Title: Exergy-based ecological optimisation of a turbofan engine

Authors: Tayfun Tanbay; Ahmet Durmayaz; Oguz Salim Sogut

Addresses: Institute of Energy, Istanbul Technical University, Maslak, Istanbul, TR-34469, Turkey ' Institute of Energy, Istanbul Technical University, Maslak, Istanbul, TR-34469, Turkey ' Department of Naval Architecture and Ocean Engineering, Istanbul Technical University, Maslak, Istanbul, TR-34469, Turkey

Abstract: A novel ecological optimisation is performed by introducing a new coefficient of ecological performance (CEP) defined by propulsive power per unit exergy destruction rate as the objective function for a single spool turbofan engine with an unmixed exhaust considering finite-rate heat transfer from a thermal reservoir at constant temperature. The optimum values for the selected design parameters of compressor pressure ratio, fan pressure ratio, bypass ratio and turbine inlet temperature are determined numerically to maximise this objective function. Furthermore, the overall efficiency, specific thrust, exergy destruction factor, and exergetic sustainability index are considered as the additional objective functions and optimised with respect to the same parameters for comparison. The results show that: i) the compressor pressure ratio range of 15-25.8 provides a good compromise between energy efficiency and ecological performance; ii) a relatively high pressure ratio with a limited flow rate of air through the fan increases ecological performance of the turbofan engine for commercial aircrafts.

Keywords: exergy destruction; ecological optimisation; coefficient of ecological performance; turbofan engines; commercial aircraft; heat transfer; compressor pressure ratio; fan pressure ratio; bypass ratio; turbine inlet temperature; exergy efficiency; specific thrust; exergetic sustainability index.

DOI: 10.1504/IJEX.2015.068231

International Journal of Exergy, 2015 Vol.16 No.3, pp.358 - 381

Received: 14 Oct 2013
Accepted: 13 Apr 2014
Published online: 25 Mar 2015 *

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