Impact of Diesel Butyl Palmitate Fuel Blend on Engine Performance, Emissions, Soot Nanostructure, and Morphology Characteristics

Abstract Butyl palmitate is a long-chain fatty acid ester, similar to the fatty acid methyl esters that formulate biodiesel. Butyl palmitate was synthesized in the laboratory by esterification of palmitic acid recovered from depolymerized plastic waste from Malviya National Institute of Technology, Jaipur, India. Butanol used for the reaction was purchased from the market. The synthesized butyl palmitate was then tested as a fuel in an engine. In this experimental investigation, the impact of diesel and BP25 (75% (v/v) diesel blended with 25% (v/v) butyl palmitate) fuel was evaluated on engine performance, emissions, soot morphology, and nanostructural properties. For a comparative analysis, the experiments were carried out at 3.5 kW at 1500 rpm in a water-cooled, single-cylinder, four-stroke diesel engine. The engine was coupled with a 7.5 kW eddy current dynamometer. The study investigated performance (brake thermal efficiency), combustion (in-cylinder pressure), emissions (hydrocarbon (HC), CO, NOx), and soot characteristics (morphology, nanostructure via transmission electron microscopy (TEM), Raman, and Fourier transform infrared spectroscopy (FTIR) analyses) of the test fuels. Soot particles were sampled for 15 min under a dilution ratio of ∼15 and an exhaust air velocity of ∼0.75 m/s. Use of BP25 fuel enhanced engine performance by improving brake thermal efficiency. TEM analysis revealed that diesel soot consisted of smaller, more uniform particles, while BP25 produced larger, more agglomerated soot particles. This sustainable biofuel and experimental investigation contributes to societal goals such as public health and climate action.