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293 full-text articles. Page 1 of 11.

On The Hyperbolicity Of The Two-Fluid Model For Gas–Liquid Bubbly Flows, Nithin Panicker, Alberto Passalacqua, Rodney O. Fox 2018 Iowa State University

On The Hyperbolicity Of The Two-Fluid Model For Gas–Liquid Bubbly Flows, Nithin Panicker, Alberto Passalacqua, Rodney O. Fox

Chemical and Biological Engineering Publications

The hyperbolicity condition of the system of partial differential equations (PDEs) of the incompressible two-fluid model, applied to gas–liquid flows, is investigated. It is shown that the addition of a dispersion term, which depends on the drag coefficient and the gradient of the gas volume fraction, ensures the hyperbolicity of the PDEs, and prevents the nonphysical onset of instabilities in the predicted multiphase flows upon grid refinement. A constraint to be satisfied by the coefficient of the dispersion term to ensure hyperbolicity is obtained. The effect of the dispersion term on the numerical solution and on its grid convergence ...


Call For Abstracts - Resrb 2018, June 18-20, Brussels, Belgium, Wojciech M. Budzianowski 2017 Wojciech Budzianowski Consulting Services

Call For Abstracts - Resrb 2018, June 18-20, Brussels, Belgium, Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.


Registration Form Resrb 2018, Wojciech M. Budzianowski 2017 Wojciech Budzianowski Consulting Services

Registration Form Resrb 2018, Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.


Abstract Template Resrb 2018, Wojciech M. Budzianowski 2017 Wojciech Budzianowski Consulting Services

Abstract Template Resrb 2018, Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.


Mixed Municipal Solid Waste Hygienisation For Refuse-Derived Fuel Production By Ozonation In The Novel Configuration Using Fluidized Bed And Horizontal Reactor, Witold Zukowski 2017 Cracow University of Technology

Mixed Municipal Solid Waste Hygienisation For Refuse-Derived Fuel Production By Ozonation In The Novel Configuration Using Fluidized Bed And Horizontal Reactor, Witold Zukowski

Witold Zukowski

Purpose
This study aimed to determine whether mixed municipal solid waste used for alternative fuel production can be effectively treated with ozone hygienisation in a gaseous phase.
Methods
It was determined that the use of a fluidised bed reactor and a horizontal reactor with respect to processing the light fraction and the heavy fraction of waste effectively contributes to the elimination or reduction of the number of selected groups of microorganisms inhabiting mixed municipal solid waste. With the use of microbiological analysis, the presence of vegetative bacteria, spores, fungi, actinomycetes and pathogenic bacteria, i.g. Staphylococcus spp., Escherichia coli, Salmonella ...


Bubble Dynamics And Bed Expansion For Single-Component And Binary Gas-Solid Fluidization Systems, Bowen Han 2017 The University of Western Ontario

Bubble Dynamics And Bed Expansion For Single-Component And Binary Gas-Solid Fluidization Systems, Bowen Han

Electronic Thesis and Dissertation Repository

Gas-solid fluidized beds are widely used in industrial dry coal preparation to separate waste from coal (still a primarily important energy source worldwide). It is the density difference between coal and the waste that enables the separation. Experiments were carried out in a two dimensional gas-solid fluidized bed. Filtered air at room temperature was used as the fluidizing gas, while magnetite, sand (two types) and FCC catalyst particles belonging to Geldart groups A and B were used as bed particles. Image processing and Matlab were applied for bubble size and velocity measurements. Bubble properties and bed expansion in fluidized beds ...


Simulating Gas-Liquid Flows In An External Loop Airlift Reactor, Deify Law, Francine Battaglia, Theodore J. Heindel 2017 Virginia Polytechnic Institute and State University

Simulating Gas-Liquid Flows In An External Loop Airlift Reactor, Deify Law, Francine Battaglia, Theodore J. Heindel

Theodore J. Heindel

The external loop airlift reactor (ELALR) is a modified bubble column reactor that is composed of two vertical columns that are connected with two horizontal connectors. Airlift reactors are utilized in fermentation processes and are preferred over traditional bubble column reactors because they can operate over a wider range of conditions. Computational fluid dynamics (CFD) simulations can be used to enhance our understanding of the hydrodynamics within these reactors. In the present work, the gas-liquid flow dynamics in an external loop airlift reactor are simulated using CFDLib with an Eulerian-Eulerian ensemble-averaging method in two-dimensional (2D) and three-dimensional (3D) coordinate systems ...


