Study on the Microflow Field Output Performance: Effects of Rib/Channel Dimensions and Sensitivity to Operating...

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Bipolar plate design is critical for fuel cell performance, impacting mass transfer, water discharge, and electron transport.
• Reducing bipolar plate thickness and utilizing microflow fields (<1 mm) are key for high-power density stacks but require further experimental validation.

Purpose of the Study:

• To experimentally investigate the performance of stainless-steel bipolar plates with microflow fields (0.2:0.8 mm, 0.3:0.7 mm, 0.5:0.5 mm).
• To evaluate the sensitivity of these microflow fields to cathode humidity, inlet pressures, and operating temperature.

Main Methods:

• Fabrication of three stainless-steel bipolar plates with varying rib/channel widths (0.2:0.8 mm, 0.3:0.7 mm, 0.5:0.5 mm).
• Experimental testing of these plates against a graphite control (1.0:1.0 mm).
• Analysis of performance under different cathode inlet humidity (RHc), anode/cathode pressures (Pa/Pc), and cell temperatures (Tcell).

Main Results:

• The SS-0.5/0.5 plate achieved a 59.05% higher peak power density compared to the graphite G1.0/1.0 plate.
• Optimal performance was observed at low cathode inlet humidity (RHc).
• High RHc (60%) led to water accumulation and increased mass transport resistance at high current densities.
• Microflow fields showed negligible sensitivity to anode/cathode pressures.
• Increased cell temperature significantly reduced concentration losses and alleviated water accumulation.

Conclusions:

• Microflow fields in stainless-steel bipolar plates offer superior power density compared to conventional graphite plates.
• Operating conditions, particularly low humidity and elevated temperature, are crucial for maximizing the efficiency of microflow field designs.
• Further research into water management in microflow fields at high humidity and current densities is warranted.