Relative flow direction modes and gradual porous parameters for radiation transport and interactions with thermochemical reaction in porous volumetric solar reactor

Abstract

The reformation of methane to hydrogen and carbon monoxide in a solar volumetric reactor is a promising method to use the solar energy, which converts solar energy into chemical energy. Due to the non-uniform solar radiation at the optical aperture and the complex flow and radiation in porous media, the relative flow direction modes and porous parameters of the reactor should be carefully designed to improve the thermochemical reaction performance and reliability. In this contribution, three different relative flow direction modes are designed, which innovatively investigate the effects on the relative direction between solar radiation and fluid flow in the volumetric reactor. In addition, the local non-thermal equilibrium model is applied and the effect of the porous medium on the concentrated transmission characteristics of solar irradiation is considered. Moreover, the Gaussian Distribution Model (GDM) is applied to simulate the actual characteristics of concentrated solar energy. The results show that opposite inlet mode (OI) has the highest methane conversion rate, which is 46.43%. Then, based on OI, the gradual porosity and porous diameter distributions are designed and their effects on the methane conversion are analyzed. The methane conversion can reach 54.3% by employing a quadratic distribution for the porosity and the use of layered aperture arrangement can further improve the conversion rate to 58.96%. This contribution can provide a guidance for porous volumetric solar reactor design to improve the thermochemical reactions performance and reliability.