Melting property analysis of Kelvin structure composites phase change material based on pore scale

To enhance the thermal energy storage performance of phase change material (PCM) for efficient heat dissipation in high-power electronic devices, this study conducted pore-scale melting simulations of metal foam composite phase change material (MFCPCM) with a porosity of 0.97 in a 40 mm-side-length square cavity using a Kelvin cell structure as the skeleton. The effects of cells per unit length (CPL) on the melting process of MFCPCM were investigated concerning melting rate, natural convection patterns, temperature uniformity and thermal energy storage performance. Results demonstrated that the Kelvin structure can significantly enhance PCM thermal properties. Compared to pure paraffin, MFCPCM with CPL=4 reduced the complete melting time by 31.7%, decreased the maximum temperature difference by 64% and exhibited a heat storage efficiency 1.09 times that of pure paraffin. However, the enhancing effect of the Kelvin structure on MFCPCM thermal performance progressively diminished with increasing CPL. Furthermore, distinct differences in natural convection and heat transfer mechanisms within the PCM induced by melting were observed for different CPL. As CPL increasing, the internal circulation loops transition was from triangular to trapezoidal shapes, leading to significantly improved temperature uniformity and a continuously increasing internal heat transfer rate. Therefore, the rational design of MFCPCM with varying CPL can hold promise for achieving a uniform and efficient melting and heat storage process.