Modeling and Variable Flow Rate Optimization of Vanadium Redox Flow Battery Based on 4D Multi-physics Coupling

To address the constraints of multi-physics field coupling on the energy efficiency of Vanadium Redox Flow Batteries (VRBs), and the challenge of balancing internal polarization losses with pump power in traditional models, a 4D fully coupled dynamic model integrating electrical, hydraulic, chemical, and thermal characteristics was developed. This model deeply integrates hydraulic, electrochemical, and thermodynamic modules within an equivalent circuit framework. Specifically, the equivalent circuit module describes the real-time external terminal voltage response and electrical characteristics; the hydraulic module captures the evolution of circulating pump power loss as a function of flow rate; the electrochemical module enables fine-grained decoupling of activation and concentration polarization losses; and the thermodynamic module achieves dynamic correction of reaction rate constants via the Arrhenius equation.Building upon the 4D coupled model, a variable flow rate adaptive control strategy based on State of Charge (SOC) feedback was proposed. By analyzing the competitive coupling between polarization overpotentials and pump power loss, the strategy dynamically matches the optimal electrolyte circulation flow rate in real time. Simulation results demonstrate that the proposed model provides a more accurate characterization of voltage response and loss distribution under complex operating conditions. Compared to traditional constant flow rate modes, the proposed strategy effectively enhances the overall operational efficiency of the system.