An Algebraic Model for a Zinc/Bromine Flow Cell

Abstract

An algebraic model for a parallel plate, zinc/bromine flow cell is presented and used to predict various performance quantities, which are compared to those predicted by using previously published differential equation models. The results presented compare well with previous work. The model is based on the concept of using well‐mixed zones and linear concentration and potential profiles for the diffusion layers and the separator. The Butler‐Volmer equation is used for the electrochemical reactions, and the homogeneous reaction between bromine and bromide is included.

A Simple Model for a Zinc/Bromine Flow Cell and Associated Storage Tanks

“…Each steady-state solution is obtained according to the method described in (13). The method shown there consists essentially of setting the left-hand sides of Eq.…”

“…[10]- [14] of Ref. (13) equal to zero and solving the resulting set of algebraic equations. This approximation will hereafter be referred to as the pseudo steady-state approximation.…”

“…They also presented a review of the modeling work that has been done on the zinc/bromine flow cell. More recently, Simpson and White (13) presented an algebraic model that is applicable to low-conversion reactors at steady state.…”

“…In the model development of Ref. (13), it is assumed that the concentration profiles within the reactor can be approximated by a series of constant and linear regions and that the potential profiles can be approximated by a series of linear regions as shown in Fig. 1 tanks and by making time-dependent predictions.…”

Modeling the Performance of a Zinc/Bromine Flow Battery

“…Evans and White [24] presented a mathematical model of a Zn/Br 2 flow cell including a porous layer on the bromine electrode and a porous separator to predict their effect on the cell performance during charge and discharge. Simpson and White [25] developed an algebraic model for a parallel plate, Zn/Br 2 flow cell using the Butler-Volmer equation for the electrochemical reactions and the homogeneous reaction kinetics between bromine and bromide to predict various cell performance quantities. Kalu and White [26] presented a mathematical model for a Zn/Br 2 cell that considers the effects of an increase or a decrease in the cathode channel width due to zinc removal on discharge and zinc deposition on charge, respectively, as well as the effect of an organic bromine complexing agent on the cell performance.…”