Effects of Composite Sandwich Endplates on the Cold Start Characteristics of PEMFC 2010-01-1091
End-plates are highly stiff plates that hold together the components composing a fuel cell stack, i.e. Membrane Electrode Assemblies (MEAs), Gas Distribution Layers (GDLs) and bipolar plates, offering sufficient contact pressure between them. The proper contact pressure is required not only to improve energy efficiency of a stack by decreasing ohmic loss but also to prevent leakage of fluids such as hydrogen, air, or coolant. When a fuel cell starts in cold environment, heat generated in a fuel cell stack as a result of electrochemical reactions should not be used much to increase the temperature of endplates but to melt ice inside the stack to prevent ice-blocking and to increase the temperature near the three-phase-boundary on MEAs. However, to satisfy the high stiffness required, massive metallic endplates have been used despite their inferior thermal characteristics: high thermal conductivity and large thermal inertia. These metallic endplates may deteriorate the cold-start characteristics of a fuel cell stack. However, fiber reinforced composite materials have high potential for the bipolar plate applications due to their high stiffness and good thermal properties. In this work, composite sandwich endplates were developed through Axiomatic Design procedure in which a design matrix was established with their functional requirements and design parameters. In addition, their effects on the cold start characteristics of a fuel cell stack were investigated analytically and experimentally as well.