Numerical energy and exergy evaluation for a multiple-layer latent heat storage unit enhanced with nanoparticles under different seasons

Latent heat thermal energy storage unit alleviates the mismatch between energy supply and demand. However, the sole melting temperature of a phase change material in a single-layer heat storage unit does not adapt well to the environment. Therefore, the mechanisms associated with the better environmental adaptability of a multiple-layer heat storage unit are explored in this study based on energy and exergy evaluations via comparison with single-layer units. An innovative methodology is proposed to discuss transient thermal energy and exergy, and exergy distribution of these heat storage units in different seasons. Results show that the multiple-layer units address the limitations of single-layer units by exhibiting excellent heat storage capacity and quality, as well as uniform melting and exergy distribution. Compared with the single-layer unit with a melting temperature of 49 °C, the multiple-layer unit exhibits a 56.64% higher energy in the winter. Moreover, the exergy is 57.14% higher than that of the single-layer unit with a melting temperature of 33 °C in the summer. This study reveals the mechanism of excellent thermal energy storage performance of the multiple-layer latent heat storage unit in different seasons.