Effects of Injection Timing and Injection Pressure on Combustion Characteristics and Emissions of Ethanol ED95 under Partially Premixed Combustion Condition

The purpose of this study is to investigate the effects of injection timing and injection pressure on combustion characteristics and emissions of the direct injection single cylinder CI engine fueled with ethanol ED95 fuel (95% hydrous ethanol blended with 5% commercial additive by volume) under partially premixed combustion condition. The engine was modified to increase the compression ratio from 18 to 28. The experiment was tested at maximum engine load under a constant engine speed for all testing conditions.

The experimental results show a lower coefficient of variation (COV) for the indicated mean effective pressure (IMEP), which implies that higher combustion stability is achieved when the injection timing is advanced. However, the ignition delay significantly increases. In addition, when injection timing is advanced and the injection pressure is increased, THC and CO emissions increase due to lower combustion efficiency. Despite limitation of working operation at high load on ED95, it is remarkable to note that the indicated thermal efficiency of all ED95 experiments are achieved slightly higher compared to diesel.