Abstract
Keywords
Two-Stroke Engine, Scavenging-Port Injection, CNG, S.I. Engine
Abstract
This paper presents the effect of application of scavenging-port injection to a two-stroke two-cylinder boat engine fueled with a compressed natural gas (CNG). Experiments were carried out at a constant speed of 3000 rpm and WOT condition with varying excess air ratio in lean region. A CNG injector for a production automobile engine was utilized and installed into the scavenging ports. Comparison was made with homogeneous charge operation using a gas mixer. By applying the scavenging-port injection, unburned-fuel in the exhaust gas was reduced close to half which must be due to the reduction of fuel short-cutting during the gas exchange process. The lean-bum limit was extended from the excess air ratio of 1.21 to 1.57. The maximum decrease of BSFC reached to 25 %. This suggests that stratified-combustion could he realized in its lean-hum region.