Effect of diesel fuel injection parameters on performances and efficiency of a turbocharged dual-fuel compression ignition engine operating on propane

The paper presents results of investigation on a turbocharged dual-fuel engine operating on propane. The obtained results are presented in form of adjustment characteristics of the injection timing of diesel fuel pilot dose for a few chosen values of the boost pressure as well as injection timing of the main dose. The principal objective of this research was to observe the effect of diesel fuel injection parameters on thermal, mechanical and overall efficiencies of the investigated engine. Diesel fuel was delivered divided in two doses. Both, ratio between the doses and their injection timing were varied. Injection timing of the first dose varied in a broad range and depended on the boost pressure. Injection timing of the second dose varied in a narrower range, mainly due to considerable changes in the combustion process. The investigation were carried out for three values of the first dose preserving, at the same time, a constant energy quantity delivered with diesel fuel. The energy share of propane at each measuring point was equal to ca. 70%. The investigation were carried out for three values of the boost pressure, i.e. 200, 400 and 600 [mbar] but also for the naturally aspirated version. The obtained results answered a number of questions regarding the strategy of selection of diesel fuel injection parameters taking into consideration engine performances as well as thermal, mechanical and overall efficiencies at a high share of the gaseous fuel.