An innovative approach for establishing the unconstrained melting correlation of phase change materials encapsulated within hot water tanks

This study introduces a novel methodology that utilizes stepwise regression-elimination to establish an unconstrained melting correlation for phase change materials (PCMs) encapsulated within hot water tanks. This approach progressively eliminates the impact of influencing parameters, enabling the development of correlations without presupposing its specific form. Moreover, it remains robust even when the total melting time exhibits a nonlinear relationship with influencing parameters under logarithmic conditions. To validate the methodology, a detailed exploration was conducted for PCMs encapsulated in cylindrical latent heat storage units (LHSUs) within hot water tanks. Initially, a comprehensive analysis was performed to understand the relationship between various influencing parameters and the total melting time. Subsequently, correlations were established for the liquid fraction and total melting time, respectively. The findings revealed that the total melting time does not always exhibit a linear correlation with influencing factors under logarithmic conditions. The established correlations successfully captured the relationships between influencing parameters and the liquid fraction or total melting time. When comparing the numerical results of the correlation, the errors for the liquid fraction ranged from −15 % to +15 %. Furthermore, the absolute error for the total melting time was below 4.83 %, demonstrating the high accuracy of the proposed method. •An innovative approach for establishing unconstrained melting correlation.•The proposed method can establish correlations without presupposing the form.•Fototal displays a nonlinear relationship with ξ under logarithmic conditions.•Correlations of both total melting time and liquid fraction were established.•The established correlations showed a high level of accuracy.