Similitude Analysis For Gas-Liquid-Fiber Flows In Cocurrent Bubble Columns, Chengzhi Tang, Theodore J. Heindel 2017 Iowa State University

Similitude Analysis For Gas-Liquid-Fiber Flows In Cocurrent Bubble Columns, Chengzhi Tang, Theodore J. Heindel

Theodore J. Heindel

Gas-liquid-fiber systems are different from conventional gas-liquid-solid systems in that the solid material (i.e., fiber) is flexible, has a large aspect ratio, and forms flocs or networks when its mass fraction is above a critical value. With its wide application to the pulp and paper industry, it is important to investigate the hydrodynamics of gas-liquid-fiber systems. In this paper, 19 parameters that influence gas holdup in gas-liquid-fiber bubble columns are critically examined and then a dimensional analysis based on the Buckingham Pi Theorem is used to derive the dimensionless parameters governing gas-liquid-fiber bubble column hydrodynamics. Seven dimensionless parameters that ...


Stability Issues For Gas-Liquid Flows In Bubble Columns, Deify Law, Francine Battaglia, Theodore J. Heindel 2017 Iowa State University

Stability Issues For Gas-Liquid Flows In Bubble Columns, Deify Law, Francine Battaglia, Theodore J. Heindel

Theodore J. Heindel

In the present work, gas-liquid flow dynamics in a bubble column are simulated with CFDLib using an Eulerian-Eulerian ensemble-averaging method in a two dimensional Cartesian system. The time-averaged gas holdup simulations are compared to experimental measurements of a cylindrical bubble column performed by Rampure et al. [1]. Numerical predictions are presented for the time-averaged gas holdup at various axial heights as a function of radial position. The effects of grid resolution, bubble pressure model, and drag coefficient models on the numerical predictions are examined. The bubble pressure model is reported to account for bubble stability, thus providing physical solutions. The ...


Using X-Rays For Multiphase Flow Visualization, Theodore J. Heindel, Jeremy L. Hubers, Terrence C. Jensen, Joseph N. Gray, Alexander C. Stiegel 2017 Iowa State University

Using X-Rays For Multiphase Flow Visualization, Theodore J. Heindel, Jeremy L. Hubers, Terrence C. Jensen, Joseph N. Gray, Alexander C. Stiegel

Theodore J. Heindel

Gas-liquid, gas-solid, liquid-solid, and gas-liquid-solid multiphase flows are difficult to visualize, characterize, and quantify because the systems are typically opaque. Invasive or noninvasive measurement methods are typically used for determining internal flow and transport characteristics of these complex flows. The difficulty with invasive methods is that they can alter the internal flow of a multiphase system causing interference with realistic process measurements. X-ray imaging provides one family of noninvasive measurement techniques used extensively for product testing and evaluation of static objects with complex structures. These techniques have been extended to visualize dynamic systems, such as those which characterize multiphase flows ...


Repeatability Of Gas Holdup In A Fluidized Bed Using X-Ray Computed Tomography, Joshua B. Drake, Theodore J. Heindel 2017 Iowa State University

Repeatability Of Gas Holdup In A Fluidized Bed Using X-Ray Computed Tomography, Joshua B. Drake, Theodore J. Heindel

Theodore J. Heindel

Characterizing the hydrodynamics in fluidized beds is important to many processes from producing biofuels to coating pharmaceuticals. X-ray computed tomography (CT) can quantify local time-averaged phase fractions in multiphase systems that are highly dynamic, like fluidized beds. This paper describes the calibration methods used to produced CT images of a 15.24 cm diameter fluidized bed, how in-house software used these CTs to calculate gas holdup, and how well multiple CTs of a dynamic fluidized bed produced repeatable results while varying bed material and superficial gas velocities. It was concluded there is a very high degree of repeatability using the ...


