Numerical Simulation Study On Flow,Heat Transfer And Reaction Coupled Of Solar Energy Applied To Fluidized Bed Reactor

As a kind of clean and renewable energy,solar energy has become the key to the road of carbon neutrality and net zero emission.Solar thermal utilization technology comes into being at the right moment.In the research field of solar thermal power generation and thermochemical energy storage,the application of fluidized bed reactor for solar radiation collection and thermal storage is worth exploring.The mechanism of adding radiation process in gas-solid multiphase flow is complex.At present,there is almost no research on the flow and heat transfer reaction process of three-dimensional simulation of solar thermochemical reaction in fluidized bed reactor.In this paper,the flow and heat transfer reaction characteristics of solar energy applied to fluidized bed reactor are studied by threedimensional simulation,with the help of Computational Fluid Dynamics(CFD).The flow,reaction and radiation processes of solar energy in external double circulating fluidized bed reactor and internal circulating fluidized bed reactor were numerically simulated.A theoretical model of flow,heat transfer and reaction coupling is established for the application of solar energy in fluidized bed reactors.Based on the EulerEuler method,the gas-solid two-phase flow in the fluidized bed reactor is mathematically modeled.The interaction between the radiation source term and the radiation field in the fluidized bed reactor is described by Discrete Ordinate(DO)model and the Solar Load model.The chemical reactions in the external double-circulating fluidized bed reactor and the internal circulating fluidized bed reactor are added.The numerical simulation of the coupling process of flow,heat transfer and reaction in the external double circulating fluidized bed reactor was carried out.The distribution of particles and gas products in the reactor and the heat transfer characteristics between the two reactors were analyzed,as well as the instantaneous change of particles in the solid circulation loop.The effects of different radiation fluxes and different inlet velocities on the coupling characteristics of flow,heat transfer and reaction in the reactor were compared and analyzed.It is concluded that when the radiation flux or inlet velocity increases,the particle volume fraction and particle velocity of the circulation loop will increase.As the reaction proceeds,the gas product gradually increases,and the solid particle temperature in the area with high particle volume fraction in the reactor is also relatively high.The flow,heat transfer and reaction coupling process in an internally circulating fluidized bed reactor using solar energy was numerically simulated.The product distribution in the reactor was analyzed,and the particle motion and heat transfer characteristics at different inlet velocities were compared.It is concluded that the increase of inlet velocity promotes the fluidization and reaction of particles in the reactor,accelerates the recirculation of particles,enhances the heat transfer between particles and gas,and the particle absorption coefficient increases with the increase of particle volume fraction.