Abstract:

The transport and freezing characteristics of super-cooled water in proton exchange membrane fuel cell (PEMFC) were studied to find effective sub-freezing start-up strategies and to explore the feasibility of utilizing super-cooled water transport to improve the sub-freezing start-up capability. The water storage capacity and sub-freezing start-up capability of PEMFC were estimated, and the amount of cumulative water during subfreezing start-up process was measured experimentally. The results show that the transport of the super-cooled water in the PEMFC at –10 ℃ and –20 ℃ can effectively expand fuel cell water storage capacity leading to the improvement of the sub-freezing start-up capability. The survival time of the PEMFC can be prolonged by increasing the temperature and reducing the start-up current density and fuel cell active area. However, the randomness of sub-freezing start-up process resulting from the existence of the super-cooled water in the PEMFC will affect the stability of super-cooled water utilization.

Key words: proton exchange membrane fuel cell (PEMFC) , sub-freezing start-up ,  super-cooled water , randomness