Fuel Injection Strategy for Utilization of Mineral Diesel-Methanol Blend in a Common Rail Direct Injection Engine

Methanol fueled internal combustion (IC) engines have attracted significant attention due to their contributions in reducing environmental pollution and fossil fuel consumption. In this study, a single-cylinder research engine was operated on MD10 (10% (v/v) methanol blended with mineral diesel) and baseline mineral diesel to explore an optimized fuel injection strategy for efficient combustion and reduced emissions. The experiments were conducted at constant engine speed (1500 rpm) and load (3 kW) using two different fuel injection strategies, namely, single pilot injection (SPI) and double pilot injection (DPI) strategy. For each pilot fuel injection strategy, the start of main injection (SoMI) timing was varied from -3 to 6° crank angle (CA) before top dead center (bTDC). To examine the effect of fuel injection pressure (FIP), experiments were performed at three different FIPs (500, 750, and 1000 bars). Results showed that the MD10 fueled engine resulted in superior combustion compared with baseline mineral diesel, which was further improved by DPI at higher FIPs. The use of DPI strategy was found to be more effective at higher FIPs, resulting in higher brake thermal efficiency (BTE), lower exhaust gas temperature (EGT), and reduced oxides of nitrogen (NOx) emissions compared with SPI strategy. Detailed investigations showed that the addition of methanol in mineral diesel reduced particulates, especially the accumulation mode particles (AMP). Different statistical analysis and qualitative correlations between fuel injection parameters showed that higher FIP and advanced SoMI timings were suitable for particulate reduction from the MD10 fueled engine.