Study On Individual Cell Voltage Uniformity Of PEMFC Stack

That the single cell of PEM fuel cell stack have lower voltage can produce short-board effect, constraining high performance of the stack. This paper aims to study individual cell voltage uniformity of the PEM fuel cell stack in the rated condition. By means of experiments and theoretical analysis, the various operating parameters on individual cell voltage uniformity can be studied. The Taguchi method is applied to determine the optimum operating parameters of the PEM fuel cell stack.The main research contents and results are as follows:(1) Theoretic analysis indicated that the main factors on individual cell voltage uniformity of the PEM fuel cell stack will be different as the load is at different regions of current density; The average deviation from the mean cell voltage, suitable for all situations, can reflect individual cell voltage uniformity really and effectively, which is considered to be the best evaluation method.(2) When operating parameters of the PEM fuel cell stack increase,the individual cell voltage uniformity gets better gradually, reaches the optimal value, and then becomes worse gradually. This phenomenon was mainly because the impact operating parameters have on the individual cell voltage uniformity has a dual effect, when the positive effect is greater than the negative effect, its individual cell voltage uniformity gets better; when the positive effect than negative effect, its individual cell voltage uniformity gets worse. When the stoichiometric ratio of air,inlet pressure,the temperature and humidity are 4,200kPa,60℃and 80%, respectively,individual cell voltage uniformity of the PEM fuel cell stack reaches the best.(3) In the operating parameters, reaction gas inlet pressure are highly significant factors and the stack temperature T and the stoichiometric ratio of air are significant factors; When the stoichiometric ratio of air,inlet pressure,the temperature and humidity are 4,200kPa,60℃and 80%, respectively,individual cell voltage uniformity of the PEM fuel cell stack reaches the best. In the working conditions, when the load is 180A, a 0.692% average deviation from the mean cell voltage is measured, within the calculated confidence intervals[0.531%0.851%]. This case states that the best conditions optimized is reproducible and reliable.