Novel Power Cycle for Combined-Cycle Systems and Utility Power Plants

Abstract

The description of a new power cycle, based on the use of a multicomponent working fluid, was published earlier. A thermodynamic analysis of this cycle has demonstrated its superiority over the currently used Rankine Cycle, and a distribution of losses in the subsystems of this cycle has been established. A new, improved variant of the cycle, which provides 10% efficiency improvement over the initial variant, has been developed. The new variant employs a cooling of the working fluid between turbine stages and a recuperation of the released heat for supplementation of the boiler heat supply. Analysis shows that with this new, improved cycle efficiencies of up to 52% for a combined-cycle system employing standard turbines, and of up to 55% when modern high-temperature gas turbines are employed, can be achieved. The same cycle can be utilized to retrofit existing direct-fired power plants, providing an efficiency of up to 42%. The possible implications off such a cycle implementation are briefly discussed. The Electric Power Research Institute (EPRI) is now conducting a study of this cycle.