Chemical Engineering Commons^™

Ambit Of Multiphase Cfd In Modelling Transport Processes Related To Oil Spill Scenario And Microfluidics, Abhijit Rao

LSU Doctoral Dissertations

During the ‘Deepwater Horizon’ accident in the deep sea in 2010, about 4.9 million barrels of oil was released into the Gulf of Mexico, making the spill one of the worst ocean spills in recent times. To mitigate the ill effects of the event on the environment, subsea injection of dispersants was carried out. Dispersant addition lowers the interfacial tension at oil/water interface and presence of local turbulence enhances the droplet disintegration process. The oil droplets contain a plethora of hydrocarbons which are soluble in water. In deep spill scenarios, droplets spend large amounts of time in water column; hence, …

Computational Fluid Dynamics Analysis Of Freeze Drying Process And Equipment, Nikhil P. Varma

Open Access Theses

Freeze drying is an important, but expensive, inefficient and time consuming process in the pharmaceutical, chemical and food processing industries. Computational techniques could be a very effective tool in predictive design and analysis of both freeze drying process and equipment. This work is an attempt at using Computational Fluid Dynamics(CFD) and numerical simulations as a tool for freeze drying process and equipment design.

Pressure control is critical in freeze dryers, keeping in view the product stability. In industrial freeze dryers, loss of pressure control can lead to loss of an entire batch. Pressure variation within the chamber could also lead …

Cfd Black Liquor Bed Simulation, Benjamin Ohran, Dr. Larry Baxter

Journal of Undergraduate Research

The objective of this project was to further the understanding of the bed region of a black liquor recovery boiler. The net output of carbon dioxide from burning black liquor (a paper pulping by-product) is zero, making it a desirable alternative fuel source; however, there are other problems associated with burning black liquor such as boiler fouling, and emissions of pollutants. With the understanding gained from this project it will be possible to further improve the efficiency and emissions of black liquor boilers, making it a more viable fuel alternative.

High Fidelity Chemistry And Radiation Modeling For Oxy-Combustion Scenarios, Hassan A. Abdul Sater

Theses and Dissertations

To account for the thermal and chemical effects associated with the high CO₂ concentrations in an oxy-combustion atmosphere, several refined gas-phase chemistry and radiative property models have been formulated for laminar to highly turbulent systems. This thesis examines the accuracies of several chemistry and radiative property models employed in computational fluid dynamic (CFD) simulations of laminar to transitional oxy-methane diffusion flames by comparing their predictions against experimental data. Literature review about chemistry and radiation modeling in oxy-combustion atmospheres considered turbulent systems where the predictions are impacted by the interplay and accuracies of the turbulence, radiation and chemistry models. Thus, …

Discrete Phase Simulations Of Drilled Cuttings Transport Process In Highly Deviated Wells, Doguhan Yilmaz

LSU Master's Theses

Transporting drilled cuttings from the bottomhole to the surface becomes more difficult and problematic in highly deviated wells than in vertical wells. Cuttings tend to settle down on the low side of the annulus typically in the form of a bed which can cause further problems. The height of this bed depends on many parameters such as annular domain geometry, drilling fluid density and rheology, annular flow rate, drill pipe rotation speed, cuttings size, shape, and their density. Prediction of the stationary cuttings bed height with respect to these aforementioned parameters is thus necessary to optimize the range of the …

Sedimentation Of Swarms Of Particles At Low And Moderate Reynolds Numbers, Oladapo Olanrewaju Ayeni

LSU Master's Theses

The sedimentation of a cloud of particles in a viscous fluid at low and moderate Reynolds numbers has been studied using an Eulerian-Lagrangian multiphase flow approach. We looked at the volume fraction dependence of the settling cloud and find a similar dependence in the simulations as in the theoretical predictions of (Nitsche and Batchelor 1997). The average cloud settling velocity and the velocity fluctuations around this average are found to have a functional dependence on ö^1/3 at negligible Reynolds number. The velocity fluctuations display strong anisotropy with the magnitude of the vertical component almost three times the magnitude of the …

