Effects of ethanol and methyl formate additions on characteristics of pre-vaporised palm methyl ester laminar diffusion flame. (1st December 2022)

• Record Type: Journal Article
• Authors: Lee, Chia Chun; Tran, Manh-Vu; Tan, Boon Thong; Scribano, Gianfranco; Chong, Cheng Tung
• Is Part Of: Fuel. Volume 329(2022)
• Publication Date: 2022-12-01
• Subjects: Ethanol -- Laminar coflow diffusion flame -- Methyl formate -- OpenFOAM -- Palm methyl ester; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2022.125518
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: Ethanol and methyl formate additions decrease the height of palm methyl ester flames. Addition of ethanol and methyl formate decreases the flame stability limit. Dilution effect of the additives is dominant compared to thermal and chemical effects. Effects of additives are fundamentally linked to the differences in molecular structures. CO and NO emissions decrease with the addition of ethanol and methyl formate. Abstract: Motivated by the growing interest in the application of renewable fuels and combustion efficiency, gaining a detailed understanding of the effect of oxygenated additives on the structure and shape of the biodiesel laminar coflow diffusion flame is of fundamental and practical importance. In the experiment, the amount of ethanol and methyl formate in the nitrogen-diluted biodiesel mixtures was 10% vol. while maintaining a constant fuel mole fraction. The results showed that adding ethanol and methyl formate decreased the flame height regardless of the variation of the fuel jet velocities, with methyl formate demonstrating a greater reduction effect on the flame height. Besides that, the addition of these oxygenated additives has a significant influence on the flame stability, which was characterised by the parameters such as liftoff height, liftoff velocity, and blowout velocity. The oxygenated additives addition reduced the flame stability limit, with methyl formate showing a greater decrease in flame stability limit based on the observation of the blowout velocity. The dilution effect of the oxygenated additives was identified as the dominant effect on the flame structure and stabilisation through the decoupling analysis when compared to the thermal and chemical effects. Further analysis revealed that the difference in the influence of the oxygenated additives on the combustion characteristics was attributed to the physicochemical properties of the fuel mixtures, such as the molecular diffusivity, energy density, and fuel decomposition. These parameters can be fundamentally related to the difference in the molecular structures between ethanol and methyl formate. On the other hand, the addition of these oxygenated additives decreased both carbon monoxide and nitrogen oxide concentrations; however, the differences in the pollutant concentrations between ethanol and methyl formate were insignificant.