A Parametric Thermodynamic Evaluation of High Performance Gas Turbine Based Power Cycles

This paper discusses the gas turbine performance enhancement approach that has gained a lot of momentum in recent years in which modified Brayton cycles are used with humidification or water/steam injection, termed “wet cycles,” or with fuel cells, obtaining “hybrid cycles.” The investigated high performance cycles include intercooled steam-injected gas turbine cycle, recuperated water injection cycle, humidified air turbine cycle, and cascaded humidified advanced turbine cycle, Brayton cycle with high temperature fuel cells (molten carbonate fuel cells or solid oxide fuel cells), and their combinations with the modified Brayton cycles. Most of these systems, with a few exceptions, have not yet become commercially available as more development work is required. The results presented show that the cycle efficiency achievable with the aforementioned high performance systems can be comparable or better than a combined cycle system, a currently commercially available power generation system having maximum cycle efficiency. The main emphasis of this paper is to provide a detailed parametric thermodynamic cycle analysis, using uniform design parameters and assumptions, of the above mentioned cycles and discuss their comparative performance including advantages and limitations. The performance of these cycles is also compared with the already developed and commercially available gas turbines without water/steam injection features, called “dry cycles.” In addition, a brief review of the available literature of the identified high performance complex gas turbine cycles is also included in this paper.