FUEL
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2022
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IF 8.035
Yang Liu,Xiaobei Cheng,Yuchen Ya,Bowen Wang,Pu Zhang,Kai Zhang,Yishu Xu
PODE 3 , with the molecular formula of CH 3 O(CH 2 O) 3 CH 3 , is considered a highly competitive alternative fuel due to the absence of C C bond and its high oxygen content, and have been shown to significantly reduce soot emission when applied as a diesel fuel additive. However, the effect of PODE 3 addition on the oxidation reactivity of soot generated in the flame remains unclear which is of great importance for the optimal design of the post-treatment devices during its application. In this work, the impact of PODE 3 (0 %, 10 %, and 20 % by volumetric fraction) addition on the oxidation reactivity of soot at different maturity and oxidation degrees in n -heptane/toluene co-flow diffusion flames was specially investigated combining information on thermogravimetric analysis, high-resolution transmission electron microscope, and Raman spectroscopy. Results showed that PODE 3 substitution significantly shrank soot generation region, and increased the flame temperatures before height above burner (HAB) < 45 mm. The addition of PODE 3 improved the soot oxidation reactivity, which had a strong ability to hinder the growth of the microcrystalline carbon layers and resulted in a high content of amorphous carbon in soot particles. Specifically, it had more significant impacts on the soot in the oxidation stage than the surface growth stage. These can be explained that with PODE 3 addition, on the one hand, the “reliable carbon atom” for soot formation is significantly reduced and the amount of oxidizing species is increased, resulting in a smaller particle size and a higher content of disordered and amorphous carbon in soot particles. On the other hand, the flame temperatures increased where HAB < 45 mm, which would promote the soot formation reactions. The combined effects of these factors make PODE 3 have more significant inhibitory impacts in reactivity of soot sampled at oxidation stage than that at surface growth stage. Therefore, the impact of PODE 3 addition on soot nanostructures and oxidation reactivity is not only reflected in its chemical effect but also in temperature effect.
研究领域:
燃烧学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
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2017
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IF 4.601
Yaoyao Ying,Dong Liu
This paper explored the effects of butanol isomers, n -butanol, iso -butanol, sec -butanol, and tert -butanol, as fuel-side additives on soot nanostructure and reactivity in ethylene inverse diffusion flames (IDF) and normal diffusion flames (NDF). The variations of structures and oxidation rates among the soot samples derived from ten different flames were studied and compared using high resolution transmission electron spectroscopy (HRTEM), Raman spectroscopy, thermogravimetric analyzer (TGA), surface area and porosimetry analyzer, and elemental analyzer. Results demonstrated that soot from IDF with the additions of butanol isomers had irregular shapes with film-like materials and highly heterogeneous nanostructures, which showed both amorphous carbon and fullerenic lamellae. The shells presented more prevalently in tert -butanol-doped IDF soot, which had the longest fringe length and smallest fringe tortuosity. Whereas in the NDF as butanol isomers were individually added, the soot samples were aggregated by several tens or hundreds nearly rounded particles. All the NDF soot exhibited a typical core-shell structure with extended and planar lamellae. Soot from sec -butanol added NDF presented the lowest degree of graphitization with the shortest fringe length and largest fringe tortuosity. The TGA results revealed that the oxidation rates of the IDF soot particles were much higher than that of the NDF soot. Moreover, when butanol isomers were individually added in IDF, soot produced with n -butanol (1.34E-03 s −1 ) showed the highest reactivity with the least degree of crystallization in structure, followed by iso -butanol (1.31E-03 s −1 ), sec -butanol (1.29E-03 s −1 ) and tert -butanol (1.14E-03 s −1 ) in the sequence of reactivity. However, the oxidation rates of the soot samples generated from butanol isomers-doped NDF were in the order of sec -butanol (4.26E-04 s −1 ), tert -butanol (3.70E-04 s −1 ), n -butanol (3.52E-04 s −1 ) and iso -butanol (3.23E-04 s −1 ) from the highest to lowest. The results confirmed a relationship on structure-property between soot nanostructure and reactivity.
研究领域:
能源科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY
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2020
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IF 6.082
Yuchen Ya,Xiaokang Nie,Weiwei Han,Longkai Xiang,Mingyan Gu,Huaqiang Chu
The effects of 2, 5-dimethylfuran (DMF)/ethanol addition on the atomized combustion soot formation characteristics of n-heptane/iso-octane coflow diffusion flames are systemically studied. The changes of soot particles and deposition morphology at different heights in the flame of reference fuel with 15% ethanol (E15) and 15% DMF (DMF15) are analyzed. Results show that the addition of oxygenated fuels can increase the flame heights and decrease the brightness. With the addition of 15% ethanol and DMF, the flame heights are increased by 11.29% and 19.35% respectively, and the brightness of the edge region of the middle section of DMF15 flame is enhanced. At the nozzle, the average temperature of E15 flame increases by 80 K. The high temperature region of E15 flame enlarged and the average temperature difference of different heights is higher than 50 K. As for DMF15, the high temperature region of flame is constant, and the average temperature difference between various heights is smaller than 35 K. For three fuels, the size of the sediment particles formed at the low height above burner (HAB = 20 mm) is large, and the obvious pore structure can be seen at HAB = 60 mm. The addition of oxygenated fuels makes the pore structure distribution regular and the porosity decreases, and DMF15 (porosity = 0.2670) has larger pore structure than E15 (porosity = 0.1557). The oxygenated fuel can inhibit the formation of soot precursors and the agglomeration of soot particles, but the increase of particle size in the middle region of flame is promoted because of the increase of flame height and residence time of soot particles. As a result, the soot particle size of oxygenated fuel is decreased greatly in the oxidation stage, and the soot particle size of DMF15 (40.4%) is decreased more than that of E15 (37.1%). The effect of ethanol and DMF addition on the activation energy of low position soot is not obvious, which is about 130 kJ/mol. In the middle position of the flame, the activation energy of E15 is the highest (159.32 kJ/mol), and the activation energy of DMF15 is the smallest (148 kJ/mol). At the high position, E15 (212.07 kJ/mol) and DMF15 (226.73 kJ/mol) are less than that of DE0 (235.03 kJ/mol) respectively, indicating that the activation energy of the mature soot reduces, which is beneficial to the oxidative removal. Ethanol can dilute the fuel and increase the oxygen concentration in the mixture, while DMF can delay the ignition and prolong the residence time of soot and increase the content of disordered carbon in mature soot particles.
