THUMBS-UP: D3.3 OPTIMAL CONTROL STRATEGY OF THE SORPTION TES DEFINITION ALONG WITH SOC AND SOH MONITORING APPROACH

D3.3 Optimal control strategy of the sorption TES defi nition along with SoC and SoH monitoring approach reports the activities performed within Task 3.4 of the THUMBS-UP project, dedicated to the analysis of the optimal operating conditions of the SorTES, also including the defi nition of the method to monitor the state of charge (SoC) of the technology. As for any storage technology, one of the key parameters to properly manage its operation is the knowledge of the charging/discharging conditions. This is usually tracked thanks to the SoC parameter. Accordingly, the fi rst phase of the performed activity was dedicated to the proposition of diff erent approaches to be implemented for tracking SoC tracking of the SorTES. This analysis was complemented by a literature review of the proposed methodologies for SoC defi nition in sorption and thermochemical TES technologies. It turned out that, given the specifi c features of the technology, the proper defi nition of SoC is not trivial. Indeed, the TES capacity is mainly dependent on the level of water vapour adsorption over the sorbent material, which is a parameter hardly monitorable directly. Nevertheless, thanks to the specifi c SorTES design, in which the liquid water used for the operation of the TES is contained in a tank at the bottom of the adsorber reactor, the selected methodology to defi ne the SoC considers the continuous monitoring of the water level contained in the water tank. Indeed, since the system is operated as a closed one, no mass exchange with the surrounding is foreseen. Thus, the lowest level of the water contained in the tank represents a SoC equal to 0% (indeed, all the water is adsorbed inside the reactor) while the highest level of the water inside the container represents the SoC equal to 100% (the adsorber reactor is fully dry and ready to adsorb water for the discharging phase). For what it concerns the state of health (SoH) of the SorTES, this will be simply tracked by analysing the average change in storage capacity over cycling. In case of decrease of this capacity, this can be correlated with a loss of sorption properties inside the reactor. After having defi ned the SoC monitoring approach, a numerical model was implemented in Matlab/Simulink, to investigate the proper operation of the SorTES. The dynamic model allowed us to analyse the eff ect of external parameters, such as temperatures and power demand, over the performance achievable by the SorTES both in heating and cooling operation. Moreover, the impact of the charging rate in terms of time to complete the charging was investigated. Finally, the achievable energy storage density and round trip effi ciency also accounting for heat losses over storage time were calculated. All the numerical analyses performed will be further refi ned during the prototype testing campaign, to evaluate the KPIs needed to judge the achievable performance under controlled boundaries.