RODRIGO PIRES DA SILVA
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Artigo IPEN-doc 29609 Numerical validation of direct ethanol fuel cell operating at high temperature2023 - PANESI, A.R.Q.; SILVA, R.P.; SANTIAGO, E.I.In the present work, a three-dimensional steady-state model was developed to analyze the performance of high-temperature direct ethanol fuel cell (HT-DEFC) based on polybenzimidazole (PBI) electrolytes. A non-isothermal model of a HT-DEFC setup using a PBI/H3PO4 membrane was employed using computational fluid dynamics (CFD). This work is aiming at a validation of experimental data of HT-DEFC prototypes based on the simulation of polarization curves. The model predicts the mole concentration of H3PO4, heat and current density distributions, as well as mass fraction ethanol during operation at 180 °C. The heat transfer model was coupled to the electrochemical and mass transport, allowing that a particular heating configuration was investigated considering the temperature distribution on the PBI membrane. We have found that temperature and relative humidity (RH) are mostly related to PBI properties resulting from H3PO4 lixiviation and conductivity decreasing as well as ethanol crossover strongly interferes on the oxygen reduction reaction (ORR) rate, leading to poor HT-DEFC performance.Artigo IPEN-doc 28365 Three-dimensional CFD modeling of H2/O2 HT-PEMFC based on H3PO4-doped PBI membranes2021 - PANESI, A.R.Q.; SILVA, R.P.; CUNHA, E.F.; KORKISCHKO, I.; SANTIAGO, E.I.A complete non-isothermal model of a HT-PEMFC setup using a PBI/ H3PO4 membrane was developed, modeled, and solved using COMSOL Multiphysics. Polarization curves were simulated and compared to the corresponding experimental data. In this work, a serpentine flow field and an active area of 5 cm2 have been implemented in a computational fluid dynamics (CFD) application. The model predicts water vapor transport, mass concentration of H3PO4, temperature, and membrane current density distribution. In this model, the anode feed is pure hydrogen, and oxygen is introduced at the cathode side. The heat transfer model was coupled with the electrochemical and mass transport; a particular heating configuration is investigated for temperature distribution, emphasizing the membrane. The models showed consistency and were used to investigate the behavior of H3PO4 concentration and all transport characteristics. The concentration of phosphoric acid decreases with increasing temperature and relative humidity and the diffusive flux of water vapor increases with the decrease of the operating voltage. Two different configurations of inlet and outlet flow channels were analyzed and the results were compared.