The Study of Exhaust Gas Recirculation on Efficiency and NOx Emission in Spark Ignition Engine

The paper presents electronically controlled ignition system with exhaust gas recirculation (EGR) in two-cylinder, four-stroke SI research engine. Exhaust gas recirculation was achieved by the special spark plugs enabling flow of exhaust gases between cylinders. The flow of recirculated exhaust gas (the angle of start of recirculation and its duration) is controlled with the use of two electromagnetic valves controlled by programmable electronic unit. The designed and practically tested system was used in the studies of the influence of EGR on emissions and efficiency in SI engine. It was found that with EGR system the engine operates practically with the same efficiency as a conventional combustion system and the emission of NO_x considerably decreases at full load. The results of calculations confirm the tendency of NO_x emission decrease with EGR increase.