Improvement of ternary fuel combustion with various injection pressure strategies in a toroidal re-entrant combustion chamber

Abstract

The present experimental work focuses on the influence injection pressure and toroidal re-entrant combustion chamber in a single cylinder diesel engine fuelled with ternary fuel (diesel-biodiesel-ethanol) blend. Ternary fuel (TF) is prepared by blending 70% diesel, 20% biodiesel, and 10% ethanol blends and its fuel properties were investigated and compared with diesel fuel. Since the physic-chemical properties of TF are well behind the diesel fuel, it is proposed to be blended with 20 ppm alumina nano additives which act as an ignition enhancer and catalytic oxidizer. The resulting fuel mixture (TF + 20 ppm alumina additive) is named as high performance fuel (HPF). Experimentations were conducted on HPF subjected to various injection pressures of 18 MPa, 20 MPa, 22 MPa, and 24 MPa respectively and are operated in toroidal re-entrant chamber geometry (TG) at an injection timing of 22 ^obTDC. From experimentation, it was identified that, for TG-HPF, higher injection pressure of 22 MPa ensued highest BTE (Brake Thermal Efficiency) of 35.5% and lowest BSEC (Brake Specific Fuel Consumption) of 10.13 MJ/kWh owing to the pooled effect of higher swirl formation, improved atomization enhanced evaporation rate, and better air-fuel mixing. Emission wise TG-HPF operated at 22 MPa lowered the HC (hydrocarbon), CO (carbon monoxide), and smoke emissions by 18.88%, 7.19%, and 5.02%, but with marginally improved NOx (oxides of nitrogen) and CO₂ (carbon dioxide) emissions by 3.92% and 3.89% respectively. In combustion point of view, it is observed that injection pressure increased the cylinder pressure, heat release rate (HRR), and cumulative heat release rate (CHRR) by 5.35%, 5.08%, and 3.38% respectively indicating improved combustion rate as a result of enhanced atomization, evaporation, and high turbulence inducement. Overall, it is concluded that operating the ternary fuel at 22 MPa injection pressure at toroidal re-entrant combustion chamber results in improved performance and minimized emissions.