Preparation, Characterization, and Evaluation of Emission and Performance Characteristics of Thumba Methyl Ester (Biodiesel)

Thumba oil with a higher triglyceride content can be a promising feed for synthesizing a fatty acid alkyl ester as an alternative to pure diesel. The current study investigates the emission and performance characteristics of thumba methyl ester (TME) in compression ignition (CI) engines corresponding to variable loads and compression ratios (CRs), respectively. TME was prepared at an optimized pressure of 5 bar by hydrodynamic cavitation. The properties of TME–diesel blends with varied volume percentages of biodiesel, such as 5, 10, 15, 20, and 25, denoted B5, B10, B15, B20, and B25, respectively, were compared to pure TME (100% biodiesel) and pure diesel (100%). The B20 biodiesel blend has been observed as the optimal one based on the lower emission composition and higher brake thermal efficiency. For B20 fuel, injection at 23° before the top dead center (TDC) and a CR of 18 resulted in the lowest brake specific fuel consumption of 0.32 kg/kW h and a maximum brake thermal efficiency of 36.5%. Using titanium dioxide nanoparticles in the pre-stage of TME manufacturing has ultimately reduced the nitrogen oxide, hydrocarbon, and carbon monoxide emissions. At a CR of 18 and advanced injection 23° before TDC for a CI engine, TME derived from thumba oil has the potential to be a viable diesel substitute.