Engineering Commons^™

Enhanced Fluidization Of Nanoparticle Agglomerates, Daniel Lepek

Dissertations

Gas fluidization of nanoparticle agglomerates has recently received much attention due to the excellent way in which these novel nanornaterials can be dispersed in a gaseous medium. Nanopowders have a very high surface area to volume ratio which allows them have unique chemical and physical properties especially at the surface. Fluidization is a popular technique for the continuous dispersal of solid materials in the fluidlike state.

Recently it has been found that nanoparticles exist in a highly agglomerate state which allow them to become fluidizable. The fluidization behavior of the nanopowders is dependent on the bulk and material properties of …

Enhancement Of Fluidization And Filtration Using Nanoparticle Agglomerates And Aerogels, Jose A. Quevedo

Dissertations

Previous works have classified the fluidization behavior of nanoparticles as Agglomerate Particulate Fluidization (APF) and Agglomerate Bubbling Fluidization (ABE). These fluidization behaviors are quite different in regard to the fluidized bed expansion, the presence of bubbles and the smoothness of the bed surface, with APF nanopowders showing a much more homogeneous fluidization and a much better dispersion than ABE nanopowders which are generally very difficult to fluidize and show vigorous bubbling. In the present work, the fluidization of APF as well as ABF nanopowders is studied in depth, both conventionally, and in the presence of extemal assistance; several related topics …

Jet Assisted Fluidization Of Nanoparticle Agglomerates, Ayokunle O. Omosebi

Theses

Fluidization serves as a primary operation used to disperse, handle and process nanoparticles, but due to the complications involved with achieving homogenous fluidization of the agglomerates of nanoparticles, several methods have been developed to assist their conventional mode of fluidization.

In this work, the conventional mode of fluidization was coupled with secondary gas flow emerging from a micro jet nozzle. The effect of the jet on the fluidization behavior of various APF and ABF nanopowders was studied and compared with the pure conventional fluidization mode. Generally, experiments were conducted to find the optimal operation of the jet by varying parameters …

Inverse Solid-Liquid Fluidization Of Aerogel Granules And Its Application In Removing Oil From Water, Gaurav Babubhai Patel

Theses

Fluidization is a very well known unit operation used in the chemical industry for various purposes. Inverse solid-liquid fluidization, where the solid particles to be fluidized are less dense than the fluid, is one of the several different kinds of fluidization being studied for its potential in industrial applications. The present work focuses on finding the hydrodynamic characteristics (minimum fluidization velocity, bed expansion and pressure drop) of an inverse fluidized bed of aerogel granules and using this system to remove oil from an oil-water mixture. The solid particles employed for this study are low density (100 kg/m³) surface …

Gas Fluidization Of Nanoparticles, Qun Yu

Dissertations

The primary objective of this study is to perform a systematic investigation on the gas fluidization of various nanoparticle agglomerates. Firstly, the gas fluidization characteristics and regime classifications without any additional external force fields are identified using both experimental measurements and modeling. Secondly, the effect of introducing certain external force fields on nanoparticle fluidization is experimentally investigated. Two external force fields were applied: sound waves from a loud speaker (acoustic assistance) and in-bed magnets that were excited by an external oscillating magnetic field (magnetic assistance). Thirdly, exploratory experimental research on the use of nanoparticle agglomerates as a granular filtration media …

Fluidization Of Nanoparticles, Caroline Hijung Nam

Dissertations

During the past decade, nanoparticles (1-100 nm) and nanocomposites have become the focus of many studies due to the unique properties of nanostructured materials that make them attractive for various applications. Due to their atomic and molecular interactions, nanoparticles and nanocomposites have unique and often favorable catalytic, mechanical, optical, electronic and / or other properties. For instance, nanocrystalline copper is up to 5 times harder than conventional micron sized copper particles. Nanocomposites, such as a homogenous mixture of different nanoparticles, can also exhibit improved properties. Other examples include coating and reacting nanoparticles with a second nanostructured phase. These processes are …

Fluidization Of Agglomerates Of Nanoparticles Under Different Force Fields, Jose A. Quevedo

Theses

Nanoparticles are the focus of many research activities, and in the near future they will be handled in large amounts by industry. Fluidization is a very important unit operation which is applied in several industrial processes.

In the present work, fluidization experiments with agglomerates of nanoparticles were done under different force fields: (1) gravity force or conventional fluidization; (2) a magnetic force field, which uses magnetic particles under the influence of a magnetic field; and (3) a centrifugal force, generated by a rotating frame that simulates higher gravity conditions.

