Examining Combustion Characteristics of Water-In-Palm Oil Biodiesel Emulsified Fuels for Micro-Explosion

Micro-explosions during the combustion of palm oil water-in-biodiesel emulsified fuel caused simultaneous reduction in both NOx and smoke from the diesel engine exhaust.The existence of water particles in the palm oil biodiesel emulsified fuel cause micro-explosions due to the difference in volatilities and boiling temperatures of the water and biodiesel as the water particles reached their superheated limit first before the biodiesel.In addition, water lowers the adiabatic flame temperature and therefore acts as a heat sink during the combustion process.Ascertaining the occurrences of micro-explosion in the combustion chamber by direct visualisation is a difficult task, however, it can be made possible by observing the trends of the combustion phases.The secondary atomisation caused by the micro-explosion can be depicted on the combustion characteristics curve by determining the heat release rate of combustion.This study aimed to ascertain the occurrences of micro-explosion and reduction in flame temperature by analysing the combustion phases of water-in-palm oil biodiesel in a diesel engine with different blends of emulsified fuels.Emulsified biodiesel fuels with 11 and 13 water by volume blended with palm oil biodiesel were used as fuel in an unmodified single-cylinder direct injection engine at 0, 25, 50, 75 and 100 loads while maintaining the engine speeds at 2000 rpm.WiBE 8-8-13 shows the highest peak for both in-cylinder pressure and heat release rate with 3.87 and 23.51 increase respectively, as compared to B10 fuel at high load condition.The emission characteristics recorded by WiBE 8-8-11 shows lowest emission of NOx by 52.83 but increase the percentage of CO by 43.75 compare B10 fuel. © 2023, Institute of Technology PETRONAS Sdn Bhd.