Effect of injection pressure on combustion performance and flame morphology of biodiesel-n-butanol blends for industrial burner applications

The transition from fossil fuels to renewable alternatives has accelerated research on biodiesel utilization in industrial combustion systems. However, the high viscosity and low volatility of biodiesel often result in poor atomization and unstable flames. This study investigates the effects of injection pressure on the combustion and flame characteristics of biodiesel-n-butanol blends, aiming to enhance burner efficiency. Experiments were conducted using B40 and B100 biodiesel blended with 20% n-butanol at injection pressures ranging from 12 to 20 bar in a JL26D burner. Flame morphology, thermal efficiency, temperature distribution, and air-fuel ratio (AFR) were analyzed. The results show that increasing injection pressure produced shorter and more compact flames under the present burner conditions. The B100 + 20 vol% n-butanol blend achieved the highest thermal efficiency of 36% at 20 bar. The n-butanol-containing blends also exhibited favorable combustion trends, which may be associated with the modified fuel properties and oxygenated nature of the additive. However, because the individual contributions of injection pressure and fuel blending were not independently isolated, these results should not be interpreted as a rigorously demonstrated synergistic effect. Since direct spray and soot diagnostics were not performed, atomization- and soot-related interpretations are discussed as literature-supported inferences rather than direct measurements. These findings highlight the potential of biodiesel-n-butanol blends as a sustainable fuel option for industrial burners, contributing to cleaner and more energy-efficient power generation.