Please use this identifier to cite or link to this item: https://hdl.handle.net/10316/111984
Title: Validation of a Simplified Numerical Model for Predicting Solid–Liquid Phase Change with Natural Convection in Ansys CFX
Authors: Rosa, Nuno 
Soares, Nelson 
Costa, José 
Lopes, António Gameiro 
Keywords: phase change material (PCM); additional heat source method (AHS); natural convection; computational fluid dynamics (CFD)
Issue Date: 2023
Publisher: MDPI
Project: UIDB/50022/2020 
FCT “AdsorSeason—Long-term adsorption solar thermal energy storage”, ref. 2022.03339.PTDC 
Serial title, monograph or event: Inventions
Volume: 8
Issue: 4
Abstract: This paper presents a numerical model for simulating melting and solidification driven by natural convection, and validates it against a previous experiment. The experiment involved filling a rectangular aluminum enclosure with RT28HC Phase Change Material (PCM) to 95% of its capacity. To investigate the thermal behavior of the PCM during phase change, the enclosure underwent independent heating and cooling procedures. The simulation was conducted using ANSYS CFX®, and the additional heat source (AHS) method was implemented in conjunction with the Boussinesq approximation to account for the latent heat during melting and solidification driven by natural convection. This allowed the calculation of temperature fields, the melted fraction, and fluid dynamics during phase change. The momentum equations were modified to include a source term that accounted for a gradual decrease in fluid velocity as the PCM transitions from solid to liquid. To account for density variation, an artificial specific heat curve was implemented based on the assumption that the product of density and specific heat remains constant during phase change. The proposed numerical model achieved good agreement with the experimental data, with an average root mean square error of 2.6% and 3.7% for temperature profiles during charging and discharging simulations, respectively. This model can be easily implemented in ANSYS CFX® and accurately predicts charging and discharging kinetics, as well as stored/released energy, without any numerical convergence issues.
URI: https://hdl.handle.net/10316/111984
ISSN: 2411-5134
DOI: 10.3390/inventions8040093
Rights: openAccess
Appears in Collections:FCTUC Eng.Mecânica - Artigos em Revistas Nacionais

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