Performance Analysis of a Two phase Non-isothermal PEM Fuel Cell A. H. Sadoughi 1 and A. Asnaghi 2 and M. J. Kermani 3 1, 2 Ms Student of Mechanical Engineering, Sharif University of Technology Tehran, Iran 3 Member of Energy Conversion Research Lab., Department of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), 424 Hafez Ave., Tehran, Iran P.Code 15875-4413 Email: 1 amirhomayoun@gmail.com 2 asnaghi_abolfazl@yahoo.com 3 mkermani@aut.ac.ir ABSTRACT A two-dimensional two-phase and non-isothermal model is presented to simulate a complete proton exchange membrane fuel cell (PEM FC). Water transport and electrochemical reactions are considered and all the governing equations for flow channels, catalysts, gas diffusion layers (GDL) and the membrane are solved. The model is non- isothermal and so the effects of temperature variation on cell performance are taken into account. Two phases of water which are liquid and gas are considered in the model. The dimensions are real values which are taken from Wang and Wang (2006). The flow fields are straight channels and the flows are taken in co-direction for the oxidizer and the fuel. To consider the effects of the flow direction, the calculations are done for a sample test of counter flow too. For the specified set of cell voltages, the cell’s current densities are calculated and a polarization curve is developed for using air as oxidizer. The maximum power of the cell is also obtained. Some parametric studies are done to study the effect of the following parameters on the performance of the cell: porosity of the GDLs, porosity of the Catalysts, the channel width to length ratio, Anode Pressure, Cathode Pressure, and the oxidizer stoichiometric coefficient. The effect of each of the mentioned parameters on cell performance is obtained by keeping fixed all the others and varying only one, i.e. the partial derivative of the performance with respect to each parameter is numerically determined. The polarization curve is developed for each case. Depending on the obtained results, an optimized operating point for the whole cell is attained. For each case the base case conditions are preserved for all the parameters that don’t change. 1. INTRODUCTION Nowadays the demand for clean and renewable energy has accelerated the research activity for finding better sources. Fuel cells may be the answer to the increasing need of this kind of energy source. Fuel cells have applications in stationary, distributed, portable, mobile, and even biological power sources.[1] Fuel cells convert chemical energy directly into electricity by separation of anodic oxidation of fuel and cathodic reduction of oxygen. Protons generated at the anode transport to the cathode, where they recombine with oxygen anions to form water. Fuel cells are consist of an anode part, a cathode part and a membrane. Anode and cathode parts contain flow channels, Gas diffusion layers (GDL) and catalysts. Two plates which are called bipolar plates, are placed on the outer surfaces of the cell to collect the electrical current. One type of fuel cells are PEM (Proton Exchange Membrane) fuel cells which use Hydrogen as fuel and air as oxidizer. The electrochemical equation of Anode (1) shows that Hydrogen transforms into positive Hydrogen ions and electrons. 2 2 4 4 H H e + − → + (1) Cathode electrochemical equation (2) shows that atoms of Oxygen react with H + ions (transferred via membrane) and electrons (transferred via outer wire) to form water.