Technological Aspects Of Molecular Diagnosis Of Bacterial Infectious Diseases, Christine S. Booth

Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research

The polymerase chain reaction (PCR) is continually growing in its application, particularly in the field of molecular diagnosis of disease from clinical specimens. The main focus has been in the detection and identification of pathogens. However, quantitative PCR is increasingly utilized to determine initial pathogen load. A well-designed PCR protocol is required in all of these instances. Just as importantly, in the context of disease diagnosis; is the design of the sample processing methodology. The ideal method should concentrate the DNA and effectively isolate a high-quality DNA product, free of PCR inhibitors, while also being simple, reproducible and safe.

The …

Simulations Of The Primary Cement Placement In Annular Geometries During Well Completion Using Computational Fluid Dynamics (Cfd), Muhammad Zulqarnain

LSU Master's Theses

Effective zonal isolation during primary cementing is only possible when drilling mud in the annulus is completely displaced with cement, while the spacers aid in this process. During the displacement process the rheological properties of fluids used and the operating conditions control the motion of different fluids interfaces; desired stable interfacial displacement leads to piston like motion. Computational Fluid Dynamics (CFD) tool with the Volume-of-Fluid (VOF) has been validated against experimental and used to conduct numerical experiments in a virtual well model consisting of 50 ft vertical section of 8.765" x 12.5" annulus having initially mud and this mud is …

Applications Of Cfd Simulations On Microfluidic Systems For Nanoparticle Synthesis, Yuehao Li

LSU Master's Theses

Microfluidics has been extensively investigated as a unique platform to synthesize nanoparticles with desired properties, e.g., size and morphology. Compared to the conventional batch reactors, wet-chemical synthesis using continuous flow microfluidics provides better control over addition of reagents, heat and mass transfer, and reproducibility. Recently, millifluidics has emerged as an alternative since it offers similar control as microfluidics. With its dimensions scaled up to millimeter size, millifluidics saves fabrication efforts and potentially paves the way for industrial applications. Good designs and manipulations of microfluidic and millifluidic devices rely on solid understanding of fluid dynamics. Fluid flow plays an important role …

A Cfd Model For Thermal Conversion Of Thermally Thick Biomass Particles, Ramin Mehrabian, Selma Zahirovic, Robert Scharler, Ingwald Obernberger, Stefan Kleditzsch, Siegmar Wirtz, Victor Scherer, Hong Lu, Larry L. Baxter

Faculty Publications

A one-dimensional model for the thermal conversion of thermally thick biomass particles is developed for the simulation of the fuel bed of biomass grate furnaces. The model can be applied for cylindrical and spherical particles. The particle is divided into four layers corresponding to the main stages of biomass thermal conversion. The energy and mass conservation equations are solved for each layer. The reactions are assigned to the boundaries. The model can predict the intra-particle temperature gradient, the particle mass loss rate as well as the time-dependent variations of particle size and density, as the most essential features of particle …

Cfd Modeling Of Entrance And Exit Geometries Of A Wind Speed Accelerator., David Russ

Electronic Theses and Dissertations

Current wind power technology is not economically feasible throughout most of the United States due to low average wind speeds. A design for a small-scale wind concentrator device suitable for use in areas of low wind velocity was tested using computational fluid dynamics (CFD). Using a novel approach, the device seeks to accelerate incoming air above minimum velocities required for economical power generation. The novel approach employs a funnel shaped inlet with relief vents along the circumference, so as to alleviate backpressure. Both inlet and outlet sections utilize funnel shapes with both parabolic and hyperbolic regions. All geometry and mesh …

