Experimental investigation of ethanol/diesel and ethanol/biodiesel on dual fuel mode HCCI engine for different engine load conditions

Homogeneous charge compression ignition (HCCI) engine has fuel flexibility and potential to reduce NOX and soot emissions. The aim of this work is to investigate the effect of different mass flow rates of ethanol on dual fuel mode HCCI engine working under different load conditions. Ethanol (primary fuel) was supplied through the carburetor at the time of suction and diesel /biodiesel blend (secondary fuel) was injected to start the combustion at the end of the compression. Mass flow rate of ethanol varied by the use of different fuel jets (Jet 40, Jet 60, Jet 70, Jet 80, and Jet 90) in the carburetor. The results showed that with an increase in the mass flow rate of ethanol, ignition delay (ID) increases, combustion duration (CD), in-cylinder pressure and temperature are reduced; which leads to reduce NOX emission and smoke opacity of ethanol/diesel (E + D) and ethanol/biodiesel (E + B20) dual-fuel mode HCCI engine compared to neat diesel engine. However, HC and CO emissions are highly increased for dual fuel mode HCCI engines compared to neat diesel engine. Instead of diesel, biodiesel (B20) triggers the combustion and reduces ID (by 4 deg. crank angle (CA)) for 100% load with the use of jet 90 in the carburetor. Finally, it is concluded that Jet 40 and Jet 60 are suitable for 20% load and 40% load of engine respectively and also Jet 70 is suitable for 60%, 80% and 100% load conditions in order to optimize higher thermal efficiency, low NOX emissions and low smoke opacity.