Convective vaporization of a fuel droplet with thermal radiation absorption

The ‘extended’ and ‘effective-conductivity’ droplet vaporization models developed by Abramzon and Sirignano [Abramzon B, Sirignano WA. Droplet vaporization model for spray combustion calculations. Int J Heat Mass Transfer 1989;32(9):1605–18] are generalized to take into account the contribution of thermal radiation and the temperature dependence of liquid fuel properties. The thermal radiation effect is simulated using the simplified model for thermal radiation absorption suggested by Dombrovsky and Sazhin [Dombrovsky LA, Sazhin SS. Absorption of thermal radiation in a semi-transparent spherical droplet: a simplified model. Int J Heat Fluid Flow 2003;24: 919–27]. Physical properties of liquid fuel, including density, are evaluated at the average liquid temperature and updated at each time-step. These generalized models are applied to the analysis of the vaporization process of n-decane and diesel fuel droplets injected into hot air. It is pointed out that the radiation absorption in diesel fuel is generally stronger than in n-decane, and it needs to be taken into account in modelling the combustion processes in diesel engines. Calculations of the droplet vaporization rate performed using the simplified ‘effective-conductivity’ model with the internal radiation heat source uniformly distributed show exceptionally good agreement with results obtained based on the more accurate ‘extended’ vaporization model with the non-uniform distribution of radiation absorption. This allows us to recommend using the ‘effective-conductivity’ model with uniform radiation absorption for spray combustion calculations, including applications in internal combustion engines.

[1]  Richard Stone,et al.  Introduction to Internal Combustion Engines , 1985, Internal Combustion Engines.

[2]  R. A. Johns,et al.  A Detailed Modelling of the Spray Ignition Process in Diesel Engines , 2000 .

[3]  S. Wittig,et al.  Experimental and theoretical study of one- and two-component droplet vaporization in a high pressure environment , 1999 .

[4]  A. A. Amsden,et al.  Efficient multicomponent fuel algorithm , 2003 .

[5]  Sergei Sazhin,et al.  Droplet vaporization model in the presence of thermal radiation , 2005 .

[6]  P. Lage,et al.  Single Droplet Vaporization Including Thermal Radiation Absorption , 1993 .

[7]  M. C. Yuen,et al.  On Drag of Evaporating Liquid Droplets , 1976 .

[8]  P. Lage,et al.  Total thermal radiation absorption by a single spherical droplet , 1993 .

[9]  G. Harpole.  Droplet Evaporation in High Temperature Environments , 1981 .

[10]  Ulrich Renz,et al.  Numerical simulation of fuel sprays at high ambient pressure: the influence of real gas effects and gas solubility on droplet vaporisation , 2003 .

[11]  M. Modest.  Radiative heat transfer , 1993 .

[12]  Morgan Heikal,et al.  Thermal Ignition Analysis of a Monodisperse Spray with Radiation , 2001 .

[13]  Said I. Abdel-Khalik,et al.  An Investigation of Simple Evaporation Models Used in Spray Simulations , 2003 .

[14]  R. Reid,et al.  The Properties of Gases and Liquids , 1977 .

[15]  Morgan Heikal,et al.  Transient heating of diesel fuel droplets , 2004 .

[16]  J. C. Jaeger,et al.  Conduction of Heat in Solids , 1952 .

[17]  K. Kobe.  The properties of gases and liquids , 1959 .

[18]  S. Sazhin,et al.  Radiative Heating of Semi-Transparent Diesel Fuel Droplets , 2004 .

[19]  Geoffrey F. Hewitt.  Heat exchanger design handbook, 1998 , 1998 .

[20]  M. Renksizbulut,et al.  Numerical Study of Droplet Evaporation in a High-Temperature Stream , 1983 .

[21]  S. Sazhin,et al.  Heating and evaporation of semi-transparent diesel fuel droplets in the presence of thermal radiation , 2001 .

[22]  L. Dombrovsky.  Absorption of thermal radiation in large semi-transparent particles at arbitrary illumination of the polydisperse system , 2004 .

[23]  Berthold Noll,et al.  Diffusion controlled evaporation of a multicomponent droplet: theoretical studies on the importance of variable liquid properties , 1993 .

[24]  V. A. Ruskol.  Similar solution of laminar boundary layer equations with a flame front , 1966 .

[25]  C. H. Chiang,et al.  Numerical analysis of convecting, vaporizing fuel droplet with variable properties , 1989 .

[26]  W. Sirignano,et al.  Fluid Dynamics and Transport of Droplets and Sprays: Index , 2010 .

[27]  G. Ryskin,et al.  Flow structure in motion of a spherical drop in a fluid medium at intermediate Reynolds numbers , 1976 .

[28]  Sergei Sazhin,et al.  A simplified non-isothermal model for droplet heating and evaporation , 2003 .

[29]  W. Hall,et al.  A Theoretical and Experimental Study of the Internal Circulation in Water Drops Falling at Terminal Velocity in Air , 1972 .

[30]  William A. Sirignano,et al.  Droplet vaporization model for spray combustion calculations , 1988 .

[31]  E. V. D. Bulck,et al.  Fuel oil evaporation in swirling hot gas streams , 1998 .

[32]  Sergei Sazhin,et al.  Delayed thermal explosion in flammable gas containing fuel droplets: Asymptotic analysis , 2004 .

[33]  K. Kuo.  Principles of combustion , 1986 .

[34]  S. Sazhin,et al.  Absorption of thermal radiation in a semi-transparent spherical droplet: a simplified model , 2003 .

[35]  R. K. Ahrenkiel,et al.  Modified Kramers–Kronig Analysis of Optical Spectra , 1971 .

[36]  Sergei Sazhin,et al.  A Parabolic Temperature Profile Model for Heating of Droplets , 2003 .

[37]  G. Harpole.  Radiative absorption by evaporating droplets , 1980 .

[38]  Horn-Jiunn Sheen,et al.  Effects of ambient turbulence and fuel properties on the evaporation rate of single droplets , 2001 .

[39]  R. Clift,et al.  Bubbles, Drops, and Particles , 1978 .

[40]  Fabrice Lemoine,et al.  Energetic budget on an evaporating monodisperse droplet stream using combined optical methods: Evaluation of the convective heat transfer , 2002 .

[41]  C. Megaridis.  Comparison between experimental measurements and numerical predictions of internal temperature distributions of a droplet vaporizing under high-temperature convective conditions☆ , 1993 .

[42]  Leonid A. Dombrovsky,et al.  Radiation Heat Transfer in Disperse Systems , 1996 .

[43]  J. Dymond.  Handbook of Physical Properties of Liquids and Gases Pure Substances and Mixtures. Third Augmented and Revised Edition. By N. B. Vargaftik, Y. K. Vinogradov, and V. S. Yargin. Begell House, Inc., New York. 1996. 1359 pp. $165.00. ISBN 1-56700-063-0. , 1999 .

[44]  Shwin-Chung Wong,et al.  Internal temperature distributions of droplets vaporizing in high-temperature convective flows , 1992, Journal of Fluid Mechanics.