Oxidation Catalytic Converter and Emulsified Fuel Effects on Heavy-Duty Diesel Engine Emissions 2002-01-1277

A study was conducted to assess the effects of a water-diesel fuel emulsion with and without an oxidation catalytic converter (OCC) on steady-state heavy-duty diesel engine emissions. Two OCCs with different metal loading levels were used in this study. A 1988 Cummins L10-300 heavy-duty diesel engine was operated at the rated speed of 1900 rpm and at 75% and 25% load conditions (EPA modes 9 and 11 respectively) of the 13 mode steady-state test as well as at idle. Raw exhaust emissions' measurements included total hydrocarbons (HC), oxides of nitrogen (NO_x) and nitric oxide (NO). Diluted exhaust measurements included total particulate matter (TPM) and its primary constituents, the soluble organic (SOF), sulfate (SO₄^2-) and the carbonaceous solids (SOL) fractions. Vapor phase organic compounds (XOC) were also analyzed. The SOF and XOC samples were analyzed for selected polynuclear aromatic hydrocarbons (PAHs).

The effect of the emulsified fuel without the OCC in the exhaust system was studied first. The emulsion reduced NO_x by 16% and 6% at Modes 11 and 9 respectively. The reduction in TPM was 26% at Mode 11 and 45% at Mode 9. Solids reduced by 61% at Mode 11 and 66% at Mode 9. Total hydrocarbons increased by 33% at Mode 11 along with carbonyl emissions (aldehydes and ketones, by 76%), SOF (by 38%) and XOC (by 56%) using the emulsified fuel. BSFC reduced at all modes with the emulsion after correction for water in the emulsified fuel. An OCC was used in the exhaust system to reduce the HC and its associated emissions (aldehydes and ketones, SOF, XOC) along with TPM emissions. The HC emissions were reduced by 69% with OCC 1 and by 75% with OCC2 at Mode 11 with the emulsion. The SOF and XOC were reduced by 69% and 85% with OCC1 and by 81% and 89% with OCC 2 using the emulsion at Mode 11. Carbonyl emissions were reduced with both OCCs at Modes 11 and 9 using the emulsion.