Among the significant results with agglomerates of nanoparticles, conventional fluidization was …

Vibration-Induced Densification Of Granule Materials, Ninghua Zhang

Dissertations

Physical experiments as well as discrete element simulations of vibration are carried out. The use of different amplitudes and frequencies are applied in the experiments to facilitate the observation of densification trends with mono-disperse acrylic spheres and multi-disperse polyethylene pellets. For mono-disperse acrylic spheres, four densification trends are found at different vibration conditions, and attaining the "maximum density" is closely related to the combination of vibration frequency and amplitude, in agreement with experiments in the literature. For multi-disperse polyethylene pellets, there is a substantial increase in solids fraction due to the effects of particle shape and surface friction. Computer simulations …

Fluidization And Soot Filtration In A Rotating Fluidized Bed, Gui-Hua Qian

Dissertations

A horizontal rotating fluidized bed (RFB) has been investigated for the removal of soot from diesel engine exhaust. This requires necessitating an understanding of the nature of fluidization, particle mixing and filtration in the RFB.

In an RFB, particles are subject to a centrifugal force which can be much larger than the force of gravity. Therefore the Geldart classification for conventional fluidized beds must be modified for rotating fluidized beds. A theoretical analysis shows that group A particles (minimum bubbling velocity U_mb > minimum fluidization velocity U_mf can shift to group B U_mb = U_mf and group …

Evaluation Of Rotating Fluidized Bed As A Dry Coater, William Christopher Dunphy

Theses

Coating of particles is normally carried out with the use of environmentally unfriendly solvents. Development of dry coating methods is therefore quite important.

A Rotating Fluidized Bed was constructed, instrumented and verified as to operation. Twelve coating experiments were carried out with PMMA 200μm mean diameter as host and alumina 0.25μm primary particle size as guest with the RFB being operated in the fully fluidized range.

In all analyzed samples, coating was observed. Analysis was carried out on the qualitative basis by SEM and EDX.

Predictions Of Catalyst Utilization With Continuous Replacement In Multistage Continuous Reactors From Batch Reactor Data, Norman M. Feinberg

Theses

This thesis presents a new equation for predicting catalyst utilization with continuous replacement in multistage continuous reactors from batch reactor data.

An equation is derived from experimental data for a. no-replacement system which predicts catalyst activity as a function of time. The assumption of constant inventory, constant replacement rate and perfect mixing permit the calculation of catalyst age distribution. By combining age distribution with a measure of catalyst productivity, as determined from activity as a function of time, an equation for catalyst utilization was derived. The case used to prepare this equation was where the activity decline curve appears as …

Combined Feedforward-Feedback Control Of A Fluidized-Bed Reactor, Reginald Eugene Mitchell

Theses

Feedforward control, feedback control, and combined feedforward-feedback control were studied on an analog computer to evaluate their effectiveness in controlling a fluidized-bed reactor used for the decomposition of cumene. Proportional, proportional-integral, proportional-derivative, and proportional-integral-derivative modes of control were investigated. Step changes in set-point and load were used as disturbances. The Ziegler-Nichols method and the process reaction curve method of Cohen and Coon were compared in determining values of KC, Ti, and Td which gave optimum control of the fluidized-bed reactor.

Control equation were obtained from the block diagrams of the systems and solved on an EAI TR-20 Analog Computer.

It …

Effect Of Column Diameter On Mixing In Water Fluidized Beds, Donald P. Schiesl

Theses

In this investigation, the effect of column diameter and flow rate on the mixing characteristics of fluidized beds were studied.

Tests were made on columns of 4, 6, 8 and 10 inches in diameter using water to fluidize glass beads of 0.0185 inches in diameter. The tests were run both at minimum and three times minimum fluidization. Step, impulse, and sinusoidal forcing signals were fed to the columns, using a sodium chloride solution as a tracer with the inlet and outlet concentrations being monitored continuously by a conductivity recorder.

The result of this study showed increased fluid dispersion with increasing …

Effect Of Column Diameter On The Frequency Response Of Water Fluidized Beds, Edward C. Maiuro

Theses

The effect of column diameter on the frequency response of water fluidized beds was investigated.

Studies were made on four columns ranging from four to ten inches in diameter. Water was used to fluidize the beds which consisted of spherical glass beads .0185 inches in diameter. A trace solution of sodium chloride was sinusoidally introduced into the beds. Inlet and outlet concentrations were continuously measured by an electrical conductivity recorder. Separate frequency response tests were conducted on the inlet calmning section in an attempt to obtain the frequency response of this region alone. Results of the tests were expressed as …