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Title:
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Numerical simulation of a finned-tube LHTES system: influence of the mushy zone constant on the phase change behaviour
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Author:
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Arena, Simone; Casti, Efisio; Gasia, Jaume; Cabeza, Luisa F.; Cau, Giorgio
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Notes:
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This work presents a numerical investigation on latent heat thermal energy storage (LHTES) systems during the phase change process. The numerical analysis, based on the apparent heat capacity formulation, was carried out through a two-dimensional axisymmetric numerical model developed by means of the COMSOL Multiphysics software. A thermal energy storage system based on the configuration of a double tube heat exchanger with finned surfaces was used as an experimental test case and the commercial paraffin RT35 was selected as phase change material (PCM). The influence of the heat transfer by convection, in particular the influence of the term describing the mushy zone in the momentum equation, was investigated during the whole charge and discharge processes. Three different values of the constant Amush, equals to 104, 106 and 108 were selected as well as two different values of the HTF volumetric flow rate were adopted in order to reproduce both laminar and turbulent flow regimes. The results are reported in terms of temperature, melting fraction and phases evolution during the whole melting and solidification processes, and compared to previous experimental tests carried out in the laboratories of the University of Lleida, Spain. A good agreement with the experimental results was obtained showing that the mushy zone constant has a significant influence on the interface shape and motion. The results show that large values of Amush determine an increase of the mushy region reducing the natural convection effects during the charge phase. Thus, the proper evaluation of the mushy zone constant allows providing a deeper understanding of the phase change behaviour, resulting in an important parameter for accurate modelling of LHTES systems.
The work was partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER)). Jaume
Gasia and Prof. Luisa F. Cabeza would like to thank the Catalan Government for the quality accreditation given to
their research group (2014 SGR 123). GREA is certified agent TECNIO in the category of technology developers
from the Government of Catalonia. This project has received funding from the European Commission Seventh
Framework Programme (FP/2007-2013) under Grant agreement Nº PIRSES-GA-2013-610692 (INNOSTORAGE)
and from the European Union’s Horizon 2020 research and innovation programme under grant agreement No
657466 (INPATH-TES). Jaume Gasia would like to thank the Departament d'Universitats, Recerca i Societat de la
Informació de la Generalitat de Catalunya for his research fellowship (2017 FI_B1 00092). |
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Subject(s):
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-PCM
-Thermal Energy Storage
-Mushy zone constant
-Latent Heat
-Numerical simulation |
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Rights:
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cc-by-nc-nd (c) Arena et al., 2017
http://creativecommons.org/licenses/by-nc-nd/4.0/
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Document type:
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Article
Article - Published version |
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Published by:
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Elsevier
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