Date of Award

Spring 1-1-2017

Document Type

Thesis

Degree Name

Master of Science (MS)

First Advisor

Nicole J. Labbe

Second Advisor

John W. Daily

Third Advisor

G. Barney Ellison

Abstract

Microreactors are useful tools for understanding the short residence time reactions of biomass polymers and fuel molecules. When coupled with sensitive detection methods, microreactors have the ability to detect all molecules produced in the reactor, including stable, meta-stable, and radical species, making microreactors one of the few experiments where nearly all chemical species may be detected. At the University of Colorado Boulder, our microreactor studies have involved very small (~1 mm internal diameter, ~28 mm long) silicon carbide (SiC) tubes to study short residence time pyrolysis reactions in conjunction with photoionization mass spectrometry (PIMS) and Fourier transform infrared spectroscopy (FTIR). While much has been learned from this configuration, qualitative analysis is hampered by the fact that the pressure and velocity vary greatly within the reactor. To improve the performance of the Boulder microreactor system, this work explores modifying the reactor geometry to achieve better control over the thermofluid properties. Computational fluid dynamics (CFD) simulations were employed to explore how thermofluid properties within the reactor change as a function of reactor geometry, and a converging-nozzle structure was found to be the ideal geometry to control the internal thermodynamic conditions. New reactor prototypes were fabricated based on the simulation results. To verify the results of the CFD simulations for the new reactor geometry, a series of experiments are proposed to compare the performance of the original Boulder reactors with the new prototype reactors. These experiments will be conducted with the reactors installed in the PIMS configuration. Finally, a survey of potential alternative micro-reactor materials was conducted for future microreactor development. Currently, the SiC microreactor is limited to thermal decomposition experiments due to SiC reactivity with oxygen. To move towards oxidation experiments, a new material for the microreactor must be identified. Thermal conductivity, structural stability, and non-reactivity were all considered in the survey. The new microreactor designed in this thesis will assist scholars to carry out fundamental kinetic measurements of short residence time oxidation reactions of fuels in the future, which will lead a deeper understanding of fuel properties and promote the development of new fuel efficient, less-polluting engine technology.

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