The effect of ethanol-water fumigation on the performance and emissions from a direct-injection diesel engine.

Abstract

The effect of ethanol fumigation and water injection on the performance and exhaust emissions from a 1.9-liter Volkswagen TDI diesel engine was investigated. The engine tests were conducted at a speed of 1700 rpm, and at loads of 40, 80, and 120 N-m. One hundred-proof ethanol, 200-proof ethanol, and distilled water were used as fumigants; they were injected into the intake air through a single air-atomizing nozzle mounted in the engine's intake manifold. Two flowrates of fumigant were used: 25% and 40% of the volumetric diesel fuel flowwrate at the corresponding baseline operation. The atomizing nozzle was mounted either downstream or upstream of the aftercooler, and it was found that the upstream configuration resulted in more consistent results- probably due to improved evaporation and mixing of the fumigant with the intake air. In general, when compared to baseline operation, both ethanol and water resulted in reductions in the emissions of NOx, total particle number, and total particle volume concentrations. At 1700 rpm and 80 N-m, the most significant (up to 25%) reductions in NOx emissions were obtained with water injection, whereas ethanol resulted in more pronounced reductions in total particle number (about 40%) and total particle volume concentrations (about 30%). The HC emissions were dramatically increased with ethanol fumigation, particularly with 200-proof ethanol. The brake thermal efficiency was slightly decreased with both proofs of ethanol. As far as the emissions of NOx and PM are concerned, the fumigation of 100-proof ethanol yielded better results than the fumigation of 200-proof ethanol.