Numerical Study of Melting and Thermal Energy Storage of Power‐Law Nano‐Enhanced Phase‐Change Materials in a Partitioned Channel

ABSTRACT In this study, we numerically examine the melting and energy storage process of non‐Newtonian nano‐enhanced phase‐change materials in a partitioned cavity. Three phase‐change materials (PCMs), namely, PCM‐1OM55, PCM‐2‐OM65, and PCM‐3‐RT55, are examined in four configurations: homogeneous single‐PCM (Case I), homogeneous partitioned‐PCM (Case II), heterogeneous multi‐PCM (Case III), and hybrid multi‐PCM (Case IV) arrangements. The influence of the power‐law index ( n ), the angle of inclination of the cavity ( γ ), the volume fraction of nanoparticles ( φ ), the Rayleigh number ( Ra ), and the Stefan number ( Ste ) on melting behavior and energy storage is systematically investigated using the finite‐volume method coupled with the enthalpy–porosity approach. The results show an overall better thermal performance of the heterogeneous multi‐PCM (Case III), with the minimum melting time and the highest thermal energy storage capacity. The difference between the maximum and minimum melting times of the investigated configurations is 52.19%. The pseudoplastic fluid ( n = 0.8) melts about 17% faster than the Newtonian fluid and 19.62% faster than the dilatant fluid ( n = 1.2) while giving a small increase in stored thermal energy. The melting time increases by 6.5% as the volume fraction of nanoparticles increases from 0% to 6%, while the stored thermal energy decreases slightly despite the improved effective thermal conductivity. Moreover, the Rayleigh number enhancement favors the natural convection that enhances the melting acceleration and the energy storage. Increasing the Stefan number decreases the melting time but reduces the total thermal energy stored. The results indicate the potential of multi‐PCM arrangements and non‐Newtonian rheology to enhance latent thermal energy storage performance.