A spherical capsule with water based Nanofluid (50 nm Al2O3) phase change material during charging process was studied experimentally. The experiments were conducted with pure water and the NFPCM with volumes fractions 0.5%, 1%, 1.5%, and 2%. The results show that there is a significant effect of
Nanoparticle concentration on thermal properties of PCM which sequentially reduces complete charging time for all HTF volume flow rates and also at different HTF inlet temperature. The percentage of reduction in complete charging time at HTF inlet temperature 12 C attained approximately 32%, 28%, 18%, 12% at HTF volume flow rate of 12, 10, 8, 6 lpm respectively.