Impact of different nano additives on performance, combustion, emissions and exergetic analysis of a diesel engine using waste cooking oil biodiesel

Biodiesel is derived from waste cooking oil (WCO) by transesterification. Methyl ester was prepared by mixing diesel and biodiesel oils as 20% by volume. Nano particles as TiO₂, Al₂O₃ and CNTs were blended with biodiesel blend at different concentrations of 25, 50, and 100 mg/l to enhance the physicochemical fuel characteristics to obtain clean and efficient combustion performance. An experimental setup was incorporated into a diesel engine to investigate the influence of these nano-materials on engine performance, exergy analysis, combustion characteristics and emissions using WCO biodiesel-diesel mixture. Enriching methyl ester mixture with 100 ppm titanium, alumina and CNTs (B20T100, B20A100 and B20C100) increased the thermal efficiency by 4%, 6% and 11.5%, respectively compared to B20. Biodiesel blending with nano additives B20T100, B20A100 and B20C100 decreased the emissions of CO (11%, 24% and 30%, respectively), HC (8%, 17% and 25%, respectively) and smoke (10%, 13% and 19%, respectively) compared to B20. However, the noticeable increase of NO_x was estimated by 5%, 12% and 27% for B20T100, B20A100 and B20C100, respectively. Finally, the results showed the rise in peak cylinder pressure by 5%, 9% and 11% and increase in heat release rate by 4%, 8% and 13% for B20T100, B20A100 and B20C100, respectively. The fuel exergy of B20T100, B20A100 and B20C100 are lower than biodiesel blend B20 by 6.5%, 16% and 23% but the exergetic efficiency are increased by 7%, 19% and 30% at full load about B20.