Natural convection during a phase change of sodium acetate trihydrate

A latent heat storage system has higher storage capacity than a sensible heat storage system. Sodium acetate trihydrate has large latent heat at the temperature, 58$^{\circ}$C, suitable for a hot-water supply system. The present study focused on convection in a phase change process to understand the heat transfer from the phase change material(PCM). The convection occurred only in certain conditions of supercooling temperature and PCM concentration. A spicular crystal grew quickly and the thermal convection couldn't be detected at large supercooling temperature with high concentration of PCM. In the range of 5 $\sim$ 13$^{\circ}$C of supercooling temperature, the buoyancy driven convection due to the latent heat of PCM was measured using the PIV. It was also observed that a part of CH$_{3}$COONa-3H$_{2}$O solution was sucked into the growing spicular crystals to supply CH$_{3}$COONa at the condition with small concentration and at 5 $\sim$ 13$^{\circ}$C of supercooling temperature.