Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
7 results
Search Results
Item NUMERICAL INVESTIGATION ON THE EFFECTS OF INHOMOGENEOUS GAS DIFFUSION LAYER AND IMPACT OF INTERFACIAL CONTACT RESISTANCE ON PERFORMANCE OF POLYMER ELECTROLYTE FUEL CELLS(International Association for Hydrogen Energy, IAHE, 2022) Shinde, U.; Padavu, P.; Koorata, P.K.A three-dimensional single-channel is modeled numerically to simulate homogeneous and inhomogeneous gas diffusion layer (GDL). The effect of interfacial contact resistance (ICR) between flow field ribs and GDL is also studied. The present study involves GDL being considered as a single component (homogeneous) in one case while in another case, GDL being considered with varying porosities to depict the inhomogeneity. The inhomogeneity in GDL is assumed to occur due to localized deformation induced due to non-uniform contact pressure. The study reveals increased availability of reactants at higher current loads in the case where ICR is assumed negligible. This study explains how the presence and absence of ICR impact reaction concentrations, water concentration, current density and polarization curve of polymer electrolyte fuel cells. It is observed in polarization curve that the presence of ICR has effect both in ohmic and mass transport region. This work involves considering 4 cases viz: homogeneous GDL, inhomogeneous GDL, homogeneous GDL with ICR and inhomogeneous GDL with ICR. © 2022 Proceedings of WHEC 2022 - 23rd World Hydrogen Energy Conference: Bridging Continents by H2. All rights reserved.Item Review on physical and chemical properties of low and high-temperature polymer electrolyte membrane fuel cell (PEFC) sealants(Elsevier Ltd, 2022) Kumar, V.; Koorata, P.K.; Shinde, U.; Padavu, P.; George, S.C.Sealants (or gaskets) play an exceptional role in the efficient functioning of polymer electrolyte membrane fuel cells (PEFCs). They prevent leakage of reactant gases and coolants from the perimeter of cell. Also, they circumvent the direct mixing of reactant gases in the active region of the PEFC. Sealants ensure electrical insulation, preventing a short circuit between anode and cathode of the PEFCs. Sealants enhance the safety, thereby improving the functional performance of the PEFCs. In addition, the sealants have functional requirements that contain excellent physical and chemical properties to withstand the working conditions of PEFCs. Hence, the physical and chemical properties of the sealants are crucial for improving the sealing capability as well as the performance of PEFC. In this article, properties such as weight loss, indentation load, elastic modulus, hardness, hysteresis loss, chemical composition and chemical structure of well-known PEFC sealants are reviewed. These PEFC sealants are classified into low-temperature PEFC (LT-PEFC) and high-temperature PEFC (HT-PEFC) sealants, depending on the operational temperature. The polymeric materials such as silicone rubber, fluoroelastomers (FKM), ethylene propylene diene monomer (EPDM) rubber, polytetrafluoroethylene (PTFE) rubber, etc. are found to be suitable sealant materials for PEFCs. © 2022 Elsevier LtdItem 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 Electrical/flow heterogeneity of gas diffusion layer and inlet humidity induced performance variation in polymer electrolyte fuel cells(Elsevier Ltd, 2023) Shinde, U.; Koorata, P.K.; Padavu, P.A three-dimensional single-flow channel computational model is used to investigate the performance characteristics of polymer electrolyte fuel cells (PEFC). The combined influence of non-uniform interfacial contact resistance (ICR) and inlet relative humidity (RH), along with the heterogeneous flow properties of the gas diffusion layer (GDL) on the PEFC performance is evaluated. The study considers combinations of full and partial humidification of anode and cathode reactants. Results reveal heterogeneous GDL with non-uniform ICR distribution results in a slight ∼4.4% reduction in current density at 0.3V compared to the homogeneous case. However, under same electrical/flow heterogeneities, the current density is observed to increase by ∼19% to ∼1.3A/cm2 under fully humidified anode and partially humidified cathode (i.e., RHa|RHc = 100%|60%) as compared to ∼1.1A/cm2 under symmetric RHa|RHc = 100%|100%. Interesting observations are made on the temperature distribution and cathodic water fractions. The variation in anodic inlet humidity is observed to have no impact on temperature distribution in the membrane, whereas variation in cathodic inlet humidity is effective in reducing the temperature in the channel regime with a 4K (kelvin) difference among all the cases. It is noted here that the overpotential map is not an indicator for performance loss, at least at full inlet humidity. This parameter is observed to depend on water concentration in the cathode. The study provides a detailed analysis of the distribution of reactant mass fraction, water concentration, current density, temperature, cathodic overpotential, and cell performance for all the simulated cases. © 2022 Hydrogen Energy Publications LLCItem 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 LtdItem Numerical investigation on the effects of inhomogeneous gas diffusion layer and impact of interfacial contact resistance on the performance of polymer electrolyte fuel cells(Elsevier Ltd, 2024) Shinde, U.; Koorata, P.K.; Padavu, P.In this study, a three-dimensional single channel is numerically modeled to simulate the polymer electrolyte fuel cell (PEFC) with a homogeneous and inhomogeneous gas diffusion layer (GDL). The influence of interfacial contact resistance (ICR) between GDL and current collector ribs (GDL|CC) is also studied. In the present study, GDL is considered as a single component (homogeneous) in one case and inhomogeneous with varying electrical and flow properties to illustrate the inhomogeneity in another case. The inhomogeneity in GDL is primarily caused by localized deformation due to non-uniform contact pressure during fuel cell assemblies. The consideration of ICR is observed to have a significant effect on both the ohmic and mass transport regions of the polarization curve. Inhomogeneous GDL with ICR, considered close to a practical scenario, shows a ∼7% drop in performance evaluation at 0.3V. The study reveals increased consumption of reactants at higher current loads when ICR is assumed negligible. This study examines the effects of homogeneous GDL, inhomogeneous GDL, and the impact of ICR on the distributions of reactant concentration, water concentration, temperature, current density, and polarization curve in PEFC. This study presents the practical aspects of PEFC considering inhomogeneous GDL electrical and flow properties. © 2023 Hydrogen Energy Publications LLCItem Performance enhancement in polymer electrolyte membrane fuel cell with flow traps and field gradients: A Numerical Study(Elsevier Ltd, 2024) Padavu, P.; Koorata, P.K.; Kattimani, S.; Gaonkar, D.N.Efficient reactant distribution and water removal are critical during polymer electrolyte fuel cell (PEFC) operation. The bipolar plate and its corresponding flow field design are vital among the PEFC components for enhancing reactant transport and water removal. The issues arising in the PEFC during the high current operation, such as reactant starvation and water removal, can be alleviated by improving the flow channel geometry. In this study, we analyze the variation in overall PEFC performance and corresponding reactant transport phenomenon for two independent design cases. The converging gradient design without channel traps at 0.4 V operating voltage exhibited a current density increment of 6.85% against the conventional design. Moreover, at 0.4 V, including channel traps enhanced the current density, as we observed a current density increment of 7.1% for the converging design with channel traps against the conventional design without channel traps. Likewise, at 0.4 V, the diverging design with channel traps exhibited a current density increment of 5.85% against the diverging design with no channel traps. Further, enhanced reactant distribution is observed in the catalyst layer upon introducing channel traps in the flow field design. © 2024 Hydrogen Energy Publications LLC