Preparation and thermal energy storage behaviour of stearic acid–TiO2 nanofluids as a phase change material for solar heating systems

This paper investigates the phase change behaviour of newly prepared stearic acid–TiO2 nanofluids as composite phase change materials (PCMs). TiO2 nanoparticles of 0.05, 0.1, 0.15, 0.2, 0.25, 0.3 wt% were dispersed in stearic acid, individually. The phase change temperatures and latent heats of nanofluids for melting and solidification processes were determined by differential scanning calorimetry (DSC). The complete melting and solidification times of nanofluids were reduced by 7.03, 12.56, 19.59, 28.64, 35.17, 43.72% and 6.62, 13.57, 20.53, 26.82, 34.11, 41.39% for 0.05, 0.1, 0.15, 0.2, 0.25, 0.3 wt% TiO2 nanoparticles, respectively. Time reductions of both the processes proved thermal conductivity enhancement of nanofluids and it was ascertained with laser flash analyzer (LFA) measurements. Based on the results, stearic acid based composites could be recommended as potential candidate for low temperature solar thermal energy storage applications due to their better thermal reliability, chemical stability and heat transfer characteristics.