21 Mar 2002

Evaluation of diesel fuel cetane and aromatics effects on emissions from Euro 3 engines

Report no. 4/02: Following EPEFE, the influence of two important diesel fuel quality parameters one missions remained under debate. These were the difference (if any) between natural and additive-derived cetane and the influence of aromatics content. Another key issue was how emissions from more modern engines would be influenced by fuel quality.

CONCAWE has therefore conducted a rigorous test programme to examine exhaust emissions from three light-duty vehicles and two heavy-duty engines representing Euro 3 technology levels. Two fuel matrices were tested to evaluate the influence of cetane (natural and improved) and aromatics (mono- versus poly-).

Fuel effects were generally small compared to engine technology effects and test variability. Despite the rigorous test design, statistically significant fuel effects were difficult to identify. Increasing cetane number had no significant effect on NOx or PM, but directionally reduced emissions of HC and CO. Cetane trends did not differentiate between natural and additive-derived cetane. Aromatics effects were small and showed variation between vehicles.

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