Abstract/Details

NMR experiments on vibrofluidized and gas fluidized granular systems


2008 2008

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Abstract (summary)

This dissertation presents experimental studies of granular media using Nuclear Magnetic Resonance (NMR). Two different processes, vibrofluidization and gas fluidization of granular media, were investigated.

In the first study, we measured the number density profiles and velocity distributions of the particles in a three-dimensional vibration system with pulse field gradient (PFG) NMR and magnetic resonance imaging (MRI) techniques. The experiments were repeated with three different values of N I and two different values of Γ, where N I is the number of layers of particles in the sample cell and Γ is the dimensionless acceleration of the vibration. We found the velocity distribution function is generally non-Gaussian except at the top of the sample. NMR data were fitted to a hydrodynamic theory, which successfully models the density and temperature profiles away from the vibrating container bottom. A temperature inversion near the free upper surface is observed, which is explained by the presence of a non-zero transport coefficient µ in inelastic systems.

In the second study, we applied a fast 1D MRI technique to monitor the bubble motion in a fluidized bed. The measured bubble velocity is in excellent agreement with a model based on a potential flow theory. The number density profiles and the displacement distributions of particle were measured using PFG-NMR and MRI with various gas flow rates at different bed heights. We found no particle motion before bubbles are generated in the bed. The displacement distribution results imply that slugging phase is dominant at higher regions of the bed. The velocity distribution of convective particle flows in bubbling phase is fitted to a simple potential flow model, which shows reasonable agreement.

Indexing (details)


Subject
Condensed matter physics
Classification
0611: Condensed matter physics
Identifier / keyword
Pure sciences; Gas fluidization; Gas fluidized beds; Granular media; Pulse field gradient NMR; Vibrofluidization
Title
NMR experiments on vibrofluidized and gas fluidized granular systems
Author
Huan, Chao
Number of pages
220
Publication year
2008
Degree date
2008
School code
0118
Source
DAI-B 69/09, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9780549822202
Advisor
Candela, Donald
Committee member
Dinsmore, Anthony; Menon, Narayanan; Peleg, Micha
University/institution
University of Massachusetts Amherst
Department
Physics
University location
United States -- Massachusetts
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3329953
ProQuest document ID
304566603
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304566603
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