| At present,the development of renewable energy is an important part of China's sustainable energy development.At the same time,developing safe and efficient energy storage technology is an important means to solve the non-steady state characteristics of renewable energy generation.Different energy storage technologies have their own advantages and disadvantages.The Redox liquid-flow batteries usually have the characteristics of long life,high efficiency,and independent design of power and capacity.They have become suitable chemical energy storage technologies for large-scale energy storage,and Redox liquid-flow batteries will become the development trend of energy storage technologies in the future.The Redox liquid-flow battery is referred to as liquid-flow battery for short.According to its structural characteristics without ion exchange membrane,it can be divided into double liquid-flow battery and single liquid-flow battery.Zinc nickel single-liquid flow battery is a single-liquid flow battery without ion exchange membrane.It was proposed by the Chemical Prevention Research Institute in 2007.It uses sintered nickel oxide as the positive electrode of the battery,zinc as the negative electrode of the battery,and the electrolyte as an alkaline zincate solution.The coupling problem of seepage,mass transfer and electrochemical reaction in sintered nickel porous electrode by lattice Boltzmann method,the main research work of this paper is as follows:(1)Firstly,according to the cell structure,the structure characteristics of the sintered nickel porous medium of the battery and the flow in the porous medium,the isothermal calculation model of the lattice Boltzmann in the Cartesian coordinate system is established based on the seepage control equation on the REV scale.Based on the LBE model of the internal percolation of porous media in Guo et al.,combined with the flow control equation of porous media and the force term considered under the REV scale,the parameter porosity of the porous medium is added to the distribution function to derive the relevant formula;Descriptive electrode is obtained by Chapman-Enskog expansion.The macroscopic equation of flow in the porous medium finally yields the macroscopic physical quantity of the percolation of the porous medium of the electrode.Finally,the internal seepage model of the electrode porous medium is constructed.(2)Based on the structural characteristics of the porous electrode of Zn-Ni single liquid flow cell,a two-dimensional calculation region model of porous positive electrode was established,combining with the control equation model.On this basis,the flow field distribution in the region was calculated by LBM on the REV scale,and the flow velocity,channel width,porosity and other conditions in the calculation area were changed to study the internal seepage situation of the sintered nickel positive electrode.The influence,and the change law of seepage velocity is analyzed.(3)According to the internal mass transfer and chemical reaction process of nickel positive electrode sintered by zinc-nickel single liquid flow cell,a REV-scale model can be established to describe its internal mass transfer and chemical reaction.The simulation calculation is performed by the lattice Boltzmann method to simulate the process of charging and discharging.The steady state reaction of positive charge state at 50 % results in the distribution of electrolytic fluid channels and electrodes.The effects of inlet velocity and discharge current density on internal mass transfer and chemical reaction of electrode and the variation of liquid ion concentration were investigated. |
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