02248nas a2200205   4500008004100000022001400041245017100055210006900226260000900295300001200304490000800316520142900324653002501753653002301778653004001801653002501841100002301866700002101889856013201910       2019                        eng d  a0009-250900aAnalytical solutions of an isothermal two-dimensional model of a cathode flow channel in transport limited operational regimes of a proton exchange membrane fuel cell0 aAnalytical solutions of an isothermal twodimensional model of a   cMAR   a166-1750 v1963 a<p>In the quest for obtaining accurate closed-form analytical expressions for polarization curve of a proton exchange membrane fuel cell (PEMFC), we have recently presented a two-dimensional model that accounts for oxygen concentration gradient and velocity gradient along the depth of a cathode flow channel. The model was developed for the case when Tafel kinetics of oxygen reduction reaction (ORR) on the cathode governs the overall rate of oxygen consumption. An improved match between predictions of the model and full three-dimensional simulations was obtained over the entire range of current density compared with earlier models which assumed homogenous oxygen concentration in the channel depth and plug flow velocity profile. In reality however, ORR kinetics is often not the rate limiting step for oxygen consumption in the cathode catalyst layer (CCL) at high current density since the Tafel kinetics is modulated by transport resistances in the CCL. In this article, we extend our two-dimensional analytical model to two different transport-limited regimes of CCL operation namely, slow oxygen transport across the CCL and slow proton transport across the CCL. We compare model predictions with results of full three-dimensional simulations in both cases and show that they are in excellent agreement even in these transport limited operational regimes of PEMFC. (C) 2018 Elsevier Ltd. All rights reserved.</p>10aAnalytical modelling10aPolarization curve10aProton exchange membrane fuel cells10aTransport resistance1 aThosar, Aniket, U.1 aLele, Ashish, K.  uhttps://library.ncl.res.in/content/analytical-solutions-isothermal-two-dimensional-model-cathode-flow-channel-transport-limited02945nas a2200229   4500008004100000022001400041245010500055210006900160260001100229300001100240490000800251520217200259653002302431653001402454653001002468653002302478100002302501700002102524700001802545700002102563856013102584       2019                        eng d  a0009-250900aComprehensive analytical model for polarization curve of a PEM fuel cell and experimental validation0 aComprehensive analytical model for polarization curve of a PEM f  cOCT 12  a96-1170 v2063 a<p>The kinetics of cathodic oxygen reduction reaction (ORR) in a proton exchange membrane fuel cell (PEMFC) is significantly modulated by the resistances for transport of reactants to the catalytic sites offered by different components of the fuel cell. This modulation governs the polarization curve of the PEMFC. Consequently, the various operating, geometric and material parameters of the fuel cell dictate the polarization curve. The effects of these parameters on the polarization curve over the entire range of current density, from zero to limiting current, can be predicted using detailed numerical simulations, which are however expensive. Analytical models, although simple can capture the essential details of physico-chemical processes occurring inside a PEMFC and are significantly inexpensive. In this article, we derive an analytical equation of the polarization curve which is valid over the entire range of current density. Specifically, the representative situation of a humidified low temperature PEMFC is considered wherein oxygen transport resistance in the cathode catalyst layer (CCL) is encountered at lower current density than proton transport resistance in the CCL. A novel experimental methodology is illustrated to confirm that this is indeed the case. Next, we elucidate a procedure to determine in-situ oxygen diffusion coefficients in the various domains of an operational PEMFC. Finally, it is shown that the analytical polarization curve predicted using these parameters is in excellent agreement with the experimental and numerically simulated polarization curves over the entire range of current density. The significance of this work is that the analytical model relates the performance of a PEMFC to all operating and geometric parameters as well as the average transport and kinetic properties of the materials used in its different components, without the need for computationally expensive numerical simulations. The model can therefore provide useful insights for enhancing the performance of PEMFC in different regimes of current density as well as for diagnostic purposes. (C) 2019 Elsevier Ltd. All rights reserved.</p>
10aFuel cell equation10aModelling10aPEMFC10aPolarization curve1 aThosar, Aniket, U.1 aAgarwal, Harshal1 aGovarthan, S.1 aLele, Ashish, K.  uhttps://library.ncl.res.in/content/comprehensive-analytical-model-polarization-curve-pem-fuel-cell-and-experimental-validation