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A methodology has been developed to enable a single, gaseous sample to be collected from the diluted exhaust stream of heavy duty diesel engines operating over the European 13 mode ECE R49 emission cycle. The sample consists of timed contributions of dilute exhaust gas from each mode (weighted appropriately) to provide a gas sample that is representative of the complete cycle. The sample is collected in a Tedlar bag prior to GC analysis for individual hydrocarbon speciation. This methodology has also been extended to allow for the collection of a representative carbonyl sample using 2,4-dinitrophenyl-hydrazine (2,4-DNPH) impregnated cartridges. Results obtained from these systems are reported and compared to results obtained from light duty (diesel and gasoline) investigations.

The effect of fuel quality on exhaust emissions from 2 heavy duty diesel engines has been measured over the ECE R49 test cycle. The engines were selected to represent technologies used to meet Euro 1 and 2 emission standards (1992/93 and 1995/96); engines 1 and 2 respectively. The test fuels were prepared by a combination of processing, blending and additive treatment. When comparing the emissions from engines 1 and 2, using base line data generated on the CEC reference fuel RF73-T-90, engine technology had the major effect on emission levels. Engine 2 reduced both particulate matter (PM) and carbon monoxide (CO) levels by approximately 50%, with total hydrocarbon (THC) being approximately 75% lower. Oxides of nitrogen (NOx) levels were similar for both engines. The variations in test fuel “quality” had marginal effects on emissions, with the two engines giving directionally opposite responses in some cases.

The purpose of this study is to evaluate catalysts suitable for the reduction of particulate emissions from heavy duty diesel engines over the European R49 cycle. Catalyst formulations were screened in a laboratory reactor in order to select promising candidates for further evaluation in test engines. The approach was to evaluate different support materials in relation to storage of sulphates and the optimisation of precious metal loadings with promotors and inhibitors. The objective was to obtain the optimum balance between gaseous activity and particulate control. Catalysts selected from the screening process were installed on a test bed engine. Emissions were measured over the European R49 test procedure, to determine the effect of fuel properties on catalyst efficiency and exhaust emissions. The test engine was selected to represent the technology used to meet Euro 1 emissions standards (1992/3).

The use of small indirect injection (IDI) diesel engines in passenger cars has gained popularity, as fuel economy becomes a salient feature of vehicle running costs. The broadening in the application of this engine from light commercial vehicles has placed a greater emphasis on customer acceptability. Particular concern is being given to noise levels at low loads and speeds and at idle. Coupled with this is the need to meet the more stringent exhaust emission regulations being imposed both in the United States and Europe. The IDI engine is fitted with variable geometry pintle type nozzles, which allow small quantities of fuel to be sprayed into the combustion chamber before the main injection period. Combustion is initiated by the fuel/air mixture produced during the nozzle prelift, and the remainder of the fuel burns steadily as it is injected. Deposit formation in injector nozzles (Nozzle Coking) causes partial or total blockage in the prelift range.