The maritime sector faces major challenges to reduce its impact on global warming. The use of methanol as a fuel alternative is considered one of the more promising options to be implemented in a relatively short to medium time frame; based on the potential availability, emission reduction, energy density, potential to be synthetically produced, scalability of production, and its implementation on board ships (both new build and retrofitted).

This report investigates potential improvements of the injection system, to achieve complete evaporation in the air inlet of a port-fuel injection engine to avoid wall-wetting of the scavenger air receiver and inlet valve. As a result, the methanol-air mixture in the cylinder would become more homogeneous and able to provide 100% of the rated engine power. Earlier research indicated that the wall-wetting fuel film and its evaporation rate directly affect the air-fuel ratio of the in-cylinder mixture, stability of the combustion process, and overall engine performance. The study includes the development of an injection model simulating low-pressure port-fuel injection, similar to the system fitted on our Caterpillar test engine, and the development of a single-droplet evaporation model to gain inside into the evaporation process of 100% methanol.

Based on the performed experimental research, we conclude the average droplet size ranges between 100 and 120 μm. The average droplet speed was determined at ±35 m/s and the spray angle at 20°. At room temperature and pressure, the injection spray ended against the back-glass of the evaporation chamber, indicating almost none of the ethanol evaporates under these conditions. The injection length exceeds at least ±40 cm at atmospheric temperature and pressure, which is in line with the results of the single-droplet evaporation model.