Analysis Of The Dynamic Response Affecting The Fuel Cell Lifetime And Economic Evaluation Of The Fuel Cell

Lifetime and cost are two main factors that affect the commercialization of Proton Exchange Membrane Fuel Cells(PEMFC). As to real operating conditions in vehicular application, the main character is that fuel cells always operate in variable load condition. And frequent load changing has the most serious influence on the performance degradation in all operating conditions. Studying the dynamic response of PEMFC to a load change and the numerical relationship with operating parameters and structural parameters have the greatest significance to the optimization of operating conditions and the mitigation of the lifetime degradation. In many existent studies about prolonging fuel cell lifetime or reducing its cost, a new lifetime evaluation method that considers the cost is imperative,which can be conducted to confirm the optimum design lifetime and the service lifetime, and have great practical significance.This paper reviewed the existing studies. Based on the researches on these literatures, strengths and weaknesses were analysed in this paper, then the research topic was proposed. An equivalent circuit model and a three-dimensional model were set up to calculate the PEMFC voltage response to a load change, and then tests were conducted to verify the results. Experimental and numerical studies were combined to study the influence of operating perameters, loading parameters and structural parameters on the voltage response. Based on the theoretical derivation and characteristic analysis, functions of three voltage response constants were presented. A starvation index number was defined to indicate the starvation grade. Operating parameters, loading parameters and structural parameters were included in the function of starvation index. These functions were an excellent guidance for designing, so as to improve the fuel cells dynamic performance.The measures promoting the fuel cells dynamic performance were studied. The functions of three voltage response constants and the starvation index were combined to present a dynamic optimization model. The starvation phenomenon was classified into local starvation and overall starvation. The diagnostic threshold value of the three stages was presented, which can be applied to optimize operating conditions. The mitigation measures avoiding the occurrence of starvation of PEMFC were studied, which included optimizing load pattern, gas pre-supply pattern, hybrid pattern and using advanced electrode material.The PEMFC economic lifetime evaluation method was presented. Based on the degradation character of the polarization curve, the PEMFC available operating range was defined. In the available operating range, the total cost including the manufacture cost and the other costs during its lifetime were considered. The average cost was the ratio of the total cost to the service time. The economic lifetime was the service lifetime corresponded to the minimum value of the average cost. The sensitivities of affecting factors to the economic lifetime were studied. The PEMFC economic lifetime evaluation method was a determination method for the fuel cell design life based on the ratio of optimal benefits and costs. It can help the engineers to choose appropriate materials and techniques, instead of merely to pursue prolonging the fuel cell lifetime.