Date

2016

Author

Sezgin, Berna

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High temperature polymer electrolyte membrane fuel cells (HT-PEMFC) are considered as the next generation of fuel cells since high temperature operation for PEM fuel cells has several advantages such as single phase operation, high carbon monoxide tolerance, low or zero carbon emission and removal of some equipment from the system. In order to obtain high performances, HT-PEMFC systems should be optimized in terms of dimensions, materials, operating conditions and other parameters. Modeling can help to pre-estimate the effects of different design parameters and operating conditions on the fuel cell performance, which shortens the required time for these analysis in reference to the time spent for experiments. In this study, three-dimensional (3-D) model of HT-PEMFC is developed. The model is implemented as isothermal and steady-state. Model domains are considered for two different geometries: single flow channel and multiple flow channels. Models are simulated by using licensed software package program Comsol Multiphysics 5.0, and its Fuel Cells & Batteries module. The program has solved the governing equations by finite element method. Moreover, it is an advantage to use this program for HT-PEMFC modeling by the reason of including Fuel Cell module. In the scope of this study, some critical parameters are prescribed as effective parameters for HT-PEMFC performance. These are inlet velocities (or flow rates) of reactant gases to the both anode and cathode inlet gas channels, conductivity of the membrane and meshing strategy. Influences of inlet velocities of reactant gases and conductivity of the membrane are studied for both single channel and multiple channel HT-PEMFC models, while influence of meshing strategy is studied for only multiple channel HT-PEMFC model. It is seen that increasing inlet velocities of reactants (hydrogen and air) enhances HT-PEMFC performance as long as enough oxygen is supplied to the system. In addition, increasing proton conductivity of the membrane provides better performance for both channel geometries. For the effect of meshing strategy, it is found that the results are more accurate for small size of mesh elements. For all models that have been developed are validated with the experimental data.

Subject Keywords

Fuel cells., Electrochemistry., Proton exchange membrane fuel cells .

URI

http://etd.lib.metu.edu.tr/upload/12620619/index.pdf
https://hdl.handle.net/11511/26163

Collections

Graduate School of Natural and Applied Sciences, Thesis