A novel economic analysis and multi-objective optimization of a 200-kW recuperated micro gas turbine considering cycle thermal efficiency and discounted payback period

Abstract

One pivotal way of boosting efficiency and reducing overall cost of micro-gas turbines, utilized in residential buildings, is to generate energy from waste heat. In this study, a novel multi-objective optimization is performed to maximize the thermal efficiency of a 200-kW micro-gas turbine and minimize the discounted payback period of the system equipped by plate-fin recuperator using NSGA-II. An elaborate sensitivity analysis is presented to show the impacts of geometrical design variables on cycle thermal efficiency and annual cost. To conduct a detailed economic analysis, main consumed costs (total capital investment, operational and maintenance costs), and profits (due to electricity production, and reductions of fuel consumption, CO2 emissions and exergy destruction), are considered. Total capital investment consists of fixed-capital investment (direct costs, including onsite and off-site costs, and indirect costs) and other outlays. Optimization results are displayed by a set of designs called Pareto-optimal front. Based on the optimization results, cycle thermal efficiency and discounted payback period of the best optimal design are equal to 29.8% and 1.4 year, respectively. For this case, average share of profits related to fuel consumption, exergy, electricity and environment over 20 years of operation are equal to 49.55%, 48.07%, 2.33% and 0.05%, respectively.