Combustion of green fuels for power generation in gas turbine

Xiao, Hua 2018. Combustion of green fuels for power generation in gas turbine. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The main objective of this thesis is to investigate the fundamental combustion process of ammonia-based fuels and the application on swirl-stabilised flames in the context of engineering type gas turbine combustion. The present study begins with a fundamental validation and mechanism reduction for chemical kinetics of ammonia/methane combustion. Different-sized reduced mechanisms of the well-known Konnov’s mechanism were compared at high-pressure conditions relevant to gas turbine devices. The reduced models can benefit the future simulation work with considerably less computational cost. Then characteristics of ignition delay time, laminar flame speed and emissions were obtained over a wide range of equivalence ratios and ammonia fractions. Prediction results showed a good potential of ammonia/methane to be used in gas turbine engines with relatively low emission. In the second part of this dissertation, in order to identify reaction mechanisms that can accurately represent ammonia/hydrogen kinetics at industrial conditions, various mechanisms were tested in terms of flame speed, combustion products and ignition delay against experimental data. It was preliminarily found that the Mathieu mechanism and Tian mechanism are the best suited for ammonia/hydrogen combustion chemistry under practical industrial conditions. Based on the Mathieu mechanism, an improved chemical mechanism was developed. Verification of the established model was quite satisfying, focusing particularly on elevated conditions which are encountered during gas turbine operation. Finally, a first assessment of the suitability of a chosen 70%NH3-30%H2 (%vol) blend was performed for utilisation within a gas turbine environment. It was found that stable flames can be produced with low NOx emissions at high equivalence ratios. Also, results showed that high inlet temperature conditions representative of real gas turbine conditions can significantly improve the combustion efficiency and reduce NOx emissions. A numerical gas turbine cycle calculation was performed indicating more research are required to enable higher efficiencies using ammonia/hydrogen.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Uncontrolled Keywords:	Gas turbine; Combustion; Power generation; Green fuels; Ammonia; Energy.
Date of First Compliant Deposit:	5 June 2018
Last Modified:	13 Apr 2021 13:59
URI:	https://orca.cardiff.ac.uk/id/eprint/111951

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