Spray characteristics of biofuels for advance combustion engines

Abstract

This study investigates spray characteristics, flashing and non-flashing, of unsaturated neem biodiesel (BD), biodiesel-ethanol (BDE50) blend, and diesel for application in advanced combustion engines. Fuel properties, injection pressure, nozzle geometry, and the surrounding ambient gas conditions govern the spray breakup and air-fuel mixing. The spray characteristics of fuel is studied at various injection pressure and ambient gas densities using the high-speed shadowgraphy technique. BDE50 shows improved spray dispersion with distinct tree-shaped spray morphology at ambient density of 1.14 kg/m 3 and injection pressure of 50 MPa. Theoretical analysis confirms occurrence of cavitation due to high volatile component (ethanol) in biofuel mixture and throttling conditions. At high ambient gas density and injection pressure, diesel and BDE50 exhibit high spray cone angle. Neem biodiesel maintains high tip penetration and low cone angle due to poor atomization. The study recommends use of BDE50 blend for achieving improved mixture formation in engines. • Dual (reactivity) biofuels spray atomization strongly controls the air-fuel mixing and combustion. • Cavitation induced flashing with BDE50 spray shows improved spray dispersion with distinct tree shaped spray morphology. • Theoretical analysis confirms cavitation (in BDE50) by throttling conditions. • Recommended to use the BDE50 instead of biodiesel for achieving the improved mixture formation.