Reversible processes in fuel cell systems and sustainable system architectures

FUEL 270

Wolfgang G. Winkler, winkler@rzbt.haw-hamburg.de, Fuel Cell Lab, Hamburg University of Applied Sciences, Berliner Tor 21, Hamburg, 20099, Germany
The main exergy losses in power conversion processes can be related to combustion and heat transfer. Combined cycles with gas turbines give the opportunity to reduce the exergy losses of the heat transfer to the steam cycle by reducing the flue gas temperature by the work of the gas turbine. But only fuel cells specifically SOFCs give the opportunity to operate a combustion process in a principally reversible way allowing a complete reversible process chain of energy conversion by combining it with heat engines however with irreversible components. The practical importance of a reversible process structure is in general that it determines the structure of the most effective real system architecture and its behavior as well. The method of using reversible structures can be applied at cell level, at stack level, at system level, and at an integration level of the fuel cell system in an application as e.g. in automobiles. A main outcome of these considerations is a thermodynamic explanation of the benefits of an all electric system architecture and of heat recovery and insulation. The increasing importance of electrochemical devices is not only caused by fuel cells because electric storage as batteries and ultracaps are further key components of these future mechatronic system architectures. The utilization of the potential of the reversible process by a multi hybrid system architecture is a real option to introduce a sustainable technology in a number of applications. Electrochemical devices will become key components. The paper will explain the reversible processes as a scientific background of engineering solutions based on electrochemical devices and indicate possible synergies between emerging technologies.