Su Han Park

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.

Study on the Injection Characteristics using Injection Rate in a Direct-injection Gasoline Injector with Multi-hole

This paper presents an experimental study on the GDI injector with Bosch method. The injection characteristics, such as the injection quantity, the injection rate, the maximum velocity of the nozzle exit and the injection delay were studied through the change of the injection pressure, the tube pressure and energizing duration in injection rate measurement device using nheptane. The injection quantity is increased by increasing injection pressure, decreasing tube pressure or increasing energizing duration. As the difference of the injection quantity changed, the shape of injection rate was moved with a constant form. The maximum velocity of the nozzle exit showed a tendency to increase as the injection pressure is increased. However, tube pressure did not affect. Overall, it was confirmed that the closing delay is longer than the opening delay in all conditions. As the injection pressure increased, the result has a tendency to decrease the closing delay, it did not affect the opening delay. Reduction of the closing delay showed the reduction of the injection duration. the tube pressure and energizing duration did not affect the injection delay (opening delay, closing delay).