Thermochemical energy conversion behaviour in the corrugated heat storage unit with porous metal support

Because of the low charging temperature, salt hydrate-based adsorption thermochemical energy storage (TCES) is currently a significant technology that promises long-term energy storage. A corrugated-shaped heat storage unit (HSU) in which embedding porous metal bracket is proposed in this work to enhance heat transfer between the thermochemical material (TCM) wrapped inside and the heat fluid transfer (HTF) in the external corrugated channel. The thermo-chemical conversion behaviours, including reactive transport processes during dehydration (charging) and hydration (discharging), as well as the influence of parameters, are comprehensively investigated. The numerical results indicate that increasing the HTF temperature facilitates the charging process while the discharging can be promoted by decreasing reaction bed temperature. The time required to complete charging and discharging for the reference cases is 2990 s and 5700 s. For both charging and discharging powers of reactive bed, the values dramatically surge in a short time and then gradually decrease, with the maximum powers of 2638 W and 1866 W, respectively. Boosting evaporation temperature (water vapour pressure) accelerates hydration while the effect of condensation temperature on dehydration is insignificant. The reaction period can be further shortened by heightening the thermal conductivity of TCM, and the porosity also has a distinct influence on the reaction. Compared to the storage unit of a straight external channel without a metal bracket inside, this heat storage module saves 34% and 23% in charging and discharging times. The results of this work provide insights into the prediction and improvement of thermochemical conversion behaviours.

Automated summary

This study proposes a corrugated-shaped heat storage unit with an embedded porous metal bracket to enhance heat transfer and comprehensively investigates thermo-chemical conversion behaviors. Numerical results show that increasing the heat fluid transfer temperature facilitates charging while decreasing reaction bed temperature promotes discharging. Increasing evaporation temperature and thermal conductivity of the thermochemical material can shorten the reaction period.