Characterization and performance investigation of UiO-66 for low-grade thermochemical adsorption heat storage

Thermochemical energy storage can improve low-grade energy utilization efficiency, thereby reducing buildings' operating energy consumption. However, common thermochemical thermal storage materials have poor stability and low energy storage density. To this end, it put forward to use UiO-66 as a novel low-grade thermal energy storage material. It was synthesized and characterized, and its thermal conductivity, optimal activation tem-perature and time, adsorption kinetics and thermal energy storage density were also comprehensively studied. The results showed that the thermal conductivity of UiO-66 was 0.282 W/(m & sdot;K) at 30 degrees C. The optimal activation temperature and time for UiO-66 were 100 degrees C and 1.5 h taking into account the balance between the high water uptake and energy saving. The water uptake of UiO-66 at 30 degrees C and 80% RH reached 0.410 g/g, 2.1 times that of Zeolite 13X. The adsorption behavior of water vapour in UiO-66 was accurately described by the pseudo-second -order kinetic model. The thermal energy storage density of UiO-66 was 818 kJ/kg, which was 1.6 times higher than that of Zeolite 13X (515 kJ/kg), demonstrating excellent thermal storage performance. To sum up, the research results showed that UiO-66 had application potential in low-grade thermal energy storage fields such as heat from solar collector and industrial waste heat.