A Numerical Parametric Study of a Double-Pipe LHTES Unit with PCM Encapsulated in the Annular Space

Latent heat thermal energy storage (LHTES) with Phase Change Materials (PCM) represents an interesting option for Thermal Energy Storage (TES) applications in a wide temperature range. A tubular encapsulation model of an LHTES with PCM was developed, and the calculated data were analyzed. In addition, a parametric analysis for the preferable system geometry is presented. Organic paraffin RT18 with a melting point of 18 degrees C was utilized as PCM for different geometries of LHTES, and the addition of internal and external fins and their influence on LHTES thermal conductivity was investigated. One-step heat exchange from outdoor air to PCM and from PCM to water characterizes the LHTES system in solidification and melting processes, respectively. A 2D axisymmetric model was developed using Comsol Multiphysics 6.0. The LHTES unit performance with PCM organic paraffin RT18 encapsulated in electrospun fiber matrices was analyzed. The study results show that longer internal fins shorten the melting and solidification time. Direct contact of PCM electrospun fiber matrix with 23 degrees C water showed instant melting, and the phase change process was accelerated by 99.97% in the discharging cycle.

Automated summary

Latent heat thermal energy storage with Phase Change Materials (PCM) is a promising option for Thermal Energy Storage (TES) applications. This study developed a tubular encapsulation model and conducted a parametric analysis to optimize the system geometry and investigate the influence of internal and external fins on thermal conductivity. The results also showed that using PCM organic paraffin RT18 encapsulated in electrospun fiber matrices enabled rapid phase change processes.