TY - CONF

T1 - Method to analyze the spatial current distribution in an operating PEFC based on NMR mesurement using small planer surface coils

AU - Ogawa, Kuniyasu

AU - Yokouchi, Yasuo

AU - Haishi, Tomoyuki

AU - Ito, Kohei

N1 - Funding Information:
This work was conducted under the Development of Advanced Measurement and Analysis Systems program of the Japan Science and Technology Agency (JST). The measurement system was developed by MRTechnology, Inc., NEOMAX Engineering, Ltd., and Digital Signal Technology, Inc. The software for NMR measurement was developed by Mr. Seitaro Hashimoto of EXA CORPORATION. The MEA was built by Dr. Sangkun Lee and Mr. Masaaki Hirano of the Hydrogen Utilization Engineering group at Kyusyu University. Some components of the fuel cells were made by FC Composite Inc. and Yamato Inc. The authors wish to thank all of those mentioned above for their contribution to this study.

PY - 2014

Y1 - 2014

N2 - In order to measure the local current density generated in a polymer electrolyte fuel cell (PEFC), nuclear magnetic resonance (NMR) signals were acquired by a coil inserted in a PEFC with a power generation area of 50 mm × 50 mm. Eight small planar surface coils with inner diameters of 0.6 mm were inserted between the gas diffusion layer and the membrane electrode assembly of the fuel cell. Changes in the frequency of the NMR signals due to local currents generated in the PEFC were recorded and analysed. To compute the spatial distribution of these local currents from the measured frequency shifts, it is necessary to use an inversion analysis based on the Biot-Savart law, which connects current and magnetic field strength. An algorithm developed in this study was used to quickly minimize the difference between the frequency shift calculated from an assumed current distribution and that measured experimentally. The algorithm uses the dependence of frequency shift on local current based on the equations of electricity and magnetism. In this paper we describe the derivation of the proportionality relation and the inversion algorithm. The computation time required for the inversion using the developed algorithm was a few tens of seconds. Using the developed algorithm, the spatial distribution of local current density generated in the PEFC was analysed.

AB - In order to measure the local current density generated in a polymer electrolyte fuel cell (PEFC), nuclear magnetic resonance (NMR) signals were acquired by a coil inserted in a PEFC with a power generation area of 50 mm × 50 mm. Eight small planar surface coils with inner diameters of 0.6 mm were inserted between the gas diffusion layer and the membrane electrode assembly of the fuel cell. Changes in the frequency of the NMR signals due to local currents generated in the PEFC were recorded and analysed. To compute the spatial distribution of these local currents from the measured frequency shifts, it is necessary to use an inversion analysis based on the Biot-Savart law, which connects current and magnetic field strength. An algorithm developed in this study was used to quickly minimize the difference between the frequency shift calculated from an assumed current distribution and that measured experimentally. The algorithm uses the dependence of frequency shift on local current based on the equations of electricity and magnetism. In this paper we describe the derivation of the proportionality relation and the inversion algorithm. The computation time required for the inversion using the developed algorithm was a few tens of seconds. Using the developed algorithm, the spatial distribution of local current density generated in the PEFC was analysed.

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M3 - Paper

AN - SCOPUS:84964452162

T2 - 15th International Heat Transfer Conference, IHTC 2014

Y2 - 10 August 2014 through 15 August 2014

ER -