Numerical analysis of ethanol concentration and strain rate on diffusion flame characteristics

doi:10.11949/0438-1157.20201376

Abstract

Abstract:

Analysis on the flame characteristics of ethanol counter flame combustion is the key to understand the formation of diffusion flame and guide the design of ethanol counter flame burners. The combustion characteristics of the diffusion flame of ethanol diluted with air and nitrogen are simulated by using the counter flame diffusion flame model combined with the optical thin radiation model, and the influences of ethanol concentration and strain rate on the flame structure, temperature distribution and temperature sensitivity of the peak temperature location are discussed. The results show that with the increase of ethanol concentration, the CO and H₂ reaction zone moves to the fuel side, the flame area becomes wider, the peak flame temperature gradually increases, and the rising trend gradually slows down, and the influence of intermediate products and CO on temperature sensitivity decreases. With the increase of strain rate, free radicals and CO increase, intermediate products decrease, component distribution area and flame area become narrower, flame temperature peak gradually decreases, and the influence of intermediate products and CO on temperature sensitivity gradually increases.

Key words: fuel, ethanol, counter flame, flame characteristics, strain rate, numerical analysis

摘要：

研究液体燃料乙醇对冲燃烧的火焰特性是理解扩散火焰形成和指导乙醇对冲燃烧器设计的关键。采用对冲扩散火焰模型，结合光学薄辐射模型，模拟空气与氮气稀释下乙醇形成的扩散火焰，探讨了乙醇浓度和应变率对扩散火焰的火焰结构、温度分布和温度峰值处的温度敏感性的影响规律。结果表明：随着乙醇浓度的增加，CO和H₂反应区域向燃料侧移动，火焰区域变宽，火焰温度峰值逐渐升高，升高趋势渐缓，中间产物和CO对温度敏感性的影响减弱；随着应变率的增加，自由基和CO增多，中间产物减少，组分的分布区域和火焰区域变窄，火焰温度峰值逐渐降低，中间产物和CO对温度敏感性的影响逐渐增强。

关键词: 燃料, 乙醇, 对冲火焰, 火焰特性, 应变率, 数值分析

CLC Number:

TK 16

SHI Dunfeng, GAN Yunhua, LUO Yanlai, JIANG Zhengwei, ZHOU Yi. Numerical analysis of ethanol concentration and strain rate on diffusion flame characteristics[J]. CIESC Journal, 2021, 72(5): 2801-2809.

石敦峰, 甘云华, 罗燕来, 江政纬, 周毅. 乙醇浓度和应变率对扩散火焰特性的数值分析[J]. 化工学报, 2021, 72(5): 2801-2809.

Figures/Tables 11

Fig.1 Schematic diagram of flame structure

Table 1 Simulation conditions（TF=360 K，TO=298 K，P=0.1 MPa）

工况	燃料侧u_F/(cm·s^-1)	氧化剂侧u_O/(cm·s^-1)	当量比Φ	摩尔分数		应变率a/s^-1
工况	燃料侧u_F/(cm·s^-1)	氧化剂侧u_O/(cm·s^-1)	当量比Φ	乙醇	氮气	应变率a/s^-1
1	11.18	10.50	1.32	0.15	0.85	30
2	11.02	10.50	1.74	0.20	0.80	30
3	10.87	10.50	2.14	0.25	0.75	30
4	10.18	10.50	4.01	0.50	0.50	30
5	9.61	10.50	5.68	0.75	0.25	30
6	9.13	10.50	7.20	1.00	0.00	30
7	21.74	21.00	2.14	0.25	0.75	60
8	32.61	31.50	2.14	0.25	0.75	90

Fig.2 The comparison between experimental and simulated results of flame temperature

Fig.3 The distributions of temperature, heat release rate and component of diffusion flame (XF=0.25,a=30 s-1)

Fig.4 The distributions of temperature, heat release rate and component of diffusion flame (XF=0.75,a=30 s-1)

Fig.5 The distributions of temperature, heat release rate and component of diffusion flame (XF=0.25,a=90 s-1)

