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)

Because it can be produced in a green form methanol is envisioned as a potential fuel replacing conventional Diesel fuel to directly reduce greenhouse gases (GHG) impact of maritime transportation. For these reasons, Original Equipment Manufacturers (OEMs) are working to make methanol easier to use in Compression Ignition (CI) engines. While it is an easy to use substance with manageable energy content, methanol has a few drawbacks, such as: high latent heat of vaporization, high auto-ignition temperature. These drawbacks have an impact on the quality of combustion and therefore solutions have to be found and are still being studied to give methanol a Diesel like behavior. One solution is to use a pilot fuel for ignition in quantities that remain high (> 20 %). A previous study carried out at the PRISME laboratory highlighted the possibility of using a Combustion Enhancer based on Nitrates (CEN) at additive levels. Here the CEN impact in methanol is studied through the use of a New One-Shot Engine (NOSE), a high pressure, high temperature (HPHT), optically accessible vessel. Many parameters are explored: the Ignition Delay Time (IDT) by UV analysis and with photomultiplier (PM) which allow for verification, the vapor and liquid penetration by shadowgraphy technique and Diffused Back-Illumination (DBI) and the Lift-Off Length (LOL) also by Ultra-Violet analysis. As much as possible, the spray A conditions (60 bar, 900 K, injection parameters) recommended by the Engine Combustion Network (ECN) were observed. However, to be more representative of the previous study carried out on an engine, the compression temperature was increased to close to 950-1000 K. This study shows that the addition of CEN (5 % by volume) directly blended to methanol allows for a reduction of the IDT, of the LOL and a stabilization of the flame along the jet penetration. This is a fundamental study in order to start understanding the effect of the additive on methanol.