乙醇掺氢燃料预混层流燃烧特性的研究
详细信息    本馆镜像全文|  推荐本文 |  |   获取CNKI官网全文
摘要
21世纪能源及车用燃料的多元化,开发及应用生物质能等可再生能源及清洁替代燃料,是净化空气保护环境、解决矿产燃料不足的必然趋势。乙醇和氢气都是良好的内燃机代用燃料,能有效的改善现有内燃机的燃烧和排放性能,在乙醇中掺烧少量氢气能达到良好的燃料互补作用。由于含水酒精重整燃料中含有乙醇及氢气,故本文创新性地整合了乙醇-氢气混合气的化学反应机理,通过实验与数值计算重点研究了乙醇-氢气混合气的预混层流燃烧特性。
     通过乙醇-氢气混合气的定容燃烧弹实验,得到了不同当量比、不同氢气比例的混合气的火焰传播速率、层流燃烧速率、马克斯坦长度、火焰厚度、火焰前锋面结构、质量燃烧流量等参数,研究结果表明:随着氢气比例的增大,乙醇-氢气混合气的火焰传播速率(拉伸、无拉伸)、层流燃烧速率(拉伸、无拉伸)、质量燃烧流量(其增加率略小于层流燃烧速率的增加率)亦逐渐增大,马克斯坦长度则逐渐降低。而在当量比1.2时,火焰传播速率、层流燃烧速率等达到峰值,偏离该当量比后,速率均降低。在低氢气比例条件下(低于40%),马克斯坦长度随当量比的增大,呈现逐渐降低的趋势;高氢气比例(高于60%)时则相反。燃烧产物的生成速率随着拉伸率的增加而增加,燃气的消耗速率随着拉伸率的增加而减小。另外,容弹内燃烧压力的变化表明容弹中的燃烧是在近似绝热条件下进行的。而通过火焰的纹影图片,观察到了3种火焰的不稳定性。同时拟合了乙醇-氢气混合气的无拉伸层流燃烧速率的经验公式。探索了乙醇-氢气混合气的稀燃极限,发现掺氢能拓宽燃料的稀燃极限。
     对乙醇和氢气的化学反应机理进行了整合,在乙醇的反应机理中,添加氢气机理中包含的H2O2+O2=HO2+HO2基元反应以及O组分、O2组分的热力学数据,形成了新的乙醇-氢气混合气的反应机理,并通过敏感性分析和反应速率分析法对整合后机理进行了详细分析。同时,为了预测NO的排放,在新的乙醇-氢气混合机理中添加了泽利多维奇机理。在上述机理的基础上,运用CHEMKIN软件计算了不同初始条件下的乙醇-氢气混合气的火焰传播速率、层流燃烧速率、绝热火焰温度、CO和NO排放以及火焰结构等,为实验研究起到了辅助作用。
     通过数值计算结果和实验结果的层流燃烧速率和火焰传播速率的对比,发现对比结果具有良好的吻合性,表明本文中整合的机理适用于计算不同氢气比例下的稀混合气和化学计量比附近乙醇-氢气混合气的燃烧和化学反应过程。
The diversification of energy and vehicle fuels in the 21st century, developments and applications of bio-energy and other renewable and clean alternative fuels are the inevitable trends towards purifying air, protecting the environment and solving the problem of mineral fuel shortage. As being good alternative fuels, both ethanol and hydrogen can improve effectively the performance of combustion and reduce emissions. The mixture of ethanol with small quantities of hydrogen can achieve good complementary actions.Based on the reformed hydrated alcohol fuels containing ethanol and hydrogen, this paper has studied the premixed laminar combustion properties of ethanol-hydrogen mixtures through experiment and numerical calculation and integrated the chemical reaction mechanism of ethanol-hydrogen mixtures.
