ENERGIFORSKNING-ENERGIFORSKNING

The ADONIS project exploits complementarities and synergies of a broad international consortium, consisting of world-leading researchers from Europe and Japan, to produce a technically-sound and accurate assessment about the effect of ammonia utilisation on the thermodynamic cycle performance of small-sized gas turbines, fired with either pure ammonia or hydrogen/ammonia fuel blends. The latter fuel types, characterised by higher heating value compared to pure ammonia, can be obtained by partial ammonia decomposition in catalytic crackers that exploit the gas turbine waste heat thereby potentially enabling an increase in the efficiency of the thermodynamic cycle. In pursue of the main project objective, the research activities are organized in 4 Work Packages (WPs) addressing different crucial aspects of the fuel switch from conventional hydrocarbons (natural gas, fuel oil) to ammonia based fuels: WP1 - Assessment of the overall gas turbine cycle performance (Lead: Silesian University of Technology - Participants: all). The research work has proceeded along two main directions. On one side, high-level thermodynamic models have been utilised to estimate the electrical and thermodynamic efficiency of small gas turbines fired with ammonia blends in combined heat and power applications (1 manuscript submitted to a journal is under review). On the other side, relatively coarse CFD simulations, based on the numerical solution of a Reynolds-Averaged system of differential equations (RANS), have been performed to assess the effect of the fuel switch on the combustion system stability and performance (1 manuscript submitted to a journal is under review). WP2 - Characterisation of flame-wall interactions (Lead: University of Tokyo - Participant: SINTEF). The effects of ammonia-based fuel blends on the process of flame-wall interaction is investigated using high-resolution numerical simulations and detailed experimental measurements. Flame-wall interactions take place in situations where the combustion process is confined by a closed vessel (e.g. in the combustion chamber of a gas turbine) and the flame propagates towards the wall and finally impinges on its surface. Often, this process can affect combustion efficiency (amount of unburnt fuel), flame stability (flashback/blowout), pollutants formation and wall heat transfer during quenching, even causing permanent alteration of the material that constitutes the solid surface. Comparison of experimental measurements with results from the numerical simulations indicate that the latter are able to capture with satisfactory accuracy the flame-wall quenching process. However, the lack of a sufficiently detailed kinetics scheme for heterogeneous surface chemistry is a challenge that cannot be resolved within the scope of the project. WP3 - Characterisation of the flame thermo-acoustic response for ammonia-based fuels (Lead: AIST - Participants: ZHAW, SINTEF). The research work consists of parallel activities investigating and modelling acoustically-forced ammonia flames: AIST conducts experimental measurements, SINTEF performs advanced Large-Eddy Simulation (LES) and ZHAW models the flame response by extracting flame-transfer functions and matrices derived from the numerical simulations and experimental measurements. A peer-reviewed journal paper has been published in the context of WP3. WP4 - Characterisation of ammonia liquid spray penetration, vaporization and ignition (Lead: IFP - Participant: University of Orleans). In a joint effort combining advanced numerical modelling and simulations of the ammonia spray with state-of-the-art experimental measurements the research work in WP4 has provided novel insights into the characteristics of liquid ammonia injection and vaporisation at conditions relevant to gas-turbine combustors.

The project ADONIS aims to enable ammonia utilization in MGT for distributed carbon- free power generation. The project will produce a state-of-the-art assessment of the MGT cycle performance (WP1) underpinned by three constitutive building blocks that address three important open questions of fundamental scientific nature. These are: flame-wall interaction in ammonia/hydrogen flames (WP2), thermoacoustic characteristics of ammonia/hydrogen flames of (WP3) and fuel injection optimization, mixture preparation and ignition (WP4). WP1. Design and optimization, using thermodynamic cycle and CFD simulations, of a generic MGT fueled with ammonia, both for power generation as well as for a cogeneration configuration (SUT). The combustion chamber geometry will be selected based on existing gas turbine designs available from the open literature (e.g. Turbec T100). WP2. Advancement of basic scientific knowledge in the field of laminar and turbulent near-wall reactive flows deploying both state-of-the-art experimental measurements (AIST/UT) and numerical modelling (SINTEF) building upon previous work on the topic of flame-wall interactions in Japan and Norway. WP3. The thermoacoustic characteristics of ammonia-hydrogen flames is investigated aiming to close the currently existing knowledge gap. Low-order models that are able to represent the flame response to acoustic disturbances will be created (ZHAW) based on numerical simulations (SINTEF) and laboratory experiments (AIST). WP4. The first task of WP4 will concern the realization of an experimental database that characterizes liquid ammonia sprays and subsequent vaporization at different conditions (U Orleans). The second part of the WP aims at using CONVERGETM RANS or/and LES computations in MGT configurations to assess the impact of ammonia vaporization on the combustion process (IFP).