Study on solar-driven methanol steam reforming process in parabolic trough solar receiver-reactors by developing an optical-thermal-chemical model of realistic porosity distributions

Abstract

The catalyst particle packing characteristics have a significant impact on improving the comprehensive energy conversion performance and economic benefits of sustainable solar-driven thermochemical hydrogen production systems. However, corresponding accurate and efficient numerical research tools or methods still need to be developed. In this paper, a three-dimensional comprehensive optical-thermal-chemical coupling model with catalyst particle packing characteristics is proposed for the parabolic trough solar receiver-reactor (PTSRR) of methanol steam reforming reaction (MSRR) for hydrogen production. This model is developed by combining a Monte Carlo ray tracing optical model, a computational fluid dynamics model, a MSRR comprehensive kinetic model with a Blender rigid body packing model. After validation, it was found from comparisons with previous studies that this model can represent relatively realistic catalyst porosity distributions of packed-bed reactors at a very low computational cost. Then, this model was applied to obtain the porosity of different PTSRR-MSRRs and optimize the catalyst size and shape, to achieve better comprehensive performance as well as economic benefits of higher overall efficiency and catalyst utilization efficiency. The results reveal that the PTSRR-MSRRs filled with cylinders and Raschig rings (R-PTSRR) can achieve similar high methanol conversion rate, while the R-PTSRR has more advantages with its lower average resistance coefficient and CO selectivity. After weighing the methanol conversion rate, the overall efficiency and the catalyst utilization efficiency, the optimum R-PTSRR is highly recommended. This study provides a useful option for rapid comprehensive analysis and optimization of similar solar-driven thermochemical conversion processes on catalyst particle packed beds.