Experimental investigation of the effects of different injection parameters on a direct injection HCCI engine fueled with alcohol–gasoline fuel blends

• High load extension for HCCI engine was performed by using alcohol–gasoline blends.
• Combustion characteristics were less affected from SOI1 compared to SOI2 and IR.
• Reduction in MPRR with high thermal efficiency was provided.

In this study, the effects of a two stage direct injection strategy were investigated on the combustion of a homogeneous charge compression ignition (HCCI) engine fuelled with alcohol–gasoline blends. For each injection, the injection timings and fuel quantity were adjusted to get the desired mixture formation in the cylinder, and engine performance was investigated at a high equivalence ratio and constant engine speed. The first injections were selected during the intake stroke and the second injections at the end of the compression stroke by using different injection ratios. Five different fuels (gasoline, E10, E20, M10 and M20) were used at the same energy input conditions. The results showed that the maximum pressure rise rate (MPRR) increased as an earlier start of the first injection (SOI1) timing by using alcohol–gasoline blends. It was found that the start of second injection (SOI2) timing has strong effects on the HCCI combustion and performance parameters as compared to the SOI1 timing although injection ratio (IR) was changed. The maximum cylinder gas pressure (Pmax), indicated that mean effective pressure (imep) and thermal efficiency can be directly controlled by using the SOI2 timing. The operating range of E10, E20 and M10 test fuels extended, as the MPRRs of these fuels were decreased with the use of optimum injection parameters.