Experimental investigation on PEM fuel cell cold start behavior containing porous metal foam as cathode flow distributor

Metal foam has been regarded as one of the most important replacement for the conventional flow distributor of commercial fuel cells in recent years. One critical issue for the commercialization of proton exchange membrane (PEM) fuel cell is the successful startup from subzero temperatures. In this study, experimental tests on a PEM fuel cell using nickel metal foam as the cathode flow distributor are carried out to investigate the cold start performance. The cold start performance is also compared to a PEM fuel cell with parallel flow channels. Both galvanostatic and potentiostatic control are considered. The results show that under normal operating conditions the metal foam PEM fuel cell exhibits higher maximum net power density than the cell with parallel flow channels, whereas the parallel channel case exhibits slightly better performance at lower current densities. For cold start tests, metal foam is superior to the conventional parallel flow channel under galvanostatic control, due to its extremely porous structure, uniform mass and heat distribution. It is more difficult for PEM fuel cell under potentiostatic control to successfully start up due to possible ice blockage at the outlet.