CFD-DEM-based simulation of Ca(OH)2/CaO thermochemical energy storage process in a novel baffled moving bed reactor
The Ca(OH)2/CaO thermochemical energy storage technology has garnered significant attention owing to its attractive features of high energy storage density and cost-effectiveness,positioning it as a promising advancement in energy storage methodologies.Nonetheless,traditional fixed bed reactors may pose challenges with their potential to yield a diminished heat storage rate for Ca(OH)2 particles.To address the challenge of low heat storage rate in conventional fixed bed reactor,a novel baffled moving bed structure is introduced.The heat storage process of Ca(OH)2 particles in the moving reactor bed under the influence of gravity is studied by using the coupled method of computational fluid dynamics and discrete element method(CFD-DEM).Compared to porous media models,CFD-DEM offers a closer approximation to real flow conditions and provides detailed physical information at the particle scale.The results indicate that the moving bed achieves a higher heat storage rate compared to its fixed bed counterpart under identical conditions,providing evidence for the feasibility of employing a moving bed as a thermochemical reactor.The introduction of baffles in the moving bed is able to extend the particle residence time in the reactor,consequently amplifying both the heat storage rate and energy storage efficiency.However,it concurrently results in an increased pressure drop on the gas side.The simulations under various inlet conditions reveal that elevating the gas temperature at the reactor inlet positively impacts the heat storage rate.Within specific ranges,an increase in the inlet gas flow rate can improve the energy storage rate,albeit with caution against excessively high flow rates that could induce blockages and diminish the overall heat storage rate.Notably,the inlet solid flow rate exhibits an optimum value,maximizing the comprehensive heat storage rate of the reaction bed.
discrete element methodcalcium hydroxidethermochemical energy storagemoving bed reactornumerical simulation
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