Exergoeconomic environmental optimization of piston-prop aircraft engines

It is a great importance to determine the optimum working conditions of thermal systems in terms of efficient energy utilziation. Beside this, economic and environmental assessments also play an important role. In this thesis, exergoeconomic and exergoenvironmental analysis methods are applied to a four-cylinder, spark ignition, naturally aspirated and air-cooled piston-prop aircraft engine for both flight opeartions, landing takeoff (LTO) and an hour cruise. Further, an exergoeconomic environmental optimization is undertaken to determine the optimum cruise conditions. In takeoff phase, the maximum exergy work rate, exergy input rate, relative cost difference and exergoeconomic factor are found to be 111.90 kW, 476.51 kW, 116.06%, and 98.81%, respectively while the minimum exergoenvironmental factor is calculated to be 16.06% in the same phase. The results of an hour cruise, the maximum exergy input rates (410.60 kW), the maximum exergy destruction rate (167.10 kW) and the minimum unit cost of the fuel (116.80 $/GJ) are obtained in 1000 m altitude, 75% rated power setting and 18 air-to-fuel ratio (AF). The maximum exergy efficiency (19.98%) and exhaust exergy rate (170.05 kW) and the minimum relative cost diffirence (62.29%), specific environmental impacts of products (8.26 mPts/MJ) and relative environmental difference (61.54) are found in 1000 m altitude, 75% rated power setting and 13 AF ratios. As a result of the optimization, while the maximum exergy efficiency varies from 15.17% to 19.80%, the minimum unit cost of the fuel ranges from 117.53 $/GJ to 130.05 $/GJ, and specific environmental impacts of the product is in the range of 8.66 mPts/MJ to 11.86 mPts/MJ. In the light of the results, an improvements needs to be done in approach and taxi phases, and optimum cruise was realized at low altitude, high-power setting, and low AF ratios.Keywords:Piston-prop aircraft engine, Exergoeconomic analysis, Exergoenvironmental analysis, Optimization