Document Type

Thesis - University Access Only

Award Date

2011

Degree Name

Master of Science (MS)

Department / School

Mechanical Engineering

Abstract

This thesis investigated bubble and liquid circulation patterns and heat transfer of two phase gas-liquid flows in a bubble column photobioreactor (PBR) using Computational Fluid Dynamics (CFO). Experimental and computational studies have been completed that focused on the hydrodynamics and heat transfer within a rectangular column photobioreactor (34.29 cm long x 15.25 cm wide x 34.29 cm tall) with a single spargei tocated at the center of its base (33.02 cm X 1.27 cm). This thesis also investigated the influence of bubble sizes, column geometry configuration, and sparger placement on bubble and fluid flow pattern and heat transfer within a column photobioreactor. The information on heat transfer between heated surfaces and a gas-liquid dispersed bed is essential for designing a photobioreactor. Bubble size and shape affect the hydrodynamics and heat transfer as does bubble interaction with other bubbles (multiple bubbles in a flow versus single bubbles and wall effects on bubble(s) which are not symmetrical or bubbles not centered on the reactor cross-section). The gas bubbles and the water-based media within the photobioreactor are modeled using the Lagrangian-Eulerian approach. A low Reynolds k-epsilon turbulence model is used to predict near-wall flow patterns. A flat surface photobioreactor is used to achieve sufficient light penetration into the system. The main interaction forces between the bubbles and the media, e.g., drag forces, added mass forces, and lift forces are considered. Despite their importance, the effects of these parameters are largely not understood. In this thesis, the numerical simulation results were presented for various geometries which can be useful for predicting the scalability of PBR systems. The computational results were validated with experimental data and from current literature.

Library of Congress Subject Headings

Bioreactors -- Mathematical models

Computational fluid dynamics

Microalgae

Biomass energy

Format

application/pdf

Number of Pages

107

Publisher

South Dakota State University

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