Performance of a packed bed solar energy storage system having large sized elements with low void fraction

► A Packed bed solar energy storage system in low void fraction range was carried out in this paper. ► Reynolds number, void fraction and sphericity of bed elements strongly affected the Nusselt number and friction factor. ► The elements with maximum value of Nusselt number and elements with minimum value of friction factor were found. ► Thermo-hydraulic parameter has been found to be maximum for spherical shaped elements. ► Statistical correlations were developed for the present experimental values of Nusselt number and friction factor.