Effect of nanoparticle size during discharging of NePCM in TTHE: A numerical investigation

Abstract

The addition of nanoparticles is an effective strategy to upgrade the thermo-physical properties of phase change material. This paper concerns the effect of nanoparticle size on the discharging (solidification) of nanoparticles enhanced phase change material in triple-tube heat exchanger. The commercial tool Ansys Fluent is used to create the two-dimensional numerical model. For solidification, enthalpy-porosity has been adopted, while the change in properties of the material due to addition of nanoparticles is defined by the user defined function. The size of nanoparticles is varied as 20 nm, 30 nm and 40 nm during the analysis. The model has been validated against the reported result in the literature. The results from the transient numerical analysis shows that the total discharging time being shortened by around 25% and 40% for the phase change material with 30 nm and 40 nm size nanoparticles respectively compared to the phase change material with 20 nm size nanoparticles. It is observed that the drop of average temperature during the discharging process increases while increasing the size of nanoparticles in phase change material.