Porous cathodes of NiO(Li), Co-doped LiFeO2, and LiCoO2 for the molten carbonate fuel cell (MCFC) were examined in a comparative study using electrochemical impedance spectroscopy at temperatures of 923,973, and 1023 K. Using this technique the contributions of charge transfer and diffusion to the impedance could be separated. The impedance results as a function ol gas composition were compared with theoretical predictions using the thin-film model leading to the conclusion that the most predominant diffusing species in porous MCFC electrodes are molecular oxygen and carbon dioxide. The reaction mechanism is probably the same for all three cathodes involving either the reduction of peroxycarbonate or the reduction of dissociated oxygen. The remaining difference in gas dependencies can then be explained by assuming a low coverage of oxide ions on LiFeO2 while NiO(Li) and LiCoO~ have intermediate coverage by oxide ions. From the temperature dependence of the impedance an estimate may be given of the activation energies of the polarization processes.
The objective of the current work is to support the design of a pilot hydrogen and electricity producing plant that uses natural gas (or biomethane) as raw material, as a transition option towards a 100% renewable transportation system. The plant, with a solid oxide fuel cell (SOFC) as principal technology, is intended to be the main unit of an electric vehicle station. The refueling station has to work at different operation periods characterized by the hydrogen demand and the electricity needed for supply and self‐consumption. The same set of heat exchangers has to satisfy the heating and cooling needs of the different operation periods. In order to optimize the operating variables of the pilot plant and to provide the best heat exchanger network, the applied methodology follows a systematic procedure for multi‐objective, i.e. maximum plant efficiency and minimum number of heat exchanger matches, and multi‐period optimization. The solving strategy combines process flow modeling in steady state, superstructure‐based mathematical programming and the use of an evolutionary‐based algorithm for optimization. The results show that the plant can reach a daily weighted efficiency exceeding 60%, up to 80% when considering heat utilization.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.