Thermochemical energy storage by LiNO_3-doped Mg(OH)_2: Rehydration study

摘要

Thermochemical energy storage (TCES) is an emerging technology promising for reuse of industrial waste heat and harvesting solar energy. Recently, a novel material, namely, a magnesium hydroxide doped with lithium nitrate LiNO3/Mg(OH)(2), was suggested for TCES at temperature lower than 300 degrees C [1]. The LiNO3 additive to Mg(OH)(2) was found to decrease the Mg(OH)(2) dehydration temperature by 76 degrees C which, to the best of our knowledge, is the largest depression reported in the literature so far. The large heat storage capacity (1250 J/g) and fast dehydration made this material promising for TCES.In this work, the LiNO3/Mg(OH)(2) is studied with a focus on the reverse reaction of its hydration by water vapour which allows the stored heat to be released. The rehydration kinetics is studied at various temperatures (90-150 degrees C), water vapour pressures (16.7-33.5 kPa), and LiNO3 contents (0.5-20 wt.%) to outline the boundary conditions of closed TCES cycle for which this material may be used. The material is found to be stable in ten successive de-/rehydration cycles. Finally, the applicability of the material for storage of heat from some particular heat sources is discussed.