Experimental investigation on high energy-density and power-density hydrated salt-based thermal energy storage

Abstract

• High energy and power density hydrated salt-based TES device. • Performance evaluation of TES device at different conditions for hot water heating. • Phase-change temperature of 50 ℃ and phase-change enthalpy of 184.5 kJ·kg −1 . • Energy storage density is 2.6 times higher than that of conventional water tank. • High energy storage density (∼88.4 kWh·m −3 ) and high power density (669.9 W·kg −1 ) Thermal energy storage based on phase change materials (PCMs) plays a key role in bridging the gap between energy supply and demand for renewable energy applications. Hydrated salt is one kind of the most promising PCMs due to high phase-change enthalpy, non-flammability and low cost. Herein, we design and fabricate a lab-scale high energy-density and power-density thermal energy storage (TES) device using hydrated salt-based phase change composite (PCC). The thermophysical properties of the hydrated salt-based PCC are characterized and the thermal performances of the PCC-based TES device are analyzed at different operating conditions during charging and discharging processes. The Differential Scanning Calorimeter (DSC) analysis shows that the PCC has high phase-change enthalpy of 184.5 kJ·kg −1 and suitable phase-change temperature of 50 ℃ for hot water heating. The experimental results show that the PCC-based TES device exhibits high specific energy storage density up to 88.4 kWh·m −3 , approximately 2.6 times higher than the conventional water tank storage device. In discharging process, the PCC-based TES device exhibits high energy density (∼81.6 kWh·m −3 ), high efficiency (∼92.3 %), high power density (∼669.9 W·kg −1 ), and stable output hot water temperature (45 ∼ 47 ℃) at different water flow rates (0.42 ∼ 2.42 L·min −1 ) and inlet cold water temperatures (8 ∼ 25 ℃).