MODELING AND SIMULATION OF THE CONCENTRATION OF SPECIES FOR A DIRECT ETHANOL FUEL CELL

Resumo

The generation of energy is a subject in constant debate, either for its efficiency and renewa-
bility or for the emission of pollutants. In addition, energy consumption has grown over the years, and

fossil fuels, which account for around 80% of the world’s energy generation, run the risk of becoming
scarce. A technology with renewable features that has proven to be promising and more efficient than
traditional power generators is the fuel cell, making the process clean and efficient. The fuel cell is an

electrochemical device that directly converts chemical energy into electricity. In this work, a numeri-
cal model is developed for fuel cells with proton exchange membrane and fed by ethanol. The model

takes into account the flow, the variation of the concentration of chemical species, the rate of passage of
ethanol through the membrane and the overpotential losses in the anode and the cathode. In addition,
the concentration of each species is modeled according to the current density of the fuel cell. The finite
element method is used to calculate the flow and concentration of the species in different layers of the
cell (inlet and outlet channels, diffusion layer and catalyst layer). The Crank-Nicolson method is used

for time discretization. Overpotential losses are calculated using parameters obtained with the numeri-
cal model. These losses can be estimated by calculating the activation, the ohmic polarization and the

concentration overpotentials. The flow results, the variation of the species concentration, passage of the
ethanol through the membrane and the limiting current density are shown. Results of cell voltage are
compared for different catalysts and temperatures with experimental data found in the literature.