Fig.6 The influence of ethanol concentration on temperature distribution and heat release rate (a=30 s-1)

Fig.7 The influence of strain rate on temperature distribution and heat release rate (XF=0.25)

Fig.8 The effects of ethanol concentration and strain rate on the peak flame temperature

Fig.9 The influence of ethanol concentration on the temperature sensitivity coefficient at the peak temperature point (a=30 s-1)

Fig.10 The influence of strain rate on temperature sensitivity coefficient at the temperature peak point (XF=0.25)

References 33

1	Maruta K. Micro and mesoscale combustion[J]. Proceedings of the Combustion Institute, 2011, 33(1): 125-150.
2	Ong B C, Kamarudin S K, Basri S. Direct liquid fuel cells: a review[J]. International Journal of Hydrogen Energy, 2017, 42(15): 10142-10157.
3	Zhang X W, Pan L, Wang L, et al. Review on synthesis and properties of high-energy-density liquid fuels: hydrocarbons, nanofluids and energetic ionic liquids[J]. Chemical Engineering Science, 2018, 180: 95-125.
4	刘红, 何阳, 蔡畅, 等. 乙醇和正丁醇添加剂对喷雾冷却的影响[J]. 化工学报, 2019, 70(1): 65-71.
	Liu H, He Y, Cai C, et al. Influence of ethanol and n-butanol additives on spray cooling[J]. CIESC Journal, 2019, 70(1): 65-71.
5	Ju Y G, Maruta K. Microscale combustion: technology development and fundamental research[J]. Progress in Energy and Combustion Science, 2011, 37(6): 669-715.
6	Balat M, Balat H, de Öz C. Progress in bioethanol processing[J]. Progress in Energy and Combustion Science, 2008, 34(5): 551-573.
7	Balat M, Balat H. Recent trends in global production and utilization of bio-ethanol fuel[J]. Applied Energy, 2009, 86(11): 2273-2282.
8	Lefebvre A H, Ballal D R. Gas Turbine Combustion: Alternative Fuels and Emissions[M]. Florida: CRC Press, 2014: 485.
9	Chen J, Peng X F, Yang Z L, et al. Characteristics of liquid ethanol diffusion flames from mini tube nozzles[J]. Combustion and Flame, 2009, 156(2): 460-466.
10	Xu T, Gao X N, Yang J, et al. Experimental and numerical simulation study of the microscale laminar flow diffusion combustion of liquid ethanol[J]. Industrial & Engineering Chemistry Research, 2013, 52(23): 8021-8027.
11	Yang Z L, Xu T, Gan Y H. Experimental study on the diffusion flame using liquid ethanol as fuel in mini-scale[C]//Proceedings of ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer. Tainan, Taiwan, China, 2009: 853-857.
12	杨泽亮, 薛峰, 甘云华. 陶瓷管作燃烧器的乙醇扩散小火焰实验研究[J]. 热科学与技术, 2008, 7(4): 367-372.
	Yang Z L, Xue F, Gan Y H. Experimental study of small jet diffusion flame of alcohol with ceramic tube as burner[J]. Journal of Thermal Science and Technology, 2008, 7(4): 367-372.
13	甘云华, 陈邵有, 杨泽亮, 等. 液体乙醇微尺度扩散火焰高度的影响因素研究[J]. 工程热物理学报, 2010, 31(11): 1957-1960.
	Gan Y H, Chen S Y, Yang Z L, et al. Study on the factors affecting the micro diffusion flame height of liquid ethanol[J]. Journal of Engineering Thermophysics, 2010, 31(11): 1957-1960.
14	Gan Y H, Xu J L, Yan Y Y, et al. A comparative study on free jet and confined jet diffusion flames of liquid ethanol from small nozzles[J]. Combustion Science and Technology, 2014, 186(2): 120-138.
15	甘云华, 佟洋, 罗智斌. 乙醇在微尺度单电极燃烧器内的雾化与燃烧[J]. 化工学报, 2015, 66(11): 4597-4602.
	Gan Y H, Tong Y, Luo Z B. Electro-spraying and combustion of alcohol in micro-combustor with single electrode[J]. CIESC Journal, 2015, 66(11): 4597-4602.
