Numerical Analysis of Three Operating Parameters on Dynamic Cell Performance of Proton Exchange Membrane Fuel Cell

Abstract:

In order to characterize the effects of operating temperature， relative humidity， and back pressure on the proton exchange membrane fuel cell （PEMFC） performance at the applied step current， a dynamic transfer （DT） model that accounts for the coupled variation between relative humidity and operating temperature is established， which illustrates the characteristic relationship between membrane electrode parameters and PEMFC performance parameters in terms of operating temperature and relative humidity， and analyses the differences between two operating parameters on the transient response of water transport inside PEM， output voltage， and power density distribution with time at the applied step current. A combination of theoretical calculations and experiments is proposed. First， the DT model including geometry and meshes is embedded into Fluent and the data in the solver of Fluent is called to simulate the electrochemical reactions. Secondly， experiments are conducted regarding the effect of temperature（50 ℃， 60 ℃ and 70 ℃）， back pressure（0 and 10 kPa）， and relative humidity（50%， 75% and 100%） on the transient response like voltage and power density. Finally， the transient response for voltage output， water transport inside the PEM， and power density distribution with time via polarization curves， contours， and I-P curves with time are compared and analyzed. The results indicate that the DT model is in good agreement with the experimental data observed， which elucidates that the anode relative humidity determines the capability of power density to operate steadily after the applied step current and the power density response time and the amplitude of undershoot are related to membrane. When the back pressure is 10 kPa，the anode relative humidity is 75%， and the cathode relative humidity is 100% at an operating temperature of 60 °C， PEMFC has the best dynamic performance.