Date of Award

Summer 1995

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Electrical Engineering

First Advisor

Gaggioli, Richard

Second Advisor

Lewis, James

Third Advisor

Dunbar, William R.

Abstract

This thesis is intended to be a broad study of conventional and advanced state-of-the- art power generation systems, with a particular emphasis on phosphoric acid and molten carbonate fuel cell systems. Herein the basic modeling and analysis methods of systems are presented. A proper evaluation of system performance requires second-law analysis techniques. In addition, some basic pinch technology concepts are employed to provide further insight into the performance of the various heat exchange networks in the system under analysis. Both onsite and the larger distributed power plant systems are studied. On the small scale level, stationary engines and phosphoric acid fuel cell energy systems are analyzed and compared. At the larger scales, a recently proposed conventional cogeneration facility and a state-of-the-art molten carbonate fuel cell power plant are studied and compared. The comparison of competing technologies is limited to strictly thermodynamic performance. Economics and emissions are not presented here, but these topics are recognized as considerable driving forces for the future success of fuel cell systems. The use of second-law analysis enables system inefficiencies to be pinpointed. In the analyses contained within the present study, the two largest plant inefficiencies were found in the combustion and heat transfer processes. Typically, irreversibilities associated with combustion can be on the order of 30% of the total available energy input to the plant. The use of fuel cells, due to their ability to "control" the oxidation process, eliminate a large portion of the plant combustion losses. Four power plant systems are analyzed and using second-law methods, assisted by pinch technology, system design improvements are suggested. In the case of the fuel cell systems, system redesigns are made toward approaching an "optimal" power plant design.

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