Experimental diagnostics of PEM fuel cells

Abstract

In this study, water removal techniques were experimentally developed as a diagnostic tool for the investigation of polymer electrolyte membrane (PEM) fuel cell performance in order to achieve consistent, reliable and repeatable performance. The three water removal methods developed include cell orientation, cell shaking and hydraulic permeation, and instantaneous improvement in the fuel cell performance had been observed when these methods were employed. All the experiments were carried out with a single PEMFC with the active surface area of 50 cm2. Pure hydrogen was used as fuel and air was used as oxidant. It was found that operating the fuel cell at an orientation of 45 degrees towards gas outlet ports helped removing trapped liquid water from the cathode side; when cell assembly was shaken during the fuel cell operation, liquid water was observed to be removed from the cell structure and cell performance was improved. Water removal by hydraulic permeation was achieved by maintaining the pressure of hydrogen stream 10 kPa lower than that of air stream, which helped water removal by the anode gas stream. It was observed that the simultaneous application of these water removal methods allowed the test results obtained to be consistent, reliable and repeatable, and in general it increased the performance by 25% in ohmic polarization region and 30% in mass transport dominant region. Then these methods were applied to investigate the effects of the various operating conditions on the performance of the PEM fuel cell, including the effect of reactants temperature, pressure, stoichiometry, humidification and cell aging.