IVAN KORKISCHKO
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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.Artigo IPEN-doc 27739 Performance analysis of a water ejector using Computational Fluid Dynamics (CFD) simulations and mathematical modeling2021 - MARUM, VICTOR J. de O.; REIS, LIVIA B.; MAFFEI, FELIPE S.; RANJBARZADEH, SHAHIN; KORKISCHKO, IVAN; GIORIA, RAFAEL dos S.; MENEGHINI, JULIO R.A quasi-one-dimensional (1D) mathematical model coupled with Computational Fluid Dynamics (CFD) simulations of a water ejector is presented. Using data from CFD simulations, the mathematical model was used to calculate the friction loss coefficients of the ejector components, to predict its maximum efficiency point and to delimit its envelope of operation. The CFD approach was validated with experimental data and employed the finite element method to test the main turbulence models found in the literature (k-ε, k-u and k-u SST) for incompressible-flow ejectors. A set of operational conditions (OP) was tested and results show that the k-u SST turbulence model is the most suitable to capture the ejector flow characteristics in all OP. In addition, for higher entrainment ratio (M) values, it was observed a possible correlation between how well the boundary layer can be solved and how the model is able to capture the ejector efficiency curve. Moreover, for lower M values, another possible correlation may be stated between how the turbulence model is able to capture the velocity profile.