Electronic system layouts have increasingly become smaller and more compact. To address the growing demand for performance, dynamic thermal management with thermal energy storage has emerged as an attractive solution. Phase change materials (PCM) can store and release large amounts of heat through melting or solidification. However, they are limited by their thermal conductivity, which is several orders of magnitude lower than traditional heat sinks. To address this design weakness, we have developed a novel composite consisting of vertically aligned carbon nanotube arrays infiltrated with PCM to deliver a high thermal conductivity storage medium that also maintains the high latent heat capacity of the native PCM. This study numerically and experimentally investigates the design of an encapsulated CNT-PCM composite and its impact on the temperature rise and peak temperature of an electronic device. Different form factors have been experimentally tested. The composite's impact on a heating element is measured experimentally, and a numerical model is developed and verified using the experimental results. Additional models are designed to evaluate the effect of composite thickness on thermal response.
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Figure of Merit-Based Optimization Approach of Phase Change Material-Based Composites for Portable Electronics Using Simplified Model
Abstract This work presents an approach to optimally designing a composite with thermal conductivity enhancers infiltrated with phase change material based on figure of merit (FOM) for thermal management of portable electronic devices. The FOM defines the balance between effective thermal conductivity and energy storage capacity. In this study, thermal conductivity enhancers are in the form of a honeycomb structure. Thermal conductivity enhancers are often used in conjunction with phase change material to enhance the conductivity of the composite medium. Under constrained heat sink volume, the higher volume fraction of thermal conductivity enhancers improves the effective thermal conductivity of the composite, while it reduces the amount of latent heat storage simultaneously. This work arrives at the optimal design of composite for electronic cooling by maximizing the FOM to resolve the stated tradeoff. In this study, the total volume of the composite and the interfacial heat transfer area between the phase change material and thermal conductivity enhancers are constrained for all design points. A benchmarked two-dimensional direct computational fluid dynamics model was employed to investigate the thermal performance of the phase change material and thermal conductivity enhancer composite. Furthermore, assuming conduction-dominated heat transfer in the composite, a simplified effective numerical model that solves the single energy equation with the effective properties of the phase change material and thermal conductivity enhancer has been developed. The effective properties like heat capacity can be obtained by volume averaging; however, effective thermal conductivity (required to calculate FOM) is unknown. The effective thermal conductivity of the composite is obtained by minimizing the error between the transient temperature gradient of direct and simplified model by iteratively varying the effective thermal conductivity. The FOM is maximized to find the optimal volume fraction for the present design.
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- Award ID(s):
- 1738793
- NSF-PAR ID:
- 10338900
- Date Published:
- Journal Name:
- Journal of Electronic Packaging
- Volume:
- 144
- Issue:
- 2
- ISSN:
- 1043-7398
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1115/1.4052074
