Situ Visualization of Water in PEMFC Using MRI

In the standard condition with 80% RH (Fig. 6b), a water content, X [H20/S03H], of around 8 in the membrane and partial dehydration at the anode were observed at a current density of 0.2 A/cm2. This suggested that electro-osmosis was influential, even at this current density, because the membrane (Nation 1110, du Pont, 254 Hm) was thicker than usual. In the dry condition (40% RH), the water content in the membrane was around 3 (Fig. 6c) and the water content profile was flat. This can be attributed to molecular diffusion in the membrane, as fast chemical diffusion at this water content has been reported by Zawodzinski et al.41 It was also noted in both cases of 80% RH and 40% RH that the water generated in the cathode catalyst layer was not sufficiently transported to the membrane. This means that little water generated at the cathode condensed and was exhausted to the cathode gas channel as liquid. In the case of 92% RH shown 

Balcom et al. developed a novel diagnostic technique suitable for a thin-film by MRI.42 The authors obtained one-dimensional water content profiles with nominal resolution of 6 p,m using a prototype resonator and double half k-space spin echo single-point imaging (SPI) technique.15 Even at room temperature, partial dehydration of the membrane in the anode side was captured clearly with high spatial resolution. 

MRI visualization with contrast imaging is frequently applied in other applications as described in literature,37-39 but is not widely 

All demonstrated by using MRI visualization reported so far shows its unique and strong ability as powerful tools for investigation of water in PEMFCs, which is important for evaluating and optimizing fuel cell materials, components, design and operating conditions. 

TUNABLE DIODE LASER ABSORPTION SPECTROSCOPY (TDLAS) AS A DIAGNOSTIC TOOL FOR IN-SITU DETECTION OF WATER VAPOR CONCENTRATION IN PEMFCs 

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