Development and characteristics analysis of salt-hydrate based composite sorbent for low-grade thermochemical energy storage

Wei Li, Jiří Jaromír Klemeš, Qiuwang Wang and Min Zeng

Renewable Energy, 2020, vol. 157, issue C, 920-940

Abstract: Salt-hydrate based thermochemical energy storage is currently a momentous technique utilized for long-term energy storage due to the reversible gas-solid reaction under low-temperature. Among available salt candidates, LiOH·H2O is a promising thermochemical material owing to its high heat storage density of 1400 kJ/kg and low charging temperature. The expanded graphite (EG) is selected as a host matrix owing to its excellent thermal conductivity and abundant microstructure, which can promote the heat and mass transfer. This work focuses on the thermochemical performances of the form-stable LiOH·H2O/EG composite sorbents. Five samples were being synthesized with EG contents of 0, 5, 8, 12 and 15 wt%. These porous sorbents are characterized to understand the microstructure and thermophysical properties. Considering the comprehensive effect of thermal conductivity and storage density, as well as the adsorption kinetics, the 8 wt% EG-doped sample is the most favourable sorbent, which possesses the thermal conductivity of 6.92 W/(m K) and energy density of 1120 kJ/kg. The cyclability results also reveal the energy capacity of this composite maintains ∼90% of the original after ten consecutive heat charging (dehydration) and discharging (hydration), suggesting good stability. Additionally, the active energy of 2.58 × 109 s−1 and pre-exponential factor of 59.5 kJ/mol for the sorbent is derived. Finally, the thermal power of 123 W and thermal efficiency of 83.6% are achieved for the storage unit in simulation. All these results further confirmed the feasibility of the developed composite sorbent in low-grade heat storage.

Keywords: Thermochemical energy storage; Composite thermochemical material; LiOH·H2O; Adsorption kinetics; Cycle stability; Numerical simulation (search for similar items in EconPapers)
Date: 2020
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Citations: View citations in EconPapers (9)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:157:y:2020:i:c:p:920-940

DOI: 10.1016/j.renene.2020.05.062

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