Application of Methanol with an Ignition Additive in a Heavy-duty Turbo-charged Compression Ignition Engine

For CI combustion of methanol, the influence of fuel additive (ignition improver) and fuel injection timing are studied in a heavy-duty and turbo-charged compression ignition (CI) engine. The engine operates at 1400 rpm and has a compression ratio of 16. The charge air pressure is 1.5 bar and a charge air temperature of 373 K is used. The injected liquid methanol is premixed with a fuel additive that eases ignition and combustion through a higher cetane number compared to neat methanol. The start of combustion (SOC) and the fuel heat release rate (HRR) are calculated from a measured cylinder pressure profile that is applied for the energy balance of the trapped cylinder gas. With 5 % (kg/kg) fuel additive, the methanol has a relatively long ignition delay (ID) that tends to promote a premixed-like combustion process. At higher additive fractions (up to 10 %) the combustion shifts into a more traditional diesel-like process that involves a mixing controlled phase. A multi-zone simulation model indicate, moreover, that the ignition delay is mainly coupled to a chemical delay, rather than a physical delay.