Fuel cell classification

Fuel cells are primarily classified into five categories (Table 11.1) according to the electrolyte material used. Since the choice of electrolyte material plays an important role in determining the operating temperature of the fuel cell, this parameter may be used interchangeably in fuel cell classification. Table 11.1 presents the different kinds of fuel cells, respective electrolytes used, and operating temperature range of the fuel cell. 

Most fuel cells being developed consume either hydrogen or fuels that have been preprocessed into a suitable hydrogen-rich form. Some fuel cells can directly consume sufficiently reactive fuels such as methane, methanol, carbon monoxide, or ammonia, or can process such fuels internally. Different types of fuel cells are most appropriately characterized by the electrolyte that they use to transport the electric charge and by the temperature at which they operate. This classification is presented in Table 7.4. 

The other type of model is the macrohomogeneous model. These models are macroscopic in nature and, as described above, have every phase defined in each volume element. Almost all of the models used for fuel-cell electrodes are macrohomogeneous. In the literature, the classification of macrohomogeneous models is confusing and sometimes contradictory. To sort this out, we propose that the macrohomogeneous models be subdivided on the basis of the length scale of the model. This is analogous to dimensionality for the overall fuel-cell models. 

The fuel cell electrode reactions are catalyzed by different materials in different temperature ranges. A classification of the fuel cells can be made on the basis of the electrolyte, which in turn determines the operating temperature and, with it, the catalysts to be applied in the electrodes. The electrode reactions that take place in the different types of fuel cells are summarized in Table 3, which also lists the electrolytes and operating temperatures [56]. 

Table 3.2 Classification of fuel cells and their main characteristics...

Table 3.2 reports the classification of the different types of fuel cells with some technical characteristics [6]. In this table the different electrolytes are specified together with the type of ions exchanged through them, while the catalysts indicated are those used on both anode and cathode to accelerate the semi-reactions (not necessary for SOFC thanks to their high operative temperature). 

Several fuel ceU types are imder development, and they have a variety of potential applications. Fuel cells are being developed to power passenger vehicles, commercial buildings, homes, and even small devices such as laptop computers. The type of fuel cell technology utilized is often dictated by the constraints of its operating environment. Thus, we have chosen the following application classification scheme stationary, portable, and mobile applications. 

This is also called the Solid Polymer Fuel Cell (SPFQ and the Direct Methanol Fuel Cell (DMFC) is included in this classification. These cells use a solid perfluorinated sulfonated polymer ion exchange membrane (e.g. DuPont Nafion) [65] in the form of a thin plastic film, which serves as the electrolyte in the PEM fuel cell operating at 50-100°C. 

The most common classification of fuel cells is by the type of electrolyte used as shown in Table 1 which summarizes the most commonly used fuel cell technologies and their applications. The operating temperature and useful life of a fuel cell dictate the physicochemical and thermomechanical properties of materials used in the cell components (i.e., electrodes, electrolyte, intercoimect, cm-rent collector, etc.)... 

Principles, Functions, and Classification of Fuel Cells 435 Tab. 2 Operating parameters of different types of fuel cells... 

General Aspects and Classification of Fuel Cell Systems. Despite their... 

Carbonate Fuel Cell), and SOFC (Solid Oxide Fuel Cell). An exception to this classification is the DMFC (Direct Methanol Fuel Cell) which is a fuel cell in which methanol is directly fed to the anode. The electrolyte of this cell is not determining for the class. Table 1.1 compares the different types of fuel cell systems [2, 5-8]. A schematic representation of a fuel cell with reactant and product, and ions flow directions for these types of fuel cells are shown in Figure 1.2 [6]. 

Fuel-cell hybrid systems are also very attractive for material handling applications as a replacement for batteries in electric-powered forklift trucks. The classification of forklift trucks is shown in Figure 36.19 and can be divided into three classes [74] ... 

Fuel cells are electrochemical devices that convert chemical energy contained in fuel directly into electrical energy through electrochemical reactions. Fuel cells consist of an anode, where the fuel is oxidized, a cathode where the oxidant is reduced and an electrolyte which separates anode from cathode and conducts ions. The general classification of fuel cells is usually based on the type of electrolyte used, and their operation conditions are typically related to the characteristics of the electrolyte. More detailed discussion of fuel cells as stand-alone power sources can be found in the next chapter of this book. 

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