A Comparison of the Proton Exchange Membrane Fuel Cell Water Balance Measured Simultaneously with the Water Knock-out Method and Hot Wire Anemometry

The water balance of a proton exchange membrane fuel cell (PEMFC) can provide valuable insight into the state of the fuel cell. The most commonly applied method to measure the water balance is the knock-out method where the flaw gas of anode and/or cathode is cooled down and the condensed amount of water is weighed and compared to the amount of product water, while over the past years our group has developed a new method by applying hot wire anemometry at the anode outlet. In this work, a comparison between the knock-out and hot wire methods is experimentally demonstrated for 3.8 kW water-cooled PEMFC stack. The stack is run under wet conditions at different current densities and stoichiometric ratios. The hot-wire method has shown a higher sensitivity and an instant response for the measured water balance. Meanwhile, the knock-out method showed less sensitivity, much slower time response, and higher inaccuracies.