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

Journal Article · Thu Dec 01 04:00:00 EST 2011 · Langmuir

DOI:https://doi.org/10.1021/la2033737· OSTI ID:1082175

Dursch, Thomas J. ^[1]; Ciontea, Monica A. ^[2]; Radke, Clayton J. ^[1]; Weber, Adam Z. ^[3]

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1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Univ. of California, Berkeley, CA (United States)
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Nucleation and growth of ice in the fibrous gas-diffusion layer (GDL) of a proton-exchange membrane fuel cell (PEMFC) are studied 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. Finally, a validated rate expression is now available for predicting ice-crystallization kinetics in GDLs.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Fuel Cell Technologies Program (EE-3F)
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 1082175
• Report Number(s): LBNL--5393E
• Journal Information: Langmuir, Journal Name: Langmuir Journal Issue: 2 Vol. 28; ISSN 0743-7463
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Nucleation
crystallization
differential scanning calorimetry
freeze
gas diffusion layer
induction time
kinetics
model
phase change