Numerical Modeling of the Effect of Nanoparticle Concentration on Solidification Rate of Phase Change Materials in Thermal Energy Storage Systems

Considering the growing rate of energy consumption as well as significant enhancement in worldwide energy demand, it is necessary to improve the performance of energy storage, i.e., melting and solidification rates in thermal energy storage systems. Phase change materials (PCMs) with high latent heats of fusion and proper melting points can be used as alternatives in energy storage systems. The most serious shortcoming in the existing PCMs is low thermal conductivity which confines the rate of energy storage. This issue can be tackled using nanoparticles with much higher thermal conductivities conjugated with the existing PCMs. In this research, effect of nanoparticle addition into PCMs along with copper fins inside both un-finned and finned triplex-tube thermal energy storage systems on PCM solidification rate was investigated numerically. Furthermore, various parameters including nanoparticle type (Al2O3, Ag, CuO, and Cu), concentration (1 and 3%) and diameter (20 and 80 nm) were analyzed for augmentation of the solidification time. The obtained results revealed that the simultaneous presence of fins and 3% of nano-Al2O3 with a 20 nm average diameter can save solidification time up to 67.11%.