Date of Award
2024
Document Type
Open Access Dissertation
Degree Name
Doctor of Philosophy in Mechanical Engineering-Engineering Mechanics (PhD)
Administrative Home Department
Department of Mechanical Engineering-Engineering Mechanics
Advisor 1
Jeffrey S. Allen
Committee Member 1
Scott Miers
Committee Member 2
Ana Dyreson
Committee Member 3
Chang Kyoung Choi
Committee Member 4
Debjyoti Banerjee
Abstract
Supercooling in phase change materials (PCMs) and the associated challenges in enhancing thermal conductivity through nanoparticle dispersion prompted this investigation. Existing literature exhibits inconsistencies in thermal conductivity improvements, suggesting a potential correlation with nanoparticle migration induced by thermophoresis. To address this, a novel temperature-dependent scaling parameter, \(\xi\), was introduced to predict particle migration propensity. A strong association was observed between higher \(\xi\) values and diminished thermal conductivity enhancements, indicating a significant influence of nanoparticle movement on heat transfer.
To further elucidate this relationship, a Nanoparticle Interaction Parameter \(N_\text{{pl}}\) was developed, incorporating critical fluid properties and interfacial effects. The derived critical Nanoparticle Interaction Parameter \(N_\text{{pl}}^*\) provides a temperature-independent metric for predicting migration potential based solely on nanoparticle characteristics. This parameter offers a valuable tool for researchers to optimize experimental conditions for enhanced thermal conductivity.
A computational fluid dynamics (CFD) model was employed to validate the proposed migration prediction framework. Simulations demonstrated the correlation between \(\xi\) and observed particle distribution patterns in both single-phase and two-phase systems. Moreover, the impact of phase change cycling on particle dispersion was investigated, revealing the influence of thermal loading conditions on particle migration behavior. By substituting nanoparticles with nucleating clusters, the study further explored the connection between nucleation site migration and supercooling.
This research offers a comprehensive understanding of nanoparticle migration in nanofluids and PCMs, providing valuable insights into the factors affecting thermal conductivity enhancement. The findings contribute to the development of effective strategies for mitigating supercooling and optimizing the performance of phase change energy storage systems.
Recommended Citation
Sharma, Udit, "STUDY OF NANOPARTICLE DISPERSED PHASE CHANGE MATERIALS AND THE IMPACT OF TEMPERATURE GRADIENT ON THE POTENTIAL FOR PARTICLE MIGRATION", Open Access Dissertation, Michigan Technological University, 2024.