Combustion Behaviour of Diesel Engine Operated with Water Emulsified Diesel

Abstract

An experimental study was conducted to investigate the combustion behaviour of a constant speed, 5.5 kW, 4-stroke, single-cylinder, water cooled, direct injection (DI) diesel engine fueled with water emulsified diesel. Water emulsified diesel prepared with 20% water/diesel ratio, 0.9% surfactant amount at 2200 rpm of stirrer with hydrophile-lipophile balance (HLB) value 4.3 was checked for fuel properties. The cylinder gas pressure (CGP) was higher in water emulsified diesel as compared to diesel for similar engine loading. The peak CGP was found to be 95.86 and 95.18 bar for water emulsified diesel and diesel, respectively at full engine load. At higher engine load, better turbulence of combustible mixture and oxidation of soot particles by OH radicals in water emulsified diesel helped in raising the peak rate of pressure rise. A higher ignition delay was observed in the combustion of water emulsified diesel. Water  emulsified diesel exhibited ignition delay of 23, 21, 19, 18 and 17 degree crank angle (°CA) at no load, 25, 50, 75 and 100% load, respectively as compared to  20, 20, 18, 14, and 9°CA with diesel for similar engine loading. The longer ignition delay period in water emulsified diesel helped in burning of more fuel leading to higher instantaneous heat release rate (Qn). At full engine load, its value was found to be 223.06 and 207.90 J/°CA for water emulsified diesel and diesel, respectively.