Effect of Al2O3 nanoparticles addition on the thermal characteristics of paraffin wax

Phase change materials are well employed in thermal energy storage systems due to their high thermal storage capacity; however, the problem with phase change materials lies in their low thermal conductivity. The experimental work presented here investigates the effect of adding Alumina (Al2O3) nanoparticles to paraffin wax (Bio-PCM). The resultant nanofluids contain nanoparticles with 1 % and 3 % volume fractions, with corresponding mass fractions of 4 % and 11 %, respectively. It was found that the thermal properties of the prepared nanofluids under investigation exhibit a nonlinear increase in the thermal conductivity with the volume fraction of nanoparticles. A reduction in the latent heat of paraffin wax-based nanofluids was also observed as the volume fraction of nanofluids increased. The results also show the dependence of thermal conductivity on the temperature, where more significant enhancement was observed as the temperature increased. The optimal volume fraction of nanoparticles suspended in the wax was determined to be at 1 % VF with a thermal conductivity value of 0.307 W/m.K at room temperature and latent heat of 207.43 J/g with a melting temperature of 33.63 °C. Furthermore, a stability test was performed to test the thermal conductivity of the mixture under continuous melting and solidification cycles.