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As part of an ongoing investigation, the influence of In Cylinder Pressure (ICP) and fuel injection pressure on the soot formation processes in a diesel fuel spray were studied. The work was performed using a rapid compression machine at ambient conditions representative of a modern High Speed Direct Injection diesel engine, and with fuel injection more representative of full load. Future tests will aim to consider the effects of pilot injections and EGR rates. The qualitative soot concentration was determined using the Laser Induced Incandescence (LII) technique both spatially and temporally at a range of test conditions. Peak soot concentration values were determined, from which a good correlation between soot concentration and injection pressure was observed. The peak soot concentration was found to correlate well with the velocity of the injected fuel jet.

The DETR/SMMT/CONCAWE Particulate Research Programme was designed to investigate the effects of vehicle/engine technology level, fuel specification and various operating conditions on emissions of particle mass, number and size. Results from the heavy duty part of the programme and details of the measuring protocols have already been published. This paper gives the results of the light duty study. This consisted of six vehicles and eight fuels covering gasoline, Diesel and LPG technologies. These six vehicles represented Euro II (1996) and Euro III (2000) technologies. Diesel fuels included EN590 (1996), EN590 (2000), UK ultra low sulphur Diesel (UK ULSD) and Swedish Class I Diesel, while gasoline fuels comprised EN228 (1996), EN228 (1999) and UK ultra low sulphur gasoline (UK ULSG).

The XUD9 IDI 6-hour steady-state test was developed to evaluate the nozzle coking propensity of diesel fuels. After the CEC 1997 Round-Robin, it was concluded that this test could not discriminate between fuels with the statistical confidence required for CEC tests. Furthermore, it was noted that the test would have to be considerably improved if it was to have any chance of meeting the CEC statistical standards. In 1998, Texaco proposed a 10 hour cyclic test as a replacement for the 6 hour steady-state test. A Task-Force was formed to investigate whether this test was a suitable alternative. After a mini Round-Robin, using the 10 hour cyclic test method, the high potential of the test was confirmed. Dynamic fuel injection timing was identified as the single most important parameter affecting nozzle coking. Cost-effective equipment was selected for measuring dynamic fuel injection timing accurately.

This programme involved the testing of two Euro II compliant diesel vehicles over the current European legislated drive cycle. The aim of the programme was to determine and compare the emissions of 100% virgin vegetable oil (VVO100) and a baseline UK marketplace Ultra Low Sulphur (ULSD) diesel fuel. A splash blend of 5% rapeseed methyl ester in ULSD (RME5) was also evaluated. Results of tests on RME5 showed that generally the effects on emissions compared to ULSD were small for regulated and most unregulated emissions. There was some evidence of a PM10 benefit for RME5 fuel. VVO100 showed large increases in HC (up to 250%) and CO emissions in both vehicles, as well as increases in polycyclic aromatic hydrocarbons (PAH), compared to ULSD. Effects on NOx and particulate were vehicle - specific.

The impact of lubricant sulphur and phosphorus levels on the formation of nucleation mode particles was explored in a light duty diesel vehicle operating over the New European Drive Cycle (NEDC). All measurements were undertaken using a Scanning Mobility Particle Sizer (SMPS), sampling from a conventional Constant Volume Sampler (CVS) system. Rigorous sampling system and vehicle conditioning procedures were applied to eliminate oil carry-over and nanoparticle artifact formation. An initial vehicle selection process was undertaken on vehicles representing three fuel injection strategies, namely; distributor pump, common rail and unit injector. The vehicles met Euro III specifications and were all equipped with oxidation catalysts. Idle and low load stability were key requirements, since these conditions are the most significant in terms of their propensity to generate nucleation mode particles.

Tasked by the Engine Lubricant Technical Committee (ELTC) of the Co-ordinating European Council (CEC), the Rating Steering Group (CEC SL071) and the Co-ordinating Research Council (CRC) Rating Advisory Panel have been working on the “Harmonisation” of rating methods within Europe. It has been recognised that during the last 40 years of product and technological advancements within the oil and additive industries the practical measurement of product performance has remained relatively unchanged. This paper reviews the current rating methods used within Europe and the benefits a single rating method could have on the future “Global” market place.

An Iveco Cursor 8 heavy-duty Diesel engine (7.8L, 6 cylinder) meeting Euro III emission regulations and equipped with a catalyst based passively regenerating Diesel particulate filter (CB-DPF) system, was used to investigate the impact of lubricant formulation on exhaust emissions. Measurements of both regulated and unregulated emissions were made during ESC and ETC cycles undertaken during a strictly controlled experimental protocol. Testing was carried out using ultra low sulphur, Swedish Class 1 Diesel fuel and a range of lubricant formulations. No significant effects of lubricant composition were observed on regulated gaseous emissions. However, the number of nucleation mode particles appeared to be both drive cycle and lubricant formulation dependent. Test methodology proved to be key; with engine, exhaust and dilution tunnel preconditioning and test order a major influence on ESC particle emissions.

The effect of pre-catalyst speciation on lean NOx catalysis was investigated using a chemically defined fuel matrix. Nine model fuels and a diesel fuel were injected into the exhaust stream of a medium duty diesel engine prior to a DeNOx catalyst. NOx conversions ranged from 9% at a mid speed and load test point to 43% at a higher load test point. On an absolute basis, model fuels produced up to 34% greater NOx conversions relative to diesel. Speciation revealed that, compared with low temperature test points, cracking and oxidation at peak torque significantly modified the auxiliary HC input to the catalyst. The quantity of ‘cracked’ derivatives of the auxiliary fuel, namely alkene and carbonyl species, correlated well with NOx conversions.