Experimental Investigation of Solidification and Melting Characteristics of Nanofluid as Pcm for Solar Water Heating Systems

In this study, thermal and heat transfer characteristics of nano based PCM during energy storage and release processes were investigated. This work also presented the preparation of nanofluid, which is solid-liquid composite material consisting of TiO2 nanoparticles (NPs) embedded into melting palmitic acid. Size of the TiO2 nanoparticles synthesized by sol-gel method was measured by using transmission electron microscope (TEM). Differential scanning calorimetry (DSC) measurements were used to determine the phase change temperatures and latent heats of nanofluids for melting and solidification processes. From the experimental results, it was observed that complete melting times of nanofluids with 0.1, 0.2 and 0.3 wt% of TiO2 nanoparticles were reduced by 6.43, 14.62 and 21.05% respectively, than the palmitic acid. Similarly, complete solidification times of nanofluids with 0.1, 0.2 and 0.3 wt% of TiO2 nanoparticles were reduced by 6.18, 12.37 and 20.11% respectively, than the palmitic acid. Based on all results, it was clearly understood that the dispersed nanoparticles into palmitic acid had enhanced the heat-transfer characteristics of palmitic acid in a better way, which in turn would accelerate the energy storage and release rates faster as compared to that of palmitic acid. Thus, the newly prepared nanofluids could be considered as a promising candidate for solar water heating system.