使用中子射线照相法精确测量质子交换膜的面内含水量。
Accurate measurement of the through-plane water content of proton-exchange membranes using neutron radiography.
作者信息
Hussey D S, Spernjak D, Weber A Z, Mukundan R, Fairweather J, Brosha E L, Davey J, Spendelow J S, Jacobson D L, Borup R L
机构信息
Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
出版信息
J Appl Phys. 2012;112(10). doi: 10.1063/1.4767118.
The water sorption of proton-exchange membranes (PEMs) was measured using high-resolution neutron imaging in small-scale fuel cell test sections. A detailed characterization of the measurement uncertainties and corrections associated with the technique is presented. An image-processing procedure resolved a previously reported discrepancy between the measured and predicted membrane water content. With high-resolution neutron-imaging detectors, the water distributions across N1140 and N117 Nafion membranes are resolved in vapor-sorption experiments and during fuel cell and hydrogen-pump operation. The measured water content of a restricted membrane at 80 °C is shown to agree with gravimetric measurements of free-swelling membranes over a water activity range of 0.5 to 1.0 including at liquid equilibration. Schroeder's paradox was verified by water-content measurements which go from a high value at supersaturated or liquid conditions to a lower one with fully saturated vapor. At open circuit and during fuel cell operation, the measured water content indicates that the membrane is operating between the vapor- and liquid-equilibrated states.
在小型燃料电池测试部件中，使用高分辨率中子成像技术测量了质子交换膜（PEM）的水吸附情况。本文详细介绍了与该技术相关的测量不确定度和校正方法。一种图像处理程序解决了先前报道的测量膜含水量与预测值之间的差异。借助高分辨率中子成像探测器，在蒸汽吸附实验以及燃料电池和氢泵运行过程中，解析了N1140和N117 Nafion膜上的水分布情况。结果表明，在80°C下受限膜的测量含水量与自由溶胀膜在水活度范围为0.5至1.0（包括液体平衡时）的重量法测量结果一致。通过含水量测量验证了施罗德悖论，即在过饱和或液体条件下含水量较高，而在完全饱和蒸汽条件下含水量较低。在开路和燃料电池运行期间，测量的含水量表明膜在蒸汽平衡和液体平衡状态之间运行。
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