Performance Enhancement in Proton-Exchange Membrane Fuel Cell for Cathode Pulsating Flow

The effect of cathode flow pulsation on the performance enhancement of a 10-cell proton-exchange membrane fuel cell is investigated. We perform the experiment using two pulsation devices. One pulsation device, i.e., acoustic woofer, generates a pulsating flow, which is added to a unidirectional flow supplied from a compressed air tank. The other pulsation device is a crankshaft system that produces a pure oscillatory flow without mean flow. In the case of cathode pulsating flow with mean flow, the fuel cell power output and the limiting current density dramatically increase as pulsating frequency increases at given pulsating amplitude, while the fuel cell efficiency slightly decreases. This result is contributed that the pulsating flow enhances the dispersion inside the cathode channels, and then improving the oxygen and temperature distributions. This performance enhancement by cathode pulsating flow is more distinct at low cathode mean flow rates. In the case of cathode pulsating flow without mean flow, the fuel cell stack is operated despite cathode mean flow is absent. The limiting current density is extended as the pulsating frequency and swept distance (amplitude) increase. When the pulsating frequency and swept distance are 2.38Hz and 13.65mm respectively, the fuel cell performance is equal to that the cathode mean flow rate is 1.29 lpm. Also, the case of pulsating flow is more stable at the concentration loss region than the case of non-pulsating flow for the same performance conditions.