     The flame speed、laminar burning velocity、Markstein length、flame thickness、flame front surface structure and the burning flux are obtained by the experimental study of ethanol-hydrogen mixtures at different equivalent ratios and hydrogen proportions on the constant volume combustion bomb. The results show that:with the increase of the hydrogen proportion, the flame speed (stretched and unstretched)、laminar burning velocity(stretched and unstretched) and the burning flux increase gradually (the increase rate of the burning flux is slightly less than the laminar burning velocity), Markstein length decreases. While the flame speed and the laminar burning velocity achieve peaks at an equivalent ratio equal to 1.2 and decrease after deviating from this value. Markstein length decreases with the increase of the equivalent ratio in low hydrogen proportions (less than 40%) and the opposite happens when hydrogen proportion is more than 60%. The generation rate of combustion products increases with the increase of the stretched ratio whereas the gas consumption rate decreases when the stretched ratio is increased. Besides the change of the pressure shows that the combustion in the constant volume combustion bomb is carried out under conditions similar to adiabatic conditions. Three kinds of flame instabilities are observed in flame pictures. Meanwhile fit the empirical formula of the unstretched laminar burning velocities of ethanol-hydrogen mixtures. Explore the lean burn limit of ethanol-hydrogen mixtures, and hydrogen enhancement in ethanol can extend the lean burn limit.
     Through adding the basic element reaction H2O2+O2=HO2+HO2 and thermodynamic datum of O and O2 which are contained in the hydrogen mechanism to the ethanol mechanism, the chemical reaction mechanism of ethanol-hydrogen is integrated. By the methods of sensitivity and ROP, the consumption rates of ethanol and hydrogen are analyzed in details. Meanwhile in order to predict NO emissions, Zeldovich mechanism is added to the new ethanol-hydrogen mechanism. Based on the above mechanism, the flame speed、laminar burning velocity、adiabatic flame temperature、CO/NO emissions and the flame structure of ethanol-hydrogen mixtures in different initial conductions are calculated using CHEMKIN software, and this calculation plays a key role in the experimental study.
     Comparison shows good agreements between numerical calculation and experimental results of burning velocity and flame speed, and this means that the integrated mechanism of this paper can be used to calculate the combustion process of ethanol-hydrogen mixtures with different hydrogen proportions at conditions which are stoichiometric ratio and lean mixture.
引文
[1]崔心存.车用替代燃料与生物质能[M].中国石化出版社.2007-9.
    [2]可再生能源中长期发展规划.国务院发改委.2007-8.
    [3]中国汽车产业发展报告[M].社会科学文献出版社2008.
    [4]baike.baidu.com/view/377414.htm[DB/OL].访问时间2010-11.
    [5]蒋德明,黄佐华.内燃机替代燃料燃烧学[M].西安:西安交通大学出版社,2007.
    [6]国家发展和改革委员会赴欧洲考察团.欧洲可持续发展能源政策及对我国的启示[J].中国能源,2003-4.
    [7]李格升,游伏兵,高孝洪.含水酒精在发动机上的应用研究[J].武汉理工大学学报(交通科学与工程版).2008-12,32(6):994-997.
    [8]崔心存,熊立生,徐惠英等.柴油机掺烧氢气的性能研究[J].内燃机科技,上海交通科技大学出版社,1995(10).
    [9]李径定,陆英清,杜天申等.汽油-氢混合燃料的实验研究[J].内燃机工程,1982(4).
    [10]游伏兵.含水酒精重整燃料发动机研究.[D].武汉理工大学2008.
    [11]吴建强,李格升,游伏兵,董建.车用含水酒精重整器研究[J].中国汽车工程学会年会论文集.2008(2):1568-1570.
    [12]徐旭常,周力行.燃烧技术手册[M].北京:化学工业出版社2007.10.
    [13][美]威廉斯.燃烧理论.李荫亭等译[M].北京:科学出版社,1976:1-18.
    [14]Peters T, Rogg B. Reduced kinetic mechanisms for applications in combustion systems [M]. New York:Springer,1992.
