Comparison of enthalpy-porosity and lattice Boltzmann-phase field techniques for the simulation of the heat transfer and melting processes in LHTES devices

Thermal energy torage (TES) is a key enabling technology for the efficient exploitation of distributed generation systems based on renewable energy sources. Among the available options, research on latent heat TES (LHTES) solutions has been particularly active in the last decade, due to their ability to store and release high amounts of thermal energy in a very narrow temperature range. LHTES devices are based on phase change materials (PCMs), which act as thermal sinks or sources during their solid-to-liquid transition and vice-versa. As such, the development of reliable numerical tools for the prediction of the heat transfer and phase change characteristics of PCMs is of foremost importance, to help designing innovative and efficiently integrated LHTES implementations. In the present paper, the consolidated enthalpy-porosity (EP) method is compared to a novel lattice Boltzmann-phase field (LB-PF) algorithm in the simulation of a standard numerical benchmark for paraffin-like PCM melting problems. Performances and limitations of the two approaches are discussed, including the influence of model-related and purely numerical parameters. Outcomes from this study are used to confirm general guidelines for the application of well established methodologies, as well as to suggest new pathways for out-of-standard modeling techniques.