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 22 for “"Axial dispersion"”.
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Effect of axial dispersion on interphase mass transfer in packed absorption columns
… mass transfer coefficient and gas phase axial mixing Peclet numbers. Experiments were performed on the absorption of carbon dioxide from a mixture of carbon dioxide and nitrogen in a packed column. Absorption was performed using 1/4, 3/8 and l/2 inch Raschig rings, with a packing height …
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Scale-up of column flotation
… is a function of flotation rate constant, axial dispersion, retention time and fractional air hold-up within the cell. Mathematical expressions have been developed which describe each of these parameters and the manner in which they respond to changing column geometry and flow conditions. …
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Flow-through membrane microreactor for intensified heterogeneous catalysis
… taking into account pore size distribution and axial dispersion, allows to quantify deviations from ideal plug flow behavior. Both influences are combined in a single parameter effective dispersion model. For low axial dispersion caused by high axial velocities and absolute pressures, the pore …
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Scale-up of oscillatory flow mixing
… from these investigations are interpreted as axial dispersion coefficients and also compared with results obtained computationally using a fluid mechanics approach to simulate flow fields and the injection of inert tracers into those flow fields. Significant clarification is reported …
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Microfluidic synthesis of colloidal nanomaterials
… segmented gas-liquid flows overcome the large axial dispersion effects associated with single-phase laminar flows. Microchannel devices that yielded uniform, stable gas-liquid segmented flows over three orders of magnitude in flow velocity were first developed.
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Macroscopic convection in the thin-film processor
… i.e., one that includes the effects of axial dispersion of the process fluid. Such a parameter would be helpful in the design and scale up of thin-film equipment. The following approach was used to investigate this proposal: first, experimental fluid residence time distributions were …
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Microfluidic reactors for the synthesis of nanocrystals
… recirculation has the dual of effect of reducing axial dispersion and greatly improving the mixing efficiency - factors which have a strong influence on the ultimate size and size distribution of NCs produced.
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Characterization and application of vortex flow adsorption for simplification of biochemical product downstream processing
… and two modeling approaches, a one-dimensional dispersion convective model and a two-region vortex flow model. It was concluded that the axial dispersion in the vortex flow system is distinct in different vortex flow regimes.
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A Model of Transient Heat Transfer in a Packed Bed of Alumina Particles
… storage system. A novel mechanism to simulate axial dispersion and heat loss from the boundary of the sensible heat system to the environment is introduced. The most challenging topics to develop a robust heat transfer model are related to heat loss term, selecting the more reliable method to …
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Experimental and modeling studies using packed bed reactors: Liquid phase ethylene production by hydrogenation of acetylene
… of reactors (with and without thermowell), the axial dispersion coefficient and dynamic liquid holdup were measured and correlated. The reactor performance was evaluated in the packed bed with the downflow and upflow of the reactants. Both the mode resulted in high conversion and ethylene …
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Efficiency of PAHs removal from clayey soil using supercritical fluid extraction
… of the phenanthrene in the solid pores, axial dispersion in the fluid phase and external mass transfer to the fluid phase from the particle surface. This model, involving partial differential equations, was solved using the finite difference. The model showed the relationship between …
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Continuous blending of dry pharmaceutical powders
… using an residence time distribution models like axial dispersion models. These ow behavior studies were followed by blender performance studies. The dependence of the mixing performance of the continuous blending system on different operational variables like rotation rates of mixing elements and …
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Downstream Processing with Affinity Chromatography. A Study of a Continuous Process for Biospecific Adsorption
… and applied to the experimental results. Axial dispersion could be identified as the predominant 'mass transfer' mechanism. A simulation model was build, based on the data analysis results. The model was verified successfully against the experimental data.<br/><br/>Continuous separation …
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Reaction calorimetric and spectroscopic studies of an ionic liquid synthesis
… on the flow rate of the fluid a reduction of the axial dispersion predicted by the Taylor-Aris theory by a factor of 4 is possible.
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Poly(ethylenimine)-Functionalized Pyroxene Nanoparticles Embedded on Diatomite for Removal of Total Organic Carbon from Industrial Wastewater: Batch and Fixed-bed studies
… behavior was described using a convection-axial dispersion model that had a good fit with the obtained experimental data. Interestingly, this innovative technique was successfully applied at Executive Mat Ltd, here in Calgary in their rotary drum filter after optimizing some operational …
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Wall Heat Transfer Coefficient in a Molten Salt Bubble Column
… column wall and the liquid were measured at five axial locations. A mechanistic model for estimating the kinematic turbulent viscosity and dispersion coefficient was developed from a mechanism of momentum exchange between large circulation cells. By analogy between heat and momentum transfer, …
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Hydrodynamics, Mixing, and Mass Transfer in Bubble Columns with Internals
… can simulate the radial gas velocity profile and axial gas mixing in the presence and absence of internals. Finally, this work aims to validate all the observed experimental results and models in larger columns with and without internals to have a better understanding of the scale-up effects in …
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Thermodynamic and kinetic phenomena in the enzymatic conversion of acetophenone to 1-(R)-phenylethanol in a continuous gas/solid reactor
… along the packed bed was investigated and axial dispersion of the reacting compounds along the packed-bed was predicted. Nevertheless, the dispersion over the packed-bed was overlaid by a pronounced adsorption of acetophenone, reaching up to 6 mgacetophenone/mgprotein. The role of water was …
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Mathematical modelling and control of agitated extraction columns
… and the backmixing coefficients to handle the axial dispersion phenomena encountered in the course of column operation. The parameters were estimated by minimizing the differences between the experimental and the model predicted concentration profiles at steady state conditions using non-linear …
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CFD-DEM modelling of liquid-solid-gas flow in rotary drums and an application in solar panel leaching
… mixing performance (e.g., mixing index and axial dispersion) are studied. The work sheds light on the process optimization of multiphase flow in rotary drums. 2) Given the nonspherical nature of particles in many rotary drum applications, Chapter 4 studies the transportation mechanism of …
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