Verification And Validation Of Cfd Simulations For Local Flow Dynamics In A Draft Tube Airlift Bioreactor, Hu Ping Luo, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Airlift Reactors Have Been Recognized as One of the Promising Photobioreactors for Biomass/bio-Energy Production, Where Mixing Has Significant Impact on the Reactor Performance. in Recent Years, using CFD Simulations to Track Microorganism Cells and to Generate their Trajectories in the Reactor for Reactor Performance Evaluations Becomes More Common. However, there is a Lack of Systematic and Rigorous Verifications and Validations of the Reliability of CFD Models in Particle Tracking Against Experimental Measurements in the Open Literature, Which is Vital for the Faithful Application of CFD in Reactor Design and Scale-Ups. in This Work, We Attempt to Evaluate the Reliability of …

Time-Averaged Modelling Of Cfbs – Analysis Of The Terms In The Momentum Equations, Sirpa Kallio, Maiju Seppälä, Veikko Taivassalo

The 13th International Conference on Fluidization - New Paradigm in Fluidization Engineering

The features of the terms in the time-averaged momentum equation for the solid phase are examined for three CFB units ranging from a laboratory-scale unit to a small CFB boiler. The CFD simulations were based on the Eulerian granular model of the Fluent software. The time-averaged terms calculated during the time dependent simulations are analysed and conclusions on their relative importance are drawn. An analysis of the terms in the vertical solids momentum equation in the central region of a CFB is presented.

Cfd Simulation Of A Liquid-Fluidized Bed Of Binary Particles, Long Fan, John Grace, Norman Epstein

The 13th International Conference on Fluidization - New Paradigm in Fluidization Engineering

The ability of computational fluid dynamics to predict the expansion and segregation of a binary solids mixture in a liquid-solid fluidized bed is investigated. Unsteady laminar flow is simulated by a modified two-dimensional Eulerian-Eulerian model in Fluent 6.3. The predictions are compared with experimental results for binary particles in the same narrow (1.00-1.18 mm) size range, but with different densities, 1600 and 1900 kg/m3, fluidized by water (1). The voidages and heights of two layers which form, each dominated by one particle species, were found to be sensitive to small changes in particle properties (diameter, density, sphericity), as well as …

Dem-Cfd Modelling Of A Fluidized Bed Spray Granulator, Lennart Fries, Sergiy Antonyuk, Stefan Heinrich, Stefan Palzer

The 13th International Conference on Fluidization - New Paradigm in Fluidization Engineering

Coupled DEM-CFD simulations have been performed to study the hydrodynamics of a Wurster granulator on the scale of individual particles. Based on extensive material tests, the collision behaviour of dry "Gamma"-Al2O3 particles is identified and incorporated into the model. The effect of process parameters like air flow rate and geometry details like the Wurster position is studied. Based on a physical description of the material properties, an effective tool for design and scale-up of a Wurster granulator is obtained.

Understanding The Hydrodynamics In A 2-Dimensional Downer By Cfd-Dem Simulation, Yongzhi Zhao, Yi Cheng, Yulong Ding, Yong Jin

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The gas-solid flows in a 2-dimensional downer were simulated using a CFD-DEM method. The predicted macro-scale flow structure had good agreement with the experiments. The distinct clustering phenomena at meso-scale were revealed throughout the downer. Influences of the collision properties of the wall and the particles on the hydrodynamics in downer were investigated.

Effect Of Particle Size Distribution On The Performance Of A Catalytic Fluidized Bed Reactor, Sanjib Das Sharma, Todd S. Pugsley

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Computational Fluid Dynamics (CFD) has been used to model ozone decomposition in a two-dimensional fluidized bed of 2.0 meters height and 0.1 m width. Simulations were carried out with mono-size, bimodal, and wide catalyst particle size distributions with the same mean diameter to model the effect of fines on the reaction. CFD predictions fall within 20% of the experimental data.

