Faculty Publications
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Item Numerical investigation on the improved reactant mass transport with depth-dependent flow fields in polymer electrolyte fuel cell under inhomogeneous gas diffusion layer compression(Elsevier Ltd, 2021) Padavu, P.; Koorata, P.K.; Bhat, S.D.In this work, a numerical model is developed to analyse the effects of depth-dependent reactant flow field geometry under inhomogeneous gas diffusion layer (GDL) compression on the mass transport process and performance of polymer electrolyte fuel cell (PEFC). The types of depth-dependent flow channels considered in this study are: converging channel (depth continuously decreasing) and diverging channel (depth continuously increasing), and the conventional flow field designs. The model is investigated for local and global inhomogeneity due to GDL compression. The localized inhomogeneity is introduced in the flow-field rib as well as channel regions. The results are compared for reactant concentration, water concentration, local current density, and the polarization curve for different flow channel combinations. It is observed that the availability of reactants is higher in case of converging channel design, which leads to an increase in cell performance at higher currents. However, this is subjected to GDL inhomogeneity in compression. We observe in this study that such inhomogeneity, instead of having a significant impact on cell performance, lead to minimal influence in terms of reduction in cell performance. This we observe is due to improved H2 availability at anode and reduced O2 distribution at cathode that ultimately impacts respective hydrogen oxidation reaction (HOR) and reduction in oxygen reduction reaction (ORR). This study aims to investigate the cases for altered variation in cell performance due to change in depth-dependent flow fields. © 2021Item Model based evaluation of water management and membrane hydration in polymer electrolyte fuel cell with reactant flow-field gradients(Elsevier Ltd, 2023) Padavu, P.; Koorata, P.K.; Kattimani, S.Efficient water management and intrinsic membrane hydration are critical requirements of polymer electrolyte fuel cells (PEFC) under high load current. PEFC undergoes performance loss during high current demand due to reactant depletion, water flooding, and membrane hydration. Hence, water management and membrane hydration become vital for endured life of PEFC itself. Further, flow field optimization assists in overcoming the critical transport factors affecting the PEFC performance. A model-based approach is envisioned to understand effective water management wherein reactant flow channel gradients are designed to investigate its advantages and limitations. Here, we show efficient water management of these cells at high current demand where reactant distribution governs the cell characteristics. On comparing the current density distribution of the flow field designs under both Maximum Humid and Partial Humid inlet conditions, we observe a 16.46% increase in current density distribution in converging design (partial humid condition) compared to the lowest current density obtained in diverging design (max humid condition) at 0.4 V. Further, we observed that the current density distribution in the converging design improved by 3.68% and 6.19% compared to the straight (conventional) and diverging design, respectively, under max humid condition at 0.4 V. Similarly, under the partial humid condition, the current density improved in the converging design by 3.46% and 4.98% compared to conventional and diverging designs respectively at 0.4 V. Using a comprehensive numerical analysis of reactant flow channel gradient designs, we show that the membrane hydration of operating cells is controlled through variation in transport characteristics. © 2023 Elsevier Ltd