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Inorganic salt hydrates are promising phase-change materials (PCMs) for thermal energy storage due to their high latent heat of fusion. However, their practical application is often limited by their unstable form, dehydration, large supercooling, and low thermal conductivity. Porous melamine foam and its carbonized derivatives are potential supporting porous materials to encapsulate inorganic salt hydrate PCMs to address these problems. This work investigates the effect of pyrolysis temperature on the morphology and structure of the carbonized foams and their thermal energy storage performance. Pyrolysis of melamine foam at 700−900 °C leads to the formation of crystalline sodium cyanate and sodium carbonate particles on the foam skeleton surface, which allows the spontaneous impregnation of the carbon foam with molten CaCl2·6H2O.The form-stable foam-CaCl2·6H2O composite effectively suppresses supercooling and dehydration, demonstrating the efficacy of carbon foam as a promising supporting material for inorganic salt hydrate PCMs.
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Utilizing Ragone framework for optimized phase change material-based heat sink design in electronic cooling applications
This study explores the latent thermal energy storage potential of an organic phase change material with porous copper foam and its applicability in electronic cooling under varying heat load conditions. The organic phase change material, n-eicosane, is known for its inherently low thermal conductivity of 0.15 W/mK, rendering it vulnerable during power spikes despite its abundant latent heat energy for phase transition from solid to liquid. Porous copper foams are often integrated into n-eicosane to enhance the composite’s thermal conductivity. However, the volume fraction of the phase change material in the porous foam that optimally improves the thermal performance can be dependent on the boundary condition, the cut-off temperature, and the thickness. A finite difference numerical model was developed and utilized to ascertain the energy consumption for the composite of n-eicosane with two kinds of porous copper foam with varying porosity under different heat rates, cut-off temperatures, and thickness. In addition, the results are compared with a metallic phase change material (gallium), a material chosen with a similar melting point but significantly high thermal conductivity and volumetric latent heat. For validation of the numerical model and to experimentally verify the effect of boundary condition (heat rate), experimental investigation was performed for n-eicosane and high porosity copper foam composite at varying heat rates to observe its melting and solidification behaviors during continuous operation until a cut-off temperature of 70 ◦C is reached. Experiments reveal that heat rate influences the amount of latent energy storage capability until a cutoff temperature is reached. For broad comparison, the numerical model was used to obtain the accessed energy and power density and generate thermal Ragone plots to compare and characterize pure gallium and n-eicosane - porous foam composite with varying volume fractions, cutoff temperature, and thickness under volumetric and gravimetric constraints. Overall, the proposed framework in the form of thermal Ragone plots effectively delineates the optimal points for various combinations of heat rate, cutoff point, and aspect ratio, affirming its utility for comprehensive design guidelines for PCM-based composites for electronic cooling applications
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- Award ID(s):
- 2209776
- PAR ID:
- 10529830
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- International Journal of Heat and Mass Transfer
- Volume:
- 227
- Issue:
- C
- ISSN:
- 0017-9310
- Page Range / eLocation ID:
- 125518
- Subject(s) / Keyword(s):
- Phase change materials Thermal energy storage Porous foam
- 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/10.1016/j.ijheatmasstransfer.2024.125518
