This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Investigations on NOx and Smoke Emissions Reduction Potential through Diesel-Water Emulsion and Water Fumigation in a Small Bore Diesel Engine
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on November 30, 2020 by SAE International in United States
In the present work, a relative comparison of addition of water to diesel through emulsion and fumigation methods is explored for reducing oxides of nitrogen (NOx) and smoke emissions in a production small bore diesel engine. The water to diesel ratio was kept the same in both the methods at a lower concentration of 3% by mass to avoid any adverse effects on the engine system components. The experiments were conducted at a rated engine speed of 1500 rpm under varying load conditions. A stable water-diesel emulsion was prepared using a combination of equal proportions (1:1 by volume) of Span 80 and Tween 80. The mixture of Span 80 in diesel and Tween 80 in water was homogenized using an IKA Ultra Turrax homogenizer with tip stator diameter 18mm at 5000 rpm for 2 minutes. The water-in-diesel emulsions thus formulated were kinetically stable and appeared translucent. No phase separation was observed on storage for approximately 105 days. The fumigation experiments were carried out by injecting water using a low pressure solenoid operated port fuel injector (PFI) installed in the intake manifold. The timing and duration of PFI are controlled by a National Instruments driver module. The results obtained show that the engine brake thermal efficiency and brake specific fuel consumption improve by nearly 5% with the emulsion compared to baseline diesel. The peak pressures are lower and the ignition delay is shorter with emulsion compared to fumigation. Both emulsion and fumigation reduces NOx emissions but the reduction is higher with water injection. However, smoke emissions are significantly higher by almost two fold with fumigation as compared to those with emulsion. Overall, it is observed that utilizing water emulsion has a potential to simultaneously reduce NOx and smoke emissions along with better engine performance as compared to fumigation method.