液体燃料碳原子数对微尺度扩散火焰特性的影响
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摘要
为了解微尺度扩散火焰燃烧特性,选用正戊烷、正庚烷、正辛烷、正癸烷、正十二烷五种不同液体烷烃,进行燃烧实验。结果表明:火焰在不同流量下会呈现球型、椭球型、细长型、聚积型以及喷射型;燃料含碳越多,其火焰燃烧极限越小。对于每种烷烃,火焰高度H与Re都呈线性正相关,燃料含碳量越多,火焰高度H随Re变化越小;Roper火焰长度预估模型对于液体烷烃同样适用,实验所得数值与模型的误差在25%以内。火焰管壁温度随流量增大而降低,火焰温度随流量增大而升高,火焰温度与火焰形态有关;不同燃料的管壁温度和火焰温度都随含碳量增大而降低。
In order to get characteristics of the micro-scale diffusion flame of liquid fuels, n-pentane, nheptane, n-octane, n-decane, n-dodecane were studied experimentally. The following results are obtained.( 1)The diffusion flame shapes are different, including spherical shape, ellipsoidal shape, slender shape, agminated shape and explosive shape depending on the flow rate; the more carbon contained in the fuel, the smaller the combustion limit is.(2) The flame height is proportional to Reynolds number, and the fuel containing more carbon has smaller ratio of flame height and Reynolds number. Roper's model for estimating diffusion flame height applies to liquid alkane as well. The error between the experiment value and the model is within 25%.(3) The temperature of tube wall decreases as the flow rate increase, and the temperature of flame increases instead. The flame temperature depends on the shapes of these flame. The temperature of tube wall and flame temperature of different fuel decrease with the increase of carbon content.
In order to get characteristics of the micro-scale diffusion flame of liquid fuels, n-pentane, nheptane, n-octane, n-decane, n-dodecane were studied experimentally. The following results are obtained.( 1)The diffusion flame shapes are different, including spherical shape, ellipsoidal shape, slender shape, agminated shape and explosive shape depending on the flow rate; the more carbon contained in the fuel, the smaller the combustion limit is.(2) The flame height is proportional to Reynolds number, and the fuel containing more carbon has smaller ratio of flame height and Reynolds number. Roper's model for estimating diffusion flame height applies to liquid alkane as well. The error between the experiment value and the model is within 25%.(3) The temperature of tube wall decreases as the flow rate increase, and the temperature of flame increases instead. The flame temperature depends on the shapes of these flame. The temperature of tube wall and flame temperature of different fuel decrease with the increase of carbon content.
引文
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[2]Sinha A,Ganguly R,Puri I K.Control of Confined Non-premixed Flames Using a Microjet[J].International Journal of Heat and Fluid Flow,2005,26(3):431-439.
[3]Kuwana K,Tagami N,Mizuno S,et al.Extinction of Laminar Jet Diffusion Microflames[J].Proceeding of the Combustion Institute,2009,32(2):3115-3121.
[4]Won S H,Cha M S,Park C S,et al.Effect of Electric Fields on Reattachment and Propagation Speed of Tribrachial Flames in Laminar Coflow Jets[J].Proceedings of the Combustion Institute,2007,31(1):963-970.
[5]Won S H,Ryu S K,Kim M K,et al.Effect of Electric Fields on the Propagation Speed of Tribrachial Flames in Coflow Jets[J].Combustion and Flame,2008,152(4):496-506.
[6]Matta L M,Neumeier Y,Lemon B,et al.Characteristics of Microscale Diffusion Flames[J].Proceedings of the Combustion Institute,2002,29(1):933-939.
[7]Baker J,Calvert M E,Murphy D W.Structure and Dynamics of Laminar Jet Micro-Slot Diffusion Flames[J].Journal of Heat Transfer,2002,124(4):783-790.
[8]Pham T K,Dunn-Rankin D,Sirignano W A.Flame Structure in Small-Scale Liquid Film Combustors[J].Proceedings of the Combustion Institute,2007,31(2):3269-3275.
[9]Sadasivuni V,Agrawal A K.A Novel Meso-Scale Combustion System for Operation with Liquid Fuels[J].Proceedings of the Combustion Institute,2009,32(2):3155-3162.
[10]Kyritsis D C,Coriton B,Faure F,et al.Optimization of a Catalytic Combustor Using Electrosprayed Liquid Hydrocarbons for Mesoscale Power Generation[J].Combustion and Flame,2004,139(1-2):77-89.
[11]Yuliati L,Seo T,Mikami M.Liquid-Fuel Combustion in a Narrow Tube Using an Electrospray Technique[J].Combustion and Flame,2012,159(1):462-464.
[12]Li J,Huang J,Yan M,et al.Experimental Study of N-heptane/Air Combustion in Meso-Scale Burners with Porous Media[J].Experimental Thermal&Fluid Science,2014,52(1):47-58.
[13]Li J,Huang J,Zhao D,et al.Diffusion Combustion of Liquid Heptane in a Small Tube with and without Heat Recirculating[J].Combustion Science&Technology,2012,184(10-12):1591-1607.
[14]Chen J,Peng X,Yang Z,et al.Characteristics of Liquid Ethanol Diffusion Flames from Mini Tube Nozzles[J].Combustion and Flame,2009,156(2):460-466.
[15]杨泽亮,刘志成,甘云华.液体燃料小尺度扩散火焰影响因素分析[J].顺德职业技术学院学报,2009,7(4):15-18.
[16]杨泽亮,甘云华,赖伟其.液体燃料扩散小火焰的实验研究[J].热科学与技术,2009,8(2):151-155.
[17]Roper F G.The Prediction of Laminar Jet Diffusion Flame Sizes,Part I:Theoretical Model[J].Combustion and Flame,1977,29(3):219-226.
[18]Roper F G,Smith C,Cunningham A C.The Prediction of Laminar Jet Diffusion Flame Sizes,Part II:Experimental Verification[J].Combustion and Flame,1977,29(3):227-234.
[19]梅开,邱佐祯,李军伟,等.液体燃料在毛细管出口廓然火焰燃烧特性[J].航空动力学报,2017,32(9):2100-2109.
[20]程能林.溶剂手册[M].北京:化学工业出版社,2007.
[21]Sunderland P B,Mendelson B J,Yuan Z G,et al.Shapes of Buoyant and Nonbuoyant Laminar Jet Diffusion Flames[J].Combustion and Flame,1999,116(3):376-386.