航空煤油冰点及黏温关系的分子动力学模拟
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摘要
航空煤油的冰点和黏温特性是衡量煤油低温流动性的重要质量指标。本文以某航空煤油的碳数分布、碳氢质量比、芳香烃饱和烃质量比等参数为依据,建立了5种烃混合的煤油体系模型,进行了分子动力学模拟。根据密度和扩散系数随温度的变化预测了煤油体系的冰点,模拟冰点值与实验结果一致;通过计算径向分布函数分析了冰点温度附近煤油体系内部的微观结构,发现同种分子间的聚集是影响煤油冰点温度的主要原因,芳香烃对煤油体系冰点的影响大于链状饱和烃的影响;采用Rouse Model模拟了煤油体系的黏温关系,模拟黏温指数与通过实验拟合的黏温指数相同,模拟黏度随温度的变化趋势与实验结果一致。
Freezing point and viscosity-temperature relationship are important quality indexes for evaluating low temperature fluidity of aviation kerosene. A kerosene model composing of 5 alkane molecules was established based on a carbon number distribution,carbon/hydrogen mass ratio and aromatic hydrocarbons/saturated hydrocarbons mass ratio. The kerosene model was studied by molecular dynamics simulation. Freezing point was predicted according to the sudden change of density-temperature and diffusion coefficient-temperature curves and the simulated freezing point is consistent with the experimental value. The radial distribution function was simulated to analyze the microstructure of kerosene modelled at temperatures close to freezing point. The results showed that aggregation between like molecules was the main reason that influenced the freezing point. Aromatic hydrocarbons had greater influence than saturated hydrocarbons on the freezing point. The Rouse Model was employed to study the viscosity-temperature relationship of the kerosene model. The simulated viscosity index was identical to test data,showing good agreement between simulated and experimental viscosity changes with temperature.
Freezing point and viscosity-temperature relationship are important quality indexes for evaluating low temperature fluidity of aviation kerosene. A kerosene model composing of 5 alkane molecules was established based on a carbon number distribution,carbon/hydrogen mass ratio and aromatic hydrocarbons/saturated hydrocarbons mass ratio. The kerosene model was studied by molecular dynamics simulation. Freezing point was predicted according to the sudden change of density-temperature and diffusion coefficient-temperature curves and the simulated freezing point is consistent with the experimental value. The radial distribution function was simulated to analyze the microstructure of kerosene modelled at temperatures close to freezing point. The results showed that aggregation between like molecules was the main reason that influenced the freezing point. Aromatic hydrocarbons had greater influence than saturated hydrocarbons on the freezing point. The Rouse Model was employed to study the viscosity-temperature relationship of the kerosene model. The simulated viscosity index was identical to test data,showing good agreement between simulated and experimental viscosity changes with temperature.
引文
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[16]YANG Q,YANG X P,LI X.D,et al.The curing and thermal transition behavior of epoxy resin:A molecular simulation and experimental study[J].Rsc Advances,2013(3):7 452-7 459.
[17]YANG Q,CHEN X,HE Z,et al.The glass transition temperature measurements of polyethylene:Determined by using molecular dynamic method[J].Rsc Advances,2016,6(15):12 053-12 060.
[18]KWON T W,SONG H L.Molecular dynamics simulation studies of mid-size liquid n-alkanes,C12-C160[J].Bulletin of the Korean Chemical Society,2015,36(4):1 165-1 171.
[19]CHOI J,YU S,YANG S,et al.The glass transition and thermoelastic behavior of epoxy-based nanocomposites:A molecular dynamics study[J].Polymer,2011,52,5 197-5 203.
[20]陈正隆.分子模拟的理论与实践[M].北京:化学工业出版社,2007.[CHEN Z L.The theory and practice of molecular dynamics[M].Beijing:Chemical Industry Press,2007.]
[21]殷开梁,闫朋克,孙静,等.生物柴油分子系统凝固过程的分子动力学模拟[J].计算机与应用化学,2011,28(5):602-606.[YINK L,YAN K P,SUN J,et al.Molecular dynamics simulation on solidification process of bio-diesel molecular systems.Computers and Applied Chemistry,2011,28(5):602-606.]
