Study on Self-Humidification in PEMFC with Crossed Flow Channels and an Ultra-Thin Membrane

Area of Science:

• Electrochemistry
• Energy Conversion
• Materials Science

Background:

• Proton exchange membrane fuel cells (PEMFCs) are crucial for clean energy generation.
• Achieving efficient self-humidification in PEMFCs is key to simplifying system design and reducing costs.
• Understanding the impact of operating conditions on self-humidification is vital for optimizing PEMFC performance.

Purpose of the Study:

• To develop and validate a 3D model of a PEMFC with crossed channels for self-humidification analysis.
• To investigate the feasibility of self-humidification in PEMFCs without external humidifiers.
• To examine the effects of operating conditions on self-humidification and cell performance.

Main Methods:

• Development of a 3D computational model for a PEMFC with crossed channels and an ultra-thin membrane.
• Experimental validation of simulation results using a PEMFC stack with identical configurations.
• Systematic variation of operating conditions, including temperature, pressure, and current density, to assess self-humidification.

Main Results:

• Crossed flow channels enhance water distribution uniformity, improving performance under low/no humidification.
• Anode external humidifiers can be eliminated, with negligible performance difference (≤3%) between 0% and 100% relative humidity.
• Self-humidification is achievable in PEMFC stacks at or below 90 °C with back pressures of 100-200 kPa.
• Voltage crossover points, indicating optimal self-humidification, occur between 60-80 °C with suitable pressure.
• Performance is limited by membrane unsaturation at low relative humidity and flooding at high relative humidity, with an optimal current density dependent on pressure and temperature.

Conclusions:

• Crossed channel design facilitates effective self-humidification in PEMFCs.
• PEMFC systems can operate without external humidifiers, simplifying design and potentially reducing costs.
• Optimal operating conditions (temperature, pressure, current density) are critical for achieving efficient self-humidification and maximizing performance.