太阳能直接辐照下碳酸钙颗粒的粗颗粒CFD-DEM模拟

Coarse-grained CFD-DEM Modelling of Calcium Carbonate Pellets Under Direct Solar Irradiation

钙基热化学储热材料具有无毒、储能密度高、与超临界CO_(2)热力循环相容性好等优点,是下一代高温太阳能热发电站极具潜力的储能候选材料之一。但是,常规热化学储热技术是采用基于间接表面吸收式反应器,这种技术具有高热损失低效率等劣势。因此,我们提出了一种太阳能直接辐照下的流化床粒子反应器。采用计算流体动力离散元法(CFD-DEM)和粗颗粒法(CGPM)耦合蒙特卡洛法(MCRT)对聚光太阳能下碳酸钙储热过程进行了数值模拟。结果表明:利用两种模型均可预测碳酸钙粒子系温升和反应所需要的时间,CGPM与传统CFD-DEM结果吻合较好。另外,随着打包系数的增大,CGPM模型表现出良好的计算性能,计算时间明显短于CFD-DEM模型。所建立的CGPM-MCRT模型对大规模高效直接辐照热化学储热系统的设计具有重要指导意义。

The thermochemical energy storage based on Calcium carbonate(CaCO3)shows great potential for the next generation of high temperature solar thermal power station due to its nontoxicity,high energy storage density,and good compatibility with supercritical CO_(2) thermal cycle.However,conventional thermochemical heat storage technology is based on indirect surface-heating,which suffers high heat loss and low efficiency.Therefore,we propose a fluidized particle reactor under direct solar irradiation.A Computational Fluid Dynamics-Discrete Element Method(CFDDEM)and coarse-grained method(CGPM)coupled with the Monte Carlo method(MCRT)are built to simulate the energy storage process.The results show that the temperature rise and reaction time of CACO3 particles can be predicted by the two models,which are in good agreement with the traditional CFD-DEM results.In addition,with the increase of the packing coefficient,the CGPM model shows good computational performance,and the computational time is significantly shorter than that of CFD-DEM model.The established CGPM-MCRT model has important guiding significance for the design of large-scale and efficient direct irradiation thermochemical heat storage system.The temperature rising and reaction time can be predicted,and the results of CGPM are in good agreement with those of traditional CFD-DEM.In addition,with the increase of the packing coefficient,the computational time of CGPM is significantly shorter than that of CFD-DEM model.The established CGPM-MCRT model will guide the design of efficient direct solar-driven thermochemical heat storage system.