Investigating combustion and emissions parameters in an ethanol fuelled low temperature combustion engine

Low temperature combustion (LTC) engines such as homogeneous charge compression ignition engine (HCCI) have lower nitrogen oxide (NOx) and particle matter (PM) with higher efficiency. In this paper, one single cylinder, air cooled, direct injection Yanmar diesel engine is converted to HCCI engine fuelled with ethanol. Variation of combustion parameters, emissions and combustion noise level were studied by using 30 steady state HCCI operating points at 1350 RPM for four levels of equivalence ration at different intake air temperature (Tin). The results indicate that due to with lower amount of adiabatic flame temperature for HCCI engine, exhaust temperature (Texh) is lower than typical catalyst light-off temperatures (260°C) so, with using catalyst converter for this kind of engine the efficiency of catalyst converter may decrease. With increasing the Tin for all equivalence ratios the combustion noise level (CNL) increase and reach to the higher amounts near 90 dB (ringing region). With retarding the combustion timing, the adiabatic flame temperature decreases so higher amount of air pollution (unburned hydrocarbon (uHC)) is produced and engine operates near misfire region.