2026 年 21 巻 3 号 p. 26-00159
This study examines the combustion, performance, and emission characteristics of a gasoline direct injection compression ignition (GDCI) engine. A conventional single cylinder, water-cooled, direct injection, stationary diesel engine was modified to operate in GDCI mode by replacing mechanical fuel injection system with gasoline direct injection system. The engine features a flat cylinder head, hemi-spherical re-entrant piston bowl, central-mounted injector, with a compression ratio of 16.5 developing 7.46 kW at 1500 rpm. Injection, exhaust gas circulation, and intake boost systems were employed as control strategies. Experiments were conducted at No load, Part-load, and Full load conditions under partially premixed compression ignition mode without switching to diffusion-controlled combustion. At no load conditions without EGR, NO, UBHC, CO, and smoke opacity were 53 ppm, 5 ppm, 0.21% and 5%, respectively. The coefficient of variation of IMEP remained below 5% and the exhaust temperature was under 180 °C. The engine achieved a BSFC of 240 g/kWh at 1500 rpm and 2 bar BMEP. At full load condition, emissions of NO, HC, CO, and smoke opacity were 642 ppm, 4 ppm, 0.48% and 19%, respectively. Near-Stoichiometric mixtures without EGR delivered a peak BMEP of 5.28 bar at 1500 rpm. The results demonstrate stable combustion with reduced noise, optimized combustion phasing, and improved efficiency under all operational conditions.
