Influence of the fuel spray angle and the injection strategy on the emissions reduction characteristics in a diesel engine

摘要

This study describes the effects of the fuel injection angle and the multiple-injection strategies on the combustion, the emissions and the performance characteristics in a common-rail diesel engine. To conduct this investigation, a single-cylinder diesel engine with four valves was used, and various injection strategies with different parameters such as the spray angle, the timing and a single injection or multiple injections were applied. The combustion pressure, the heat release rate and the emissions were measured by a combustion and exhaust emissions analyser system. An injection spray angle of 156 degrees resulted in higher nitrogen oxide emissions than an injection spray angle of 60 degrees did, as the time between the first injection and the second injection increased. Also multiple injections resulted in lower levels of soot and hydrocarbon emissions than a single injection did. A multiple-injection strategy with a dwell time of 20-40 degrees crank angle before top dead centre and the first injection at 60 degrees crank angle before top dead centre or 50 degrees crank angle before top dead centre improved the engine power and lowered the fuel consumption compared with the results for a single injection.