More than 90% of worldwide cargo transportation is carried out by ships. The marine engines must be continuously improved and redesigned to keep up with increasingly tight legislation, regulations and standards. A major recent change is that finally, CO2 reduction targets have been set for marine transportation too. One of the ways of realizing them, is through the use of alternative and/or renewable fuels. The dual-fuel fumigation concept seems to be promising in the near future. In this concept, the high-octane fuel (e.g., methanol, biogas) is premixed in the intake manifold, and a small diesel injection (pilot) is used to ignite the mixture.
Since this pilot fuel still leads to net CO2 emissions and the formation of pollutants, it should be as small as possible. However, an excessively small pilot can turn out in insufficient ignition energy for the given gas-mixture, which as a consequence results in poor combustion efficiency and increased unburned hydrocarbons. A stale and robust pilot injection is of great importance to the engine operation. In collaboration with ABC (Anglo Belgian Corporation), a marine engine manufacturer, we will explore the possible solutions for a reliable pilot injection strategy. In addition, the injection profile (or mass flow rate) is an important boundary condition for engine combustion modelling. Thus, we will also look into possibilities for converting the measured profiles to an injection profile that can be fed to engine simulations.
Experiments will be conducted in a unique setup, the Ghent University Combustion Chamber I (GUCCI). A PLN (Pump-Line-Nozzle) fuel injection system, originating from ABC, is used. The atomization and combustion of a fuel spray can be studied by using different optical techniques. Spray images can be obtained with a high speed digital camera.
Previous thesis work focused on the measurement methodologies for the pilot injection fuel mass. Based on this work, modelling of the injection profile could be explored to provide a more accurate 'boundary condition' for the dual-fuel fumigation combustion. The proposed model also needs to be validated under different injection system configurations (injection pump components, injector components … ). Key parameters determining the injected mass and injection profile will be reconsidered, giving better insight into the injection process.