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

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° resulted in higher nitrogen oxide emissions than an injection spray angle of 60° 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° crank angle before top dead centre and the first injection at 60° crank angle before top dead centre or 50° crank angle before top dead centre improved the engine power and lowered the fuel consumption compared with the results for a single injection.