Isothermal Ice Crystallization Kinetics in the Gas-Diffusion Layer of a Proton-Exchange-Membrane Fuel Cell

被引：34

作者：

Dursch, T. J. ^{[1
,2
]}

Ciontea, M. A. ^{[1
]}

Radke, C. J. ^{[1
,3
]}

Weber, A. Z. ^{[2
]}

机构：

[1] Univ Calif Berkeley, Chem & Biomol Engn Dept, Berkeley, CA 94720 USA

[2] Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Environm Energy Technol Div, Berkeley, CA 94720 USA

[3] Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Div Earth Sci, Berkeley, CA 94720 USA

来源：

LANGMUIR | 2012年 / 28卷 / 02期

关键词：

COLD-START; POROUS-MEDIA; CATALYST LAYER; WATER; NUCLEATION; MODEL; GROWTH; PEFC; TEMPERATURE; PERFORMANCE;

D O I：

10.1021/la2033737

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

Nucleation and growth of ice in the fibrous gas-diffusion layer (GDL) of a proton-exchange membrane fuel cell (PEMFC) are investigated using isothermal differential scanning calorimetry (DSC). Isothermal crystallization rates and pseudo-steady-state nucleation rates are obtained as a function of subcooling from heat-flow and induction-time measurements. Kinetics of ice nucleation and growth are studied at two polytetrafluoroethylene (PTFE) loadings (0 and 10 wt %) in a commercial GDL for temperatures between 240 and 273 K. A nonlinear ice-crystallization rate expression is developed using Johnson-Mehl-Avrami-Kolmogorov (JMAK) theory, in which the heat-transfer-limited growth rate is determined from the moving-boundary. Stefan problem. Induction times follow a Poisson distribution and increase upon addition of PTFE, indicating that nucleation occurs more slowly on a hydrophobic fiber than on a hydrophilic fiber. The determined nucleation rates and induction times follow. expected trends from classical nucleation theory. A validated rate expression is now available for predicting ice-crystallization kinetics in GDLs.

引用

页码：1222 / 1234

页数：13

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