    [15]Khitrin L N. Physics of Combustion and Explosion [M]. Moscow:Moscow State University Press,1957.
    [16]冯鹏飞,顾小磊,黄佐华.异丁醇-空气层流燃烧速率的测定[J].科学通报,2010,55(8):718-727.
    [17]Yu G., Law C. K. and Wu C. K., Laminar flame speeds of hydrocarbon+air mixtures with hydrogen addition[J]. Combustion and Flame,1986,63(3):339-347.
    [18]McMillian Michael H. and Lawson Seth A., Experimental and modeling study of hydrogen/syngas production and particulate emissions from a natural gas-fueled partial oxidation engine [J]. International Journal of Hydrogen Energy,2006,31(7):847-860.
    [19]Halter F., Chauveau C., Djebaili-Chaumeix N., et a 1., Characterization of the effects of pressure and hydrogen concentration on laminar burning velocities of methane-hydrogen-air mixtures[J].Proceedings of the Combustion Institute,2005,30(1):201-208.
    [20]Naha S., Briones A. M. and Aggarwal S. K., Effect of fuel blends on pollutant emissions in flames [J].Combustion Science and Technology,2005,177(1):183-220.
    [21]O'Connaire, M., H. J. Curran, J. M. Simmie, W. J. Pitz, C. K. Westbrook. A Comprehensive Modeling Study of Hydrogen Oxidation [J].Int.J.Chem.Kinet.36:603-622,2004 (UCRL-JC-152569).
    [22]Marinov, N. M. A Detailed Chemical Kinetic Model for High Temperature Ethanol Oxidation [J].Int. J. Chem. Kinet.31:183-220 (1999); Lawrence Livermore National Laboratory, Livermore, CA, UCRL-JC-131657.
    [23]唐华浩.含水乙醇重整混合气层流燃烧特性理论计算与实验研究.[D].武汉理工大学.2009-4.
    [24]Gu X J, Haq M Z, Lawes M,et al. Laminar Burning Velocity and Markstein Lengths of Methane-Air Mixtures [J].Combustion and Flame,2000,121(1/2):41-58.
    [25]Bradly D, Hicks R, Lawes M, et al. The Measurement of Laminar Burning for Iso-Octane-n-Heptane-Air Mixtures at Elevated Temperature and Pressures in an Explosion Bomb [J].Combustion and Flame,1998,115(1/2):126-144.
    [26]Markstein G. Nonsteady flame propagation [M].New Yor:McMillan Publication,1964.
    [27]廖世勇,井明科.乙醇-空气预混层流火焰特性的实验研究[J].内燃机学报,2007,25(5):469-474.
    [28]张志远,黄佐华,向俊,等.高温高压条件下甲醇_空气_稀释气层流燃烧速率测定[J].自然科学进展,2008-11,18(11):1304-1314.
    [29]蒋德明,黄佐华.内燃机替代燃料燃烧学[M].西安:西安交通大学出版社,2007.
    [30]Xuan Zhang, Zuohua Huang, Zhiyuan Zhang, etc. Measurements of laminar burning velocities and flame stability analysis for dissociated methanol-air-diluent mixtures at elevated temperatures and pressures [J]. International Journal of Hydrogen Energy,2009, 34(11):4862-4875.
    [31]蒋德明.内燃机燃烧与排放学[M].西安:西安交通大学出版社,2001.
    [32]孙俊,李格升.预混燃烧气体层流燃烧速率和马克斯坦长度的测定方法[J].武汉理工大学学报(交通科学与工程版).2010-6月,34(3):565-568.
    [33]孙俊,李格升.乙醇重整富氢混合气燃烧特性的理论分析[J].华中科技大学学报:自然科学版,2010-3,38(3):129-132.
    [34]Law C K, Sung C J.Structure, Aerodynamics, and Geometry of Premixed Flamelets [J]. Progress in Energy and Combustion Science,2000,26(4/6):459-505.
