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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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Thermal impedance in pulsed energy storage systems with phase change materials
Phase change materials (PCMs) have tremendous capacity as passive components to recover and repurpose thermal energy from transient power systems. However, PCMs are only effective if the time scale of the thermal energy storage and retrieval rates match those required for a particular system. We develop a framework to assess the efficiency of pulsed thermal energy storage based on the concept of “thermal impedance,” drawing upon an analogous approach from electrical energy storage. We experimentally characterize a 1 cm thick paraffin-infiltrated copper foam composite PCM subject to pulsed heat boundary conditions up to 1 W cm−2 and demonstrate a decrease in thermal impedance by up to a factor of 2.5× in the regime in which melting occurs (τon = 10^−1 to 10^2 s) relative to a reference case in which melting does not occur. This represents both a signature of the ability to extract or retrieve thermal energy via latent heat, as well as an experimentally accessible measure that provides insight into the internal dynamics of a composite PCM volume. These principles can serve to design the internal structure of composite PCM elements for pulsed thermal systems.
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- Award ID(s):
- 1847956
- PAR ID:
- 10659558
- Publisher / Repository:
- AIP Publishing
- Date Published:
- Journal Name:
- Journal of Applied Physics
- Volume:
- 139
- Issue:
- 1
- ISSN:
- 0021-8979
- Subject(s) / Keyword(s):
- Phase transitions Thermal energy Energy storage Heat transfer Thermal conductivity Thermodynamic properties Composite materials
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1063/5.0304273
