Comparison of Diesel-Water Emulsion and Water Vapor Induction Methods for Simultaneous Reduction in NO <sub>x</sub> and Smoke Emissions of a Diesel Engine



Automotive Technical Papers
Authors Abstract
Simultaneous reduction of oxides of nitrogen (NOx) and smoke emissions from diesel engines has always been a challenging task. In this research work, a relative comparison of diesel-water emulsion and water vapor induction methods has been made to examine NOx and smoke emissions reduction potential of a light-duty diesel engine. The water concentration was maintained at 6% of the total fuel in the emulsion and 6% of the total incoming air mass in the fumigation method. A stable diesel-water emulsion is prepared using commercially available surfactants, Span 80 and Tween 80 at 10% concentration. The stability of the emulsion was examined by visual inspection. The droplet size was quantified using dynamic light scattering technique and the emulsion was deemed stable for approximately 105 days on storage at room temperature. To generate water vapor in the intake manifold, 20 ultrasonic atomizers are utilized. The flow rate of water vapor is controlled by using a control valve so as to precisely fix the water vapor concentration. As compared to the baseline reference diesel fuel, fumigation with water results in negligible changes in the brake thermal efficiency (BTE) and brake-specific fuel consumption (BSFC), whereas with diesel-water emulsion there is a 3% increase in BTE and 8% decrease in BSFC. The combustion phasing is delayed with both diesel-water emulsion and water vapor induction owing to a longer ignition delay; however, the peak pressure does not vary significantly with respect to neat diesel operation. The NOx emissions are effectively reduced with both the methods with a maximum reduction of 14% at full load condition. The smoke emissions are more effectively reduced by diesel-water emulsion with a maximum reduction of 50%. This could be because of the microexplosion phenomenon, which improves fuel-air mixing. Thus, considering simultaneous reduction in NOx and smoke emissions along with improved engine performance, water-diesel emulsion could be a very effective fuel modification approach for diesel engines.
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Gowrishankar, S., Rastogi, P., Bhasker, P., and Krishnasamy, A., "Comparison of Diesel-Water Emulsion and Water Vapor Induction Methods for Simultaneous Reduction in NO x and Smoke Emissions of a Diesel Engine," SAE Technical Paper 2020-01-5076, 2020,
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Aug 14, 2020
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Technical Paper