Enhancing output performance and thermoelectric conversion efficiency in thermal regeneration ammonia-based flow battery through a novel W-like flow channel

In addressing the global challenges of energy efficiency and environmental sustainability, the Thermal Regeneration Ammonia-based Flow Battery (TRAFB) is increasingly gaining attention due to its potential for application in low-grade waste heat recovery. Therefore, this study innovatively introduces a novel W-like flow channel (WFC) with the expectation of enhancing the mass transfer, output performance, and thermoelectric conversion efficiency of the TRAFB. Through visualization and quantitative analysis, the performance of the TRAFB with the WFC is compared with that of the battery with the traditional straight flow channel (SFC) across various aspects, including mass transfer characteristics, reactant concentration characteristics, output performance, discharge behavior, and thermoelectric conversion efficiency. The findings indicate that compared to the SFC, the WFC significantly improves TRAFB performance, particularly under high current density conditions. By adjusting two characteristic parameters of the novel flow channel—the depth and width of the semi-elliptical obstacles—the battery performance can be further enhanced. When both the depth and width are set to 0.8 mm, the peak power density of the battery increases by 57.58% compared to the SFC. Moreover, operating the TRAFB with the WFC configured in this setting at a current density of 300 A/m² exhibits a 21.11-fold increase in Cu²⁺ flux, a 7.83-fold increase in effective mass transfer coefficient, a 309.49-fold improvement in reactant uniformity, a 97.78-fold increase in electric capacity, and a 15.95-fold enhancement in thermoelectric conversion efficiency. These findings provide an important theoretical basis and practical guidance for the optimized design and efficient application of TRAFB.