[22]LI M,LIU X Y,et al.Molecular dynamics simulation on glass transition temperature of isomeric polyimide[J].Express Polymer Letters,2009,3(10):665-675.
[23]陈敏伯.计算化学--从理论化学到分子模拟[M].北京:科学出版社,2009.[CHEN M B.Computational chemistry-from theoretical chemistry to molecular dynamics[M].Beijing:Science Press,2009.
[24]MONDELLO M,GREST G S.Molecular dynamics of linear and branched alkanes[J].Journal of Chemical Physics,1995,103(103):7 156-7 165.
[25]MONDELLO M,GREST G S,GARCIA A R,et al.Molecular dynamics of linear and branched alkanes:Simulations and nuclear magnetic resonance results[J].Journal of Chemical Physics,1996,105(12):5208-5215.
[26]ZHANG L Q,GREEN M L.Analyzing properties of model asphalts using molecular simulation[J].Energy&Fuels,2007,21(3):1 712-1 716.
[27]MONDELLO M,GREST G S.Viscosity calculations of n-alkanes by equilibrium molecular dynamics[J].Journal of Chemical Physics,1997,106(106):9 327-9 336.
[28]ZHANG L Q.Physical and mechanical properties of model asphalt systems calculated using molecular simulation[D].Rhode:University of Rhode Island,2007.
[29]BALASUBRAMANIAN S.Shear viscosity of linear alkanes through molecular simulations:Quantitative tests for-decane and-hexadecane[J].Molecular Simulation,2012,38(14):1 234-1 241.
[2]MONDELLO M,GREST G S.Molecular dynamics of linear and branched alkanes[J].Journal of Chemical Physics,1995,103(103):7 156-7 165.
[3]STEVENS M J,MONDELLO M,GREST G S,et al.Comparison of shear flow of hexadecane in a confined geometry and in bulk[J].Journal of Chemical Physics,1997,106(17):7 303-7 314.
[4]殷开梁.分子动力学模拟的若干基础应用和理论[D].杭州:浙江大学,2006.[YIN K L.The application and theory of molecular dynamics[D].Hangzhou:Zhejiang University,2006.]
[5]KWON T W,SONG H L.Molecular dynamics simulation studies of mid-size liquid n-alkanes,C12-C160[J].Bulletin of the Korean Chemical Society,2015,36(4):1 165-1 171.
[6]MAKRODIMITRI ZΑ,HELLER A,KOLLER T M,et al.Viscosity of heavy n-alkanes and diffusion of gases therein based on molecular dynamics simulations and empirical correlations[J].Journal of Chemical Thermodynamics,2015,91:101-107.
[7]于维铭.航空煤油替代燃料火焰传播速度与反应动力学机理研究[D].北京:清华大学,2014.[YU W M.Study on flame speed and chemical reaction mechanism for alternative fuels of aviation kerosene[D].Beijing:Tsinghua University,2014.]
[8]于维铭,袁振,钟北京.航空煤油火焰传播速度实验与动力学研究[J].工程热物理学报,2014(10):2 102-2 107.[YU W M,YUANZ,ZHONG B J.Experimental and kinetic study on flame speed of aviation kerosene[J].Journal of Physical Thermodynamics,2014(10):2 102-2 107.]
[9]SUN H.COMPASS:An ab initio force-field optimized for condensed-phase applicationsoverview with details on alkane and benzene compounds[J].Journal of Physical Chemistry B,1998,102(38):7 338-7 364.
[10]MIKAMI Y,LIANG Y,MATSUOKA T,et al.Molecular dynamics simulations of asphaltenes at the oil-water interface:From nanoaggregation to thin-film formation[J].Energy&Fuels,2013,27(4):1 838-1 845.
[11]张军,房体明,王业飞,等.烷烃油滴在超临界二氧化碳中溶解的分子动力学模拟[J].中国石油大学学报(自然科学版),2015,39(2):124-129.[ZHANG J,FANG T M,WANG Y F,et al.Molecular dynamics simulation of dissolution of n-alkanes droplets in supercritical carbon dioxide[J].Journal of China University of Petroleum(Editon of Natural Science),2015,39(2):124-129.]
