Chemical Engineering Commons^™

The Effect Of Riser End Geometry On Gas-Solid Hydrodynamics In A Cfb Riser Operating Above Fast Fluidization Regimes, Larry Shadle

Fluidization XV

Riser hydrodynamics are a function of the gas and solids flow rates as well as the exit geometry, particularly when operated above the upper transport velocity. This work compares the exit voidage for multiple geometries and two different Geldart class B solids: glass beads and coke. Geometries were changed by modifying the volume of an abrupt T-shaped exit above the lateral riser exit. This was accomplished by positioning a plunger at various heights above the exit from zero to 0.38 m. A correlation was developed for the exit voidage as a function of the noted length and the following hydrodynamic …

Pickup Velocity Of Nanoparticles, Jia Wei Chew, J. Ruud Van Ommen, Aditya Anantharaman

Fluidization XV

This paper represents the first systematic study of the pneumatic conveying of nanoparticles. The minimum pickup velocity, U_pu, of six nanoparticle species of different materials (i.e., silicon dioxide (SiO₂), aluminum oxide (Al₂O₃) and titanium dioxide (TiO₂)) and surfaces (i.e., apolar and polar) were determined by the weight loss method. Specifically, the weight loss method involves measuring the mass loss from the particle sample at various superficial gas velocities (U), and the U_pu is the U value at which mass loss is zero. Nanoparticles were picked up as …

Spouting Behavior Of Binary Mixtures Of Spherical And Cylindrical Particles, Douglas W. Marshall, Nicholas W. Eimers, Nathan A. Yergenson, David C. Drown

Fluidization XV

Circulation of particles in a spouted bed is influenced by the aspect ratio of the particles. Circulation of high-aspect particles, such as grains, is similar to bulk flow of powders within a hopper, while circulation of spherical particles is better represented by funnel flow.

Deposition of high quality and high integrity coatings on nuclear fuel particles requires good circulation of the fuel particles to ensure a narrow distribution of coating thicknesses and uniform coating properties. Spouting studies were conducted with using air at room temperature in a 2-D model of a nuclear fuel particle coater to investigate the influence of …

Heat Transfer Challenge And Design Evaluation For A Multi-Stage Temperature Swing Adsorption (Tsa) Process, Gerhard Hofer, Tobias Pröll, Johannes Fuchs, Gerhard Schöny

Fluidization XV

Functionalized solid amine-based temperature swing adsorption (TSA) processes have recently been proposed as a potential way to reduce the energy-penalty of post-combustion carbon capture processes (1). If TSA is to be carried out at large scale and with high energy-efficiency, continuously operated counter-current contactors are required for thermodynamic reasons. This could, generally, be achieved by using moving bed contactors. However, the heat exchange requirement of TSA is significant and heat transfer is poor in fixed and moving beds. Therefore, multi-stage fluidized bed contactors with counter-current flow of solids and gas phase and immersed heat exchange surfaces may solve the heat …

Hydrodynamics Of Compartmented Fluidized Beds For Concentrated Solar Power Applications, Roberto Solimene, Riccardo Chirone, Andrea Paulillo, Piero Salatino

Fluidization XV

Application of fluidized beds to collection and thermal storage of solar radiation is beneficial in Concentrated Solar Power (CSP) systems thanks to their well-known inherently good thermal performances. Non-conventional design and operation of fluidized beds based on uneven or unsteady (pulsed) fluidization (1), may further enhance their thermal performances improving the potential for applications in the very demanding CSP systems. Dense gas-fluidized beds have the potential to effectively accomplish three complementary tasks: the collection of incident solar radiation; the heat transfer of the incident power to immersed tube bundles of high-efficiency steam and/or organic Rankine cycles (ORC) and the thermal …

Attrition Rate Of Iron Ore In The Gas-Solid Fluidized Beds With The Wide Size Distribution, Dong-Hyun Kang, Chang Kuk Ko, Dong Hyun Lee

Fluidization XV

The effects of superficial gas velocity (U_g = 1.25 – 3.00 m/s) and distributor hole size (8.0 – 12.4 mm) on the attrition rate of iron ore in a gas-solid fluidized bed with 0.076 m ID ´ 3.7 m height with or without circulation were investigated. The particle density and the Sauter mean diameter of fresh iron ore were 3,705 kg/m³ and 357 m, respectively. When the kinetic energy rate from the orifice was equal or greater than 180 J/s, the trend of attrition rate could be determined. The attrition rate was determined by measuring the fractional mass …

Carbon Dioxide Recovery By Means Of Tsa In A Sound Assisted Fluidized Bed Of Fine Activated Carbon, Raganati Federica, Ammendola P

Fluidization XV

A large decrease in CO₂ emissions through capturing and separation will be required to keep greenhouse gases at tolerable levels (1). Though several CO₂ capture technologies have been proposed, temperature swing adsorption (TSA), consisting in adsorbing the CO₂ on a solid material and, then, inducing the sorbent regeneration and CO₂ recovery by a temperature increase and gas purge, has the potential to become one of the leading techniques by complementing or replacing the current absorption technology due to its low energy requirement (2). With reference to the sorbent, great attention is focused on fine powders (3). …

