Performance and emissions analysis of additional ethanol injection on a diesel engine powered with A blend of diesel-biodiesel

• Tests in a diesel engine with ethanol injected into the intake air were presented.
• A decrease in engine efficiency with the addition of ethanol was found.
• The CO and THC emissions increased while NOx emissions decreased with ethanol content.
• It was noticed a reduction in the opacity for moderate ethanol amounts.
• The additive DTBP led to a slight reduction in fuel consumption, CO and THC emissions.

This work shows the performance and emissions profile of a diesel engine operating with ethanol injected into the air of the inlet manifold in time with the high-pressure injection of a mixture of diesel and biodiesel. The ethanol injection uses an electronic management system that detects the high-pressure pulse in the diesel injection line as the injection trigger. The air intake temperature reduction caused by the ethanol injection could be evaluated. The tests were made in an engine at 1800 rpm, connected to an electric generator. The high-pressure injection fuel was always a binary blend of diesel and biodiesel, which was supplemented by injected ethanol, producing 5 different fuel compositions. The first of the tested compositions was the binary blend without ethanol, while the others had increasing alcohol content. The fifth composition used 15% of ethanol but had a 0.4% of the additive di-tert-butyl peroxide mixed in the main fuel. The addition of ethanol led to a reduction in diesel fuel consumption, although the overall energy expenditure was increased. The emissions profile showed a consistent reduction in NOx emissions and opacity with the addition of ethanol, breaking up the traditional inverse relationship between NOx and PM emissions, but shown an increase in CO and THC emissions. The energy analysis showed a decrease in engine efficiency with the addition of ethanol. The use of the additive showed a slight increase of engine efficiency and the reduction of the CO and THC emissions. There was a significant reduction in the air intake temperature with the use of ethanol, suggesting that part of the reduction of NOx may be attributed to this temperature reduction. It was proven that the ethanol addition can be an important method to reduce the amount of NOx in the exhaust gases of diesel engines.