Naslov
Polarization Change Curves for Characterization of Fuel Cell Stacks Performance Degradation

Autori
Bezmalinović, Dario ; Šimić, Boris ; Barbir, Frano

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Proceedings 2014 CARISMA Conference / - , 2014

Skup
CARISMA 2014

Mjesto i datum
Cape Town, Južnoafrička Republika, 01.12.2014. - 03.12.2014

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
degradation; fuel cell; polarization change curve;

Sažetak
The polarization-change curve is a curve obtained by subtracting the actual cell potential from the potential at the beginning of life (BOL) for an entire spectrum of current densities. By the shape of the curve it is possible to distinguish between different sources of performance losses, or polarizations, namely: 1) activation polarization (kinetic losses), 2) ohmic or resistive losses 3) concentration polarization or mass transport losses and 4) internal currents and/or crossover losses. For example, the polarization change curve of a 10-cell stack, that was operated for 1600 hours under current control using a predefined 24 h load cycle, and exhibited potential degradation of 35, 8 microV/hr per cell (at 0, 4 A/cm2) shows that this degradation was caused by an increase in activation polarization, an increase in cell resistance and an increase hydrogen crossover. The combined effects of stack development and a selection of operating parameters, resulted in significantly prolonged operation (15000 hours) with significantly reduced degradation of 10, 3 microV/hr per cell (at 0, 4 A/cm2). The polarization change curve showed that activation polarization and hydrogen crossover did not increase over time, and degradation was caused solely by an increase in cell resistance. The polarization change curves provide some insight in degradation causes in fuel cell stacks and therefore may be used as a diagnostic tool, not only at the end of the life but throughout the operating life so that the corrective measures, such as changes in operating conditions, could be taken.

Izvorni jezik
Engleski

Znanstvena područja
Kemijsko inženjerstvo, Strojarstvo

POVEZANOST RADA