Exploring the effects of diesel start of injection and water-in-ethanol concentration on a reactivity controlled compression ignition engine

Wet ethanol applications in compression ignition engines may become important in the coming years due to the possibility of replacing a fossil fuel by a renewable one, with low production cost and accessible production in remote regions. In this context, this research sought to explore the use of renewable fuel and its potential for operation in an engine with reactivity-controlled compression ignition (RCCI) combustion. Ricardo single-cylinder research engine was used. Fuel direct injection into the cylinder was performed in just one step, and to make possible the RCCI operation, the following parameters were varied: water-in-ethanol concentration, ethanol port fuel injection duration, and the start of injection (SOI) crank angle. By varying these parameters, it was possible to explore 38 different test conditions in dual-fuel mode and 2 baseline tests. Operations in RCCI were only possible over 74% replacement, with advanced SOI (333 degrees and 326 degrees). Diesel replacement reached 86% (mass basis). However, the results did not demonstrate a significant increase in indicated thermal efficiency. Furthermore, only with the highest water-in-ethanol concentrations, the engine operated stably at SOI of 326 degrees. For similar replacements, the advancement of SOI has reduced CO emissions, while NOx emissions have increased.