Mesoscopic process of multiphase reactive flow and heat transfer during direct cold start process in Pt/C particle coated in ionomer of PEMFC

Abstract

To explore multiphase reactive flow and heat transfer process during direct cold start in catalyst layer of proton exchange membrane fuel cell, a pore scale model was established. Effects of released gaseous water particle number, platinum volume fraction, ionomer thickness, and carbon support diameter were studied. The results reveal that due to obstruction of ice at bottom, oxygen cannot fully enter the bottom. After motion of solid ice is completely melted, the obstruction of the bottom on oxygen transport weakens, and oxygen gradually enters the bottom of the catalyst layer. As the number of gaseous water particles increases, the frost layer becomes thicker, and the resistance of the frost layer to oxygen diffusion becomes more significant. The increase in platinum particles elevates temperature within the catalyst layer, accelerating melting of solid ice within the catalyst layer. The carbon support diameter only has an effect on the intermediate concentration region. When the carbon support diameter is 26 nm, more oxygen enters the ionomer due to the weakened obstruction of the frost layer. Increasing the carbon support diameter lowers the temperature within the catalyst layer.