Author's School

School of Engineering & Applied Science

Author's Department/Program

Energy, Environmental and Chemical Engineering


English (en)

Date of Award

January 2009

Degree Type


Degree Name

Doctor of Philosophy (PhD)

Chair and Committee

Milorad Dudukovic


This dissertation outlines the development of novel, in-situ and relatively inexpensive optical measurement techniques for use in opaque multiphase reactors at elevated temperature: 350 ┬░C) and pressure: 180 bar) environments where conventional measurement techniques either cannot be used or are difficult or expensive to implement. Important parameters: such as gas holdup, specific interfacial area, bubble velocity, bubble chord lengths, liquid level, and phase transition) in opaque, multiphase reactors at industrially relevant conditions are lacking in the literature. A miniaturized 4-point probe is developed and methodology outlined that can simultaneously capture local gas holdup, interfacial area, size, and velocities of bubbles in a multiphase stirred tank reactor where small bubble sizes can be expected, especially at elevated pressures and/or high agitation rates. The miniaturized 4-point probe accurately captures bubble dynamics of bubbles as small as 850 microns at elevated temperature and pressure. Single-point probes are also developed that are moveable under high pressure that can measure liquid level in a reactor as well as the volumetric expansion of carbon dioxide expanded liquids: CXLs are an emerging green technology). A reflectance-based probe: a 7-fiber, hexagonally packed bundle) that detects critical opalescence and thus the phase transition of complex, multicomponent systems from the subcritical to the supercritical state is also developed for the investigation of CXLs. Most importantly, detailed instructions for construction of all of the above optical probe technologies are provided in a step-by-step manner.



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