THE SCHOOL OF MATERIALS SCIENCE AND ENGINEERING

GEORGIA INSTITUTE OF TECHNOLOGY

Under the provisions of the regulations for the degree 

DOCTOR OF PHILOSOPHY 

on Tuesday, November 24, 2020

2:00 PM

via

BlueJeans Video Conferencing 

https://bluejeans.com/120252940/3244?src=calendarLink

will be held the

DISSERTATION PROPOSAL DEFENSE 

for

Daron Spence

“Understanding Heat Management Enabled by Silica Based Insulating Microstructures and Dielectric Mirrors ”

Committee Members:

Prof. Shannon Yee, Advisor, ME

Prof. Kyriaki Kalaitzidou, ME/MSE

Prof. Natalie Stingelin, ChBE/MSE

Prof. Baratunde Cola, ME/MSE

Jaswinder Sharma, Ph.D., Oak Ridge National Laboratory 

Abstract:

Due to increasing global temperatures, the energy used for space cooling in buildings will increase by 300% by 2050 and account for 13% of all electricity usage worldwide. Consequently, to meet global cooling demand, fossil fuels and refrigerants, which release carbon dioxide and volatile chemicals with large global warming potentials, will be used at higher rates.  This increase in greenhouse gas emissions thus results in a growing demand for space cooling. Several energy consumption models indicate the importance of reducing energy usage to slow the rate of global warming [1].  Improving the performance of conventional thermal materials can directly reduce the amount of energy required for space cooling by reducing the thermal load on buildings [2]. Therefore, the theoretical framework, synthesis and characterization of super insulating and low emissivity thermal materials will be critical in efforts to reduce these thermal loads.

The theoretical framework that predicts the effective thermal conductivity (ETC) of super-insulating hollow silica particles (HSPs) in a binary matrix is first presented. Discussion of the framework is followed by the synthesis process needed to achieve the designated particle parameters. Additionally, electromagnetic properties of thin-films are presented to inform the design parameters for dielectric mirrors. I propose four areas to contribute to scientific knowledge of these materials. First, I propose a parametric study to investigate the physical parameters that govern the effective thermal conductivity of HSPs. Second, I propose the thermal assessment of a ternary composite material with interstitial fillers in between particle clusters. Third, I propose the means for characterizing the mechanism and degree of switchability achieved by polymer dielectric mirrors used to variably reflect solar radiation over a tunable range. Lastly, I propose a novel in-situ technique to characterize the dielectric mirror’s thermal conductivity and chemical state as a function of switching degrees. The proposed work will provide a deeper understanding of the relationship between HSP design and performance and provide necessary information to further develop the foundation of switchable dielectric mirrors used for dynamic thermal radiation management.