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Document Type

Thesis - University Access Only

Award Date

2013

Degree Name

Master of Science (MS)

Department / School

Mechanical Engineering

First Advisor

Stephen P. Gent

Abstract

This thesis consists of three different studies where designs of rectangular column photobioreactors (PBRs) are changed based on the sparger types, spacings, and positions. Computational Fluid Dynamics (CFD) is used to predict fluid flow patterns, thermal profiles and additional hydrodynamic and heat transfer parameters in these photobioreactors. 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. Average bubbles drag coefficient and average bubbles Nusselt number is defined in term of average bubble Reynolds number. Laboratory scale experimental studies are used to validate the predicted results from simulations. This research shows how bubble and liquid flow pattern changes with the change of sparger type. It is observed how distance between photobioreactor wall and sparger influences the wall attachment of bubble plume. Appropriate design of the sparger is one of the many challenges in scaling up photobioreactor systems. In flat plate bubble column PBR, the sparger is responsible for all the mixing effects as no additional mechanical device is used to facilitate the mixing. Sufficient mixing helps distribute radiation evenly to all the cells, and also allows the cells to get the various nutrients they need. Mixing improves productivity by increasing the frequency of cell exposure to light and dark volumes of the reactor and by increasing mass transfer between the nutrients and cells. However, limited research has been done showing the effects of sparger on hydrodynamics and heat transfer parameters for flat plate bubble column PBR. This research demonstrates how CFD modeling tools may be used to predict the flow and heat transfer characteristics within photobioreactors, which is necessary for effectively designing commercial scale systems.

Library of Congress Subject Headings

Bioreactors
Biomass energy
Mixing
Algae

Description

Includes bibliographical references (pages 101-110)

Format

application/pdf

Number of Pages

129

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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