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In this paper blends of diesel and gasoline (dieseline) fuelled Partially Premixed Compression Ignition (PPCI) combustion and the comparison to conventional diesel combustion is investigated. The tests are carried out using a light duty four cylinder Euro IV diesel engine. The engine condition is maintained at 1800 rpm, 52 Nm (equivalent IMEP around 4.3 bar). Different injection timings and different amounts of EGR are used to achieve the PPCI combustion. The results show that compared to the conventional diesel combustion, the smoke and NOx emissions can be reduced by more than 95% simultaneously with dieseline fuelled PPCI combustion. The particle number total concentration can be reduced by 90% as well as the mean diameter (from 54 nm for conventional diesel to 16 nm for G50 fuelled PPCI). The penalty is a slightly increased noise level and lower indicated efficiency, which is decreased from 40% to 38.5%.

Combustion behaviour and emissions characteristics of different blending ratios of diesel and gasoline fuels (Dieseline) were investigated in a light-duty 4-cylinder compression-ignition (CI) engine operating on partially premixed compression ignition (PPCI) mode. Experiments show that increasing volatility and reducing cetane number of fuels can help promote PPCI and consequently reduce particulate matter (PM) emissions while oxides of nitrogen (NOx) emissions reduction depends on the engine load. Three different blends, 0% (G0), 20% (G20) and 50% (G50) of gasoline mixed with diesel by volume, were studied and results were compared to the diesel-baseline with the same combustion phasing for all experiments. Engine speed was fixed at 1800rpm, while the engine load was varied from 1.38 to 7.85 bar BMEP with the exhaust gas recirculation (EGR) application.

Conventional diesel-fuelled Partially Premixed Compression Ignition (PPCI) engines have been investigated by many researchers previously. However, the ease of ignition and difficulty of vaporization of diesel fuel make it imperfect for PPCI combustion. In this study, dieseline (blending of diesel and gasoline) was looked into as the Partially Premixed Compression Ignition fuel for its combination of two fuel properties, ignition-delay-increasing characteristics and higher volatility, which make it more suitable for PPCI combustion compared to neat diesel. A series of tests were carried out on a Euro IV light-duty common-rail diesel engine, and different engine modes, from low speed/load to middle speed/load were all tested, under which fuel blend ratios, EGR rates, injection timings and quantities were varied. The emissions, fuel consumption and combustion stability of this dieseline-fuelled PPCI combustion were all investigated.

In this study, the application of two closely coupled Diesel Particle Filters (DPFs), composed of an assistant DPF and a main standard honeycomb DPF, was investigated. A series of tests were carried out on a light-duty common-rail Euro 4 diesel engine and the emissions were measured and compared with those when a standard DOC+DPF system was used for the after-treatment. Replacing the DOC with an assisting DPF (ADPF) showed significant advantages in the reduction of particles, which had a direct impact in reducing the soot loading rate of the main DPF by up to 30%. Its oxidation characteristics not only showed equivalent exhaust-conversion efficiency, which concern the regulated gaseous emissions (CO and HC) under most engine conditions, but also continuously regenerated the soot it trapped.

Pilot injection has been used widely in diesel engines for its NOx and noise reducing characteristics. In this paper, its impacts to the particle emissions were studied using a light-duty common-rail Euro 4 diesel engine with different pilot injection strategies. Three steady-state engine modes were selected from the EU legislative diesel engine test cycle to represent low, medium and high engine speeds and loads. The quantities and injection timings of the pilot injection strategies were then varied. The particle number concentration and size distributions were investigated along with the smoke and regulated gas emissions such as the NOx trade-off. These results indicate how a pilot injection alongside a main injection can increase the particle size compared to a single main injection event. Furthermore, the split injection was closely related to the engine mode.

In this study, the particle emission characteristics of 10% alternative diesel fuel blends (Rapeseed Methyl Ester and Gas-to-Liquid) were investigated through the tests carried out on a light duty common-rail Euro 4 diesel engine. Under steady engine conditions, the study focused on particle number concentration and size distribution, to comply with the particle metrics of the European Emission Regulations (Regulation NO 715/2007, amended by 692/2008 and 595/2009). The non-volatile particle characteristics during the engine warming up were also investigated. They indicated that without any modification to the engine, adding selected alternative fuels, even at a low percentage, can result in a noticeable reduction of the total particle numbers; however, the number of nucleation mode particles can increase in certain cases.