A Simple Analytical Model of Coupled Single Flow Channel over Porous Electrode in Vanadium Redox Flow Battery with Serpentine Flow Channel

TL;DR

This paper presents a simple analytical model for the coupled flow in a serpentine channel and porous electrode in vanadium redox flow batteries, predicting flow and current density with good accuracy.

Contribution

It introduces an analytical model combining Navier-Stokes and Darcy-Brinkman equations for the flow and current density prediction in VRFB electrodes.

Findings

Model predictions align with reported numerical simulations.

Maximum current density estimated at 377 mA/cm² for given flow velocity.

Flow effects on porous layer flow are quantitatively analyzed.

Abstract

A simple analytical model of a layered system comprised of a single passage of a serpentine flow channel and a parallel underlying porous electrode (or porous layer) is proposed. This analytical model is derived from Navier-Stokes motion in the flow channel and Darcy-Brinkman model in the porous layer. The continuities of flow velocity and normal stress are applied at the interface between the flow channel and the porous layer. The effects of the inlet volumetric flow rate, thickness of the flow channel and thickness of a typical carbon fiber paper porous layer on the volumetric flow rate within this porous layer are studied. The maximum current density based on the electrolyte volumetric flow rate is predicted, and found to be consistent with reported numerical simulation. It is found that, for a mean inlet flow velocity of 33.3 cm s-1, the analytical maximum current density is estimated to be 377 mA cm-2, which compares favorably with experimental result reported by others of ~400 mA cm-2.