To what extent does local oscillation influence the thermal performance of finned PCM-based energy storage systems: A numerical study

Abstract

Enhancing the thermal performance of phase change materials (PCMs) is vital for improving the efficiency of energy storage systems. While fins are widely used to expedite the melting process by boosting thermal conductivity, their effectiveness diminishes as melting progresses and natural convection becomes dominant. Meanwhile, local mechanical oscillation has emerged as a promising technique to further accelerate melting, though its isolated use has been the primary focus of prior studies. The combined effect of fins and local oscillation, particularly their interaction in influencing the heat transfer dynamics of PCM, remains unexplored. Thus, this study develops a numerical model to investigate the interaction between various fin configurations (namely, sinusoidal, and positive/negative straight fins) and local oscillation within a finned rectangular enclosure. Moreover, the local oscillator’s placement on the hot wall, as well as its proximity to the fins, are among key factors analyzed. The results demonstrate that negative rectangular fins consistently deliver superior thermal performance, while the effectiveness of local oscillation diminishes when placed between fins, particularly as the melting front progresses. The optimal configuration is a vertical oscillator positioned at the base of the hot wall near a negative fin, which achieves a 64.3 % reduction in melting time. Notably, as the lower fin is installed closer the bottom wall of the enclosure, two distinct mechanisms arising from extension of the heating area and local flow stimulation by the oscillator plate, though differing fundamentally, result in similar effects during the later stages of the melting process, thereby diminishing the overall influence of localized oscillation on the melting process.