CFD modelling of low-temperature PCM thermal energy storage

This paper presents a two-dimensional transient CFD model of a PCM-based thermal energy storage system subjected to high-pressure carbon dioxide heating. The enthalpy–porosity method was applied to simulate the melting process, incorporating latent heat effects into the energy equation. The governing mass, momentum, and energy equations were solved in ANSYS Fluent 2025R2, with turbulence modelled using the k–ω SST approach. Real gas properties of CO₂ at 80 bar and 400 K were implemented based on NIST REFPROP data. The results show the temporal evolution of the liquid fraction and confirm that the melting rate decreases over time due to the low thermal conductivity of the PCM. The study demonstrates the usefulness of transient CFD modelling for the optimization of PCM thermal energy storage systems.