A novel two-dimensional effectiveness-NTU method for high-temperature cascade latent heat storage

• New 2D ε-NTU method offers more accurate optimization of cascade latent heat storage than 1D models • Cascade configuration reduces thermal resistance and improves heat transfer efficiency. • Metal wool integration enhances effectiveness by 54% in single PCM configuration and 20% in Cascade. • Cascade reduces melting time by 27% compared to single PCM. This study presents a novel two-dimensional effectiveness number of transfer unit (ε-NTU) method to characterise and optimise cascade latent heat storage (CLHS) systems, incorporating metal wool enhancement for improved thermal performance. The proposed model provides a more accurate and computationally efficient alternative to conventional one-dimensional approaches for analysing heat transfer in high-temperature latent heat storage (LHS) applications. Current performance evaluation methods still lack precision due to the reliance on simplified assumptions regarding material properties and heat transfer dynamics. Moreover, most enhancement strategies focus on single-PCM systems, necessitating dedicated research efforts for CLHS-specific solutions. Validation through computational fluid dynamics (CFD) simulations demonstrates strong agreement, confirming the method’s reliability in predicting thermal behaviour during both charging and discharging processes. The results reveal that the cascade configuration reduces thermal resistance and enhances heat transfer efficiency, while the addition of metal wool increases the effectiveness of the system by up to 54% in single latent heat storage (SLHS) and 20% in CLHS without additives. These findings establish the two-dimensional ε-NTU method as a robust design and optimisation tool for next-generation thermal energy storage systems in renewable energy real-world applications.