[12]任强,代振宇,周涵.重油胶体结构的介观模拟[J].石油学报,2013,29(1):86-94.[REN Q,DAI Z Y,ZHOU H.Mesoscale simulation on colloidal structures of heavy oil[J].Acta Petrolei Sinica,2013,29(1):86-94.
[13]王大放.用分子动力学方法模拟高压电场对碳酸钙结晶过程的影响[D].青岛:中国石油大学(华东),2010.[WANG D F.Molecular dynamics simulation on the impact of high voltage electrostatic field on crystallization of calcium carbonate aqueous solution[D].Qingdao:China University of Petroleum(East China),2010.]
[14]RAPAPORT D C.The art of molecular dynamics simulation[M].Cambridge:Cambridge University Press,2004.
[15]郑东,于维铭,钟北京.RP-3航空煤油替代燃料及其化学反应动力学模型[J].物理化学学报,2015(4):636-642.[ZHENG D,YU WM,ZHONG B J.RP-3 aviation kerosene surrogate fuel and the chemical reaction kinetic model[J].Acta Physico-Chimica Sinica,,2015(4):636-642.]
[16]YANG Q,YANG X P,LI X.D,et al.The curing and thermal transition behavior of epoxy resin:A molecular simulation and experimental study[J].Rsc Advances,2013(3):7 452-7 459.
[17]YANG Q,CHEN X,HE Z,et al.The glass transition temperature measurements of polyethylene:Determined by using molecular dynamic method[J].Rsc Advances,2016,6(15):12 053-12 060.
[18]KWON T W,SONG H L.Molecular dynamics simulation studies of mid-size liquid n-alkanes,C12-C160[J].Bulletin of the Korean Chemical Society,2015,36(4):1 165-1 171.
[19]CHOI J,YU S,YANG S,et al.The glass transition and thermoelastic behavior of epoxy-based nanocomposites:A molecular dynamics study[J].Polymer,2011,52,5 197-5 203.
[20]陈正隆.分子模拟的理论与实践[M].北京:化学工业出版社,2007.[CHEN Z L.The theory and practice of molecular dynamics[M].Beijing:Chemical Industry Press,2007.]
[21]殷开梁,闫朋克,孙静,等.生物柴油分子系统凝固过程的分子动力学模拟[J].计算机与应用化学,2011,28(5):602-606.[YINK L,YAN K P,SUN J,et al.Molecular dynamics simulation on solidification process of bio-diesel molecular systems.Computers and Applied Chemistry,2011,28(5):602-606.]
[22]LI M,LIU X Y,et al.Molecular dynamics simulation on glass transition temperature of isomeric polyimide[J].Express Polymer Letters,2009,3(10):665-675.
[23]陈敏伯.计算化学--从理论化学到分子模拟[M].北京:科学出版社,2009.[CHEN M B.Computational chemistry-from theoretical chemistry to molecular dynamics[M].Beijing:Science Press,2009.
[24]MONDELLO M,GREST G S.Molecular dynamics of linear and branched alkanes[J].Journal of Chemical Physics,1995,103(103):7 156-7 165.
[25]MONDELLO M,GREST G S,GARCIA A R,et al.Molecular dynamics of linear and branched alkanes:Simulations and nuclear magnetic resonance results[J].Journal of Chemical Physics,1996,105(12):5208-5215.
[26]ZHANG L Q,GREEN M L.Analyzing properties of model asphalts using molecular simulation[J].Energy&Fuels,2007,21(3):1 712-1 716.
[27]MONDELLO M,GREST G S.Viscosity calculations of n-alkanes by equilibrium molecular dynamics[J].Journal of Chemical Physics,1997,106(106):9 327-9 336.
[28]ZHANG L Q.Physical and mechanical properties of model asphalt systems calculated using molecular simulation[D].Rhode:University of Rhode Island,2007.
[29]BALASUBRAMANIAN S.Shear viscosity of linear alkanes through molecular simulations:Quantitative tests for-decane and-hexadecane[J].Molecular Simulation,2012,38(14):1 234-1 241.