Melting heat transfer behavior in side-heated enclosures: a regime-based review

This paper aims to develop a unified, regime-based framework to characterize melting heat transfer behavior in side-heated enclosures and to critically evaluate existing scale analysis and heat transfer correlations. Although phase change materials are widely used in latent thermal energy storage systems, predicting their melting behavior remains challenging because the dominant heat transfer mechanism shifts from conduction to natural convection. To capture this, the melting process is typically divided into four regimes: (I) conduction regime, (II) mixed conduction-convection regime, (III) quasi-steady state convection regime, and (IV) solid shrinking regime. However, many empirical heat transfer correlations were not designed with these regimes in mind or are restricted to narrow operating conditions. Based on physical principles and evidence from experimental and numerical studies, this review systematically assesses the validity of existing scaling analyses and empirical heat transfer correlations across the different melting regimes. Robust correlations are identified for conduction- and convection-dominated stages, as well as for regime transitions. In contrast, the solid shrinking regime and melting in high aspect ratio enclosures remain poorly understood. This review highlights key research needs and supports the development of a more universally applicable framework for predictive melting models.