Proposal of a novel solar-driven thermochemical reactor for green hydrogen production using helical flow channels

The reactor is the core component of the hydrogen production system. Although hydrogen production using solar energy as the heat source can effectively reduce carbon emissions, the reactor faces the problem of uneven heating caused by the collector, and the uneven temperature distribution will significantly affect the hydrogen production process. A key characteristic of the heat collection in dish solar collectors is that the energy flux density is highest at the center and gradually decreases radially, resulting in an uneven heat distribution on the reactor surface. Therefore, the paper focuses on addressing the problem of the uneven distribution of solar concentrating temperature affecting the working efficiency of the reactor. In this study, the reactor's flow channel is designed in a helical configuration to enable the reaction gas to enter at the edge, gradually flow inward along the helical channel, and exit at the central position. Through simulation studies of the reactor under various working conditions, it was found that the helical structure can effectively facilitate the continuous temperature rise of the reaction gas, with a methane conversion rate of 94.76 %, a hydrogen yield of 1.54 mol/ mol, and a total energy conversion efficiency of 32.52 %. Thus, the design of the helical flow channels can effectively utilize the uneven solar heat distribution, allowing the reactor to operate efficiently. Previous studies have focused on enhancing the heat transfer performance of endothermic materials to achieve temperature uniformity; however, this paper adopts a novel approach by innovating the flow channel structure. This paper offers a new concept for the design of solar thermochemical reactors.