A Cfd Study Into The Influence Of The Particle Particle Drag Force On The Dynamics Of Binary Gas Solid Fluidized Beds, Olumuyiwa Owoyemi, Paola Lettieri

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

This paper presents a preliminary CFD study into the effect of the particle-particle interphase mo- mentum transfer term on the mixing and bubble dynamics of a binary gas solid fluidized consisting of particles which only differ in size. A new fluid dynamic model, implemented within a commercial CFD code, CFX4.4, is used to model the binary mixture. The governing fluid dynamic relationships for the solid phases and the fluid phase are based on “the elastic force” concept from the Particle Bed Model (1, 2). The solids pressure for each of the particulate phases is not taken into consideration in this …

Dynamic Response Characteristics Of Local Capacitive Measurement Devices With Application To Cfd Validation, Clay R. Sutton, John Chen

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The Two-Fluid Model (TFM) approach to modeling fluid-solid systems holds great promise as a means to simulate arbitrary systems, thus greatly reducing design and scale-up efforts. Unfortunately, comprehensive experimental validations of these models are still in short supply. This work addresses this issue by proposing a framework under which to relate computational fluid dynamics model results with experimental measurements on a one-to-one basis. Specifically this is performed for the case of local solids concentration transients in a bench-scale bubbling fluidized bed. The manner in which this comparison is performed has implications for the conclusions that may be drawn for a …

Homogeneous To Bubbling Regime Transition In Gas- And Liquid-Fluidized Beds Through Dem-Cfd Simulations, Alberto Di Renzo, Francesco P. Di Maio

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

DEM-CFD simulations are carried out for the water fluidization of 200 micron glass ballotini and air fluidization of cohesionless alumina 70 micron powders. In the first case, homogeneous expansion is found throughout the whole investigated range of water velocity. Alumina powders exhibits a transition to bubbling regime at a voidage value in very good agreement with results of the theory of particle bed stability. The simulated kinematic and dynamic wave propagation velocities are in good agreement with theoretical predictions.

A New Fluid Dynamic Model For The Cfd Simulations Of Fluidized Beds, Luca Mazzei, Paola Lettieri

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A new Eulerian-Eulerian multidimensional model is proposed for the study of the dynamics of dense fluidized suspensions. The main distinctive feature of this new formulation of the equations of motion resides in the closure relationships adopted to express the fluid-particle interaction force. The force accounts for three contributions: buoyant force, drag force and elastic force. The buoyant force is related to the weight of the fluid displaced by the particles. The drag force is expressed as the product of the drag exerted on an unhindered particle, subject to the same volumetric flux of fluid, and a “corrective function” dependent on …

An Investigation Of Fluidized Bed Scaling Laws By Dem Simulation, John Sanderson, Martin J Rhodes, X. Shan Wang, K. Seng Lim

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A preliminary investigation of the scaling laws for bubbling fluidized beds was undertaken using Discrete Element Method simulation. Six 2D and two 3D fluidized beds were simulated and compared using bed snapshots and dynamic pressure drop. Beds properly matched by the simplified criteria were in relatively poor agreement; agreement deteriorated further for a large scale change or a particle density mis-match. Simulations matched by the full scaling criteria agreed well at low velocities but deteriorated at higher velocities. The possible reasons for these results are discussed.

Numerical Study Of The Intrinsic And Feedback Dynamics Of A Gas-Solid Fluidized Bed, F. Bonniol, C. Sierra, R. Occelli, H. Bournot, L. Tadrist

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The aim of this paper is to understand the complex spatio-temporal patterning of the dense bed when the inlet conditions can be modified by the bed itself. In this study, the inlet conditions (fluid pressure and velocity upstream the bed) take into account resistive effects from the distributor and capacitive ones from the air-supply system (plenum). The present work addresses particularly the issue of the transition between multiple and single bubble regimes that occurs for some particular inlet conditions.

