Faculty Publications
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Item 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 LLCItem A Fast and Robust PLL Design with a Combination of Frequency-Adaptive Alpha-Beta-CDSC and SOGI(Institute of Electrical and Electronics Engineers Inc., 2025) Mondal, S.; Gayen, P.K.; Gaonkar, D.N.Recent research has focused on the enhancement of the prefiltering capability of phase-locked loops (PLL). The cascaded delayed signal cancellation (CDSC) PLL removes the low-order selective harmonic frequencies near the fundamental frequency. Here, a frequency-adaptive time delay unit is used to cope with frequency and phase variations of voltage. The high-frequency signal arising due to the frequency-adaptive loop cannot be mitigated. In effect, the transient response of adaptive CDSC-PLL shows a significant irregular pattern. Therefore, this article suggests the use of a second-order generalized integrator (SOGI) after the adaptive CDSC unit to improve the transient profile of frequency response. In the design, the high gain (K = 5.4) of SOGI is chosen to quickly settle the response of PLL at the expense of its ignorance of lower-order harmonics near the fundamental frequency. However, the lower-order harmonics are selectively eliminated by the CDSC unit. So, both prefilters complement each other's filtering capabilities. Additionally, the suggested prefilter provides improved noise immunity and eliminates DC offset via the SOGI unit. The linearized model and tuning procedure for the different control parameters of the proposed PLL are described. The real-time hardware-in-loop tests are executed to justify the optimum performance of the proposed PLL. © 2024 IEEE.