Gas Holdup In Opaque Cellulose Fiber Slurries, Sarah M. Talcott, Theodore J. Heindel 2017 Iowa State University

Gas Holdup In Opaque Cellulose Fiber Slurries, Sarah M. Talcott, Theodore J. Heindel

Theodore J. Heindel

Three different cellulose fiber types are used to study their effect on gas holdup and flow regime transition in a 10.2 cm semi-batch bubble column. The three natural fiber types include bleached softwood chemical pulp (softwood), bleached hardwood chemical pulp (hardwood), and bleached softwood chemithermomechanical pulp (BCTMP). Gas holdup is recorded over a range of fiber mass fractions (0 ≤ C ≤ 1.6%) and superficial gas velocities (Ug ≤ 23 cm/s). Experimental results show that gas holdup decreases with increasing fiber mass fraction. Homogeneous, transitional, and heterogeneous flow is observed for all three fiber types at low fiber mass fractions ...


Gas Holdup In A Cocurrent Air-Water-Fiber Bubble Column, Chengzhi Tang, Theodore J. Heindel 2017 Iowa State University

Gas Holdup In A Cocurrent Air-Water-Fiber Bubble Column, Chengzhi Tang, Theodore J. Heindel

Theodore J. Heindel

Effects of superficial liquid velocity (Ul ), superficial gas velocity (Ug ), and fiber mass fraction (C) on gas holdup (ε) and flow regime transition are studied experimentally in well-mixed water-cellulose fiber suspensions in a cocurrent bubble column. Experimental results show that the gas holdup decreases with increasing Ul when C and Ug are constant. The gas holdup is not significantly affected by C in the range of C < 0.4%, but decreases with increasing C in the range of 0.4% ≤ C ≤ 1.5%. When C > 1.5%, a significant amount of gas is trapped in the fiber network and recirculates with the water-fiber slurry in the system; as a result, the measured gas holdup is higher than that ...


Treatment Of Fast Chemistry In Fdf/Les: In Situ Adaptive Tabulation, van Vliet E., Rodney O. Fox, J. J. Derksen, S. B. Pope 2017 Iowa State University

Treatment Of Fast Chemistry In Fdf/Les: In Situ Adaptive Tabulation, Van Vliet E., Rodney O. Fox, J. J. Derksen, S. B. Pope

Rodney O. Fox

The feasibility to implement fast-chemistry reactions in a three-dimensional large eddy simulation (LES) of a turbulent reacting flow using a filtered density function (PDF) technique is studied. Low-density polyethylene (LDPE) is used as an representative reaction due to the stiff nature of the ordinary differential equation (ODE's) describing the kinetics. In FDF/LES, the chemistry needs to be evaluated many times for a large number of fictitious particles that are tracked in the flow, and therefore a constraint is put to the CPU time needed to solve the kinetics. Pope (1997) developed an in situ adaptive tabulation (ISAT) to ...


Numerical Description Of Dilute Particle-Laden Flows By A Quadrature-Based Moment Method, N. Le Lostec, Rodney O. Fox, O. Simonin, P. Villedieu 2017 Office National d'Etudes et de Recherches Aerospatiales, France

Numerical Description Of Dilute Particle-Laden Flows By A Quadrature-Based Moment Method, N. Le Lostec, Rodney O. Fox, O. Simonin, P. Villedieu

Rodney O. Fox

The numerical simulation of gas-particle flows is divided into two families of methods. In Euler-Lagrange methods individual particle trajectories are computed, whereas in Euler-Euler methods particles are characterized by statistical descriptors. Lagrangian methods are very precise but their computational cost increases with instationarity and particle volume fraction. In Eulerian methods (also called moment methods) the particle-phase computational cost is comparable to that of the fluid phase but requires strong simplificaions. Existing Eulerian models consider unimodal or close-to-equilibrium particle velocity distributions and then fail when the actual distribution is far from equilibrium. Quadrature-based Eulerian methods introduce a new reconstruction of the ...


