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Drying process of water in a Nafion membrane embedded in the fuel cell analyzed by coherent anti-Stokes Raman scattering spectroscopy
摘要： A coherent anti-Stokes Raman scattering (CARS) spectroscopy system was designed to measure the transient behavior of the humidi?cation of a Na?on membrane used in a polymer electrolyte fuel cell (PEFC). We observed a variation in the intensity of the O–H stretching vibration peak of water during dry and wet gas ?ow. From our measurements, we found that our system showed a high time resolution enough to measure humidi?cation variation in a Na?on membrane in a PEFC. The high acquisition rate revealed the nonequilibrium process of the dehydration or hydration of the Na?on membrane through the temporal variation in the intensity of the O–H stretching vibration peak. The peak consisted of three peaks, suggesting that water molecules hydrated with di?erent bonding energies. The transient behavior of the peaks was probably attributed to the motion of hydration molecules in the proton channel. ? 2018 The Japan Society of Applied Physics
关键词： CARS spectroscopy,O–H stretching vibration,hydration,Na?on membrane,PEFC
更新于2025-09-04 15:30:14
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Raman thermometry in water, ethanol and ethanol/nitrogen-mixtures from ambient to critical conditions
摘要： We present investigations into remote liquid temperature sensing with Raman spectroscopy using different evaluation methods for the OH stretching vibration band. Water, ethanol and ethanol saturated with nitrogen, all as liquids or liquid-like supercritical fluids, are pumped through a heated microcapillary system at elevated pressures. Raman spectra are recorded from the liquid inside the microcapillary and are evaluated with respect to the temperature sensitivity of the OH stretching vibration. The four approaches applied are (i) to evaluate the center position of the Raman OH-band, (ii) the integrated absolute difference spectrum, (iii) the intensity ratio of two regions of the OH-band, and (iv) the intensity ratio of two fitted Gaussian peaks. The temperature range investigated covers from ambient temperature to the component’s respective boiling temperature or critical temperature at sub- and supercritical pressures. Precision and robustness of the employed methods are characterized. It is shown that two out of the four methods feature temperature deviations smaller than 5 K at all pressures, and that one method can also be applied to liquid mixtures of ethanol and nitrogen. Applicability to other liquids and mixtures is discussed.
关键词： temperature sensing,supercritical fluids,OH stretching vibration,water,Raman spectroscopy,nitrogen,microcapillary,ethanol
更新于2025-09-04 15:30:14