M.S. Thesis Presentation by Jennifer Marie Cox
Thursday, April 12, 2001

(Dr. William Wepfer, advisor)

"Analysis of a Tubular Solid Oxide Fuel Cell Stack/Modified Rankine Cycle Combination"


Issues pertaining to the clean and efficient production of power are more apparent today than ever before.  The energy industry is having to react to a dynamic environment where there are rolling black outs, stricter emission standards, and rising fuel costs.  Consumers are demanding more power with a minimal environmental impact.  The focus of power plant design is switching from large, centralized plants to combinations of advanced power production technology.

Stationary power fuel cell applications were of interest in this paper.  The objective was to examine stationary fuel cell research and apply the information to a base-load plant.  In particular, a tubular solid oxide fuel cell (TSOFC) topping cycle combined with a regenerative Rankine bottoming cycle.  The TSOFC is a beneficial addition to a traditional power cycle because the TSOFC produces power and has a high temperature exhaust.  Instead of looking to the fuel cell as a primary source of power, this research relied on the high grade rejected heat from the fuel cell to produce steam to power a steam turbine.  The power produced was seen as a benefit as opposed to the purpose of the fuel cell.

The purpose of this analysis was to quantify the positive impact of a fuel cell topping cycle on a standard power cycle.  It was assumed that the only variable operating parameter of the TSOFC would be the operating pressure.  The TSOFC is considered a packaged component of the proposed cycle.  Instead of varying the topping cycle, conditions in the bottoming cycle were chosen to examine how the cycle behaved.  The three major outputs of interest are the heat available from the fuel cell exhaust, the efficiency, and the work produced.  The primary focus was to get an overall picture of how well this system will function.

The proposed combined cycle has an increased power capacity of 91 MW and an increased overall cycle efficiency of 62%.  The addition of a fuel cell topping cycle to a Rankine cycle is to create a more efficient power cycle.  Building new power plants is a difficult, expensive, and risky.  A combination of these two cycles should form a more robust power plant; a power plant that can react to changes in the energy industry.