جستجوی مقالات مرتبط با کلیدواژه « fuel cell performance » در نشریات گروه « فنی و مهندسی »

Nanotechnology is well used in the development and performance improvement of solid oxide fuel cells (SOFCs). The high operating temperature of SOFCs (700-900 ° C) has led to serious shortcomings in their overall performance and durability. Hence, the high operating temperature has been reduced to the average temperature range of approximately 44-700 Celsius, which has improved performance and subsequently commercialized SOFCs as portable energy sources. However, at reduced temperatures, challenges arise such as increasing the internal strength of fuel cell components. Although this may not be as serious as the problems that arise at high temperatures, it still significantly affects SOFC performance. This paper deals with the work of researchers in the field of application of nanotechnology in the construction of SOFC through different methods. These methods have successfully eliminated or minimized internal resistance and shown significant improvements in SOFC energy density at reduced temperatures.

The catalyst layer is often the thinnest layer in the fuel cell، but is often the most complex part due to multiple phases، porosity، and electrochemical reactions. The performance of proton exchange membrane (PEM) fuel cell is strongly affected by the cathode catalyst layer performance. In this study، a steady state isothermal one-dimensional agglomerate model is considered and developed for the cathode catalyst layer. After writing the governing equations for the catalyst layer، differential equations for independent variables of current density، oxygen concentration and activation overpotential obtained that form a coupled system of first-order nonlinear ordinary differential equations (ODE’s) with the related boundary conditions. Then coupled system of ODE’s is solved through coding in Matlab software version 2011، using a shooting method، boundary value problem (BPV). After validating the model against experimental and theoretical results، a comprehensive parametric study is performed on the effects of fourteen parameters including operational parameters namely temperature، pressure and saturation liquid water، and structural parameters such as platinum loading، ionomer volume fraction، porosity and thickness of catalyst layer، radius and porosity of agglomerate and etc. on the catalyst layer performance. It was found that saturation liquid water، ionomer volume fraction and agglomerate radius have the greatest effect on the performance.

In this study، we propose a configuration of partially blocked oxidant channel with baffle plates transversely inserted in the cathode channel and effects of the fluid dynamics due to the presence or non-presence of the baffles and their effect on the fuel cell performance is investigated. A 3D model with the presence of baffle plates is considered and a set of equations (continuity، momentum، species and charge together with electrochemical kinetics) in the form of single domain is developed and solved numerically. The baffles block the main flow in the cathode channel and force more reactant gases to turn to the GDL. This fact implies an enhancement of the oxygen flux at the GDL and catalyst surface، especially at the position beneath the location of the baffle plates. An increase in the number of baffles contribute to the reactant gas transport to GDL with more uniform distribution of gas in the GDL and catalyst layer، specially in high current densities، where it leads to a penalty of high pressure – loss. The predictions indicate that the local transport of the reactant gas would enhance the local current densities and the fuel cell performance in presence of baffle in the channel.