Measurement of normal stress and the shape and extent of the void formed by a horizontal jet in a fluidized bed.
Item
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Title
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Measurement of normal stress and the shape and extent of the void formed by a horizontal jet in a fluidized bed.
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Identifier
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AAI9417447
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identifier
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9417447
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Creator
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Chen, Libin.
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Contributor
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Adviser: Herbert Weinstein
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Date
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1994
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Chemical
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Abstract
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In the first section of this work, an experimental apparatus and approach were developed to measure the instantaneous changes in pressure gradient and solid volume fraction with time along a collapsing fluidized bed. Measurements were made for a single fluid cracking catalyst. The Pressure transducer and X-ray data were in excellent agreement. These data along with straightforward one-dimensional descriptions of both gas and solid phases were used to obtain the solid normal stress modulus and the drag coefficient in the solid fraction range between minimum fluidization and loose packing.;In the second section of this work, an experimental study of a horizontal jet into a 15 cm by 38 cm cross-section bubbling fluidized bed was carried out using an X-ray system. Instantaneous solid fraction averaged along chords across the bed were measured. The mean value and the fluctuating component of solid fraction were determined for two initial jet diameters, 0.64 and 1.27 cm, and three initial jet velocities, 23, 46 and 69 m/s. Maps of the mean and fluctuating components show that there are three discernable regions in the jet-influenced area of the bed. These are a coherent void, bubble trains and a surrounding compaction zone.;In the third section of this work, the influence of tap spacing on the measurement of the axial pressure gradient and the existence of a radial pressure gradient were evaluated in a riser fluidized bed. It was found that measurements with tap spacings of less than a column diameter yielded smaller solid fraction values than equivalent measurements with tap spacings of greater than one column diameter. It was also shown that the normalized standard deviation of the fluctuations increases with decreasing tap spacing over the whole regime spectrum. The experimental data also showed that a strong radial pressure gradient exists in high velocity fluidized beds.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
