Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.
This paper describes experimental results performed on the basic purge characteristics of the anodic dead-end mode fuel cell how to increase the purge period using the pulsation effect, and then how to operate anodic dead-end mode fuel cell without purge cycles. In anodic dead end mode fuel cell, the purge is essential to avoid the flooding problems caused by the liquid water formed in the channel which can block the porosity of the GDL and reduce the active area. However, the un-reacted hydrogen can be discharged in purge process although it can be thought to be a little. Therefore, the purge frequency should be as short as possible for increasing the fuel efficiency. Experimental results show that it decreased when the current density decreases, the operation pressure increased. When the pulsation effect such as various frequencies or amplitudes in the outlet of anode channel was applied to fully humidified hydrogen, the number of purge was alleviated op to one third. In addition, when the dry hydrogen was supplied and oscillated in the channel, the pulsation effect can make the purge interval much longer, moreover, it can be an auxiliary humidifier using the back diffusive water vapor, which is a novel concept of the humidification. Finally, the purge cycle was eliminated by connecting the Nation chamber to the outlet of anode, which can improve the fuel efficiency. The wall of the chamber is made of Nafion® 117 membrane that can transmit the water vapor selectively, which is also a novel concept of operating the dead-end mode fuel cell.