弹性模量对生物柴油喷油时刻影响的研究
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摘要
为研究燃油喷射系统中燃油物理特性参数对喷油时刻的影响,基于燃油密度、体积弹性模量随温度和压力变化的经验公式,建立了柴油机泵—管—嘴燃油喷射系统喷油延迟计算模型。结果表明:随着压力增加或温度下降,燃油的密度和体积弹性模量都呈线性增长趋势,且两种生物柴油的密度和体积弹性模量较为接近,但与柴油的差异明显。在温度20℃及压力10 MPa时,生物柴油(大豆油甲酯)的体积弹性模量比柴油高约182.0 MPa,且随着压力的升高,两者之间的体积弹性模量差值变小,但生物柴油的体积弹性模量仍高于柴油。以某490柴油机的燃油输送系统为例,在温度40℃和压力20 MPa条件下,由于生物柴油(大豆油甲酯)的体积弹性模量高于柴油约132.2 MPa,从喷油泵泵油到喷油器针阀开启的这段行程中,其所需输运时间比柴油提前约0.5°CA。该方法简单快捷,研究成果可为燃油喷射系统的设计提供参考。
In order to explore the influence of physical properties on fuel injection timing,a simplified model is established to estimate the injection delay for a conventional pump-line-nozzle fuel injection system of diesel engines by using empirical formulas of fuel density and bulk modulus.It is revealed that the density and bulk modulus of fuels arise linearly with the increase of pressure or the decrease of temperature. The density and bulk modulus of two types of biodiesel are equal relatively,but obviously different from diesel. Under the ambient condition of 20 ℃ and 10 MPa,the bulk modulus of biodiesel( soybean methyl ester) is 182. 0 MPa higher than that of diesel. With the increase of pressure,the difference of bulk modulus between biodiesel and diesel declines.Nevertheless,the biodiesel still has higher bulk modulus than diesel. As for the fuel delivery system in a conventional 490 diesel engine,under the ambient condition of 40 ℃ and 20 MPa,due to thatthe bulk modulus of biodiesel( soybean methyl ester) is 132. 2 MPa higher than that of diesel,the required time to deliver biodiesel from the piston pumping to the nozzle opening can be shortened by0. 5° CA than that of diesel. According to the result,this method is convenient and accurate.Meanwhile,the results can provide reference for the design of the fuel injection system.
In order to explore the influence of physical properties on fuel injection timing,a simplified model is established to estimate the injection delay for a conventional pump-line-nozzle fuel injection system of diesel engines by using empirical formulas of fuel density and bulk modulus.It is revealed that the density and bulk modulus of fuels arise linearly with the increase of pressure or the decrease of temperature. The density and bulk modulus of two types of biodiesel are equal relatively,but obviously different from diesel. Under the ambient condition of 20 ℃ and 10 MPa,the bulk modulus of biodiesel( soybean methyl ester) is 182. 0 MPa higher than that of diesel. With the increase of pressure,the difference of bulk modulus between biodiesel and diesel declines.Nevertheless,the biodiesel still has higher bulk modulus than diesel. As for the fuel delivery system in a conventional 490 diesel engine,under the ambient condition of 40 ℃ and 20 MPa,due to thatthe bulk modulus of biodiesel( soybean methyl ester) is 132. 2 MPa higher than that of diesel,the required time to deliver biodiesel from the piston pumping to the nozzle opening can be shortened by0. 5° CA than that of diesel. According to the result,this method is convenient and accurate.Meanwhile,the results can provide reference for the design of the fuel injection system.
引文
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[15]陈昊,杨璐,李江,等.生物柴油可压缩性计算及其对燃烧与排放的影响[J].中国公路学报,2014,27(3):116-121.
[16]高宗英,朱剑明.柴油机燃料供给与调节[M].北京:机械工业出版社,2009.
[17]TAT M E,VAN GERPEN J H,SOYLU S,et al.The speed of sound and isentropic bulk modulus of biodiesel at 21℃from atmospheric pressure to 35 MPa[J].Journal of the American Oil Chemists'Society,2000,77(3):285-289.
