The Effect of Electrode Parameters on Lead-Acid Battery Performance Vahid Esfahanian* 1, a , Pooyan Kheirkhah 1, b , Hassan Bahramian 1, c , Amir Babak Ansari 1, d and Goodarz Ahmadi 2, e 1 Vehicle, Fuel and Environment Research Institute, Mechanical Engineering Department, University of Tehran, Iran 2 Department of Mechanical and Aeronautical Engineering, Clarkson University, United States a evahid@ut.ac.ir, b p.kheirkhah@ut.ac.ir, c h.bahramian@ut.ac.ir, d a.b.ansari@ut.ac.ir, e ahmadi@clarkson.edu Keywords: Lead-acid battery, FLUENT, Electrode parameters, Cell voltage behavior. Abstract. The investigation of design parameters is greatly helpful to use the optimum capacity of an electrochemical cell, which can be obtained from both experimental and numerical methods. In this study, a lead-acid battery has been simulated numerically using the CFD commercial software package FLUENT. The governing equations, including conservation of charge in solid and liquid phases and conservation of species, are solved by creating user defined functions. The effect of some basic parameters such as electrode porosity, discharge current density and width of the electrodes on the cell voltage behavior of a lead-acid battery is investigated. It has been shown that the increasing of the thickness and porosity of the PbO 2 electrode has more pronounced effect on the performance of battery than the Pb one. Introduction The lead-acid batteries have been widely used as the secondary sources of energy for many years. The growing usage of this kind of batteries is due to their important characteristics such as high specific energy, high-rate discharge capability, low cost in both manufacturing and recycling, and finally high energy density. In order to improve the performance of lead-acid batteries, trial and error methods, usually based on experimental tests, have been used for many years. Experimental tests are very valuable but time-consuming and costly. Therefore, various mathematical models have been developed to predict the dynamic behavior of lead-acid batteries. Newman and Tiedemann [1] provided a comprehensive review of the development in the theory of flooded porous electrodes prior to 1975. Tiedemann and Newman [2] applied Newman's theory to the development of a complete cell model describing the discharge behavior of the lead-acid battery system. The mathematical governing equations of batteries which are obtained from the conservation laws were developed by Wang and Gu [3]. Gu et al. [4] solved the governing equation of a lead-acid battery using a multi-region formulation. Moreover, Gu et al. [5] introduced a set of governing equations which were valid in all cell regions. Therefore, it did not require any special system of equations for each region and their boundaries. They solved this system of equations by means of finite volume method (FVM). Esfahanian and Torabi [6] solved this system of equations using the Keller-Box method. Their method has a second order accuracy in space as well as time. Recently, Esfahanian et al. [7] introduced an improved and efficient mathematical model for simulation of flooded lead-acid batteries based on Computational Fluid Dynamics (CFD) and Equivalent Circuit Model (ECM). This model inherited the accuracy of CFD model and the physical understanding of ECM. Nowadays, commercial software packages have been extended considerably and play an important role in the development of many scientific areas. Recently, Esfahanian et al. [8] simulated maintenance-free (MF) lead-acid battery lid numerically, using the FLUENT software. In the present research, a two dimensional Lead-Acid cell of a battery has been simulated using the commercial CFD software package "FLUENT" for the first time. The governing equations are solved simultaneously by using appropriate user define functions. In order to check the accuracy of the Advanced Materials Research Vol. 651 (2013) pp 492-498 Online available since 2013/Jan/25 at www.scientific.net © (2013) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.651.492 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 137.82.118.162, University of British Columbia, Kelowna, Canada-23/08/14,05:28:08)