Pseudo-isothermal ice-crystallization kinetics in the gas-diffusion layer of a fuel cell from differential scanning calorimetry

Date Published
05/2013
Publication Type
Journal Article
Authors
DOI
10.1016/j.ijheatmasstransfer.2012.12.048
Abstract

Non-isothermal ice-crystallization kinetics in the fibrous gas-diffusion layer (GDL) of a proton-exchange-membrane fuel cell is investigated using differential scanning calorimetry (DSC). Non-isothermal ice-crystallization rates and ice-crystallization temperatures are obtained from heat-flow measurements in a water-saturated commercial GDL at cooling rates of 2.5, 5, 10, and 25 K/min. Our previously developed isothermal ice-crystallization rate expression is extended to non-isothermal crystallization to predict ice-crystallization kinetics in a GDL at various cooling rates. Agreement between DSC experimental results and theory is good. Both show that as the cooling rate increases, ice-crystallization rates increase and crystallization temperatures decrease monotonically. Importantly, we find that the cooling rate during crystallization has a negligible effect on the crystallization rate when crystallization times are much faster than the time to decrease the sample temperature by the subcooling. Based on this finding, we propose a pseudo-isothermal method for obtaining non-isothermal crystallization kinetics using isothermal crystallization kinetics evaluated at the non-isothermal crystallization temperature.

Journal
International Journal of Heat and Mass Transfer
Volume
60
Year of Publication
2013
Pagination
450 - 458
ISSN Number
00179310
Short Title
International Journal of Heat and Mass Transfer
Keywords
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Research Areas
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