[18]GOUW T H,VLUGTER J C.Physical properties of fatty acid methyl esters.IV.ultrasonic sound velocity[J].Journal of the American Oil Chemists'Society,1964,41(8):524-526.
[19]TAT M E,VAN GERPEN J H.Measurement of biodiesel speed of sound and its impact on injection timing[R].Ames:Nation Technical Information Service,2003.
[20]CARESANA F.Impact of biodiesel bulk modulus on injection pressure and injection timing[J].Fuel,2011,90(2):477-485.
[2]DWIVEDI G,JAIN S,SHARMA M P.Impact analysis of biodiesel on engine performance—A review[J].Renewable and Sustainable Energy Reviews,2011,15(9):4633-4641.
[3]HARADA S.Chemical and physical properties of biodiesel[D].Kansas:Emporia State University,2011.
[4]KEGL B.Influence of biodiesel on engine combustion and emission characteristics[J].Applied Energy,2011,88(5):1803-1812.
[5]CHEN G.Study of fuel temperature effects on fuel injection,combustion,and emissions of direct-injection diesel engines[J].Journal of Engineering for Gas Turbines and Power,2009,131(2):251-259.
[6]周龙保,刘忠长,高宗英.内燃机学[M].北京:机械工业出版社,2005.
[7]陈昊.进油温度对生物柴油燃烧压力及循环变动的影响[J].车用发动机,2012(5):61-65.
[8]PAYRI R,SALVADOR F J,GIMENO J,et al.The effect of temperature and pressure on thermodynamic properties of diesel and biodiesel fuels[J].Fuel,2011,90(3):1172-1180.
[9]NDIAYE E H I,BAZILE J P,NASRI D,et al.High pressure thermophysical characterization of fuel used for testing and calibrating diesel injection systems[J].Fuel,2012,98(6):288-294.
[10]RODRIGUEZ-ANTON L M,CASANOVA-KINDELAN J,TARDAJOS G.High pressure physical properties of fluids used in diesel injection systems[R].Madrid:Society of Automotive Engineer,2000.
[11]MONYEM A,VAN GERPAN J H,CANAKCI M.The effect of timing and oxidation on emissions from biodiesel-fueled engines[J].Transactions of the American Society of Agricultural and Biological Engineers,2001,44(1):35-42.
[12]BAONZA V G,CCERES M,NU'EZ J.The spinodal as a reference curve for the high-pressure volumetric behavior of liquids[J].Chemical Physics Letters,1993,216(3/6):579-584.
[13]BAONZA V G,CCERES M,NU'EZ J.High-pressure compressibility behavior of liquids referred to a pseudospinodal curve[J].Chemical Physics Letters,1994,228(1/3):137-143.
[14]梅德清,袁银男,孙平,等.生物柴油发动机燃烧火焰与放热过程特性研究[J].农业机械学报,2012,43(11):26-30.
[15]陈昊,杨璐,李江,等.生物柴油可压缩性计算及其对燃烧与排放的影响[J].中国公路学报,2014,27(3):116-121.
[16]高宗英,朱剑明.柴油机燃料供给与调节[M].北京:机械工业出版社,2009.
[17]TAT M E,VAN GERPEN J H,SOYLU S,et al.The speed of sound and isentropic bulk modulus of biodiesel at 21℃from atmospheric pressure to 35 MPa[J].Journal of the American Oil Chemists'Society,2000,77(3):285-289.
[18]GOUW T H,VLUGTER J C.Physical properties of fatty acid methyl esters.IV.ultrasonic sound velocity[J].Journal of the American Oil Chemists'Society,1964,41(8):524-526.
[19]TAT M E,VAN GERPEN J H.Measurement of biodiesel speed of sound and its impact on injection timing[R].Ames:Nation Technical Information Service,2003.
[20]CARESANA F.Impact of biodiesel bulk modulus on injection pressure and injection timing[J].Fuel,2011,90(2):477-485.