Performance improvement of a solar volumetric reactor with passive thermal management under different solar radiation conditions.

To alleviate the effect of solar radiation fluctuation on the solar volumetric reactor, phase change material (PCM) is applied to buffer the temperature vibration and improve the stability of thermochemical reactions. In this work, we analyzed the heat flow and distribution characteristics of the conventional double-walled volumetric reactor filled with PCMs (SVR1). We then proposed a novel solar volumetric reactor design (SVR2) to solve the problems of local high temperature, slow charging-discharging rate, and fluctuating methane conversion in various radiation conditions. The heat and mass transfer model coupled with thermochemical reaction kinetics was established to compare the performance of SVR1 and SVR2 under steady state, heat charging-discharging mode, and actual solar radiation fluctuation, respectively. The results show that compared to SVR1, the maximum temperature of SVR2 decreases by 106.3 K, and the minimum methane conversion rate increases from 77.4% to 93.6% under natural solar radiation fluctuation. [Display omitted] • A novel solar volumetric reactor filled with PCMs (SVR2) is proposed. • The location of the catalyst bed and the heat storage zone is rearranged. • The heat storage zone is composed of Na 2 CO 3 and SiC porous foam. • The radial temperature difference on the rear side of SVR2 is minimal. • The fluctuation of methane conversion rate in SVR2 decreases by 16.2%. [ABSTRACT FROM AUTHOR]