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SUMMARYIn this paper, various aspects of trigeneration power plants including advantages, challenges and criteria for high efficiency operation are discussed. In trigeneration systems, prime movers are treated to be the heart of the plant and thus an appropriate selection is crucial for successful operation. A comparative analysis of potential prime movers, together with a comprehensive literature review used in trigeneration and, their selection criteria are presented. A case study of a trigeneration plant based on solid oxide fuel cells and an organic Rankine cycle is examined using thermodynamic analysis. This thermodynamic analysis includes performance assessment of the system through energy and exergy efficiencies. An environmental impact assessment is also conducted based on CO 2 emissions as a measure. The present study reveals that compared to power cycle efficiency (considering net electrical efficiency), there is a minimum potential of 22% gain in efficiency when trigeneration is used. Also, it is shown that there is more than 200 kg MWh À1 reduction in CO 2 emissions when trigeneration is used compared to the case where a power cycle is only used.

SUMMARYIn this review paper, a comprehensive literature survey on macro-level modeling of solid oxide fuel cells (SOFCs) is presented. First, the current status of the SOFC modeling is assessed. Second, modeling techniques are discussed in detail. These include the thermodynamics, electrochemistry and heat transfer aspects of the modeling. Thermodynamic relations for pure hydrogen as the fuel and then gas mixture as the fuel are given. Additionally, exergy destructed due to polarizations is shown. Then, modeling equations for ohmic, activation, and concentration polarizations are given. Handling the carbon deposition problem in the modeling is discussed. The inclusion of the convection and radiation heat transfer processes to the modeling is explained. Finally, the models in literature are compared in terms of the methodology used and suggestions for increasing the accuracy of the future models are given.

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