Evaluation of diesel engine performance efficiency with biodiesel fuel derived from Linseed

Introduction
Energy is a fundamental driver of economic development worldwide. Currently, approximately 80–90% of global energy is supplied by fossil fuels, which face increasing challenges including resource depletion and environmental degradation. In response, research efforts have shifted toward developing renewable alternatives such as biodiesel. This study examines the impact of biodiesel produced from linseed oil on the performance of tractor engines, addressing the urgent need for sustainable fuel solutions in agricultural machinery that maintain operational efficiency while reducing environmental impact.
Materials and Methods
Linseed oil was extracted from local varieties in Khalkhal County using n-hexane as a solvent in a Soxhlet apparatus, yielding 33% oil. The oil was then converted to biodiesel via a transesterification reaction, and its physicochemical properties were analyzed according to the ASTM D-6751 standard. Engine performance was evaluated on a TYM tractor engine across seven speed levels (380 to 620 rpm) using four fuel blends (0%, 5%, 10%, and 25% biodiesel). A Sigma 5 dynamometer was employed to measure torque and power output, while the specific fuel consumption (SFC) was calculated from the fuel consumption rate and the measured power.
Results and Discussion
The results indicated a statistically significant relationship between engine speed and torque output (P < 0.0001). Maximum torque (563.67 Nm) was recorded at 380 rpm, while minimum torque (165.17 Nm) occurred at 620 rpm. The use of biodiesel blends led to a slight reduction in torque, decreasing from 472.9 Nm with pure diesel to 466.72 Nm with the B25 blend—a trend attributable to the lower calorific value of biodiesel. Peak power output (29.24 kW) was observed at 580 rpm. Biodiesel blends caused a minor but consistent decrease in power across all tested speeds. Specific fuel consumption (SFC) increased with rising engine speed; however, biodiesel blends significantly improved fuel efficiency, likely due to enhanced combustion efficiency and higher oxygen content.
ANOVA results showed no significant interaction between engine speed and fuel type for torque and power (P = 0.9996), but a significant interaction was observed for SFC (P = 0.031).

Conclusion
The produced linseed biodiesel complied with the ASTM D6751 standard, confirming its viability as an alternative fuel for diesel engines. Although slight reductions in torque and power output were observed—attributable to biodiesel's lower energy content—the fuel demonstrated improved consumption characteristics. This study suggests that linseed biodiesel can be effectively utilized in tractor engines, provided optimal blend ratios and operating conditions are carefully selected. Future research should focus on optimizing blend formulations and investigating emission profiles to further validate the practical application of linseed biodiesel in agricultural machinery.