Analyzing and Modeling of Co Purging for High-Temperature Proton Exchange Membrane Fuel Cells

Abstract

Purge is a simple, economical method to remove inert gases accumulated in high-temperature proton exchange membrane fuel cells (HT-PEMFC) in dead-end anode (DEA) mode. However, early works mainly focused on inert gases. Since HT-PEMFC has strong adsorption of CO, the application of inert gas methods for CO purification becomes challenging. In this paper, a CO purging model was established and verified experimentally. By using this model, the key parameter of the CO concentration within the anode was analyzed, and the theoretical extreme values were deduced. Finally, purging strategies under different operating conditions were proposed. The results show the minimum concentration of CO inside the HT-PEMFC is affected by the current, feed gas flow rate and feed gas CO concentration, while the maximum concentration of CO is also affected by the off-duration of the purge valve in addition to the above. Under the operating condition of 200 °C, the CO concentration threshold purge strategy should be adopted, while under the operating condition of 175 °C, voltage drop and CO concentration threshold purge strategies should be adopted respectively above and below the cutoff line according to the current. The research helps to solve the problem of CO accumulation in DEA mode.

Keywords: High temperature proton exchange membrane fuel cell (HT-PEMFC), CO poisoning, CO purge, Purge strategy, Dead-end anode