Heat engines, fuel cells

The reversible work tUfSystrev of a coupled fuel cell-heat engine system is independent of the state of the cell and is always equal to the Gibbs free enthalpy of the reaction ArG° at the ambient state [4], It is assumed that the standard condition is equal to the ambient state to keep the argumentation simple. This result indicates the necessary equipment to utilise the exergy of the fuel. 

Fig. 2.14 The system efficiency of the ideal and the real fuel cell-heat engine hybrid system with an exergetic efficiency he = 0.7 and the oxidation of hydrogen.

The total work of the reversible fuel cell-heat engine system can be fonnd as... 

Fig. 2.13 Simplified fuel cell-heat engine hybrid system as a reference cycle.

The process environment of the cell model in Figure 3.1 must be related reversibly to the ambient state to define the reversible system. As mentioned above we assume 17/ — 0 and the flows consist of unmixed components to assure a reversible process. Figure 3.8 shows the reversible fuel cell-heat engine system that fulfills these requirements. The reactants air and fuel in the ambient state Tq.pq are brought to the thermodynamic state of the ceil T,p by the reversible heat pumps HPA (for air) and HPF (for fuel). The necessary... 

The simplified fuel cell-heat engine hybrid cycle as a reference cycle fits the reversible system well the deviation at 1000°C is —0.76% only for the hydrogen oxidation. Figure 3.10 shows the applications of this cycle. The left-hand side of... 

The system efficiency r)syst of a hydrogen fuelled combined fuel cell-heat cycle is plotted over the cell temperature lie in Figure 2.14 on the right side. The exergetic efficiency of the fuel cell fc is varied between 0.7 and 1 and the exergetic efficiency of the heat engine he is constant at 0.7. 

Burt A.C., Celik I.B., Gemmen R.S., Smirnov A.V., 2003. Influence of radiative heat transfer on variation of cell voltage within a stack. In Proceedings of the 1st International Conference on Fuel Cell Science, Engineering and Technology, Rochester, NY, April 21-23, 2003. 

Suzuki, M., Shikazono, N., Fukagata, K. and Kasagi, N. (2006) Numerical analysis of heat/mass transfer and electrochemical reaction in an anode supported flat-tube solid oxide fuel cell, in Proceedings of FUELCELL2006, The 4th International Conference on Fuel Cell Science Engineering and Technology, Irvine, CA, June 19-21. 

VanderSteen, J. and Pharoah, J. (2004) The role of radiative heat transfer with participating gases on the temperature distribution in solid oxide fuel cells, in Proceedings of Fuel Cell Science, Engineering, and Technology, Rochester, NY, June 14-16, 2004, pp. 483 490. 

Fischer K., Seume J. (2006) Location and magnitude of heat sources in solid oxide fuel cells. In Proceedings of the 4th International ASME Conference on Fuel Cell Science, Engineering and Technology, FUELCELL2006, ASME, American Society of Mechanical Engineers, Paper... 

From a mere thermodynamic point of view, in an ideal engine or fuel cell, heat and power should be obtainable from this reaction. Since real processes show a high degree of irreversibility, a considerable amount of energy is necessary to produce ammonia from methane, air and water. The stoichometric quantity of methane derived from the... 

Natural gas engines as micro co-generati(Mi systems are still successfully introduced to the market. Why does the world need fuel-cell heating appliances (FCHA) to be developed as micro co-generation unit This question will be considered here by the customer requirements. One major customer requirement is a high electrical efficiency. This requirement is the result of two more or less simple considerations of the house owner ... 

A.F., and Shah, R.K. (2005) Heat exchangers for fuel cell and hybrid system applications, in Proceedings of 3rd International Conference on Fuel Cell Science, Engineering and Technology, FUEL CELL 2005-74176, ASME, Fairfield, NJ. 

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