Combustion characteristics and emissions of a compression ignition engine using emulsified jatropha biodiesel blend

• Selection of surfactant for emulsifying biodiesel blend with water.
• Similar fuel properties as biodiesel.
• Similar pressure-crank angle as biodiesel.
• Longer ignition delay with higher cylinder gas pressure.
• Reduced emission (NOx reduction) compared to biodiesel.

An emulsified fuel containing 10% and 15% water by volume was prepared from a diesel blend with 10% Jatropha biodiesel (JB10) to evaluate the combustion characteristics of a 10.3 kW, single cylinder, 4-stroke, water cooled, direct injection (DI) diesel engine. Initially experiments were conducted to determine the required hydrophilic–lipophilic balance (HLB). The results showed that JB10 and its emulsified fuel exhibited similar combustion stages to that of diesel with no undesirable combustion features observed such as an unacceptable increase cylinder gas pressure. With increasing percentage of water, ignition delay was longer at higher engine loads. Reductions in emission of CO, CO2, HC and NOx were observed for the emulsified fuel compared to JB10. Emulsified biodiesel can be recommended for use in place of biodiesel.