PERFORMANCE IMPROVEMENT EVALUATION OF A LATENT HEAT STORAGE UNIT ENHANCED BY VICSEK FRACTAL FINS

The mature and scale utilization of renewable energy is restricted by the deficient efficiency of latent heat storage (LHS) technology. To address this, an innovative Vicsek fractal fin is first proposed herein for the heat charging/discharging rate enhancement. The phase transition behavior and thermal characteristics of the innovative LHS unit are solved numerically and compared to the traditional one, employing the enthalpy-porosity algorithm and a two-dimensional transient model. The results indicate that Vicsek fractal fins remarkably promote the thermal efficiency of LHS units. Compared to the traditional LHS units, innovative LHS units with Vicsek fractal fins, respectively, reduce the melting/solidification duration by 16.1% and 28.7%. The melting process is divided into early thermal conduction, subsequent convective thermal transport, and later thermal conduction, while solidification processes are dominated by the initial natural convection and the subsequent continuous heat conduction. Moreover, the impact of free convection is higher on melting processes than on solidification processes. Importantly, the efficient heat transfer path of Vicsek fractal fins allows the inherent natural convection suppression to be much weaker than the improvement level of heat transfer efficiency, facilitating the interstitial thermal transport between the phase change material (PCM) and fins and improving the overall temperature uniformity of LHS units.