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Combustion characteristics of lean premixed methane/higher hydrocarbon/hydrogen flames

Zitouni, Seif-Eddine 2020. Combustion characteristics of lean premixed methane/higher hydrocarbon/hydrogen flames. PhD Thesis, Cardiff University.
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Abstract

Declining indigenous resources, increased dependence on imports and intermittent renewable energy, have resulted in an increasingly diverse energy-generation landscape. As a result, gas turbine operators face new challenges with respect to gas turbine flexibility in terms of combustion efficiency, safety and emission control. Increased reliance on liquefied natural gas, potentially containing high concentrations of heavier hydrocarbons, typically ethane and propane, coupled with the emerging prospect of hydrogen injection into national gas grids, presents associated combustion impacts not fully appreciated. This new reality underlines the necessity of developing understanding of fundamental combustion characteristics, ultimately guiding the design of future highly flexible gas turbines. This thesis aims to characterise fundamental combustion performance of methane/higher hydrocarbon/hydrogen fuels, through a combination of experimental and numerical techniques, with a focus on natural gas blends representative of fuel variations and at air fuel ratios expected in premixed low-carbon power generation facilities. The parameters identified to investigate fuel behaviour were the laminar burning velocity, Markstein Length and the Lewis Number, yielding essential physiochemical and thermo-diffusive flame information. These properties are of value when attempting to predict flame behaviour in turbulent environments, reflective of most practical gas turbine applications. The main components of natural gas, and relevant hydrogen enriched binary and tertiary mixtures were parametrically investigated, with respect to stretch-related and flame propagation behaviour at lean air fuel ratios, in addition to a comparison of numerically simulated results obtained from chemical kinetics. Effective Lewis Number models were appraised and compared to experimentally measured data, employing theoretical formulations relating Markstein Length to Lewis Number as proposed in literature. The influence of hydrogen and propane addition to the lean stability limits of premixed turbulent methane flames was examined, using a generic swirl burner, at various inlet temperature and thermal powers, with measured lean blow off limits in correlation with measured Markstein length behaviour.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Engineering
Uncontrolled Keywords: Hydrocarbon Hydrogen Flame; Laminar flame speed; Markstein Length; Lewis Number; Spherically Expanding Flames.
Date of First Compliant Deposit: 11 December 2020
Last Modified: 11 Dec 2020 09:33
URI: http://orca.cardiff.ac.uk/id/eprint/136935

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