Effects of cell-to-cell fuel mal-distribution on fuel cell performance and a means to reduce mal-distribution using MEMS micro-valves

• Published in: Journal of power sources Vol. 164; no. 1; pp. 115 - 125
• Main Authors: Hensel, J. Peter, Gemmen, Randall S., Thornton, Jimmy D., Vipperman, Jeffrey S., Clark, William W., Bucci, Brian A.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 10-01-2007; Elsevier Sequoia
• Subjects: 30 DIRECT ENERGY CONVERSION; Applied sciences; EFFICIENCY; Energy; ENERGY MANAGEMENT; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Flow imbalance; FLOW RATE; Fuel cell energy management; FUEL CELLS; MEMS; Micro-valve; PEMFC; PROTON EXCHANGE MEMBRANE FUEL CELLS; PEMFC; MEMS; Fuel cell energy management; Micro-valve; Flow imbalance; Cooling; Voltage current curve; Polymer electrolytes; Valve; Performance; Energy management; Fuel cell
• DOI: 10.1016/j.jpowsour.2006.09.049
• EISSN: 1873-2755
• ISSN: 0378-7753

Achieving uniform flow among the cells of a fuel cell stack plays a significant role in being able to operate at maximum capability and efficiency. This paper presents experimental data showing the importance of cell-to-cell fuel flow balancing on fuel cell performance, and a fuel cell energy management (FCEM) technique that has demonstrated the ability to improve stack performance. In a specially instrumented four-cell polymer electrolyte fuel cell that allows external control of the air, fuel, and water-cooling flows to each cell, fuel to a single cell was reduced.
V–
I curves collected under these unbalanced conditions are compared to curves collected when the fuel flow to each cell was balanced. Reducing the fuel flow to a single cell by 11% decreased the
V–
I curve cutoff load by 10%—demonstrating the degree of negative effect that unbalanced fuel flows can have on stack performance. Typical fuel cell stacks have no dynamic means to keep flows in the stack balanced between the cells, but through the use of custom-built, piezoelectric micro-valves, a simple flow control strategy, and this custom four-cell laboratory stack, the positive effects of FCEM flow balancing at three different fuel flow rates was demonstrated.