2-甲基四氢呋喃-空气混合气层流燃烧特性
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摘要
利用定容燃烧弹和高速纹影摄像系统,研究了不同压力和温度下的2-甲基四氢呋喃-空气混合气的球形扩张火焰.使用了非线性方法对试验数据进行处理,最终得到了初始压力为0.1～0.4 MPa、初始温度为373～453 K及当量比为0.7～1.6的无拉伸火焰传播速度、层流燃烧速度和马克斯坦长度等层流燃烧特性,并使用详细反应机理进行了化学动力学分析.2-甲基四氢呋喃的无拉伸火焰传播速率和层流燃烧速度都在当量比为1.1左右达到峰值.随着初始温度的升高和初始压力的降低,无拉伸火焰传播速率和层流燃烧速度有大幅度的提升.使用反应动力学机理得到的计算值与试验值相吻合.在初始压力为0.4 MPa的试验中观测到了火焰面的不稳定现象,大当量比时的马克斯坦长度很小,流体力学不稳定性也随压力上升而大幅度升高.通过化学动力学分析,小分子物质之间的反应对燃烧过程起到了主要影响.燃料消耗最多的路径是通过在2、5号位脱氢,从而在氧化过程中产生了较高含量的乙烯、丙烯等中间产物.
Spherical propagation flame of 2-methyltetrahydrofuran-air mixture at elevated temperature and pressure was studied by using constant volume bomb and high speed photographic technology. The non-linear method was used to process the experimental data. The unstretched flame speed,the laminar burning velocity and the Markstein length of the 2-methyltetrahydrofuran-air mixture was figured out at initial pressure of 0.1—0.4 MPa,initial temperature of373—453 K and equivalent ratio of 0.7—1.6. Chemical kinetic analysis was conducted by using detailed reaction mechanism. Results show that the unstretched flame speed and the laminar burning velocity reach their peaks at the equivalent ratio around 1.1. With the increase of the initial temperature and the decrease of the initial pressure,the unstretched flame speed and the burning velocity significantly reduce. The predictions of laminar burning velocity by reaction model shows good consistency with the experiment data under most conditions. Then,instable flame surface was observed in the experiment at 0.4 MPa. It is found that the Markstein length is very small at high pressure while the hydrodynamic instability remarkably increases with the pressure. Furthermore,chemical kinetic analysis shows that the reactions of small molecules have a major influence on the combustion process. The H abstraction reactions at sites 2 and 5 of the fuel molecular are the most efficient ways for fuel consumption,deducing the high concentration of some intermediate products such as ethylene and propylene during the oxidation.
Spherical propagation flame of 2-methyltetrahydrofuran-air mixture at elevated temperature and pressure was studied by using constant volume bomb and high speed photographic technology. The non-linear method was used to process the experimental data. The unstretched flame speed,the laminar burning velocity and the Markstein length of the 2-methyltetrahydrofuran-air mixture was figured out at initial pressure of 0.1—0.4 MPa,initial temperature of373—453 K and equivalent ratio of 0.7—1.6. Chemical kinetic analysis was conducted by using detailed reaction mechanism. Results show that the unstretched flame speed and the laminar burning velocity reach their peaks at the equivalent ratio around 1.1. With the increase of the initial temperature and the decrease of the initial pressure,the unstretched flame speed and the burning velocity significantly reduce. The predictions of laminar burning velocity by reaction model shows good consistency with the experiment data under most conditions. Then,instable flame surface was observed in the experiment at 0.4 MPa. It is found that the Markstein length is very small at high pressure while the hydrodynamic instability remarkably increases with the pressure. Furthermore,chemical kinetic analysis shows that the reactions of small molecules have a major influence on the combustion process. The H abstraction reactions at sites 2 and 5 of the fuel molecular are the most efficient ways for fuel consumption,deducing the high concentration of some intermediate products such as ethylene and propylene during the oxidation.
