The Woodruff School

SUMMARY

The need for high performance power sources has increased dramatically in recent years with the proliferation of ultra-compact electronic systems for mobile communication, man-portable and versatile military equipment, and electric vehicles. Volume- and mass- based power density are two of the most important performance metrics for portable power sources. Two innovative multifunctional reactor concepts, CO2/H2 Active Membrane Piston (CHAMP) and Direct Droplet Impingement Reactor (DDIR), are combined for the purpose of hydrogen generating fuel reforming system (onboard) for fuel cells. In CHAMP-DDIR, a liquid fuel mixture is pulse-injected onto the heated catalyst surface for rapid flash volatilization and on-the-spot reaction, and a hydrogen selective membrane is collocated with the catalyst to reduce the diffusion distance for hydrogen transport from the reaction zone to the separation site. CHAMP-DDIR allows dynamic variation of the reactor volume to optimally control the residence time and reactor conditions, such as pressure and temperature, thus improving both the reaction and separation processes. A comprehensive CHAMP-DDIR model, which couples key physical processes including 1) catalytic chemical reactions, 2) hydrogen separation/permeation at membrane, 3) liquid fuel evaporation, and 4) heat and mass transport, has been developed to investigate the behavior of this novel reactor system, aiming at maximizing the volumetric power density of hydrogen generation from methanol/water liquid fuel. The relationships between system design parameters and the rate-limiting process(es), i.e., reaction, permeation, and transport, which govern reactor output, have identified. Experimental characterization of the prototype reactor has been performed for laboratory demonstration of the concept and model validation. Both model predictions and experiments successfully demonstrate the unique practical performance improvements of CHAMP-DDIR through combining time-modulated fuel introduction and the active change of reactor volume/pressure.

SUBJECT:	Ph.D. Dissertation Defense

BY:	Thomas Yun

TIME:	Thursday, March 12, 2015, 9:00 a.m.

PLACE:	Love Building, 109

TITLE:	Fuel Reformation and Hydrogen Generation in Variable Volume Membrane Batch Reactors with Dynamic Liquid Fuel Introduction

COMMITTEE:	Dr. Andrei Fedorov, Chair (ME) Dr. Caroline Genzale (ME) Dr. Peter Kottke (ME) Dr. Christopher Jones (CHBE) Dr. Timothy Lieuwen (AE)

SUMMARY The need for high performance power sources has increased dramatically in recent years with the proliferation of ultra-compact electronic systems for mobile communication, man-portable and versatile military equipment, and electric vehicles. Volume- and mass- based power density are two of the most important performance metrics for portable power sources. Two innovative multifunctional reactor concepts, CO2/H2 Active Membrane Piston (CHAMP) and Direct Droplet Impingement Reactor (DDIR), are combined for the purpose of hydrogen generating fuel reforming system (onboard) for fuel cells. In CHAMP-DDIR, a liquid fuel mixture is pulse-injected onto the heated catalyst surface for rapid flash volatilization and on-the-spot reaction, and a hydrogen selective membrane is collocated with the catalyst to reduce the diffusion distance for hydrogen transport from the reaction zone to the separation site. CHAMP-DDIR allows dynamic variation of the reactor volume to optimally control the residence time and reactor conditions, such as pressure and temperature, thus improving both the reaction and separation processes. A comprehensive CHAMP-DDIR model, which couples key physical processes including 1) catalytic chemical reactions, 2) hydrogen separation/permeation at membrane, 3) liquid fuel evaporation, and 4) heat and mass transport, has been developed to investigate the behavior of this novel reactor system, aiming at maximizing the volumetric power density of hydrogen generation from methanol/water liquid fuel. The relationships between system design parameters and the rate-limiting process(es), i.e., reaction, permeation, and transport, which govern reactor output, have identified. Experimental characterization of the prototype reactor has been performed for laboratory demonstration of the concept and model validation. Both model predictions and experiments successfully demonstrate the unique practical performance improvements of CHAMP-DDIR through combining time-modulated fuel introduction and the active change of reactor volume/pressure.