Micro Gas Turbine Repowering With Inverted Brayton Cycle

Micro gas turbine may represent a successful energy system for distributed combined heat and power generation, if its energetic and economic performances become competitive, especially in cogenerative application. Furthermore, in the last years, the Inverted Brayton Cycle gas turbine has been reconsidered as a potential solution for the simple cycle gas turbine performance increase. In the present paper, the employment of an Inverted Brayton Cycle at the micro gas turbines discharge is investigated. The results obtained show that the electric and thermal performances of the energy system increase; moreover, the reduction of the maximum hot gas temperature in the recuperator (usually micro gas turbines are recuperated), due to the below ambient pressure expansion, may reduce the recuperator thermal stress problems. The economic impact of the repowering of simple cycle micro gas turbines with the Inverted Brayton Cycle is also investigated in the present study; the carried out analysis shows that the benefit of the Inverted Brayton Cycle depends on the fuel price and the electric energy tariff and the turbine discharge pressure can be optimized to maximize the economic performance.