2006 Fiscal Year Final Research Report Summary
Higher load current of PEMFC
| Project/Area Number |
17560188
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
ITO Kohei Kyushu University, Faculty of Engineering, Associate Professor, 大学院工学研究院, 助教授 (10283491)
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| Project Period (FY) |
2005 – 2006
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| Keywords | PEMFC / Flooding / Two-phase flow |
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| Research Abstract |
The performance of PEMFC largely depends on its water management. The flooding appeared in gas diffusion layer (GDL) and catalyst layer, which are main target to be managed, is difficult to measure and/or observe, because these layers are categorized as micro-porous media and opaque material based on carbon. On the other hand, the gas-liquid two-phase flow numerical simulation in PEMFC is developed recently. In this progress of simulation, the MM model, which is one of mathematical model to treat two-phase phenomena in porous media such as GDL, seems to successfully simulate the flooding during cell operation. However the evaluation of the simulation is not enough. Only the evaluation is based on the comparison of IV characteristic between simulation and experiment. The simulated two-phase phenomena, such as the water saturation ratio in GDL, have not been evaluated with experimental result.
In this study, we measured the water saturation in GDL with indirect method and compared its res
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ult with that obtained from simulation. We fabricated a simple interdigitated cell where the whole fluid flows forcedly in GDL, and measured the differential pressure through GDL, and estimated the water saturation ratio from its differential pressure. In numerical simulation, we formulated the full conservation equations based on MM model, and executed with the boundary condition considering the interdigitated cell. In simulation we also executed the transient calculation in which the load current changed step-wisely.
In measurement, the cell potential decreased significantly over 0.5A/cm2 load current. We successfully explained that this drop was caused by the concentration over potential accompanied with the water saturation estimated. The water saturation ratio increased with higher load current, humidification temperature, and gas utilization ratio. These operation conditions are noted as the key parameter to control the flooding in GDL. The simulated IV characteristics succeeded to reproduce the measured. But they could not show the concentration overpotential appeared in high current region. The differential pressure obtained from the simulation qualitatively agreed with the measured data within 15%. In transient calculation, the cell potential changed complexly. We could explain this with several time constant corresponding to the transport phenomena being progressed in cell. Less
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