Fuel cell systems working principles

Practical fuel cell systems are very complex to design and build—especially small, rugged ones for cars, trucks, and buses, which must stand up to bumps and to temperature variations. (This is one reason why it took so long to put the first prototypes on the road.) But the basic principle of how a fuel cell works is fairly straightforward. 

Shah and Besser presented results from their development work that was aimed at a 20-Wd methanol fuel processor/fuel cell system [436]. The principle layout of the device consisted of a methanol steam reformer, preferential oxidation, a catalytic afterburner and an evaporator The basic process and design parameters are summarised in Table 9.3. Nevertheless, it is obvious that the size of the steam reformer exceeded by far the size of all other components. The weight hourly space... 

Polymer Electrolyte membrane Fuel Cells (PEFC) are used to power uninterruptible power supplies, combined heat and power generation systems, vehicles for materials handling as well as electric vehicles, busses and light duty road vehicles. This contribution gives a short introduction into the working principles of PEFC as well as the materials and components used. 

The fuel and oxidant conditioning subsystem involves purification, preheating, and humidification devices. As mentioned in the previous chapters, PEM fuel cell durability can be improved if pure hydrogen and oxygen are supplied. However, hydrogen is usually produced from hydrocarbon fuels and ambient air is often used as the oxidant. Both of them contain impurities such as CO, SOj, NH3, and so on (Du et al, 2009). Therefore, impurity filters are important to improve the durability. Different filters have been developed to remove the different impurities (Lakshmanan et al., 2002 Donaldson Company Inc. 2003 Du et al, 2009). However, most filters work on the principle of chemical adsorption and dusty filtration, and have to be replaced or serviced periodically. This adds additional service cost to the system (Du et al., 2009). Preheating and humidification of the fuel and oxidant are also very important, not only to improve the cell performance, but also to enhance the durability of membrane. 

Fuel cells work on a basic chemical principle and use some very modern engineering. A cell contains an anode, a cathode and an electrolyte layer, with a typical system being shown in Figure 2.1. 

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