Over 90% of global trade relies on shipping, primarily powered by internal combustion engines. Marine propulsion is, therefore, a key economic sector, albeit a significant source of greenhouse gas emissions. The IMO enforces a gradual reduction of these emissions until 2040 with the goal of becoming fully sustainable by 2050. Due to the high power and energy density requirements of large ships, electrification is impractical for this purpose, creating a demand for sustainable solutions based on the internal combustion engine operated with alternative fuels. This approach also helps retain the significance of today’s expertise of SMEs that make up the majority within the market sector and typically offer few or single specialized components or services.
Alternative fuels like ammonia and methanol cannot be introduced as drop-in solutions in compression ignition engines, which are common in marine propulsion, necessitating innovative ignition systems such as pilot injection, particularly for the retrofitting of existing vessels. In order to achieve the highest efficiencies at the lowest emission levels, the subprocesses of the dual fuel combustion, i.e., the initiation of the propagating flame with a diesel pilot, including the turbulent mixing-state, the auto-ignition of the pilot fuel in the presence of a second fuel, and the flame propagation into the premixed and diluted air/ammonia or air/methanol mixture must be fundamentally investigated and understood. Currently, these processes are insufficiently explored and there is a need for research work.
In the proposed project, experimental investigations will, therefore, be carried out on various devices, such as a rapid compression machine (RCM), an injection chamber, and an optically accessible single cylinder research engine (SCE), with the aim of investigating the ignition process, spray development, and engine combustion separately. All experiments will be carried out by LEC in Graz.
Based on the ignition delays measured from the RCM, detailed reaction mechanisms for ammonia, methanol, and their mixture with diesel are being developed. They are intended to be particularly suitable for simulating ignition and combustion in combustion engines with large displacement, which is why the focus will be on operating points at high pressures. This is the non-Austrian part of the project, carried out at BTU in Germany.
The actual combustion process in the engine, consisting of turbulent cylinder internal flow, injection of the diesel pilot, ignition, and turbulent combustion, is simulated by TUW using CFD simulation. Detailed LES simulations will be carried out to provide a fundamental knowledge of the flow field. In a second step, a URANS model will be derived to provide a simulation process that is suitable for industrial needs. The mechanisms developed by the BTU are implemented and suitable spray, combustion, and turbulence/chemistry interaction models are tested, validated, and adapted to the two fuels methanol and ammonia. The results will be validated with measurements from the injection chamber and the single cylinder engine at LEC.
The deliverables will be a comprehensive and fundamental understanding of the dual fuel combustion of methanol and ammonia, which will be provided by the experiments in conjunction with the LES simulations. Further, a predictive CFD model in the URANS framework, in combination with detailed documentation, will be made available to interested partners that describes the best modelling approach to simulate the dual fuel combustion of diesel/methanol and diesel/ammonia.
This project is scheduled for a duration of 2 years and is proposed for the 40th call in the CORNET II program. This application will focus on the Austrian consortium, which will be coordinated by the Association of Metaltechnology Austria (Fachverband der Metalltechnischen Industrie – FMTI). The contents of the German partner will be appropriately described to give a clear picture of the research work for the review process. An attempt has been made to adapt the project’s description to the Collective Research template. All tasks are already described, though only the first project year could be properly scheduled.
