Thesis
Characterization of a nanostructured material with controllable thermal conductivity
Washington State University
Master of Science (MS), Washington State University
2018
Handle:
https://hdl.handle.net/2376/102348
Abstract
This thesis presents the characterization of a nanostructured packed bed with controllable thermal conductivity, to realize a thermal switch concept based on regulating the size of liquid bridges between the copper nanoparticles of the packed bed to obtain the controllable thermal conductivity. The one-dimensional water vapor diffusion model for predicting thermal conductivity of the packed bed in both transient state and steady state was developed. The thermal conductivities of packed bed were characterized for 300 nm copper nanoparticle packed beds at low pressure (0.2 Torr) and ambient pressure with varied relative humidity conditions. The thermal conductivity of the packed bed at low pressure was found to be 0.05 W/m-K. At ambient pressure with controllable relative humidity in the packed bed, thermal conductivity of packed bed increased up to 1.92 W/m-K as relative humidity rose to 74% in the packed bed. The performance of two different kinds of switch, one designed using a packed bed sandwiched between two plane silicon substrates, and the other designed using a packed bed sandwiched between a ridged surface on the top substrate and a plane surface on the bottom substrate, was investigated. Two 1-D water vapor diffusion models, based on infinite cylinder and semi-infinite plane assumptions, respectively, were used to predict the thermal conductivity of the packed bed under the two kinds of switch design from transient state to steady state. Switching ratios, the ratio of thermal conductivities as the packed bed was switched from high to low thermal conductivity were experimentally measured. For the system with plane surface silicon substrates, the switching ratios were 12, 24, and 39 and the switching time was 10, 30, and 60 minutes as relative humidity was changed from 0% to 31%, 60%, and 74%, respectively. For the system with the ridged structure surface at the top heater die, the switching ratios were 9, 25, and 36 and the switching time was about 10, 25, and 45 minutes as relative humidity was changed from 0% to 34%, 63%, and 74%, respectively.
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Details
- Title
- Characterization of a nanostructured material with controllable thermal conductivity
- Creators
- Haixia Liu
- Contributors
- Robert F Richards (Chair)Jin Liu (Committee Member) - Washington State University, Mechanical and Materials Engineering, School ofJacob W Leachman (Committee Member) - Washington State University, Mechanical and Materials Engineering, School of
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525057501842
- Language
- English
- Resource Type
- Thesis