Thermochemical energy storage by LiNO3-doped Mg(OH)2: Rehydration study. (April 2019) - Shkatulov, Alexandr
Highlights: Hydration of new thermochemical material LiNO3/MgO was studied. The hydration proceeds at T = 90-150 o C and P = 16.7–33.5 kPa. The new material showed the stable performance over 10 dehydration/rehydration cycles. Use of the new material can broaden the range of waste heat sources to be utilized. Abstract: 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 °C [1 ]. The LiNO3 additive to Mg(OH)2 was found to decrease the Mg(OH)2 dehydration temperature by 76 °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 °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.