16	Rietveld I B, Kobayashi K, Yamada H, et al. Electrospray deposition, model, and experiment: toward general control of film morphology[J]. The Journal of Physical Chemistry. B, 2006, 110(46): 23351-23364.
17	Kim J W, Yamagata Y, Kim B J, et al. Direct and dry micro-patterning of nano-particles by electrospray deposition through a micro-stencil mask[J]. Journal of Micromechanics and Microengineering, 2009, 19(2): 025021.
18	Oh H, Kim K, Kim S. Characterization of deposition patterns produced by twin-nozzle electrospray[J]. Journal of Aerosol Science, 2008, 39(9): 801-813.
19	Temperton R H, O'Shea J N, Scurr D J. On the suitability of high vacuum electrospray deposition for the fabrication of molecular electronic devices[J]. Chemical Physics Letters, 2017, 682: 15-19.
20	Hsu R Y, Liao J H, Tien H W, et al. Gas chromatography electrospray ionization mass spectrometry analysis of trimethylsilyl derivatives[J]. Journal of Mass Spectrometry, 2016, 51(10): 883-888.
21	Nomura H, Hayasaki M, Ujiie Y. Effects of fine fuel droplets on a laminar flame stabilized in a partially prevaporized spray stream[J]. Proceedings of the Combustion Institute, 2007, 31(2): 2265-2272.
22	叶宏程, 甘云华, 江政纬, 等. 乙醇荷电喷雾对冲燃烧的火焰特性[J]. 化工学报, 2019, 70(12): 4787-4794.
	Ye H C, Gan Y H, Jiang Z W, et al. Flame characteristics of alcohol electro-spraying in counter-flow combustor[J]. CIESC Journal, 2019, 70(12): 4787-4794.
23	Gan Y H, Tong Y, Ju Y G, et al. Experimental study on electro-spraying and combustion characteristics in meso-scale combustors[J]. Energy Conversion and Management, 2017, 131: 10-17.
24	Higuera F J, Tejera J M. Vaporization and gas-phase combustion of electrosprayed heptane in a small chamber[J]. Combustion and Flame, 2017, 177: 144-154.
25	Niemann U, Seshadri K, Williams F A. Accuracies of laminar counterflow flame experiments[J]. Combustion and Flame, 2015, 162(4): 1540-1549.
26	Wang Y L, Veloo P S, Egolfopoulos F N, et al. A comparative study on the extinction characteristics of non-premixed dimethyl ether and ethanol flames[J]. Proceedings of the Combustion Institute, 2011, 33(1): 1003-1010.
27	Seiser R, Humer S, Seshadri K, et al. Experimental investigation of methanol and ethanol flames in nonuniform flows[J]. Proceedings of the Combustion Institute, 2007, 31(1): 1173-1180.
28	Veloo P S, Wang Y L, Egolfopoulos F N, et al. A comparative experimental and computational study of methanol, ethanol, and n-butanol flames[J]. Combustion and Flame, 2010, 157(10): 1989-2004.
29	Li Y Z, Hu G, Liao S Y, et al. Effects of partial premixing on NO production in methanol/dimethyl ether counterflow flames[J]. Fuel, 2018, 234: 974-984.
30	Guo H S, Ju Y G, Maruta K, et al. Radiation extinction limit of counterflow premixed lean methane-air flames[J]. Combustion and Flame, 1997, 109(4): 639-646.
31	Hubbard G L, Tien C L. Infrared mean absorption coefficients of luminous flames and smoke[J]. Journal of Heat Transfer, 1978, 100(2): 235-239.
32	Mittal G, Burke S M, Davies V A, et al. Autoignition of ethanol in a rapid compression machine[J]. Combustion and Flame, 2014, 161(5): 1164-1171.
33	Berta P, Puri I K, Aggarwal S K. Structure of partially premixed n-heptane-air counterflow flames[J]. Proceedings of the Combustion Institute, 2005, 30(1): 447-453.

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