Predicting Gas-Flow Distribution In Pilot-Scale Fluidized Beds Using Cfd Simulations, Akhilesh Bakshi, C. Altantzis, A. F. Ghoniem, L. R. Glicksman

Fluidization XV

Bubbling fluidized beds are used extensively in energy and chemical industries because of their excellent heat and mass transfer characteristics. Recently, CFD has been identified as a useful tool for predicting reactor performance, but application to large scales continues to be challenging because of limitations on computational resources. Given that the hydrodynamics can largely be characterized by bubbles rising through the bed, a more feasible approach for investigating large-scale reactors is to quantify bubble dynamics and specifically, gas distribution in different phases- visible bubble flow, bubble-through flow and dense-phase flow.

In this study, 3D CFD simulations of bubbling fluidized beds …

Novel Method To Meassure Fine Particle Circulation Rates In Draft Tube Conical Spouted Beds, Idoia Estiati, Haritz Altzibar, Mikel Tellabide, Martin Olazar

Fluidization XV

The spouted bed regime is an alternative contact method to fixed and fluidized beds. The ratio between the inlet diameter and particle diameter limits the scaling-up of spouted beds (the inlet diameter should be smaller than 20-30 times the particle diameter). The insertion of a draft tube is the way of overcoming this limitation.

Particle cycle time is defined as the time the particle takes to travel from the top of the annulus downwards and back again to its starting point. Since the proportion of time spent by a particle in the spout is insignificant compared with that spent in …

Modelling Study Of Two Chemical Looping Reforming Reactor Configurations: Looping Vs. Switching, Joana F. Morgado, Schalk Cloete, John Morud, Thomas Gurker, Shahriar Amini

Fluidization XV

Autothermal Chemical Looping Reforming (CLR) is a promising technology for hydrogen production with integrated CO₂ separation. Conventional CLR employs two fluidized beds (fuel and air reactors) with an oxygen carrier circulating between them. In this way, CLR supplies heat to the endothermic reforming reaction while avoiding fuel/nitrogen mixing. This configuration can achieve steady operation and low gas leakages between reactors, but has some drawbacks. The complex interconnected configuration is challenging to scale up, especially under the pressurized conditions required for high process efficiency. Moreover, the external circulation of particles through cyclones and loop seals increases reactor costs and imposes …

Characterization Of Fuel Segregation In A Fluidized Bed By Magnetic Particle Tracking, David Pallarès, Anna Köhler, Alexander Rasch, Filip Johnsson

Fluidization XV

A Magnetic Particle Tracking (MPT) system is used to experimentally characterize the vertical distribution of fuel particles in a fluidized bed. The measurements are carried out in a fluid-dynamically down-scaled cold unit resembling a 1×1 m2 boiler operating at 850 °C. The MPT system yields spatial and temporal information of the tracer particle with accuracies in the order of 10-3 m and 10-3 s, respectively. The MPT system is used to study how fuel segregation is influenced by physical properties of the fuel (sizes and densities representing different fuel types) and operational conditions, such as fluidization velocity, bed height and …

Conference Program (Gpe 2016), Jamal Chaouki, Franco Berruti, Xiaotao (Tony) Bi, Ray Cocco

Fluidization XV

No abstract provided.

Methodological Considerations Of Electron Spin Resonance Spin Trapping Techniques For Measuring Reactive Oxygen Species Generated From Metal Oxide Nanomaterials, Min Sook Jeong, Kyeong-Nam Yu, Hyun Hoon Chung, Soo Jin Park, Ah Young Lee, Mi Ryoung Song, Myung-Haing Cho, Jun Sung Kim

Chemical & Biomedical Engineering Faculty Publications

Qualitative and quantitative analyses of reactive oxygen species (ROS) generated on the surfaces of nanomaterials are important for understanding their toxicity and toxic mechanisms, which are in turn beneficial for manufacturing more biocompatible nanomaterials in many industrial fields. Electron spin resonance (ESR) is a useful tool for detecting ROS formation. However, using this technique without first considering the physicochemical properties of nanomaterials and proper conditions of the spin trapping agent (such as incubation time) may lead to misinterpretation of the resulting data. In this report, we suggest methodological considerations for ESR as pertains to magnetism, sample preparation and proper incubation …

Light-Activated Photocurrent Degradation And Self-Healing In Perovskite Solar Cells, Wanyi Nie, Jean-Christophe Blancon, Amanda J. Neukirch, Kannatassen Appavoo, Hsinhan Tsai, Manish Chhowalla, Muhammad A. Alam, Matthew Y. Sfeir, Claudine Katan, Jacky Even, Sergei Tretiak, Jared J. Crochet, Gautam Gupta, Aditya D. Mohite

Publications and Research

Solution-processed organometallic perovskite solar cells have emerged as one of the most promising thin-film photovoltaic technology. However, a key challenge is their lack of stability over prolonged solar irradiation. Few studies have investigated the effect of light soaking on hybrid perovskites and have attributed the degradation in the optoelectronic properties to photochemical or field-assisted ion migration. Here we show that the slow photocurrent degradation in thin-film photovoltaic devices is due to the formation of light-activated meta-stable deep-level trap states. However, the devices can self-heal completely by resting them in the dark for <1 min or the degradation can be completely prevented by operating the devices at 0°C. We investigate several physical mechanisms to explain the microscopic origin for the formation of these trap states, among which the creation of small polaronic states involving localized cooperative lattice strain and molecular orientations emerges as a credible microscopic mechanism requiring further detailed studies.

