution. The temperature distribution in the heavy reflector was then calculated by simulating the conjugate heat transfer with this flow distribution as the coolant input. The turbulent nature of the flow through the cooling channels made …
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Mechanisms of antifatigue agents used in natural rubber
… of polymerisation. This is expected to cause maldistribution of APMA leading to reducing the effect of CB-D activity (while CB-A activity showed clear advantages for grafting). Further optimisation of grafting conditions is required in order to use APMA more effectively. Moreover, although …
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