Exploring the potential of a novel segmented concept of real-scale open sorption storage via CFD modeling and performance evaluation

Abstract

Sorption heat storage enables high-density, low-loss thermal energy storage from summer to winter through reversible adsorption–desorption, offering strong potential for both short-term and seasonal solar heating in residential applications. In this work, a novel segmented reactor concept is developed for an open sorption heat storage system, enabling flexible configuration and scalable capacity. A numerical simulation is developed and the performance of the designed module containing zeolite 13XBF is comprehensively evaluated with simulations under various operating conditions and performance indicators. Numerical results indicate an energy density of approximately 115.6–144 kWh/m3, depending on the boundary conditions for the proposed reactor, mostly affected by the relative humidity of incoming air. Furthermore, the segmented design yields exceptionally low pressure drops in the bed, ranging from 71 Pa to 203 Pa for mass flow rates between 50 kg/h and 120 kg/h, thereby reducing fan power requirements. Detailed simulations reveal that increasing the relative humidity of the incoming airflow and reducing the initial and inlet temperature under constant partial pressure contribute to higher output temperature, power, and energy density. Raising the inlet vapor pressure from 5 mbar to 25 mbar increased the useful energy from 23.9 MJ to 29.8 MJ, and energy density from 115.6 kWh/m3 to 143.3 kWh/m3. Increasing the airflow rate raises the instantaneous output power. However, it may also shift the outlet temperature outside the desired range for residential space heating, which highlights the importance of careful control and optimization. A CFD-based design study shows that the initial segmented reactor uses the two beds unevenly and yields imbalanced outlet temperatures, while simple geometric changes—shortening the upper bed and adding an inlet diffuser—make the flow and temperature fields more uniform, extend the high-temperature discharge period by about 22%, and increase the volumetric energy density.