Electric vehicle
ElectrolyteEdge sealing gasketEdge sealing gasketAnodeCathodeAssemblyFigure 5.14
Download 3.49 Mb. View original pdf
|
| 105 Electrolyte Edge sealing gasket Edge sealing gasket Anode Cathode Assembly Figure 5.14 The construction of anode–electrolyte–cathode assemblies with edge seals. These prevent the gases leaking out of the edge of the porous electrodes Air supplied through here Hydrogen removed through here Air removed through here Channel for distributing air over cathode Hydrogen supplied through here Channel for supplying hydrogen to surface of anode Figure 5.15 A simple bipolar plate with internal manifolding, as is usually used in PEMFCs. The reactant gases are fed to the electrodes through internal tubes 106 Electric Vehicle Technology Explained, Second Edition Figure 5.16 An example of a fairly large PEMFC system. Four separate fuel cell stacks can be seen. Each consists of 160 cells in series. (Reproduced by kind permission of MAN Nutzfahrzeuge AG. This is the fuel cell stack from the bus shown in Figure 5.2, and is made by Siemens.) most promising options are discussed elsewhere, such as in Ruge and B¨uchi (2001). It is certainly the case now, and will be for many years, that the bipolar plate makes a major contribution to the cost of a fuel cell, as well as its size and its weight. Anyone who has made fuel cells knows that leaks are a major problem. If the path of hydrogen through a stack using internal manifolding (as in Figure 5.15) is imagined, the possibilities for the gas to escape are many. The gas must reach the edge of every porous electrode – so the entire edge of every electrode is a possible escape route, both under and over the edge gasket. Other likely trouble spots are the joins between each and every bipolar plate. In addition, if there is the smallest hole in any of the electrolyte, a serious leak is certain. The result is that a fuel cell is quite a difficult system to manufacture, requiring parts that are complex to form rapidly and cheaply. Very careful assembly is required, and each fuel cell stack consists of a large number of components. The system has a very low level of fault tolerance. Download 3.49 Mb. Share with your friends:
|