Measurement of proton conductivity and water diffusivity of nafion membrane at subzero temperatures
Department of Mechanical Engineering-Engineering Mechanics
Objective of this study is to obtain the water transport characteristics of Nafion at subzero temperature for automotive application. To achieve this objective, three different properties of the membrane are quantified: water content, proton conductivity, and diffusivity. Water content is computed from measuring the difference in weight between the dry membrane and humidified membrane at each relative humidity and sub-zero temperature. To measure the weight a special environmental cell was developed and integrated with the microbalance. To quantify the proton conductivity and the water diffusivity, a conductivity measurement electrochemical cell with segmented electrode is designed and fabricated to measure the high frequency resistance across the membrane at test conditions. An equation is developed for water content in terms of relative humidity and temperature. Equations for proton conductivity and water diffusion coefficient are presented in terms of water content and temperature. These equations are developed from experimental data obtained between 243K and 303K at different relative humidity.
Measurement of proton conductivity and water diffusivity of nafion membrane at subzero temperatures.
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