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It is known that traffic related air contaminants cause power loss, decreasing lifetime or a complete failure of proton exchange membrane fuel cell (PEMFC). Therefore, the present study aims for a better understanding and the development of a data basis for further decisions in dealing with air contaminants for automobile applications. The first section provides an overview of scientific literature about the influence of important air contaminants on proton exchange membrane fuel cells (PEMFC). The second section describes an extensive study of air contaminants at possible automotive operating conditions using a full factorial matrix test. The specific variation of temperature, cell potential and harmful gas concentration resulted in 27 operating points for each used air contaminant. The gases NO, NO2, SO2, NH3, toluene and ethane were used. The results indicate significant degradation but as well the possibility of regeneration. The degradation caused by different harmful gases is both, dependent on temperature and potential. Furthermore, a clear difference of the influence of NO and NO2 at low concentrations could be shown. The experiments give an overview of the cathode harming potential of relevant air contaminants. Hence, the work provides a basis for the development of cathode air filter and regeneration techniques for automotive applications.

Gas crossover is an unavoidable phenomenon in proton exchange fuel cell membranes. Nitrogen and oxygen from the cathode pass through the membrane to the anode, while hydrogen crosses from the anode to the cathode. The hydrogen crossover leads to a reduction in efficiency due to parasitic hydrogen consumption and mixed potentials on the cathode electrode. Furthermore it causes degradation effects and pinhole formation. Hence the hydrogen crossover represents a fundamental factor for the lifetime of a fuel cell and quantification of the crossover is a key factor for membrane qualification. In this article two in situ electrochemical techniques to evaluate the hydrogen crossover are described, cyclic voltammetry and potential step method. Both methods and the achieved results are compared to each other. Finally the potential step method is applied to evaluate the hydrogen crossover as a function of the anode pressure and the hydrogen permeability coefficients are determined.

An LPG-based auxiliary power unit (APU) is currently being developed at the Centre for Fuel Cell Technology (ZBT). Due to the modular design of the APU, the reformer/burner module and the CO purification module, combined in the mobile gas processor (MGP), and the low temperature PEM fuel cell (PEM FC) can be developed and characterized simultaneously. While the separate characterizations of the MGP and the PEM FC are satisfactory during the initial coupling tests, a condensation problem occurs in the PEM FC, because of the high water content in the reformate gas. This paper presents two possible solutions for the prevention of condensation inside the PEM FC, when coupled with a gas processor. Analogous testing is carried out by supplying synthesized reformate gas to the PEM FC, resulting in a 360 W maximum electrical power output at 85 °C. New membrane electrode assemblies (MEAs), which are suitable for reformate gas operation at temperatures up to 90 °C, are integrated in this PEM FC. Furthermore, the impact of CO on PEM FC performance can be minimized by adding an airbleed of 1.0 mol-% of the complete anode gas. Thus, stable operation is achieved with the separate PEM FC, by supplying a synthesized anode gas, which includes a CO concentration constantly between 30 and 50 ppm. The coupling of the MGP with the PEM FC, under the improved operating conditions, leads to an electrical power output of 351 W. The overall APU efficiency is 28.5%.