Fuel cell definition

Assuming constant definition of industrial sectors and no changes in net foreign trade, there is a substantial structural effect of mobile fuel cells on industrial branches (see Fig. 13.13). 

Other Although not R D, it should prove beneficial for fuel cell developers to provide species tolerance specifications to fuel processor developers established by standard definition, determination methods, and measurement procedures. This would aid the fuel processor developer to develop products compatible with various fuel cell units. Of particular importance are sulfur and CO limits. 

For every molecule of hydrogen (H2) that reacts within a fuel cell, two electrons are liberated at the fuel cell anode. This is most easily seen in the PAFC and PEFC because of the simplicity of the anode (fuel) reaction, although the rule of two electrons per diatomic hydrogen molecule (H2) holds true for all fuel cell types. The solution also requires knowledge of the definition of an ampere (A) and an equivalence of electrons. 

PTC 50 ASME Performance Test Code - Will provide test procedures, methods and definitions for the performance characterization of fuel cell power systems. 

ASME PTC 50 ASME Performance Test Code 50 - Fuel Cell Power Systems provides test procedures, methods and definitions for the performance characterization of fuel cell power systems. The code specifies the methods and procedures for conducting and reporting fuel cell system ratings. Specific methods of testing, instrumentation, techniques, calculations and reporting are presented. This standard is currently being drafted and is expected to be approved and published in 2002. 

The definition of reformate tolerance is that, compared to running on pure H2, a fuel cell stack can run on reformate and show no change in performance, apart from that expected for dilution effects (of H2 due to CO2, N2, H2O). This requires the development of reformate-tolerant anode catalysts capable of tolerating the remaining levels of CO and CO2 in the fuel feed. 

The following definitions are used during the course of discussions on batteries, fuel cells, and electrochemical capacitors. 

As a compromise between the above two approaches, the third approach adopts nonactive (inert) materials as working electrodes with neat electrolyte solutions and is the most widely used voltammetry technique for the characterization of electrolytes for batteries, capacitors, and fuel cells. Its advantage is the absence of the reversible redox processes and passivations that occur with active electrode materials, and therefore, a well-defined onset or threshold current can usually be determined. However, there is still a certain arbitrariness involved in this approach in the definition of onset of decomposition, and disparities often occur for a given electrolyte system when reported by different authors Therefore, caution should be taken when electrochemical stability data from different sources are compared. 

Apart from mechanistic aspects, we have also summarized the macroscopic transport behavior of some well-studied materials in a way that may contribute to a clearer view on the relevant transport coefficients and driving forces that govern the behavior of such electrolytes under fuel cell operating conditions (Section 4). This also comprises precise definitions of the different transport coefficients and the experimental techniques implemented in their determination providing a physicochemical rational behind vague terms such as cross over , which are frequently used by engineers in the fuel cell community. Again, most of the data presented in this section is for the prototypical materials however, trends for other types of materials are also presented. 

Sometimes, there are just indirect mechanistic relationships, or the existence of completely independent transport paths (e.g., protonic charge carriers and electronic holes in oxides). Parasitic transport frequently limits the fuel-cell performance, and a mechanistic understanding is definitely useful in the development of separator materials. 

First, we will refer to the direct use of hydrocarbon fuels in an SOFC as direct utilization rather than direct oxidation. Second, we recognize that the broadest definition of direct utilization, exclusive from mechanistic considerations, should include rather conventional use of fuel by internal reforming, with steam being cofed to the fuel cell with the hydrocarbon. Indeed, this nomenclature has been used for many years with molten-carbonate fuel cells. However, because internal reforming is essentially limited to methane and because the addition of steam with the fuel adds significant system complexity, we will focus primarily on systems and materials in which the hydrocarbons are fed to the fuel cell directly without significant amounts of water or oxygen. 

The basis of this definition is that a fuel cell run by the products from the photoelectrolysis cell supplies a part of its output to the photoelectrolysis cell as electrical bias. The combined system must have a significant positive energy output to be considered as useful. 

The definition of the electrochemical Thiele modulus [Eq. (9b)J characterizing the degree of electrocatalyst utilization is a prerequisite for properly tailoring the micromorphology of porous electrocatalytic electrode coatings and fuel cell electrodes, as it allows matching of the coating or catalyst particle dimension to the catalytic activity of the material ... 

The financial support provided to fuel cell development over the last three years in the USA is shown in Fig. 52 [131]. It indicates that one may be optimistic for the future of SOFCs with regard to their technical aspects. Performance and cost of the modules developed by Westinghouse make it possible to evaluate accurately the real cost of the electricity supplied by this type of generator. It is now time to find commercial markets for them. A definitive answer to this question will very likely be given in the mid 1990s and will determine the commercialization of SOFCs. 

The second process of water vapor removal down the channel can be described by the convective flux, Q(pw,Sat PvMet)KRTA), representing the maximum amount of water vapor removed with the purge gas when the exit purge gas is fully saturated with vapor. In the above definition Q is the purge gas volumetric flow rate and A the active area of the fuel cell. Both parameters defined above have the unit of mol/s per unit of the fuel cell active area. It follows that... 

The definition of the exergy of the fuel with the thermodynamic state of the fuel cell is now shown more detailed. Similar methods are used for the reversible heating of the air and the reversible cooling of the flue gas. The reversible air heating requires... 

The answers to the above questions will be the main drivers in choosing the most appropriate approach for the model definition and implementation. A fuel cell operation, in fact, involves a relatively large and complex number of phenomena occurring at the same time, at different scale levels, and in different components of the fuel cell. 

Any governing model equations have to be supplemented by initial and boundary conditions, all together called side conditions. Their definition means imposing certain conditions on the dependent variable and/or functions of it (e.g. its derivative) on the boundary (in time and space) for uniqueness of solution. A proper choice of side conditions is crucial and usually represents a significant portion of the computational effort. Simply speaking, boundary conditions are the mathematical description of the different situations that occur at the boundary of the chosen domain that produce different results within the same physical system (same governing equations). A proper and accurate specification of the boundary conditions is necessary to produce relevant results from the calculation. Once the mathematical expressions of all boundary conditions are defined the so-called properly-posed problem is reached. Moreover, it must be noted that in fuel cell modeling there are various... 

Direct methanol fuel cell is actually a PEM fuel cell that uses methanol as fuel. Zinc/air fuel cell by definition is not a fuel cell (or at best it is a semifuel cell). Each type of fuel cells has different chemistry, operates at different temperatures and is at a different stage of development. Most of the development and demonstration to date has been with the PEM fuel cells. 

A specific idea for analysis was voiced by a forum participant with a policy and industry perspective It might be helpful to a number of hydrogen interests and producers of technology products to see if we could do a definitive study on four or five specific stationary applications of hydrogen fuel cells that have a chance to compete cost-wise, and discover in what circumstances they could compete, so that people looking to market products in the near term have a better shot at meeting their targets. ... 

This chapter has provided basic electrical fundamentals, including concepts and definitions for circuit elements, and their relationships within electric circuits. Various basic AC electric circuits were also presented. Following upon primary circuit theories, the concept of electrochemical impedance spectroscopy and basic information about EIS was introduced. This chapter lays a foundation for readers to expand their study of EIS and its applications in PEM fuel cell research and development. 

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