Performance of a 2 Stroke Cycle Spark Ignition Engine Fuelled with CNG Using Intermittent Fuel Injection from Scavenging Ports

Abstract

Performance of a 2 stroke cycle engine fuelled with CNG (Compressed natural gas) using intermittent fuel injection from a scavenging port is investigated experimentally. The test engine is a 2 cylinder, 398 cm3, 2 stroke cycle spark ignition engine. Gaseous fuel injectors are attached at the cylinder block, and a CNG is injected into the scavenging passage through a fuel injection pipe. The fuel injection pressure is set at 0.255 MPa, and the fuel is injected intermittently during the scavenging process. The length and tip geometry of the fuel injection pipe are varied, and the effect on the engine performance is investigated. Using the scavenging port fuel injection, the BSFC is reduced by 25%, and the lean burn limit extends from λ= 1.2 to 1.46, at the maximum. The peak of the NOx emission shifts to leaner side, and the THC emission is reduced by 47 % at the maximum. It is_considered that the intermittent fuel injection from a scavenging port is effective to achieve stratified combustion and reduction in fuel short circuiting through the cylinder.