Exergy Analysis of a PEM Fuel Cell System with Different Bipolar Plate Flow Fields

One of the most important part of the Proton Exchange Membrane Fuel Cell(PEMFC) is represented by the graphite-type bipolar plate, witch is also one of the most expensive components of the fuel cell system. In the present study, three different serpentine-type flow field models with folowing geometrical dimensions of channel width/rib width a/w, in mm: 0.9/0.9, 0.78/0.9 and 0.78/0.82, created by milling on graphite bipolar plates have been experimentally tested in a fuel cell. A BEKKTECH BT-552 PEMFC test station was used to investigate the electrical performance of a single fuel cell unit incorporating each of the flow field models at two different backpressures: 70 kPa and 30 kPa. The fuel cell having bipolar plates with flow channel dimensions a/w = 0.78/0.82 presented the highest exergetic efficiency at a backpressure of 70 kPa, with values between 53.3 % and 34.1 % at current densities from 0.05 to 1 A/cm² and generated electrical power between 0.23 and 3.13 W, and also the the lowest thermodinamic irreversibilities between 0.86 – 5.78 W at the same backpressure and domain for current density and power.