Thermal performance of nanoparticle-infused PCMs in honeycomb-finned cavities for high-efficiency heat storage

This study presents a novel dual-mode thermal enhancement strategy for latent heat thermal energy storage, combining nanoparticle augmentation and geometric optimization through honeycomb extended surfaces. A comprehensive numerical investigation is conducted to evaluate the melting performance of phase change materials (PCMs) enhanced with four different nanoparticles Al₂O₃, Cu, CuO, and graphene nanoplatelets (GnP) at volume concentrations of 2 %, 5 %, 8 %, and 10 %. Unlike prior works, this study provides a side-by-side comparison under identical boundary conditions, offering practical design insights for material geometry combinations. The phase change process is modelled using the enthalpy-porosity method, while natural convection is incorporated through the Boussinesq approximation. Performance metrics include liquid fraction evolution, melting time, and thermal field uniformity. Among all configurations, GnP at 10 % concentration yielded the best performance, reducing the melting time from 3000 s (pure PCM) to 1180 s without fins and further down to 950 s with honeycomb fins. The combination also resulted in a 98 % liquid fraction, temperature gradient reduction of over 60 %, and an increase in absorbed thermal energy from 170 kJ/kg to 218 kJ/kg. Other nanoparticles (Al₂O₃, Cu, CuO) showed moderate enhancements with melting time reductions ranging from 31 % to 43 %, depending on concentration and geometry. The results confirm that the synergistic integration of high thermal conductivity nanoparticles and geometrically optimized fins significantly enhances PCM thermal performance. These findings provide valuable design guidelines for advanced latent heat storage systems used in electric vehicle cooling, solar thermal collectors, and electronics thermal management.