**6. References**


(PEM) Fuel Cells. Despite a cathodic over potential loss of 20%, Pt and Pt alloys are still preferred for their resistance towards corrosion in acidic media. Pt however, being an expensive metal of low abundance, it is of interest for researchers to develop a corrosion resistant non noble metal substitutes. These non-noble metal catalysts can range from metalloporphyins and bimetallic transition metals to heat treated metal catalyst (Wang 2005; Colón-Mercado and Popov 2006; Li, Qiao et al. 2009). The main advantage of the use of nonnoble metal catalysts is the reduction in cost and ease of availability, although the precious metal based catalysts consistently have higher activity for the reaction, the results are

Mass transport limitations in PEME and PEMFC may be due to several factors. Poor control of humidification levels within the cell can result in substantial losses in potential. In addition, good electrical and ionic conduction must be achieved between the electro catalyst layer and the membrane and diffusion layers. This will enable better utilization of the

In addition, the feed provided to the PEMFC or PEME can greatly attribute to cell losses. If there are impurities present in the feed, it may affect the electrocatalyst performance or conductivity of the electrolyte. In both cases, substantial potential losses may be achieved, which may or may not be reversible, depending on the impurity present. In order to mitigate these effects, there is an on going effort to develop more tolerant electrocatalyst and

Savannah River National Laboratory is operated by Savannah River Nuclear Solutions. This document was prepared in conjunction with work accomplished under Contract No. DE-

(2004). Fuel Cell Handbook. Morgantown, WV, Department of Energy, Office of Fossil

Badwal, S. P. S., S. Giddey, et al. (2006). "Hydrogen and oxygen generation with polymer electrolyte membrane (PEM)-based electrolytic technology." Ionics 12: 7-14. Bhatia, K. K. and C.-Y. Wang (2004). "Transient carbon monoxide poisoning of a polymer

Colón-Mercado, H. R. and B. N. Popov (2006). "Stability of platinum based alloy cathode catalysts in PEM fuel cells." Journal of Power Sources 155(2): 253-263. Falcao, D. S., C. M. Rangel, et al. (2009). "Water transport through a proton-exchange

Fox, E. B., S. D. Greenway, et al. (2008). "Hydrogen isotope recovery using a cathode water vapor PEM electrolyzer." Fusion Science and Technology 54(2): 483-486.

electrolyte fuel cell operating on diluted hydrogen feed." Electrochimica Acta 49:

membrane (PEM) fuel cell operating near ambient conditions: experimental and

promising.

**4. Conclusion** 

membranes for these systems.

**5. Acknowledgment** 

2333-2341.

**6. References** 

catalyst and limit cell losses through mass transport.

AC09-08SR22470 with the U.S. Department of Energy.

Energy, National Energy Technology Laboratory.

modeling studies." Energy & Fuels 23: 397-402.


**14** 

*1China 2Japan* 

**Moisture Transport Through a Porous Plate with Micro Pores** 

*1State Key Laboratory of Engine, Tianjin University* 

*2Division of Systems Research, Faculty of Engineering, Yokohama National University* 

Considering the variety of environment problems, including global warming, that call for a reduction in emission gases, increasing the fuel efficiency and reducing exhaust gases from automobiles has become an important issue for the automobile industry. Compared to traditional automobiles, fuel cell vehicles have many advantages, including high efficiency, low emissions, and diversification of fuel supply. Therefore, fuel cell vehicles are expected to become a viable means of transportation in the 21st century. Consequently, extensive research is being conducted to develop fuel cell vehicles that use polymer electrolyte

Fuel cell systems for vehicles are composed primarily of a fuel and air supply unit, a humidifier, a cooling device, and the polymer electrolyte membrane fuel cell (PEMFC). Since the degree of ion conduction in an electrolyte film in the fuel cell is determined by the water content of the film, some water content is necessary in order to maintain ion conduction in the film. Generally, the film is humidified through gas diffusion layer (GDL) using high humidity work gases. The research on the humidifying methods and the influence of the humidity of work gases on the performance of fuel cells have been reported by Nguyen & White (1993) and Yoshikawa et al. (2000), respectively. Buchi & Scherer (2001) investigated the effects of the water content and the membrane thickness on the

From the point of view of saving space, it is desirable to recover and reuse the humidity in the exhaust gas using the supply air. In the present study, a method involving a thin porous plate for air dehumidification(Asaeda et al., 1984, 1986),in which direct recovery of the moisture of the exhaust gas to the supply air through a thin porous plate or membrane, is considered. In this case, the following phenomena may occur: 1) mass and heat transport and an accompanying phase change inside the porous plate, 2) water evaporation from the surface of the porous plate and moisture diffusion around the surface of the plate on the supply air side, and 3) condensation of moisture on the porous plate surface on the exhaust gas side. Analysis is difficult because of the complex interaction between these phenomena. Therefore, in order to simplify our investigation, as a first step, we focus on the heat and mass transport characteristics on the supply gas side and inside the porous plate. In order to fix the heat and mass transfer characteristics of the exhaust side, we assume that the

**1. Introduction** 

membrane fuel cells as a power source.

resistance of Nafion membranes in PEMFC.

Shixue Wang1 and Yoshio Utaka2