Hydrodynamics And Mass Transfer In Bubble Columns, Onkar N. Manjrekar

McKelvey School of Engineering Graduate Student Theses & Dissertations

Bubble columns and slurry bubble columns are multiphase reactors used for a wide range of applications in the biochemical, chemical, petrochemical, and metallurgical industries. In spite of their widespread usage, the scale-up of bubble columns remains an ongoing challenge. Various scale-up approaches, based on concepts ranging from ideal mixing to complex 3-D multiphase CFD models, have been used for assessing the effect of column size and gas and liquid flow rates on column hydrodynamics and reactor performance. Among these approaches, phenomenological models based on either single-class or multi-class bubbles that were validated on cold flow systems have been successful in …

Development Of Steady-State And Dynamic Flux Models For Broad-Scope Microbial Metabolism Analysis, Lian He

McKelvey School of Engineering Graduate Student Theses & Dissertations

Flux analysis techniques, including flux balance analysis (FBA) and 13C-metabolic flux analysis (MFA), can characterize carbon and energy flows through a cells metabolic network. By employing both 13C-labeling experiments and nonlinear programming, 13C-MFA provides a rigorous way of examining cell flux distributions in the central metabolism. FBA, on the other hand, gives a holistic review of optimal fluxomes on the genome scale. In this dissertation, flux analysis techniques were constructed to investigate the microbial metabolisms.

First, an open-source and programming-free platform of 13C-MFA (WUFlux) with a user-friendly interface in MATLAB was developed, which allowed both mass isotopomer distribution (MID) analysis …

Modeling, Simulation, And Analysis Of Lithium-Ion Batteries For Grid-Scale Applications, Matthew Thomas Lawder

McKelvey School of Engineering Graduate Student Theses & Dissertations

Lithium-ion batteries have become universally present in daily life, being used across a wide range of portable consumer electronics. These batteries are advantageous compared to other forms of energy storage due to their high energy density and long cycle life. These characteristics make lithium-ion batteries advantageous for many new and developing applications that require large scale energy storage such as electric vehicles and the utility grid. Typical uses for lithium-ion batteries require consistent cycling patterns that are predictable and easy to approximate across all uses, but new large scale applications will have much more dynamic demands. The cycling patterns for …

Optical Probes In Multiphase Reactors, Boung Wook Lee

McKelvey School of Engineering Graduate Student Theses & Dissertations

This dissertation examines the application of optical probe techniques in two predominant multiphase reactors used for contacting gas and liquid phases: bubble column reactors and gas-liquid stirred tank reactors. Multiphase reactors are ubiquitous in industry, and for most processes, successful operation depends on successful inter- and intra-phase contacting and mixing. Extensive modeling and experimental research efforts have been made for better reactor design, modeling, and scale-up, yet, much remains unknown about the gas phase.

Optical probes offer significant advantages for gas phase dynamics measurements. Consequently, they have been adapted by numerous researchers around the world for detailed fluid dynamic investigations …

Highly Conductive In-Sno2/Rgo Nano-Heterostructures With Improved Lithium-Ion Battery Performance, Ying Liu, Alessandro Palmieri, Junkai He, Yongtao Meng, Nicole Beauregard, Steven L. Suib, William E. Mustain

Faculty Publications

The increasing demand of emerging technologies for high energy density electrochemical storage has led many researchers to look for alternative anode materials to graphite. The most promising conversion and alloying materials do not yet possess acceptable cycle life or rate capability. In this work, we use tin oxide, SnO2, as a representative anode material to explore the influence of graphene incorporation and In-doping to increase the electronic conductivity and concomitantly improve capacity retention and cycle life. It was found that the incorporation of In into SnO2 reduces the charge transfer resistance during cycling, prolonging life. It is also hypothesized that …

Microstructure And Rheology Of Carbon Nanotubes At Air-Water Interfaces, Charles D. Young

Honors Scholar Theses

This work characterizes the material properties of carbon nanotubes at air-water interfaces for potential use in creating stable emulsions. Properties such as length, aspect ratio, contact angle, microstructural ordering, surface pressure, compression and shear elastic moduli, stresses, surface viscosities and non-linearity are explored. Challenges such as deviation from a classical analysis of monolayers are encountered in the form of aggregation, mechanical contributions, and interface relaxation. These factors are taken into account to explain experimental measurements and trends. Ultimately, existing models for more homogeneous systems are resolved with observations to offer insight and areas of promise moving forward.