研究领域:
燃烧科学
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化学工程
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
PROCEEDINGS OF THE COMBUSTION INSTITUTE
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2018
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IF 5.336
Zhan Gao,Lei Zhu,Xinyao Zou,Chunpeng Liu,Bo Tian,Zhen Huang
The dibutyl ether (DBE) has been recently identified as an alternative biofuel produced from lignocellulosic biomass . In the present study, experimental and chemical kinetics studies were carried out to investigate the effects of dibutyl ether addition to a biodiesel surrogate (methyl decanoate) on soot formation in laminar coflow diffusion flames . The mole fraction of DBE in the fuel stream varies from 0 to 40 mol%. Laser-induced incandescence (LII) technique was applied to obtain the 2D soot volume fraction distribution and a combined methyl decanoate-dibutyl ether-PAH kinetic model was constructed to analyze chemical effects of DBE addition on the concentration of key species for soot inception and growth. The experimental results show that DBE addition can indeed reduce the soot yielding and the suppressive effect is nonlinear with the mole fraction of DBE in the fuel mixture. It is found that in the flame centerline , soot reduction with more DBE addition is a combined effect of lower nucleation rate and decreasing PAHs condensation, while soot reduction effect is somewhat moderate in flame wings as the result of the competition between decreasing inception rate and enhanced surface growth caused by higher acetylene concentration. Reaction path analysis suggests that DBE addition can markedly suppress C 3 + C 3 pathways to the first aromatic ring , lead to lower A1 yield and consequently limit the aromatic growth to larger PAHs. DBE is found to be remarkably promising in terms of suppressing soot formation and reducing particle emission.
研究领域:
能源科学
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燃烧学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Chemistry
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2020
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IF 1.79
Yuchen Ya,Xiaokang Nie,Licheng Peng,Longkai Xiang,Jialong Hu,Wenlong Dong,Huaqiang Chu
Laminar diffusion flame was used to study the effect of ethanol on n-heptane flame in terms of the morphology and microstructure of soot under atomization combustion. For the same carbon mass flux at the outlet of the burner, the ratio of ethanol doping in n-heptane was changed, and the soot was collected from the axial positions of the flame at different heights using the thermophoresis probe method. The results showed that the flame height increased significantly with the increasing ratio of ethanol doping. When the ratio of ethanol and n-heptane (CE/CN) was 1.5, the flame height increased by 10 mm compared with that of pure n-heptane flame. Besides, the temperature in the center of the flame decreased with the increasing ratio of ethanol doping, but the temperature in the low position was higher than that in the pure n-heptane flame, and the temperature in the high position was lower than that in the pure n-heptane flame. However, the flame temperature was the highest when the proportion of ethanol in the mixture was greater than that of n-heptane. The temperature at the flame center decreased with the increasing ratio of ethanol doping, while the temperature at the flame edge increased with the ratio. The primary particle size of soot (soot size hereafter) in all working conditions increased with the increase of flame height, which was in line with the general growth law of soot. Moreover, the soot size at the same height decreased with the increasing ratio of ethanol doping, and this trend was most obvious at the flame height of 20 mm and 30 mm. Compared with pure n-heptane, when CE/CN was 1.5, the soot size at 20 mm and 30 mm decreased by an average of 34.83%, indicating that ethanol could inhibit the surface growth of soot particle. Furthermore, the density of soot particles collected by a single copper net decreased significantly, indicating that ethanol could reduce the production amount of soot.
研究领域:
燃烧科学
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环境工程
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE ENERGY INSTITUTE
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2022
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IF 6.47
Xuan Zhao,Dandan Qi,Kaixuan Yang,Chen Chen,Lei Xu,Yaoyao Ying,Tianjiao Li,Dong Liu
This work focused on effects of n- butanol addition on sooting transition process in iso -octane counterflow diffusion flames using optical and chemical diagnostics. Three iso -octane flames were studied with pure iso -octane, a 20% n- butanol addition mixture and a 40% n- butanol addition mixture as fuels. Optical diagnostics was carried out to determine effects of n -butanol addition on the sooting transition process using a high-resolution digital camera based on image processing and transition point extraction methods. Online gas chromatograph was used to investigate the flame chemistry in the sooting transition process. The results showed that the sooting transition point was delayed with the increase of n -butanol addition, which indicated that the addition of n -butanol could suppress the soot formation. To reveal the mechanism for effects of n -butanol on sooting transition process, kinetic simulations were further performed. The experimental results of flame chemistry were compared with the predictions from two mechanisms for iso -octane and n -butanol mixture. Both mechanisms were found to be capable of well capturing the main variations of most species in flames. After n -butanol addition, the changes of fuel-specific primary decomposition products were more obvious. It was noted that the decreased concentration of carbon which was available for benzene formation was the main reason for the delay of sooting transition point with n -butanol additions. Moreover, the inhibition of PAHs growth from n -butanol addition also could contribute to this kind of delayed effects.
研究领域:
燃烧科学
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化工工程
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光学诊断
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火焰化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）