Numerical model for polymer electrolyte membrane fuel cells with experimental application and validation

Abstract

The aim of this paper is to present a simple 3D computational model of a Polymer Electrolyte Membrane Fuel Cell (PEMFC) that simulates over time the heat distribution, energy and mass balance of the reactant gas flows in the fuel cell including pressure drop, humidity and liquid water. Although this theoretical model can be adapted to any type of PEMFC, for verification of the model and to present different analysis, it has been adapted to a single cell test fixture. The model parameters were adjusted through a series of experimental tests and the model was experimentally validated for a well defined range of operating conditions: H2/Air as reactants, flow rates of 0.5-1.5 SLPM, dew points and cell temperatures of 30-80ºC, currents 0-5 A and with/without water condensation. The model is especially suited for the analysis of liquid water condensation in the reactant channels. A key finding is that the critical current at which liquid water is formed is determined at different flows, temperatures and humidity. This study presents a dynamic model for PEMFC, which includes the computation of the thermal properties and temperature distribution of the fuel cell and the pressure drop in the reactant gases while taking into account the condensation of water, as well as the resulting effects on the flow and pressure fields. The experimental tests for parameter identification are described. The model is based on the numerical solution of heat transfer problems expressed as various equilibrium differential equations, using numerical iterative methods. In section 2 the model is described, sections 3 and 4 explain the application of the model to a specific single cell and the experimental methodology for the parameter identification and model validation; section 5 collects the principal simulation results and emphasizes the features of the model. The main conclusions are summarized in section 6.

Comparison Between Voltage and Current Boundary Conditions in PEMFC Model

“…In GDLs, the interaction between a pair of species (i,j) are characterized by the binary diffusion coefficient (9): [6] The nominal values at reference temperature and pressure are presented in Table. 2, (9) [7] The drag coefficient, n d , is the number of water molecules per proton as, Springer (11) U O [8] The ionic conductivity, ı m , depends on the water content and the temperature (12)-(13) for Ȝ>1: …”

“…U O [8] The ionic conductivity, ı m , depends on the water content and the temperature ( 12)-( 13) for Ȝ>1:…”

“…The gases enter the fuel cell in the form of flow rates. They are set through a current density reference J ref , the usual stoichiometric coefficients being here equal to unity (7)- (8).…”