Faculty Publications
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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 Development of Fast Charging Control Algorithm for Electric Vehicles(Institute of Electrical and Electronics Engineers Inc., 2022) Yadav, A.; Koorata, P.K.; Dastagiri Reddy, B.D.The rapid market integration of electric vehicles has resulted in an increase in the interest of fast charging technology. One of the major concerns associated with fast charging is safety of the operation. Fast charging involves effective communication between DC charger and battery management system through the charging control algorithm embedded in the vehicle controller unit. The development of such control strategy requires interdisciplinary cooperation between different participants. A lack of system understanding can lead to safety hazards. Here in this paper, we have developed a charging control strategy for CHAdeMO DC charger using model-based development which is a better method than conventional embedded C coding and its working is shown in a starter model of DC charger in STATEFLOW. © 2022 IEEE.Item Geometrical pole shape optimization of an outer rotor synchronous reluctance motor for output torque enhancement(Institute of Electrical and Electronics Engineers Inc., 2024) Chauhan, V.K.S.; Koorata, P.K.This article explores optimizing design for Permanent magnet (PM) free outer rotor synchronous reluctance machines to be used as in-wheel motors for electric vehicles. The primary objective is enhancing torque output by systematically analyzing various rotor pole shapes and parameters such as pole depth, arc angles, rib thickness, channel width, and fillet radii. These parameters were studied on four different types of pole shapes. Using ANSYS Maxwell software, the analysis is performed on an outer rotor motor with a diameter of 190 mm and a rated speed of 1200 RPM. The results indicate that outer rotor machines with configurations such as an inner arc angle of 9 degrees and an outer arc angle of 24 degrees exhibit optimal torque output for pole shape 1. Moreover, the study reveals that an increase in pole depth (SB) corresponds to an increase in torque output, while rib thickness reduces torque output. Additionally, the research explores the impact of fillet radii on torque performance. This study provides the effects of essential features of critical design parameters on reluctance torque for maximizing average torque in outer rotor motors utilized in EV applications. © 2024 IEEE.Item Investigation on the Influence of Soft Tissues in Knee Joint on Load Transfer Mechanism during the Gait Cycle(American Institute of Physics, 2024) Raju, V.; Koorata, P.K.Soft tissues keep the human knee joint stable and serve an essential function in limiting motion during daily activities.The goal of this work is to investigate the influence of knee components during a person subjected to walking. A 3D finite element model of a knee joint used for the analysis. The knee kinetics (forces and rotation) during the stance phase of a gait in all degrees of freedom are incorporated into the model. The contact pressure, effective Lagrange strain, maximum shear stress, effective stress and total displacement generated on all the soft tissues are compared. The meniscus shows a more excellent value in all areas concerning other tissues, and for stress values, it is 4 to 5 times greater. The result also indicates that the contact pressure of the tibial cartilage is higher than the femur cartilage throughout the cycle. However, the effective Lagrange strain of femur cartilage is higher than tibial cartilage during the initial phase of the cycle and later declined. These values might help develop comprehensive computational tools to help us better understand the knee injury and disease causes. © 2024 American Institute of Physics Inc.. 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 A review on transport properties and performance of commercial and novel membranes for anion exchange membrane water electrolyser(Elsevier Ltd, 2025) Naik, V.V.; Koorata, P.K.; Nuggehalli Sampathkumar, S.N.; Van herle, J.The growing demand for renewable-powered hydrogen drives interest in water electrolysis, making anion exchange membrane water electrolysis (AEMWE) an emerging technology. The anion exchange membrane (AEM) integrates the benefits of both the proton exchange membrane (PEMs) and alkaline water electrolysis (AWEs), enabling the use of cost-efficient transition metal catalysts instead of precious metals and operating in distilled water or low-concentration KOH electrolytes, thereby reducing corrosion issues. Like PEMWE, AEMWE offers high-purity hydrogen, broader material compatibility, and reduced system costs. Moreover, it offers a low-temperature alternative to solid oxide electrolysis (SOECs), simplifying system integration. Despite these benefits, large-scale adoption is limited by several challenges, including limited alkaline stability of membranes, trade-offs between ionic conductivity and durability, insufficient long-term stability of PGM-free catalysts, and elevated interfacial resistance at membrane electrode assembly (MEA) and porous transfer layer (PTL) junctions. These constraints are reflected in conventional AEMs, which typically exhibit limited conductivities of ∼100 mS/cm at 60–80 °C with lifetimes of under 1000 h. In contrast, commercial membranes demonstrate higher conductivities of ∼150 mS/cm, enabling improved performance, delivering current densities of 0.8–1.2 A/cm2 at voltages of 1.8–2.0 V. Recent developments in novel AEMs have further enhanced both current density and stability by 20–30 %, achieving >1.6 A/cm2 and >1500 h under optimised conditions. However, the long-term durability of PGM-free catalysts remains a critical limitation. In addition to technical performance, AEMWE also presents economic advantages over other electrolysis technologies. This review systematically evaluates commercial membranes, including Tokuyama, Fumatech, Orion, Aemion, Sustainion, and Piperion, alongside emerging alternatives. Key aspects such as chemical structures, ion transport properties, electrochemical performance, cost analysis of commercial membranes, degradation