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In this paper, the influence of sulfur and ash fraction of lubricating oil on particle emissions was investigated via experimental works. Especially, we focus on the characterizations like size distribution, morphology and element composition in diesel particles. All of the research was done on a two-cylinder diesel engine under different load conditions. Five kinds of lubricating oils with different levels of sulfur and ash fraction were used in this study, among which a kind of 5W-30 (ACEA, C1) oil was used as baseline oil. Diesel primary particles were collected by thermophoretic system, and analyzed by transmission electron microscopy and energy dispersive X-ray spectrum technique, respectively. Conclusions drawn from the experiments indicate that the sulfur and ash change the primary particle emissions directly.

Impingement of injected fuel spray against the cylinder liner (wall wetting) is one of the main obstacles that must be overcome in order for early injection Homogeneous Charge Compression Ignition (EI HCCI) combustion. In the strategies to reduce or prevent wall wetting explored in the past, limiting the spray cone angle was proved to be a useful approach. This paper is presented to study the effect of the spray cone angle on the mixture formation, particularly the region near the cylinder wall (wall wetting region), and CO/Soot emissions of an EI HCCI diesel engine. Three-dimensional modeling was performed in AVL FIRE code. The calculation grid was divided into three regions which were defined as the combustion chamber region, the wall wetting region, and the central regions. The history of the CO/soot mass of each region and the equivalent ratio/temperature (φ-T map) of wall wetting region were analyzed.

We studied the influence of extreme pressure (EP) antiwear additive on the emission and distribution of particulate matters (PMs), since EP antiwear additive is necessary to improve the property of lubricating oil with the downsizing development of engines. We used a four-cylinder, turbocharged, and inter-cooled system with SAE15W-40 lubricant diesel engine. Pure diesel and fuel blends with varying weight percentages (0.5%, 1.0%, and 1.5%) of EP antiwear additive were used. Engine speed increased by increments of 400 from 1,200 rpm to 2,800 rpm under medium load and full load. The DMS500 was used to acquire particle data, and the Wave Book was employed to record oil and cylinder pressure. Conclusions drawn from the experiments suggest that EP antiwear additive has significant effects on PM emissions and distributions. Increments and decrements were observed on the number of accumulation mode particles and nucleation mode particles with BDAW-0.5.

Cepstrum analysis method is an important part in the area of modern signal processing subject, which has a good application in noise source identification. The paper uses cepstrum method to analyze noise and vibration signals of diesel engine, separates and extracts periodic source signals with characteristic of non-harmonic order from complex spectrum waveform, and then identifies the contribution of each component to the spectrum with characteristic of non-harmonic order by analyzing noise and vibration signals of each component. The result shows that cepstrum analysis method can extract source signal from the complex spectrum waveform effectively, thus facilitate the identification of noise and vibration sources.