Numerical investigation of the thermophysical characteristics of the mid-and-low temperature solar receiver/reactor for hydrogen production

•A multiphysics coupling model is proposed to investigate the solar hydrogen receiver/reactor.•The factors influencing the solar hydrogen production are numerically studied.•The effects of the porosity on the performances of solar receiver/reactor are revealed.•The research findings provide a fundamental reference for R&D of solar receiver/reactor. With the considerations of the complex kinetic mechanisms of the methanol steam reforming using Cu/ZnO/Al2O3 catalyst, in this paper a multiphysics coupling model that integrates the mass, momentum and energy conservation governing equations is proposed to investigate the thermophysical performances of the mid-and-low temperature solar receiver/reactor for hydrogen production. The factors influencing the hydrogen production and temperature distributions of the catalyst bed, including the diameter of the receiver/reactor, the non-uniform distribution of the solar flux and the porosity of the catalyst bed, are numerically studied. The temperature distributions, mole fractions of the components and reaction rates are obtained. The influence rules of the diameter of the receiver/reactor tube on the performances of the receiver/reactor are revealed. The non-uniform distribution of the solar flux has a significant influence on the cross-sectional temperature difference of the receiver/reactor tube, the catalyst bed and the temperature rise of the catalyst bed, while has a slight impact on the methanol conversion and the collector efficiency. The effect mechanisms of the porosity on the performances of the receiver/reactor are revealed. The research findings provide a fundamental reference for the development of the mid-and-low temperature solar receiver/reactor.