An experimental investigation on the combustion characteristics of a direct injection diesel engine fuelled with an algal biodiesel and its diesel blends

Conscientious efforts by researchers established that microalgae have huge potential for future energy production. Microalgae strain Euglena sanguinea has been collected locally and cultivated in a photoautotrophic mode. The microalgae lipid is extracted from the biomass and subsequently, biodiesel (BD) has been prepared for diesel engine experimental investigation. The main objective of the present study was to analyze various combustion characteristics of underutilized E. sanguinea BD in an agricultural diesel engine. Combustion performance of E. sanguinea biodiesel and its five different diesel–biodiesel blends (ES10, ES20, ES30, ES40, and ES50) have been studied at different engine loading conditions (0–100%). At full load, ignition delay (ID) reduced by 12.04% for ES100, 8.43% for ES50 and 7.22% for ES40. Combustion duration gradually drops up to ES40 and after that it increases marginally as biodiesel (BD) dosage increases in the blend. Peak cylinder pressure (PCP) and mean gas temperature (MGT) increases with an increase in algae BD concentration in the blend. Net heat release rate (NHRR) and rate of pressure rise (RPR) decrease with an increase in the algal BD concentration in the blend. At full load, PCP and MGT of ES100 (58.11 bar and 1204.84 °C) was 3.03% and 4%, respectively, higher than diesel fuel (56.4 bar and 1160.42 °C). Peak NHRR and maximum RPR of ES100 (43.10 J/°CA and 4.8 bar/°CA) was 12.07% and 10.61%, respectively, lower than diesel fuel (49.02 J/°CA and 5.37 bar/°CA). Overall, microalgae E. sanguinea biodiesel/diesel fuel blend up to 40% (ES40) is recommended for regular use in diesel engines. Graphical abstract