Methanol Combustion in Compression Ignition Engines with a Combustion Enhancer based on Nitrates (CEN): Insights from an experimental study in a New One Shot Engine (NOSE) 2024-01-4281

Because it can be produced in a green form, methanol is envisioned as a potential fuel to replace conventional diesel fuel and directly reduce the greenhouse gas (GHG) impact of maritime transportation. For these reasons, Original Equipment Manufacturers (OEMs) working on marine applications are focusing on making methanol easily usable in Compression Ignition (CI) engines. While it is an easy-to-use substance with manageable energy content, methanol has a few drawbacks, including a high latent heat of vaporization and a high auto-ignition temperature, all of which affect combustion quality. Therefore, solutions have been found or are still under study to give it Diesel-like behavior. One solution is to use a pilot fuel for ignition in significant quantities. A previous study conducted at the PRISME laboratory highlighted the possibility of using a Combustion Enhancer based on Nitrates (CEN) as an additive. This study explores the impact of CEN in methanol using a New One Shot Engine (NOSE), which is a high-pressure, high-temperature (HPHT), optically accessible enclosure. Various parameters are examined: the Ignition Delay Time (IDT) measured by OH* chemiluminescence and with a photomultiplier for verification, the vapor and liquid penetration using Schlieren technique and Diffused Back-Illumination (DBI), and the Lift-Off Length (LOL) also determined by chemiluminescence. Wherever possible, the study adhered to the spray A conditions (60 bar, 900K, injection parameters) recommended by the Engine Combustion Network (ECN). However, to better reflect a previous study conducted on an engine, the compression temperature was increased to close to 950-1000K. Throughout this study, it is demonstrated that adding a small amount of CEN directly blended with methanol leads to a reduction in IDT and LOL, as well as a stabilization of inflammation along the jet penetration.