Analytical considerations of thermal storage and interface evolution of a PCM with/without porous media
International Journal of Numerical Methods for Heat & Fluid Flow
ISSN: 0961-5539
Article publication date: 20 June 2019
Issue publication date: 15 January 2020
Abstract
Purpose
Phase change energy storage is an important solution for overcoming human energy crisis. This study aims to present an evaluation for the thermal performances of a phase change material (PCM) and a PCM–metal foam composite. Effects of pore size, pore density, thermal conductivity of solid structure and mushy region on the thermal storage process are examined.
Design/methodology/approach
In this paper, temperature, flow field and solid–liquid interface of a PCM with or without porous media were theoretically assessed. The influences of basic parameters on the melting process were analyzed. A PCM thermal storage device with a metal foam composite is designed and a thermodynamic analysis for it is conducted. The optimal PCM temperature and the optimal HTF temperature in the metal foam-enhanced thermal storage device are derived.
Findings
The results show that the solid–liquid interface of pure PCM is a line area and that of the mixture PCM is a mushy area. The natural convection in the melting liquid is intensive for a PCM without porous medium. The porous medium weakens the natural convection and makes the temperature field, flow field and solid–liquid interface distribution more homogeneous. The metal foam can greatly improve the heat storage rate of a PCM.
Originality/value
Thermal storage rate of a PCM is compared with that of a PCM–metal foam composite. A thermal analysis is performed on the multi-layered parallel-plate thermal storage device with a PCM embedded in a highly conductive porous medium, and an optimal melting temperature is obtained with the exergy optimization. The heat transfer enhancement with metal foams proved to be necessary for the thermal storage application.
Keywords
Acknowledgements
This work is sponsored by the National Natural Science Foundation of China (51876118) and the Shanghai International Science and Technology Cooperation Fund (18160743800).
Citation
Xu, H., Wang, Y. and Han, X. (2020), "Analytical considerations of thermal storage and interface evolution of a PCM with/without porous media", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 30 No. 1, pp. 373-400. https://doi.org/10.1108/HFF-02-2019-0094
Publisher
:Emerald Publishing Limited
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