Doctoral Dissertations

Abstract

"The aim of this study, pebbles of diameter of 5 cm and a pebble-to-diameter ratio (aspect ratio) of 6 were used. In part I, the local gas velocities were studied at different radial and axial locations in the pebble bed using a sophisticated hot wire anemometry (HWA) technique, which was supported with a novel probe-protector case to protect the fragile probe, allowing the measurements to be taken between the pebbles for the first time. The local gas velocities were found to be significantly higher in the near wall region due to the higher void fractions in the near-wall region, compared to the center. In the part II, the local convective heat transfer coefficients were studied using a cartridge heated probe pebble, a micro foil heat flux sensor and a thermocouple at various radial locations, axial locations, and angular orientations and under different superficial inlet gas velocities that correspond to both laminar and turbulent flow conditions. The obtained results showed that the local heat transfer coefficients are higher in the near-wall region compared to the center of the bed, which is the same pattern as that observed for the local gas velocities. In part III, new heat transfer coefficients measurements were conducted by changing the orientation of the probe pebble and the location of the thermocouple, accordingly. This allowed us to confirm the reproducibility of the local heat transfer measurements using our measurement technique as well as to confirm the patterns of the variation of the local heat transfer coefficients along the diameter of the pebble bed. Data from all the parts of this study were compared with correlations from the literature and new correlations were developed for the predictions of the local gas velocity and local heat transfer coefficients within the experimental range of our study" -- Abstract, p. iv

Advisor(s)

AI-Dahhan, Muthanna H.

Committee Member(s)

Usman, Shoaib
Castano Giraldo, Carlo Henry
Alajo, Ayodeji Babatund
Homan, Kelly

Department(s)

Nuclear Engineering and Radiation Science

Degree Name

Ph. D. in Nuclear Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2024

Pagination

xv, 159 pages

Note about bibliography

Includes_bibliographical_references_(pages 50, 99 & 157-158)

Rights

©2024 Muhna N. Alshammari , All Rights Reserved

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 12419

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