An Investigation into Computational Modelling of Melting and Solidification of Phase Change Materials
Abstract
This thesis evaluates the effectiveness of the enthalpy-porosity approach in simulating melting and solidification of phase change materials within latent heat thermal energy storage systems. It systematically investigates the sensitivity of the computational model to four adjustable parameters: mushy zone coefficient, thermal expansion coefficient, solidus/liquidus temperatures, and latent heat. The study includes individual and combined analyses of these factors in simulations of the melting process by comparing outcomes with extensive experimental data, resulting in a calibrated melting model. The calibrated model is validated across various heating conditions in the cylindrical cavity, and then in a rectangular cavity, confirming its reliability in predicting the main features of PCM melting behavior. When applied to solidification, significant discrepancies arise in terms of overall freezing time and in the temporal evolution of the interface separating the solid and liquid regions of the domain. It is thought that a key factor influencing this discrepancy is the lack of supercooling considerations in the enthalpy-porosity model that was utilized, indicating a need for improved freezing process modeling.