IVAN KORKISCHKO
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Resumo IPEN-doc 26701 A hybrid serpentine-interdigitated flow channel geometry for fuel cells2019 - BERUSKI, OTAVIO; KORKISCHKO, IVAN; LOPES, THIAGO; FONSECA, FABIO C.; PEREZ, JOELMAFuel cells have impressive potential for decarbonization and as high efficiency power sources, however many challenges have yet to be addressed for large scale deployment and uptake. Among the many noteworthy lines of research underway, investigating the best flow field in a given device has been carried a number of times, with perhaps limited success regarding performance improvement. As a possible final attempt to look over such matters individually, from the component point of view, we propose yet another flow channel geometry for small-scale fuel cells, in particular polymer electrolyte fuel cells (PEFCs). The proposed geometry incorporates elements from the two most studied geometries, namely single serpentine and interdigitated. The rationale is that serpentine channels have large pressure drop, thus aiding in water removal, while interdigitated promises to deliver large quantities of reactants to the catalyst. However both seem to fail where the other excels, and thus devices are left to compromises. The new geometry, as well as its inspirations, are simulated in a previously validated computational model, further improved and with high spatial resolution, of a prototype PEFC cathode. The model is isothermic, non-electrochemical and disregards water, as the experimental system. However it has been shown to be useful when studying PEFCs, and a secondary goal of this work is to corroborate this. Comparing simulation results between geometries, it is seen that the hybrid geometry does inherit the characteristics of interest, i.e. high reactant utilization and pressure drop, suggesting it may be of use in real PEFCs. Finally, a niche application is proposed based on the reaction rate distribution of the hybrid geometry.Resumo IPEN-doc 26700 Unveiling fundamental transport phenomena in fuel cells2019 - LOPES, THIAGO; BERUSKI, OTAVIO; KORKISCHKO, IVAN; MANTHANWAR, AMIT M.; PISTIKOPOULOS, EFSTRATIOS N.; FONSECA, FABIO C.; MENEGHINI, JULIO R.; KUCERNAK, ANTHONY R.In situ and ex situ spatially-resolved techniques are employed to investigate reactant distribution and its impacts in a polymer electrolyte fuel cell. Temperature distribution data provides further evidence for secondary flows inferred from reactant imaging data, highlighting the contribution of convection in heat as well as reactant distribution. Water build-up from neutron tomography is linked to component degradation, matching the pattern seen in the reactant distribution and thus suggesting that high, nonuniform local current densities shape degradation patterns in fuel cells. The correlations shown between different techniques confirm the use of the versatile reactant imaging technique, which is used to compare commonly used flow field designs. Among serpentine-type designs, the single serpentine is superior in both equivalent current density and reactant distribution, showing large contributions from convective flow. On the other hand, the interdigitated design is shown to produce larger equivalent current densities, while showing a somewhat poorer reactant distribution. Considering the correlations drawn between the techniques, this suggests that the interdigitated design compromises durability in favour of power output. The results highlight how established techniques provide a robust background for the use of a new and flexible imaging technique toward designing advanced flow fields for practical fuel cell applications.Artigo IPEN-doc 25825 Spatially resolved oxygen reaction, water, and temperature distribution2019 - LOPES, THIAGO; BERUSKI, OTAVIO; MANTHANWAR, AMIT M.; KORKISCHKO, IVAN; PUGLIESI, REYNALDO; STANOJEV, MARCO A.; ANDRADE, MARCOS L.G.; PISTIKOPOULOS, EFSTRATIOS N.; PEREZ, JOELMA; FONSECA, FABIO C.; MENEGHINI, JULIO R.; KUCERNAK, ANTHONY R.In situ and ex situ spatially-resolved techniques are employed to investigate reactant distribution and its impacts in a polymer electrolyte fuel cell. Temperature distribution data provides further evidence for secondary flows inferred from reactant imaging data, highlighting the contribution of convection in heat as well as reactant distribution. Water build-up from neutron tomography is linked to component degradation, matching the pattern seen in the reactant distribution and thus suggesting that high, non-uniform local current densities shape degradation patterns in fuel cells. The correlations shown between different techniques confirm the use of the versatile reactant imaging technique, which is used to compare commonly used flow field designs. Among serpentine-type designs, the single serpentine is superior in both equivalent current density and reactant distribution, showing large contributions from convective flow. On the other hand, the interdigitated design is shown to produce larger equivalent current densities, while showing a somewhat poorer reactant distribution. Considering the correlations drawn between the techniques, this suggests that the interdigitated design compromises durability in favour of power output. The results highlight how established techniques provide a robust background for the use of a new and flexible imaging technique toward designing advanced flow fields for practical fuel cell applications.Resumo IPEN-doc 25562 Modeling, simulation and shape optimization of a proton exchange membrane fuel cell using computational fluid dynamics2018 - KORKISCHKO, IVAN; SANTIAGO, ELISABETE I.; CARMO, BRUNO S.; FONSECA, FABIO C.This paper presents the modeling, simulation and optimization of a single channel proton exchange membrane fuel cell (PEMFC) using computational fluid dynamics methods. The shape optimization of the cross section of the flow channels was employed to improve the electrical performance of the fuel cell. The minimization of the standard deviation of the current density on the longitudinal mid-plane of the membrane was the objective function of the single-objective optimization problem, the upper and lower widths of the flow channels were the control variables and a cross-section area restriction was imposed. The optimized flow-channel PEMFC presented improved electrical performance, with higher current and power densities and a more uniform current density distribution than the rectangular flow channel. It is also expected that a more uniform current distribution improves the durability and water management of the fuel cell.Artigo IPEN-doc 24378 Shape optimization of PEMFC flow-channel cross-sections2017 - KORKISCHKO, I.; CARMO, B.S.; FONSECA, F.C.This paper presents the modeling, simulation and optimization of a single channel proton exchange membrane fuel cell (PEMFC) using computational fluid dynamics methods. The shape optimization of the flow-channels was employed to improve the electrical performance of the fuel cell. The maximization of the current density was the objective function of the single-objective optimization problem, the upper and lower widths of the flow channels were the control variables and a cross-section area restriction was imposed. The optimized flow-channel PEMFC presented improved current generation characteristics, showing higher current and power densities and a more uniform current density distribution than the rectangular flow-channel.