Numerical study on novel parabolic trough solar receiver-reactors with double-channel structure catalyst particle packed beds by developing actual three-dimensional catalyst porosity distributions

Flow channel structure and operation strategy play important role in fixed packed bed based parabolic trough solar receiver-reactors (PTSRRs) for efficient hydrogen production. A horizontal separated double-channel structure with the countercurrent control strategy (H-DCS-CCS) and a vertical separated double-channel structure with the flow matching strategy (V-DCS-FMS) were proposed for better coupling of multiple physical fields in PTSRRs. A three-dimensional comprehensive numerical model was developed to simulate the complex optical-thermal-chemical process and real spatial pore structure characteristics of novel PTSRRs, based on a proposed coupling calculation procedure of actual three-dimensional catalyst porosity distributions. After validation, the effect mechanism of novel double-channel structures and operation strategies were further investigated. It was revealed that the H-DCS-CCS can significantly reduce the PTSRR maximum temperature, increasing the upper limit of the methanol conversion rate by 7.15%. The V-DCS-FMS can effectively improve the temperature uniformity and the reaction performance within tuned flow rate ratio ranges. This proposed novel concept could provide guidance for similar solar-driven thermochemical hydrogen production systems.