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The use of two or three FID hydrocarbon analysers for the determination of condensable or liquid unburned fuel is described. Each FID has upstream pumps and filters in separate sample conditioning systems operating at three different temperatures of 180C, 50C and 2C. The 50C system could operate at any temperature up to 100C, the use of 50C was because this was the temperature used for sampling diesel particulates. The difference in the three hydrocarbon readings was used to determined on a mass basis the condensable UHC over the sample temperature difference of either 180C to 2C or 180C to 50C. The latter hydrocarbon difference was shown to be close to the particulate fuel fraction of the SOF. A range of applications of this technique to both diesel and spark ignition engines are described, including the warm-up of a Ford CVH SI engine and the influence of nozzle sac volume on condensable hydrocarbon emissions in a Perkins 4-236 diesel.

A base diesel fuel with 37% 1-3 ring aromatics and 12.9% PAH was passed through a dearomatising process that removed the two and three ring aromatics and reduced the single ring aromatics to 14%. These two fuels plus a combination of 60% of the original fuel with 40% of the low aromatic fuel were tested on a Perkins Phaser TCIC diesel engine of US 1991 emissions standards over the EC 13 mode cycle. The fuels and particulate SOF were analysed for all the n-alkanes and all of the PAH of significant concentration. The high speed maximum power particulate SOF were analysed in detail for all three fuels and mass emissions of 15 n-alkanes and 15 PAH determined and 15 other non-fuel PAH searched for. Most of the results showed that the composition of the SOF in terms of n-alkane and PAH was predominantly unburnt fuel compounds, the fuel with negligible PAH had very low PAH emissions compared with the parent fuel with a high PAH content.

The relationship between a diesel engine lubricating oil consumption and the particulate volatile unburnt lube oil emissions depends on the combustion efficiency of the lube oil in the engine. Very little data exists on this topic and this is reviewed. An experimental procedure for the determination of lubricating oil consumption from a calcium mass balance between the lubricating oil and particulate was used combined with a thermogravimetric analysis of the particulate to obtain the unburnt lube oil emissions, together these techniques enabled the lube oil combustion efficiency to be determined This technique only requires the particulate filter paper as an experimental measurement in the engine test. Initial results for a Perkins 4-236 NA DI diesel engine are presented for a range of loads and speeds.