EXPERIMENTAL EVALUATION OF CELL TEMPERATURE EFFECTS ON MINIATURE, AIR-BREATHING PEM FUEL CELLS

An experimental analysis of cell temperature effects on an air-breathing, PEM fuel cell is presented. The cell was tested in three active area sizes of 5 cm(2), 10 cm(2), and 25 cm(2). The cell's design minimized the influence of self-heating by using a large thermal body in its construction which conducted heat away from the active area. This allowed for the use of a heater and controller to test a constant cell temperature uninfluenced by current density. Polarization and electrochemical impedance spectroscopy testing showed that at higher current density, elevated temperature increased the buoyancy of the air around the cell which improved open cell performance. However, the opposite is true for lower current density as membrane dehydration becomes more prevalent at higher temperatures. Schlieren imaging, in conjunction with the polarization and EIS data, shows how heated and more buoyant air boosts cell performance. Infrared imaging identifies temperature gradients on the active surface which may hinder cell performance slightly.