Abstract This study investigates the optimization of performance and emissions in a common rail direct injection (CRDI) engine using cottonseed biodiesel combined with ethanol and tert-butyl alcohol. Utilizing the Taguchi-Grey Relational Analysis (GRA) method, the research pinpointed the optimal engine parameters. For ethanol blends, the best results improved brake thermal efficiency (BTE) and lower emissions were achieved with a 15 % ethanol share (ES), 200 bar injection pressure (IP), and an injection timing (IT) of 27° before top dead center (bTDC). For tert-butyl alcohol blends (TBA), the ideal setup was a 5 % alcohol share, 27° bTDC injection timing (IT), and a higher 260 bar injection pressure (IP). Analysis of variance (ANOVA) indicated that the ethanol share (ES) was the most significant factor for brake thermal efficiency (BTE) and brake-specific fuel consumption (BSFC), while injection timing (IT) was paramount for controlling hydrocarbon (HC), carbon monoxide (CO), nitrogen oxides (NOx), carbon dioxide (CO 2 ), and smoke emissions. Conversely, for tert-butyl alcohol blends (TBA), injection pressure (IP) most affected brake thermal efficiency (BTE), the alcohol share governed BSFC, and injection timing (IT) was again the dominant factor for emissions. These findings provide critical guidance for selecting and optimizing alcohol additives in biodiesel-diesel fuel formulations.
Yadav et al. (Sat,) studied this question.