Evaluation of the NO_x emissions from heavy-duty diesel engines with the addition of cetane improvers

Abstract

The exhaust emissions from heavy-duty diesel engines (HDDEs) contribute to the degradation of ambient air quality; therefore, environmental agencies have created stringent emissions standards. Since the implementation of these standards, overall engine and fuel technology improvements have created a significant reduction in emissions. This study was completed in order to evaluate oxides of nitrogen (NO x ) emissions from fuels with and without cetane-improving additives in recent and early production electronically controlled HDDEs. Five engines spanning the model years from 1991 to 2004 were tested using the Federal Test Procedure (FTP) dynamometer cycle with both petroleum-based diesel and B20 as the neat fuel. It was found that the additives had the most impact on reducing emissions at low engine powers, but the engine power range with an NO x benefit varied between engines. The cetane improvers were found only to reduce NO x below a cylinder gas density of 35 kg/m 3 at top dead centre. The lower compression ratio of the 1992 DDC S60 engines reduced the cylinder gas density and provided a larger optimal operating range for the cetane improvers. The cetane improvers reduced NO x at low engine powers and cylinder gas density for the B20 fuel but were less effective than for the neat petroleum fuels.

Impacts of biodiesel feedstock and additives on criteria emissions from a heavy-duty engine

“…They showed that these additives can reduce NO x emission increases to some extent, however, the magnitude of the reductions was dependent on the base fuel aromatic content [39]. Several other authors have tested DTBP and 2-EHN additives and observed some potential for mitigating NO x increases with biodiesel blends [40][41][42][43][44][45]. The effect of cetane improvers tends to be less or negligible in newer engine technologies [2,40].…”

“…Several other authors have tested DTBP and 2-EHN additives and observed some potential for mitigating NO x increases with biodiesel blends [40][41][42][43][44][45]. The effect of cetane improvers tends to be less or negligible in newer engine technologies [2,40]. The results of a study performed by Durbin et al were mixed for different additives tested on a different 2006 Cummins ISM engine, with a 1% DTBP additive blend showing NO x neutrality for B20 and lower blends, while other tests using an 2-EHN additive blend were not successful at mitigating NO x emissions even at blend levels as low as 5% [10,11].…”

Characterization of exhaust emissions from palm oil-based and soybean oil-based biodiesel fueled heavy-duty transit buses

“…It is noted that the reduction of NO X at low engine loads is most probably related to the fact that biodiesel naturally has a higher cetane number than ULSD. With the use of a cetane improver in the B20 blend only a small increase in NO X is seen over the baseline ULSD [12].…”

“…A study of cetane improvers in ULSD and biodiesel fuels was conducted at West Virginia University to determine if the fuel additives could have any beneficial effects on combustion to reduce NO X emissions. The reduction of NO X with the use of biodiesel fuels is very compelling since one of the drawbacks to biodiesel fuel is the increased NO X emissions [12].…”

“…These cetane improvers were compared to a baseline of two ULSD fuels and a blend of B20 soy-based bodiesel. The neat biodiesel was blended to 20% volumetric proportions with the petroleum base being one of the ULSD baselines A large test matrix was set up for this study but not every fuel combination was tested with each engine [12].…”