DME 직접분사식 압축착화 엔진에서 파일럿 분사의 영향

Abstract

The dimethyl-ether (DME) combustion with pilot injection was investigated in a single cylinder direct injection diesel engine equipped with the common-rail injection system. Combustion performance and emissions were tested with dimethyl-ether. The main injection timing was at the top dead center, which were the best timings for maximum power output. The total injected fuel mass was fixed $22\;mm^3$ per cycle at 800 rpm. The fuel quantity and the injection timing of the pilot injection were varied from 8 to 20% of the total injected mass and from 50 to 10 crank angle degree before the main injection timing, respectively. The ignition delay decreased with the pilot injection. The indicated mean effective pressure increased when dimethyl-ether was pilot-injected at 20 crank angle degree before the main injection timing. DME showed reduction in emissions, such as particulate, hydrocarbon, carbon monoxide and nitric oxides. The hydrocarbon and the carbon monoxide emissions were increased when the pilot injection timing was advanced. The nitric oxide emission was increased by 14% with 8% of pilot injection. Bigger amount of DME pilot-injection decreased nitric oxide emission.