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

TitlePseudo-isothermal ice-crystallization kinetics in the gas-diffusion layer of a fuel cell from differential scanning calorimetry
Publication TypeJournal Article
Year of Publication2013
AuthorsDursch, Thomas J., Monica A. Ciontea, Gregory J. Trigub, Clayton J. Radke, and Adam Z. Weber
JournalInternational Journal of Heat and Mass Transfer
Volume60
Pagination450 - 458
Date Published5/2013
ISSN00179310
Keywordscrystallization, differential scanning calorimetry, gas-diffusion layer, Heat Transfer, kinetics, melt, nonisothermal crystallization, nucleation, polyesters, polymer crystallization, solidification
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.

DOI10.1016/j.ijheatmasstransfer.2012.12.048
Short TitleInternational Journal of Heat and Mass Transfer
DOI10.1016/j.ijheatmasstransfer.2012.12.048