mechanisms, and advances in MEAs are examined. The role of PGM and PGM-free catalysts in improving efficiency and reducing costs is also highlighted. Several novel membranes demonstrate performance comparable to or exceeding commercial standards, indicating strong potential for future commercialisation. Finally, the review identifies critical research gaps, including the need for alkaline-stable polymers, durable PGM-free catalysts, optimised MEA/PTL architectures to mitigate interfacial resistance, and standardised long-term testing protocols, which are essential for transitioning AEMWE from laboratory studies to scalable, cost-effective hydrogen production systems. © 2025 Hydrogen Energy Publications LLCItem Compressive cyclic response of PEM fuel cell gas diffusion media(Elsevier Ltd, 2021) Koorata, P.K.; Bhat, S.D.The fuel cell gas diffusion media (GDM) is a highly porous carbon-fiber-reinforced thin composite layer. The experimental response of these materials is observed to be highly nonlinear at low-stress levels. The cyclic mechanical response of GDM is investigated in terms of stiffness and damage parameters. The prediction of the state of deformation in GDM is vital in relating GDM's properties to ohmic and transport losses. To this end, a compressible form of the phenomenological model is proposed to capture the experimental cyclic response accurately. The model is constituent dependent; that is, the cumulative cyclic stress-strain response of GDM is a function of individual constituent phases present in the material. These individual constituents are porous matrix and reinforced fibers. The model hence derived for a typical GDM material, can predict residual strain, hysteresis, and damage quotient associated with the stress softening. This advanced model is implemented in the numerical domain to evaluate the response of the polymer electrolyte fuel cell (PEFC) unit cell. The stress-strain distribution fields are analyzed and compared with those of conventional GDM models. The results point to a remarkable deviation from the conventional notion of structural analysis. © 2020 Hydrogen Energy Publications LLCItem Case study for contact pressure improvisation with graded implant material in articular cartilages of knee joint(Korean Society of Mechanical Engineers, 2021) Raju, V.; Koorata, P.K.; Kamat, Y.In this study, the effect of graded design in comparison to homogeneous cartilage material is investigated for contact pressure distribution in the human knee joint. Knee implants are assumed a homogeneous material. In reality, cartilages are not homogeneous, and to replicate the heterogeneity of cartilages, a graded design is proposed. Simulation results show improved contact pressure distribution in the knee joint due to the graded composition of cartilages. The results are helpful in designing a new class of implant materials. © 2021, The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature.Item Numerical investigation on the sensitivity of endplate design and gas diffusion material models in quantifying localized interface and bulk electrical resistance(Elsevier Ltd, 2021) Shinde, U.; Koorata, P.K.A localized non-intuitive relationship between electrical interface contact resistance and bulk properties such as bulk electrical resistance and permeability in the fuel cell gas diffusion layer (GDL) is reported. A numerical method is adopted to investigate contact pressure and hence the interface contact resistance at the interfaces of bipolar plate (BPP)|GDL and GDL|Polymer electrolyte membrane (PEM). The results are observed to be sensitive to GDL material models as well as endplate designs. This means, endplates designed to improve the electrical contact resistance or contact pressure at the BPP|GDL interface may not necessarily assure an improvement in bulk properties, in fact, it is observed in this study that these properties are inversely related. Further, a differential deformation in GDL along with consolidation effect is predicted with compressible version of hyperelastic material model. More importantly, it is revealed that the selection of material models plays a significant role in the deformation behaviour of the GDLs irrespective of the clamping design adopted. © 2021 Hydrogen Energy Publications LLCItem Numerical investigation of cooling performance of a novel air-cooled thermal management system for cylindrical Li-ion battery module(Elsevier Ltd, 2021) Kausthubharam, n.; Koorata, P.K.; Chandrasekaran, N.Batteries strongly influence the performance of electric vehicles. Therefore it is crucial to develop a battery thermal system that is highly efficient in removing the battery pack's heat during its operation. In this paper, a numerical analysis of a lumped thermal model coupled with fluid flow equations is employed to investigate the novel air-cooled battery thermal management system (BTMS). The cooling efficiency of the proposed battery thermal system with commercial thermal interface material (3M™) is investigated by comparing it with a standard battery pack at different discharge rates. The proposed solution offers a 25% reduction in peak temperature when compared to the standard one. The thickness of the thermal interface material is found to have an insignificant impact on the battery pack's thermal performance. Introducing forced air-cooling in the battery pack reduced the maximum temperature considerably but increased the temperature difference compared to the battery pack without forced convection. Then the effect of various structural and operational parameters on the performance of the BTMS is investigated. Moving the air inlet-outlet boundaries to a central location increased the uniformity of temperature distribution in the battery pack. Although the increase in the inlet airflow velocity reduces the maximum temperature, it comes at the cost of an increase in temperature difference and power consumption. It is further observed that a reduction in ambient temperature reduces the peak temperature and makes the temperature distribution in the battery pack more homogeneous. The discharge voltage curves indicate a slight reduction in cell potential as a reducing function of temperature. © 2021 Elsevier Ltd