Numerical simulation of phase change material with enhanced close contact melting

Phase change materials (PCMs) show significant potential for latent thermal energy storage when integrated with renewable energy sources like wind and solar, as well as thermal management systems. Nevertheless, the inherent low thermal conductivity of PCM materials and the continuous migration of the melting front during phase change present challenges to the system’s power and effective energy density. This thesis explores the numerical modeling of pressure-enhanced close contact melting (CCM) as an innovative method to enhance the thermal performance of PCM, particularly paraffin, in two-dimensional rectangular containers. The numerical investigation utilizes the finite element method in the COMSOL commercial software. The study aims to examine key performance indicators of thermal management and latent heat thermal energy storage systems employing PCM. The enthalpy-porosity-based numerical model for both conventional and enhanced CCM was successfully validated against experimental results available in the literature. The study investigates the influence of various parameters, such as pressure, heat flux, and geometry, on crucial performance. The cyclic performance study of pressure-enhanced CCM indicates that it can accelerate the charging and discharging phases of a latent energy storage system. A comparative study with constrained melting as a benchmark yielded a 55% improvement in charging and a 30.8% in the discharging phase. Furthermore, it is indicated that latent energy storage systems with pressure-enhanced CCM can allocate an impressive 35-37% more thermal energy in latent form when supplied with the same amount of heat energy than conventional PCM. A parametric investigation of pressure-enhanced CCM of paraffin reveals that the interplay between viscosity and thermal conductivity significantly affects the net thermal performance of pressure-enhanced CCM. Moreover, the performance of a real 1-tetradecane NePCM under 0 wt%, 1 wt%, and 3 wt% loading of graphene nanoparticles was studied. The results show an increase in performance at 1 wt% but a decrease at 3 wt%. In conclusion, pressure-enhanced CCM offers promising potential for passive thermal management systems and latent heat Storage. However, the requirement for a continuous pressure source complicates system design and challenges scalability. Hence, further research is needed to optimize its design and assess its techno-economic value.