A numerical study on the quasi-steady spray and soot characteristics for soybean methyl ester and its blends with ethanol using CFD-reduced chemical kinetics approach. (1st June 2020)

• Record Type: Journal Article
• Authors: Cheng, Xinwei; Gan, Suyin; Ng, Hoon Kiat
• Is Part Of: Energy. Volume 200(2020)
• Publication Date: 2020-06-01
• Subjects: Ethanol -- Reduced chemical kinetics -- SME -- Soot -- Spray combustion; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2020.117540
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: This work numerically examines the quasi-steady spray combustion and soot development for soybean methyl ester (SME) and SME-ethanol blends (S90E10, S70E30). A validated reduced ethanol mechanism (37 species and 149 reactions) was formulated using a temperature sensitivity analysis under auto-ignition and jet-stirred reactor conditions. At initial pressures between 10.0 bar and 60.0 bar, initial temperatures between 750 K and 1350 K and equivalence ratios between 0.5 and 2.0, the ignition delays and key species profiles (C2 H5 OH, CO2, O2 ) of the reduced mechanism deviated by 0.5 order and 40%, respectively as compared to the experimental measurements. Subsequently, the reduced ethanol mechanism was combined with a reduced biodiesel mechanism to form a surrogate mechanism (102 species and 446 reactions) for biodiesel-ethanol blends and integrated into OpenFOAM for spray combustion modelling. Under reacting spray conditions at a constant ambient density of 22.8 kg/m 3 and ambient temperatures of 900 K and 1000 K, the spray penetrations for SME-ethanol blends were shortened by 35.5% (maximum difference). Smaller flame areas with 60 K higher local flame temperature were obtained. Due to a 20% decrease in acetylene mass fractions and soot formation rates, the peak soot volume fractions for SME-ethanol blends were 19.6% lower. Highlights: Spray/flame and soot characteristics for SME and SME-ethanol blends were studied. The spray/flame area were smaller for the SME-ethanol blends than that of SME. ID and FLLs were unaffected by the increase in ethanol content of the SME-ethanol blends. Lower SVF and soot formation/oxidation rates were found for the SME-ethanol blends.