Numerical Investigation of Flow Hydrodynamics in a Flow Field and Porous Substrate Configuration for Redox Flow Battery Application

Abstract

In the recent past, most of the literature reported that the electrolyte circulations in parallel flow field configurations exhibit severe non-uniformity with higher Pressure Drop (Δp). The present work proposes a three-dimensional computational design of flow field configurations to achieve a single-phase uniform flow with minimal pump power and flow dispersion over an active cell area of 131cm2 for All Iron Redox Flow Battery (AIRFB). Computational investigation of the Pressure Drop (Δp), electrolyte flow velocity and uniform flow distribution in the channels and through the graphite felt electrode under various flow conditions was conducted using the Computational Fluid Dynamics (CFD) tool. It is observed from the results that the Multi-Channel Serpentine Flow Field (MCSFF) has the least pressure drop among the other flow fields. However, the Cross-Split Serpentine Flow Field (CSSFF) resulted in better flow circulation and dispersion over the entire active cell area with a high uniformity index, operating at a wide range of flow rates with a reasonable Pressure Drop (Δp). The porous media permeability and a strong function of Compression Ratio (CR) were numerically validated from the well-known correlation existing in the literature. At CR 50% it was observed that the volume uniformity index of the felt was 69%, which would correspondingly enhance the rate of mass transfer and electro-kinetics at electrode felt and ion conductivity across the membrane. The CSSFF configuration is predominant in terms of uniform flow distribution and wettability at the defined operating conditions resulting in enhanced cell performance.