Abstract:

This study aims to examine the impact of temperature and humidity on the output performance of automotive fuel cells. To this end, we propose a temperature and relative humidity-current (TRH-C) model. This model accounts for three sources of water: electrochemical reaction, electroosmotic migration, and humidification and condensation. It reveals the pattern of current variations with temperature and humidity and provides a calculation formula for the electroosmotic migration coefficient characterized by water activity. To implement our model, we established a grid in COMSOL and introduced the TRH-C model, which was then calculated using the finite volume method. We then built a fuel cell test system and conducted experiments at operating temperatures of 60 ℃ and 70 ℃, and relative humidity of 50% and 100%. We compared the polarization curve obtained from the TRH-C model with the experimental data and analyzed the cloud map of current density and film water content distribution. Our findings suggest that the TRH-C model can accurately predict fuel cell performance. However, we observed that when the operating temperature is 60 ℃ and the relative humidity is 50%, the relative errors of voltage and power density (with a current density of 0.018 A/cm²) are the largest, at 3.674% and 3.696%, respectively. We also found that an increase in operating temperature results in a decrease in membrane water content, while an increase in relative humidity leads to an increase in membrane water content.

Key words: temperature and relative humidity, automotive fuel cell, current density distribution, water content