Effect Of Electrolytes On Co−Water Mass Transfer, Haiyang Zhu, Brent H. Shanks, Theodore J. Heindel 2017 Iowa State University

Effect Of Electrolytes On Co−Water Mass Transfer, Haiyang Zhu, Brent H. Shanks, Theodore J. Heindel

Brent H Shanks

The influence of various electrolytes such as sulfate, nitrate, and chloride on CO−water mass transfer was investigated in this study. The results indicate that the enhancement in the CO−water volumetric mass-transfer coefficient ranged from 1.5 to 4.7 times that of a baseline system without electrolytes, depending on electrolyte type and concentration. For those electrolytes with the same anions, copper-containing electrolytes provided stronger enhancement, whereas for those electrolytes with the same cations, sulfate-containing electrolytes showed stronger enhancement. By measuring both the CO−water volumetric mass-transfer coefficient (kLa) and the mass-transfer coefficient (kL), it was found that the ...


Uranium Sequestration By Ph Manipulation Using Nh3 Injection In The Vadose Zone Of Hanford Site 200 Area, Claudia Cardona 2017 Florida International University

Uranium Sequestration By Ph Manipulation Using Nh3 Injection In The Vadose Zone Of Hanford Site 200 Area, Claudia Cardona

FIU Electronic Theses and Dissertations

Past nuclear weapon production activities have left a significant legacy of uranium (U) contamination in the vadose zone (VZ) of the Department of Energy (DOE) Hanford Site. This U is a source of groundwater (GW) contamination. There is a concern that elevated U concentration would slowly infiltrate through the VZ, reach the GW water table, and then end up in nearby rivers and lakes. Remediation of U-contaminated low moisture content soil is a challenging task considering the VZ depth, where contamination is found between 70 and 100 m below the ground surface, and the formation of highly soluble and stable ...


Synthesis Of Biopolymer Materials Tailored For Biological Applications, Nathan P. Birch 2017 University of Massachusetts Amherst

Synthesis Of Biopolymer Materials Tailored For Biological Applications, Nathan P. Birch

Doctoral Dissertations

Biopolymers are able to address a wide variety of medical concerns from chronic wounds to stem cell cultivation to antibacterial and antifouling applications. They are non-toxic, biodegradable, and biocompatible, making them ideal candidates for creating green materials for biological applications. In this thesis, we cover the synthesis of two novel materials from the biopolymers, chitosan and pectin. Chitosan is a biocompatible antibacterial polycation and pectin is an anti-inflammatory polyanion with a strong propensity for hydrogen-bonding. The two chitosan:pectin materials, particles and hydrogels, explore some of the structures that can be created by tuning the electrostatic interactions between chitosan and ...


The Rheology And Roll-To-Roll Processing Of Shear-Thickening Particle Dispersions, Sunilkumar Khandavalli 2017 University of Massachusetts Amherst

The Rheology And Roll-To-Roll Processing Of Shear-Thickening Particle Dispersions, Sunilkumar Khandavalli

Doctoral Dissertations

Particle dispersions are ubiquitous in our daily lives ranging from food and pharmaceutical products to inks. There has been great interest in the recent years in formulation of functional inks to fabricate myriad flexible electronic devices through high-throughput roll-to-roll technologies. The formulations often contain several functional additives or rheological modifiers that can affect the microstructure, rheology and processing. Understanding the rheology of formulations is important for tuning the formulation for optimal processing. This thesis presents investigations on the rheology of particle dispersions and their impact on roll-to-roll technologies.

Shear-thickening behavior is common in particle dispersions, particularly, concentrated particulate inks. We ...


Evaluation Of A Microfluidic Mixer Utilizing Staggered Herringbone Channels: A Computational Fluid Dynamics Approach, Brian Hama 2017 Cleveland State University

Evaluation Of A Microfluidic Mixer Utilizing Staggered Herringbone Channels: A Computational Fluid Dynamics Approach, Brian Hama

ETD Archive

Microfluidic platforms offer a variety of advantages including improved heat transfer, low working volumes, ease of scale-up, and strong user control on parameters. However, flow within microfluidic channels occurs at low Reynolds numbers, which makes mixing difficult to accomplish. Adding V-shaped ridges to channel walls, a pattern called the staggered herringbone design (SHB), might alleviate this problem by introducing transverse flow patterns that enable enhanced mixing. However, certain factors affecting the SHB mixer’s performance remain largely unexplored.

In this work, a microfluidic mixer utilizing the SHB geometry was developed and characterized using computational fluid dynamics based simulations and complimentary ...


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