Efficient utilization of full-spectrum solar photons is crucial for enhancing solar energy conversion efficiency and addressing energy shortages. This study introduces an innovative concentrated ordered conversion system that utilizes a parabolic trough collector (PTC). This system integrates photocatalysis and the Rankine cycle to more effectively harness full-spectrum solar energy for hydrogen and electricity cogeneration.
In this system, higher-energy photons are absorbed by the photocatalytic layer to facilitate water splitting for hydrogen production. Meanwhile, lower-energy photons that do not have enough energy to excite electron-hole pairs (EHPs) are transmitted to the photocatalytic layer, where they are converted into thermal energy to power the Rankine cycle for electricity generation. Additionally, the heat lost from dissipated EHPs and the absorber tube’s radiation can be reused within the photocatalytic layer to preheat circulating water, raising the reaction temperature and the solar evaporator’s inlet temperature to the target of 140 °C.
To analyze the system’s performance, a solar photocatalysis model and a thermodynamic model have been developed. The results indicate that 10.34% of the input solar energy is converted into hydrogen via photocatalysis, while 17.85% is converted into electricity through the Rankine cycle. The overall exergy efficiency improves from 23.51% for a conventional PTC thermal power generation system to 28.49% for the proposed system under design conditions.
The study also examines the effects of the photocatalyst’s bandgap and temperature on the system’s exergy efficiency. It reveals that as the photocatalyst bandgap increases, the operating temperature should be lowered accordingly. The temperature of the photocatalytic layer is adjusted to achieve maximum system exergy efficiency under varying direct nominal irradiation (DNI) conditions, and it can sustain an operation temperature of 140 °C when the DNI exceeds 240 W·m−2. This research presents a new pathway to enhance the efficiency and flexibility of full-spectrum solar energy utilization.
Zhang, E., Xu, C., Gao, Y., Zhu, X., Xie, Y., Xu, M., & Zhang, Y. (2024). An efficient ordered conversion system for hydrogen and electricity cogeneration driven by concentrated solar energy. Applied Energy, 377, 124609. https://doi.org/10.1016/j.apenergy.2024.124609
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