Numerical study on a novel parabolic trough solar receiver-reactor and a new control strategy for continuous and efficient hydrogen production

In this paper, a novel parabolic trough solar receiver-reactor is proposed for continuous and efficient hydrogen production via the methanol-steam reforming reaction. With a concentric through-type tube introduced for thermal energy storage, this novel system can be effectively applied for better solar thermochemical energy conversion and management. The proposed novel system and the corresponding original system, as well as direct/indirect control strategies and parameter optimizations, were then fully investigated. This was numerically carried out by a proposed three-dimensional comprehensive model based on the finite volume method, combined with the Monte Carlo ray-tracing method and the comprehensive kinetic model of the methanol-steam reforming reaction. It is revealed that the proposed novel system has much better comprehensive characteristics and performance than that of the corresponding original system. These previously incompatible requirements, both an affordable temperature rise per unit receiver-reactor length and a nearly complete methanol conversion rate, can be achieved simultaneously in this novel system. It is also found that the previously sensitive process of the methanol-steam reforming reaction can be controlled separately or jointly, by adjusting more control variables introduced in the novel system. Moreover, this novel system could also have great potential to be improved, by tuning corresponding key operating parameters such as the inlet temperature, the flow model and the concentric tube geometry. The energy distribution of the collected solar radiation and working temperature characteristics could also be further controlled or optimized. It could provide significant guidance for similar solar-driven thermochemical applications for continuous and efficient hydrogen production.