Experimental and numerical study on heat transfer and energy storage characteristics in double-layered enclosure packed with microencapsulated phase change material

Abstract

Heat transfer and energy storage characteristics in double-layered enclosure packed with microencapsulated phase change material (MEPCM) are investigated numerically and experimentally in details. The rectangular enclosure is partitioned by an Al-plate to provide a double-layered enclosure. The top surface of enclosure is heated with varied heat flux with sine wave variation, the bottom surface is maintained at a low and constant temperature and the other vertical surfaces are thermally insulated. Two microencapsulated phase change materials made by paraffin with melting temperatures about ${\text{T}}_{\text{M}}=$28 ℃ and 37℃, are selected. The high-temperature wall heat fluxes (${\text{q}}_{\text{h}}$) of $\text{22.7sin(}\omega \text{t)}\text{W}/{\text{m}}^{\text{2}}\text{, 39.0sin(}\omega \text{t)}\text{W}/{\text{m}}^{\text{2}}$, and $\text{61.3sin(}\omega \text{t)}\text{W}/{\text{m}}^{\text{2}}$ are considered. The low-temperature wall boundary conditions are set to $\text{15}$ ℃, $\text{20}$ ℃ , and $\text{25}$ ℃$.$ The results show that better net thermal energy storage is found for a case with a higher wall heat flux at the top surface. In addition, better thermal energy storage is noted when the MEPCM with low melting temperature is packed at the upper enclosure near the heated wall. Also, more energy storage is experienced for a double-layered enclosure with a higher partitioned ratio λ. The melting point temperature of microcapsule phase change materials needs to be between high/low-temperature wall heating conditions to effectively store heat.