Affiliation:
1. Tongji University, School of Automotive Studies
Abstract
<div class="section abstract"><div class="htmlview paragraph">Proton exchange membrane fuel cell (PEMFC) is a promising next-generation energy
conversion device. The response characteristics of mass transfer and
electrochemical reactions during a transient process affect the cell performance
and still require further investigation. Experiment is conducted to measure
current density distribution under varying load and reactant flow rate in a
commercial-size single cell. Local current density around cathode inlet is
higher in normal operating conditions due to higher local oxygen concentration.
Such area performs a better transient response when a step change of load
current is demanded leading to much larger current density at cathode inlet and
lower at outlet. The redistribution of reactant gas concentration in a
commercial-size fuel cell happens after the load change and takes a few seconds.
After the redistribution a balance is reached and current density distribution
tends to get more homogeneous with lower performance at cathode inlet and higher
at outlet. Inhomogeneous current density distribution indicates inadequate use
of catalyst and more energy dissipated caused by in-plane potential difference.
Cell voltage and the overall cell performance has a negative linear correlation
with the inhomogeneity of local current density during a transient process when
fuel cell is supplied with more reactant gas or has a higher load current demand
while keeping the gas flow constant. This work leads to suggestion on flow
control strategy during dynamic load demands. The results also lay a foundation
for further study into the design of flow channel in the fuel cell for better
transient response characteristics and wider application conditions.</div></div>