Analysis of performance of cold storage in existence of nano-sized additives within complex geometry

This study presents a comprehensive simulation of the unsteady solidification process in advanced cold energy storage systems, using a water-based phase change material (PCM) enhanced with alumina nano-powder. The investigation focuses on the impact of nanoparticle diameter (dp) and concentration (ϕ) on the solidification process, aimed at optimizing the system's thermal performance. A dynamic mesh adaptation technique is employed to track the evolving ice front within an enclosure integrated with fins, ensuring accurate resolution of the transient freezing process. Given the minimal fluid motion during solidification, the study focuses solely on solving the energy equation, incorporating a time-dependent source term for phase change. The mathematical model was rigorously validated against established benchmarks, confirming its high accuracy. The findings reveal that increasing the nanoparticle concentration (ϕ) enhances the cold storage rate, with a marked improvement of 36.37 %. In contrast, the effect of nanoparticle size on freezing time follows a non-linear trend: an initial reduction of 15.85 % in freezing time occurs with larger nanoparticles, but further size increases result in a significant 38.96 % rise in freezing time. These results emphasized the prominence of optimizing both nanoparticle concentration and size for improved energy storage performance. Future work should explore the long-term stability of nano-powders in cold storage systems and their potential in commercial applications.