High Degree Decentralization for the Optimum Thermoeconomic Design of a Combined Cycle.

Decentralized design methods will always greatly facilitate the optimum design of large engineering systems whenever a High Degree of Decentralization (HDD) is achieved. HDD allows the optimization of each component by itself without significantly sacrificing the overall system optimum. In this paper, a primary engineering component costing expression is introduced, resulting in a significant HDD - called Primary Decentralized Thermoeconomic Design - for the design of gas turbine cycles with or without a steam power bottoming cycle. This costing expression is a compromise between simplicity and a representative model for engineering component costing. A requirement for such an expression is that it provides a balance not only between the capital cost expenditures and the dissipation of exergy, but also between the capital cost and the dissipation of heat removal capacity. In fact, additional exergy dissipation always results in the dissipation of more heat, which must be removed from the overall power generation cycle. Applied to a combined cycle (a gas and steam turbine cycle), such decentralization serves to show how the steam power bottoming cycle assists the gas turbine cycle. This approach produces a significant HDD which allows engineers to study many more possible improvements in combined cycles than couldmore » otherwise be considered.« less