Experimental study on the melting and solidification behavior of erythritol in a vertical shell-and-tube latent heat thermal storage unit

• Comprehensive thermophysical properties of erythritol were obtained.
• Charging and discharging behavior of erythritol was experimentally studied.
• Melting and solidification were governed by the combined effects of natural convection and conduction.
• Effects of inlet temperature, flow rate, and heat transfer fluid pressure on thermal storage performance were studied.

An experimental study on a vertical shell-and-tube latent heat thermal storage unit with erythritol as storage media and air as heat transfer fluid (HTF) is conducted to evaluate the thermal behavior and heat transfer performance of the unit. The thermophysical properties of erythritol, such as melting temperature, melting enthalpy, thermal conductivity, and viscosity, are obtained. During charging, the molten phase change material (PCM) first occupies the top region and then spreads from top to bottom. During discharging, the PCM initially solidifies from the bottom region, and then the solid–liquid interface progresses uniformly from the inner tube to the outer shell, where natural convection plays a dominant role in the heat transfer at the liquid region. Moreover, increasing the inlet temperature and the mass flow rate of the HTF during charging obviously enhances the heat transfer in the PCM and shortens the charging time. Increasing the pressure of the HTF with the same mass flow rate shows little effect on the heat transfer in the PCM. In addition, increasing the mass flow rate of the HTF helps enhance heat transfer during discharging.