Melting with natural convection with heterogeneous heating sources

This study focuses on the dynamics of melting with natural convection in a square enclosure heated from a side boundary (heating source). This is done through an ad-hoc developed numerical model based on the lattice Boltzmann method. The understanding of the convection melting process in such a setup is particularly relevant for the technical exploitation of Phase Change Materials (PCMs) as thermal energy storage and thermal management systems in different applications of technical interest in the field of sustainable energy systems. This study addresses novel and key issues related to the boundary conditions related to the heating source by considering heating sources presenting alternating insulating and conductive patches. The size of the patches has been systematically changed in order to address the role of heterogeneities in the heating source and the heat transfer phenomenon is quantified via the analysis of the dynamics of the average melting front position and the time dependence of the Nusselt number. Side-by-side comparisons between heterogeneous heating sources and homogeneous (conductive) ones are systematically investigated. It is found that the heterogeneity of the boundary conditions changes the dynamics of the heat transfer mechanism introducing additional convective mechanisms of transport that would be absent in the homogeneous case. This study is instrumental to distill engineering principles for the design and development of suitable boundary conditions to exert a passive control on the PCM system for energy storage.