Enhancing discharging performance of a phase change thermal storage unit with a fractal space-filling matrix

Abstract

The phase change thermal storage (PCTS) technique is essential for renewable energy utilization. To strengthen the heat-discharge performance, an innovative PCTS unit with a fractal space-filling matrix is proposed. Based on the established solidification model, the solidification interface transformation and temperature field evolution of the innovative PCTS unit are numerically analyzed and compared with those of conventional units. Moreover, the roles of the structural parameters of PCTS units are investigated in terms of the resulting solidification behavior, and the metal matrix is optimized in terms of the solidification duration. The results show that the fractal space-filling matrix effectively improves the heat-discharge performance. Compared to conventional PCTS units, the proposed PCTS unit with a fractal space-filling matrix produces a more uniform temperature field and enhances the solidification rate by approximately 40%. Regarding the trade-off between cost and performance, a fractal level of two is suggested to maximize the heat-discharge enhancement and minimize the manufacturing cost. To minimize the solidification duration, the optimal length and thickness ratios of the fractal space-filling matrix are found to be 0.4 and 0.5, respectively, for practical engineering applications.