Polymer electrolyte membrane fuel cells are carbon-free electrochemical energy conversion devices that are appropriate for use as a power source on vehicles and mobile devices emerging with their high energy density, lightweight structure, quick startup and lower operating temperature capabilities. However, they need more developments in the aspects of reactant distribution, less pressure drops, precisely balanced water content and heat management to achieve more reliable and higher overall cell performance. Flow field development is one of the most important fields of study to increase cell performance since it has decisive effects on performance parameters, including bipolar plate, and thus fuel cell weight. In this study, recent developments on conventional flow field designs to eliminate their weaknesses and innovative design approaches and flow field architectures are obtained from patent databases, and both numerical and experimental scientific studies. Fundamental designs that create differences are introduced, and their effects on the performance are discussed with regard to origin, objective, innovation strategy of design besides their strength and probable open development ways. As a result, significant enhancements and design strategies on flow field designs in polymer electrolyte membrane fuel cells are summarized systematically to guide prospective flow field development studies.

Transient regime effects are particularly important in fuel cells designed for vehicles. Three-dimensional modeling of a proton exchange membrane fuel cell with a serpentine channel is presented, and the response of the fuel cell to a step-change in the mass flow rates is analyzed by using the computational fluid dynamics techniques. After a validation study of the mathematical and numerical model, step increases of 20% in mass flow rates are applied to the inlet boundary conditions, and time dependent power and current density responses of the fuel cell are analyzed. Polarization curves are generated for the assessment of the fuel cell performance, and their variations in time are presented. The results show that current and power densities increase with time at low cell voltage values due to concentration losses; however, increases in power and current are negligible at high voltages.

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