Effect of Injection Pressure with Split Injection in a V6 Diesel Engine 2009-24-0049

Multiple fuel injections with higher injection pressure are a way to improve diesel engine performance and lower emissions of unburned HCs, smoke, particulate matter and carbon monoxide (CO). However this method leads to a higher level of NOx emissions. A combination of higher pressure split injection and exhaust gas recirculation (EGR) has potential in controlling NOx emissions and engine performance simultaneously. The focus of this study is to investigate the effect of variation in injection pressure with split (pilot and main) injection, (with and without cooled EGR) on engine performance and emissions. The engine used is a common rail direct injection V6 Diesel fitted with turbo-charged variable turbine geometry (VTG) turbochargers, fuelled with ultra low sulphur diesel (ULSD). The experiments include five different levels of injection pressure 300, 430, 500, 600, 700 bar, at two different engine speeds and various loads, 1500 rpm (35.1, 70.2 and 140 Nm) and 2000 rpm (43.3, 86.6 and 120 Nm).

Fuelled by ULSD, the experimental results show that the performance and emissions of the engine at higher pressure split injection were improved, compared to lower pressure. This applied to both EGR cases (EGR ON and EGR OFF). These results showed strong evidence that the increase of the injection pressure up to a certain value, can lower emissions of total hydrocarbons (THCs), carbon monoxide (CO) and particulate matter (PM). In addition, it has been shown that combination of higher pressure split injection with EGR has potential to lower nitrogen oxides (NOx) and fuel consumption without significant smoke penalties.