Investigation of the influence of the air layer on the phase change material melting process inside a hemicylindrical enclosure: A numerical approach

• The influence of the air layers on the melting of paraffin wax in a hemicylindrical enclosure was simulated using ANSYS/FLUENT software. • Paraffin wax RT42 retains a lot of latent heat in small areas as a result of its excellent thermophysical properties. • A 1 mm air layer increases paraffin wax complete melting time by 125%, and a 2 mm air layer increases it by 225%. • Early melting is driven by thermal conduction, while later stages are influenced by free convection due to density differences. • This study shows the effect of the ambient air on latent thermal storage units during the charging process. The rapid growth in energy consumption and the associated difficulties have made thermal energy storage processes using phase change materials (PCMs) a prominent subject of study and development in the last century. The exceptional thermo-dynamic characteristics of this material enable it to accumulate substantial quantities of heat within very limited spaces. The present work involved a numerical investigation of the impact of the air layer on the melting time of paraffin wax RT42 (PCM) within an enclosure with a hemicylinder shape. The enthalpy-porosity relationship is analyzed numerically using ANSYS/FLUENT 16 software. The study included three distinct scenarios that examined the thermal and mass characteristics of paraffin wax within a hemicylindrical enclosure, with the curving wall of the enclosure being thermally insulated. The initial scenario lacked any air layer on the heated vertical wall, whereas the subsequent scenario had an air layer measuring 1 mm thick on the same wall. The third scenario contained an air layer measuring 2 mm within the same wall. The findings indicated that including a 1 mm thick air layer would result in a 125% extended complete melting time of paraffin wax. Similarly, including a 2 mm thick air layer would lead to a 225% rise in the complete melting time of paraffin wax. The presented outcome demonstrates the impact of ambient air on thermal storage units during the charging procedure.