全钒液流电池建模与流量特性分析

Analysis of modeling and flow characteristics of vanadium redox flow battery

流量是影响VRB运行效率的重要因素,现有的全钒液流电池(VRB)模型较少体现流量和离子扩散耦合的影响,无法充分反映全钒液流电池系统的运行特性。为了提高VRB系统的运行效率,本文建立了全钒液流电池混合模型,该模型是在等效电路模型上增加了流体力学模型和电化学模型,其中等效电路模型体现了钒电池的电学性能,流体力学模型体现了流量对钒电池系统的影响,电化学模型体现了钒电池的化学性能,综合三种模型的特性更加全面准确的展现了VRB的相关性能,并通过仿真对比验证了混合模型的准确性。在混合模型的基础上,分析流量对钒电池系统效率的影响,结果表明充放电期间的最优流量是关于荷电状态(SOC)的函数,通过仿真分析得到不同SOC下的最优流量值,并采取SOC分段控制流量,有效地提高电池系统效率。

To improve the operation efficiency of a vanadium redox flow battery(VRB) system, flow rate, which is an important factor that affects the operation efficiency of VRB, must be considered. The existing VRB model does not reflect the coupling effect of flow rate and ion diffusion and cannot fully reflect the operation characteristics of the VRB system. Therefore, this paper establishes the hybrid model of the VRB, and hydrodynamic and electrochemical models are added to the equivalent circuit model. The equivalent circuit model reflects the electrical performance of the vanadium battery, the hydrodynamic model reflects the influence of the flow rate on the VRB system, and the electrochemical model reflects the chemical properties of the vanadium battery. The performance of VRB is demonstrated more comprehensively and accurately by synthesizing the characteristics of the three models, and the accuracy of the hybrid model is verified by their comparison. The influence of flow rate on the efficiency of the battery system is analyzed using the hybrid model. It is found that the optimal flow rate is a function of the state of charge(SOC) during charging and discharging. The optimal flow under different SOC is obtained by simulation, and the use of the SOC segment controls the flow rate and effectively improves the efficiency of the battery system.