    [35]Bradly D, Gaskell P H, Gu X J.Burning velocities, markstein lengths, and flame quenching for spherical methane-air flames:a computational study [J].Combust Flame,1996,104: 176-198.
    [36]Zhang Z Y, Huang Z H, Wang X G, et al. Measurements of Laminar Burning Velocities and Markstein Lengths for Methanol-Air -Nitrogen Mixtures at Elevated Pressures and Temperatures [J]. Combustion and Flame,2008,155(3):358-368.
    [37]Kwon S, Tseng L K, Faeth G M. Laminar burning velocities and transition to unstable flames in H2/O2/N2 and C3H8/O2/N2 mixture.Comb Flame,1992,90:230-246.
    [38]Groff E G. The cellular nature of confined spherical propane-air flames [J]. Comb Flame, 1982,48:51-62.
    [39]Anupan D, David S K T, Checkel M D. The Effects of Temperature and Pressure on Stretched, Freely Propagating, Premixed, Laminar Methane-Air-Flame[C]. SAE Paper 2006-01-0494,2006.
    [40]阎小俊,蒋德明.天然气—氢气—空气混合气的层流燃烧速率测定[J].内燃机学报,2006,24(2):97-103.
    [41]Betchtold J K, Matalon M. The development of the markstein length on stoichiometry [J].Combust.Flame,2001127:1906-1913.
    [42]Gulder O L. Laminar Burning Velocities of Methanol, Ethanol and Isooctane-Air Mixtures [A].19th Symposium (International) on Combustion[C]. The Combustion Institute Pittsburgh PA,1982.
    [43]Egolfopoulos F N, D u D X, Law C K. In 24th Symposium (International) on Combustion [C]. The Combustion Institute Pittsburgh PA 1992.
    [44]Holley A T, Dong Y, Andac M G, et al. Extinction of Premixed Flames of Practical Liquid Fuels:Experiments and Simulations [J]. Combust Flame,2006,144 (3):448-460.
    [45]CHEMKIN RELEASE 3.5, GET-035-1,REACTION DESIGN Inc.1999.
    [46]严传俊,范玮.燃烧学[M].西北工业大学出版社.2005.
    [47]Stephen R.Turns燃烧学导论:概念与应用(第2版)[M].清华大学出版社.2009-4.
    [48]Miler, J. A., and Bowman, C.T. Mechanism and Modeling of Nitrogen Chemistry in Combustion [J].Progress in Energy and Combustion Science,15:287-338(1989).
    [49]Hanson, R.K., and Salimian, S. Survey of Rate Constants in the N/H/O System. Chapter 6 in Combustion Chemistry [J]. (W.C.Gardiner, Jr.,ed),Springer-Verlag, New York,pp.361-424, 1984.
    [50]李绚天,倪明江,岑可法。煤燃烧过程中燃料NOx的生成特性[J].工程热物理学报.N11.P338-341.1990.
    [51]Law C K.Combustion Physics [M].New York:Cambridge University Press,2006:275-282.
    [52]张旎,狄亚格,黄佐华,张志远.二乙醚-空气预混合气层流燃烧速率的测定[J].内燃机学报,2010年第28卷第4期:297-302.
    [53]Bromberg L.Benchmarking of Alcohol Chemical Kinetic Mechanism for Laminar Flame Speed Calculations [J].MIT Plasma Science and Fusion Center Report PSFC JA-08-10.
    [54]马凡华,蒋德明,何文华.定容燃烧弹中预混均匀充量的层流燃烧过程计算模型[J].西安交通大学学报.
    [55]高孝洪.内燃机工作过程数值计算[M].国防工业出版社.1986.1

© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号

地址:北京市海淀区学院路29号 邮编:100083

电话:办公室:(+86 10)66554848;文献借阅、咨询服务、科技查新:66554700