Modelling investigation for multi-physics heat storage performance of solar-driven calcium looping in moving bed collector based on CFD-DEM

Abstract

Conventional solar thermochemical heat collector with direct solar-heating usually faces an issue of aperture being contaminated and the difficulty of real-time particle velocity control. Here, a three-dimensional multi-physics numerical solver coupling with optical and thermal stress sub-models is developed towards heat storage mechanization of calcium looping, considering discrete particle flow, continuous gas flow, solar radiation, temperature field, particle collision force and chemical reaction. Based on the CFD-DEM method, the particle velocity and temperature distribution in the moving bed collector present non-uniformity with a parabolic profile. Numerical simulation results show that the energy carriers can reach the high temperature of 1350 K with a calcination rate of 1.1 × 10⁻⁸ kmol s⁻¹ under the incident power of 6.68 kW, exhibiting an efficient performance. Thermal stress sub-model of energy carriers, implemented by coupling the in-house code with CFD-DEM, reveals that high temperatures lead to a better conversion rate of CaL but with a higher risk of thermal fragmentation. A new wedge-shaped structure of redistributor is further proposed to effectively alleviate the non-uniformity of the particles flow and temperature distribution. The effect of solar energy input flux, particles absorptivity and emissivity are systematically investigated, laying a solid foundation for the further research on industrial amplification processes.