Industrial-grade hydrated salt-based PCM thermal energy storage device: Thermal and economic performances
Zhengkai Xu, Xinxin Sheng, Jianyong Chen, Ying Chen, Jiacheng He, Xianglong Luo, Yingzong Liang
Abstract
Sodium acetate trihydrate (SAT) has been recognized as a promising phase change material (PCM) due to its cheapness and high melting enthalpy. However, its melting enthalpy is greatly reduced after short-term usage due to phase separation. An industrial-grade composite SAT, which is supercooling free and has excellent cycling stability, is prepared by melt-blending method. Adding thickeners enhances the SAT viscosity, which effectively prevents phase separation and maintains high latent heat even after 1000 heating–cooling cycles. To further explore the application potential of the composite SAT, the thermal performances of the thermal energy storage device (TESD) with composite SAT (SAT-TESD) are experimentally examined and compared with octadecanol (OD)-based TESD , i.e., OD-TESD. During the charging process, temperature uniformity is maintained across all PCM layers at the considered flow rate ( q v ) and inlet temperature ( T in ) of the heat transfer fluid (HTF). When q v = 51 L·h −1 and T in = 75℃, the average charging power of SAT-TESD is 12.5% lower that of OD-TESD. During the discharging process, the outlet temperature of HTF in SAT-TESD exhibits a stable temperature evolution, which is absent for OD-TESD. The discharging heat capacity of SAT-TESD is 20.48%–32.86% higher than that of OD-TESD. The economic feasibilities of SAT-TESD, OD-TESD and water-TESD are finally revealed. Compared to water-TESD, capital expenditures (CAPEX) of SAT-TESD and OD-TESD can be reduced by 27.5% and 14.6%, respectively. The superiority of SAT-TESD is more significant at where the peak-valley electricity price difference is larger. It provides a good reference for the selection of PCM in different application scenarios.