Comparison Of Simulated And Measured Flow Patterns: Solid And Gas Mixing In A 2d Turbulent Fluidized Bed, Ulla Ojaniemi, Sirpa Kallio, Alf Hermanson, Mikko Manninen, Maiju Seppälä, Veikko Taivassalo

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Results from experiments done in a 2D turbulent fluidized bed cold model are presented. Experiments were conducted to study flow patterns, particle mixing in the bed and spreading of gas blown from one side into the bed. 2D simulations of the experiments were carried out using the Eulerian multiphase models of the Fluent and MFIX CFD softwares.

Prediction Of The Dynamics Of A Fluidized Bed Reactor Using Artificial Neural Networks, Shayan Karimipour, Navid Mostoufi, Rahmat Sotudeh -Gharebagh

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The dynamic behavior of fluidized bed has been studied based on the chaos theory. The experiments were done in a fluidized bed of 0.15 m diameter using an optical fiber probe. The interval between successive clusters in the fluidized bed were calculated from the time series signals and proved to be chaotic by calculating the correlation dimension. An artificial neural network (ANN) was adapted and trained to predict the generated time series. The ANN results were compared with the predictions of the k-Nearest Neighbor (kNN) method to show the superiority of ANN in chaotic time series prediction.

Gas Fluidization And Pneumatic Conveying In Confined Beds: A Numerical Study, Yurong He, Thang Ngoc Cong, Yulong Ding, Huilin Lu

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The fluidization phenomena for gas-fine particle two-phase flow is numerically simulated in confined fluidized bed based on two-fluid model, applying body-fitted coordination for the irregular geometry zone in this work. The simulation was performed either with a partially packed fluidized bed in the bottom part applying various superficial gas velocities in bubbling region, which is used to study the bubbles formation and the average porosity in the packed zone, or with a whole packed fluidized bed applying various solid flux rates in pneumatic region, which is used to investigate the mechanism in the packed bed. The void fraction of the …

Discrete Particle Simulation Of The Gas-Solid Flow In A Circulating Fluidized Bed, K. W. Chu, B. Wang, Aibing Yu

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

This paper presents a numerical study of the gas-solid flow in a three-dimensional Circulating Fluidized Bed (CFB) by means of Combined Continuum and Discrete Method (CCDM) in which the motion of discrete particles is described by Discrete Particle Method (DPM) on the basis of Newton’s laws of motion applied to individual particles and the flow of continuum fluid by the traditional Computational Fluid Dynamics (CFD) based on the local averaged Navier-Stokes equations. The simulation is achieved by incorporating DPM codes into the commercial CFD software package Fluent. It is shown that the discrete particle simulation can capture the key flow …

Simulation Of A Pulsating Bed Using Eulerian Approach, Shyam Shankar Dokka, Hamid Arastoopour

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A numerical study of the effect of gas pulsation on the flow pattern of solid particles in a two-dimensional gas-solid fluidized bed was conducted using the Eulerian granular kinetic theory. Our simulated bed dynamics agreed well with the experimental work of Koksal and Vural, and with the Discrete Element Method (DEM) model simulations of Tsuji et al.

A Discrete Particle Simulation Study Of Solids Mixing In A Pressurized Fluidized Bed, Willem Godlieb, Niels G. Deen, J.A.M. Kuipers

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A fluidized bed containing polymeric particles is investigated using a state-of-the-art soft-sphere discrete particle model (DPM). The pressure dependency of particle mixing, flow patterns and bubble behaviour are analysed. It is found that with increasing pressure a less distinct bubble-emulsion structure and improved solids mixing can be observed.

Influence Of Bubble-Bubble Interactions On The Macroscale Circulation Patterns In A Bubbling Gas-Solid Fluidized Bed, J. A. Laverman, M. Van Sint Annaland, J.A.M. Kuipers

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The macro-scale circulation patterns in the emulsion phase of a gas-solid fluidized bed in the bubbling regime have been studied with a 3D Discrete Bubble Model. It has been shown that bubble-bubble interactions strongly influence the extent of the solids circulation and the bubble size distribution.