Comparative analysis of a Packed-Bed Thermal Energy Storage operating with pure gases and nanoaerosol

This paper investigates the thermal performance of a packed-bed thermal energy storage (TES) system and the impact of introducing nanoparticles into the working fluid. A one-dimensional transient numerical model based on Local Thermal Non-Equilibrium (LTNE) principle is validated against experimental data. Key parameters, such as temperature distribution and thermocline formation, show good agreement between numerical and experimental results with an average RMSE on the thermocline profile equal to 0.96 K during the charging phase, and 2.74 K during the discharging phase. The effect of adding nanoparticles to the working fluid are then examined. Nanoparticles enhance the fluid's effective thermal conductivity, improving heat transfer. Numerical simulations indicate that nanoparticle concentration increases the mass flow rate but decreases the volumetric flow rate, resulting in reduced pressure losses within the bed. Higher nanoparticle concentrations significantly enhance the convective heat transfer coefficient. Overall, introducing nanoparticles improves the TES system's thermal performance without significantly altering its energy storage capacity. The validated model helps optimize TES system design, balancing enhanced thermal properties and increased fluid density.