引文
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[2]Huber G W,Sara I A,Corma A.Synthesis of transportation fuels from biomass:Chemistry,catalysts,and engineering[J].Chemical Reviews,2006,106(9):4044-4098.
[3]Rudolph T W,Thomas J J.NOx,NMHC and CO emissions from biomass derived gasoline extenders[J].Biomass,1988,16(1):33-49.
[4]Lucas S V,Loehr D A,Meyer M E,et al.Exhaust emissions and field trial results of a new,oxygenated,non-petroleum-based,waste-derived gasoline blending component:2-methyltetrahydrofuran[C]//SAE Paper.Philadelphia,Pennsylvania,USA,1993,932675.
[5]Janssen D I A,Jakob D I M,Müther D I M.Tailormade fuels from biomass-potential of biogenic fuels for reducing emissions[J].Mtz Worldwide,2010,71(12):54-60.
[6]Janssen A J,Kremer F W,Baron J H,et al.Tailormade fuels from biomass for homogeneous lowtemperature diesel combustion[J].Energy&Fuels,2011,25(10):4734-4744.
[7]Moshammer K,Vranckx S,Chakravarty H K,et al.An experimental and kinetic modeling study of 2-methyltetrahydrofuran flames[J].Combustion and Flame,2013,160(12):2729-2743.
[8]王井山,樊祥山,杨康康,等.利用激波管对2-甲基四氢呋喃自燃特性的研究[J].内燃机学报,2016,34(1):1-8.
[9]Bruycker R D,Tran L S,Carstensen H H,et al.Experimental and modeling study of the pyrolysis and combustion of 2-methyltetrahydrofuran[J].Combustion and Flame,2017,176:409-428.
[10]张志远,黄佐华,郑建军,等.高温高压条件下乙醇-空气-稀释气预混合气层流燃烧特性研究[J].内燃机学报,2010,28(2):103-108.
[11]Lamoureux N,Djeba?li-chaumeix N,Paillard C E.Laminar flame velocity determination for H2-air-HeCO2,mixtures using the spherical bomb method[J].Experimental Thermal&Fluid Science,2003,27(4):385-393.
[12]Bradley D,Gaskell P H,Gu X J.Burning velocities,Markstein lengths,and flame quenching for spherical methane-air flames:A computational study[J].Combustion&Flame,1996,104(1/2):176-198.
[13]Chen Z.On the extraction of laminar flame speed and Markstein length from outwardly propagating spherical flames[J].Combustion and Flame,2011,158(2):291-300.
[14]Frankel M L,Sivashinsky G I.On effects due to thermal-expansion and Lewis number in spherical flame propagation[J].Combustion Science and Technology,1983,31(3/4):131-138.
[15]Meng X,Hu E,Li X,et al.Experimental and kinetic study on laminar flame speeds of styrene and ethylbenzene[J].Fuel,2016,185:916-924.
[16]Li Q,Zhang W,Jin W,et al.Laminar flame characteristics and kinetic modeling study of methanolisooctane blends at elevated temperatures[J].Fuel,2016,184:836-845.
[17]Jiang Y,Xu H,Ma X,et al.Laminar burning characteristics of 2-MTHF compared with ethanol and isooctane[J].Fuel,2017,190:10-20.
[18]胡二江,黄佐华,姜雪,等.C1~C4烷烃预混层流燃烧与着火特性研究[J].工程热物理学报,2013,34(3):558-562.
[19]Broustail G,Halter F,Seers P.Experimental determination of laminar burning velocity for butanol/iso-octane and ethanol/iso-octane blends for different initial pressures[J].Fuel,2013,106(2):310-317.
[20]Law C.Combustion physics[M].Cambridge:Cambridge University Press,2006.
[21]Matalon M.Flame dynamics[J].Proceedings of the Combustion Institute,2009,32(1):57-82.
[22]Sudholt A,Cai L,Heyne J,et al.Ignition characteristics of a bio-derived class of saturated and unsaturated furans for engine applications[J].Proceedings of the Combustion Institute,2015,35(3):2957-2965.