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Guet, S.C.L. (author)The gas-lift technique uses gas injection in vertical oil wells to decrease the gravitational pressure drop. The decreased pressure in the production pipe results in an increase of the pressure drop from the reservoir to the oil well and enhances the oil production. In this thesis we investigated the influence of the bubble size and initial...doctoral thesis 2004
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Groen, J.S. (author)In this project a detailed experimental analysis was performed of the dynamic flow field in bubbly flows, with the purpose of determining local hydrodynamics and scale effects. Measurements were done in gas-liquid systems (air-water bubble columns) and in gas-solid systems (air-sand bubbing fluidized beds) of different size. Amongst others with...doctoral thesis 2004
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Harteveld, W.K. (author)The aim of the thesis is to contribute to the understanding of the hydrodynamics of the gravity driven bubbly flow that can be found in bubble columns. Special attention is paid to the large scale structures that have a strong impact on several key parameters such as the degree of mixing, mass and heat transfer. An experimental investigation has...doctoral thesis 2005
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Tang, J.M. (author), Vuik, C. (author)For various applications, it is well-known that deflated ICCG is an efficient method for solving linear systems with invertible and singular co-efficient matrix. This deflated ICCG with subdomain deflation vectors is used by us to solve linear systems with singular coefficient matrix, arising from a discretization of the Poisson equation with...report 2006
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- Guet, S. (author), Ooms, G. (author) journal article 2006
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Sousa, F.S. (author), Portela, L.M. (author), Mudde, R.F. (author), Mangiavacchi, N. (author)We present a method for fully-resolved simulations of bubbly flows using a front-tracking/front-capturing technique. The method is a modification of a marker-and-cell method developed previously for free-surface flows. The basic approach is somehow similar to the front-tracking method of Tryggvason: the continuity and Navier-Stokes equations are...conference paper 2006
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Sousa, F.S. (author), Portela, L.M. (author), Mudde, R.F. (author), Mangiavacchi, N. (author)We present a method for fully-resolved simulations of bubbly flows using a front-tracking/front-capturing technique. The method is a modification of a marker-and-cell method developed previously for free-surface flows. The basic approach is somehow similar to the front-tracking method of Tryggvason: the continuity and Navier-Stokes equations are...conference paper 2006
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Tang, J.M. (author)The Preconditioned Conjugate Gradient (PCG) method is one of the most popular iterative methods for solving large linear systems with a symmetric and positive semi-definite coefficient matrix. However, if the preconditioned coefficient matrix is ill-conditioned, the convergence of the PCG method typically deteriorates. Instead, a two-level PCG...doctoral thesis 2008
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Gunyol, O. (author)The current understanding of the transport phenomena involved in the operation of industrial fermenters is not sufficient. This is reflected by the limitations seen in their design and operation. A better insight in the local processes taking place (hydrodynamics, gas dispersion, mixing, microbial kinetics) is required to be able to make a step...doctoral thesis 2017
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Kamath, S. (author), Padding, J.T. (author), Buist, K. A. (author), Kuipers, J.R. (author)A stochastic Direct Simulation Monte Carlo (DSMC) method has been extended for handling bubble-bubble and bubble-wall collisions. Bubbly flows are generally characterized by highly correlated velocities due to presence of the surrounding liquid. The DSMC method has been improved to account for these kind of correlated collisions along with a...journal article 2018
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Hamraz, Ash (author)In Pressurized Thermal Shock (PTS) applications, there is a co-existence of different flow regimes. The regimes can be divided in two main groups namely, dispersed two-phase flows and the separated two-phase flows having relatively larger interface. Simulating a two-phase flow itself is already a complex task. It gets even more complex when the flow...master thesis 2018
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Joshi, Ankit (author)Heat transfer in multiphase flow plays an important role in nature and in numerous industries such as petrochemical, automotive, food processing, ocean engineering etc. It is becoming increasingly crucial to design more efficient industrial systems to reduce the environmental impact of industrial activities because of global warming and growing...master thesis 2018
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Mandalahalli, M.M. (author), Wagner, E.C. (author), Portela, L. (author), Mudde, R.F. (author)In this work, the effect of an electrolyte (up to 2 M of NaCl dissolved in water) on a homogeneous dense bubbly flow, in an airlift bubble column, is studied using nonintrusive techniques. X-ray and high-speed imaging are used to investigate the bubble size distribution, the local and the global gas-fraction profiles. The major effect of the...journal article 2019
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Nauta, Marieke (author)Zero Emission Fuels B.V. (ZEF) is a start-up who aims to design a sustainable methanol production micro-plant, using solely air and solar energy as an input. A subsystem that has yet to be designed just upstream of the alkaline (KOH) electrolyser, is the so-called degasser. The purpose of the degasser is to remove a residue of carbon dioxide (CO...master thesis 2020
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Karageorgiou, Traianos (author)The graduation project was conducted at the CFD department of Nuclear Research And Consultancy Group (NRG) in Petten. The modeling and simulation of Taylor bubble flow using CFD can contribute significantly to the topic of nuclear reactor safety and in particular, in the emergency cooling of nuclear reactors during a loss of coolant accident, or...master thesis 2020
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Bhatraju, Chaitanya (author)Electrochemical reduction of CO2 using renewable energy sources is one of the promising avenues to pursue towards mitigating the emissions of the notorious CO2. However, the CO2 electrolysis in aqueous systems, due to the low solubility of CO2, are severely limited by mass transfer. State of the art review shows that a significant amount of the...master thesis 2021
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van der Maas, Jos (author)The worlds energy demand is rising as a result of industrial activity and advances in countries around the world. Fossil fuel sources are used to meet this demand for much of the world [1]. The way in which energy is handled causes pollution e.g., CO2 emissions, inducing climate change, therefore a more sustainable industry is desired [2, 3]....master thesis 2021
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Krikke, i.r.c. (author)During water electrolysis for the production of hydrogen and oxygen, many bubbles are formed at the electrodes. The presence of these bubbles causes a number of side effects such as a significant increase in the total cell resistance (e.g., electrical circuit resistances, transport related resistances, and electrochemical reaction resistances)....master thesis 2021
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Sarker, D. (author), Schinkel, C.V. (author), Portela, L. (author)This study reports the effect of N<sub>2</sub> and CO<sub>2</sub> bubbles on dilute to dense gas-liquid two-phase bubbly flow. A shadowgraph imaging technique captured bubble images at a high spatiotemporal resolution. The recordings of bubble images allow us to compute gas fraction distribution. It requires challenging segmentation and gas...journal article 2023
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Haverlag, Hein (author)In this research project, multiphase behaviour in zero gap alkaline water electrolyzers is investigated, focusing on the influence of various parameters including current density, electrode-wall distance and electrode height. This involves a cell containing a vertical electrode pair separated by a membrane submerged in an electrolyte that has a...master thesis 2023