A quasi-discrete model for heating and evaporation of complex multicomponent hydrocarbon fuel droplets

Abstract A quasi-discrete model for heating and evaporation of complex multicomponent hydrocarbon fuel droplets is suggested and tested in Diesel engine-like conditions. The model is based on the assumption that properties of components are weak functions of the number of carbon atoms in the components ( n ). The components with relatively close n are replaced by the quasi-components with properties calculated as average properties of the a priori defined groups of actual components. Thus the analysis of heating and evaporation of droplets consisting of many components is replaced by the analysis of heating and evaporation of droplets consisting of relatively few quasi-components. In contrast to previously suggested approaches to modelling the heating and evaporation of droplets consisting of many components, the effects of temperature gradient and quasi-component diffusion inside droplets are taken into account. The model is applied to Diesel fuel droplets, approximated as a mixture of 21 components C n H 2 n +2 for 5 ⩽  n  ⩽ 25, which correspond to a maximum of 20 quasi-components with average properties for n  =  n j and n  =  n j +1 , where j varies from 5 to 24. It is pointed out that droplet surface temperatures and radii, predicted by a rigorous model taking into account the effect of all 20 quasi-components, are very close to those predicted by the model, using just five quasi-components. Errors due to the assumptions that the droplet thermal conductivity and species diffusivities are infinitely large cannot be ignored in the general case.

[1]  Rolf D. Reitz,et al.  A vaporization model for discrete multi-component fuel sprays , 2009 .

[2]  G. Faeth.  Evaporation and combustion of sprays , 1983 .

[3]  J. Bellan,et al.  Modeling evaporation of Jet A, JP-7, and RP-1 drops at 1 to 15 bars , 2004 .

[4]  Rainer Koch,et al.  Droplet evaporation modeling by the distillation curve model: accounting for kerosene fuel and elevated pressures , 2003 .

[5]  S. Sazhin,et al.  The effective-emissivity approximation for the thermal radiation transfer problem , 1996 .

[6]  G. Angelino,et al.  Modern Research Topics in Aerospace Propulsion , 1991 .

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

[8]  U. Renz,et al.  Vaporization of a binary unsteady spray at high temperature and high pressure , 1994 .

[9]  G. Castanet,et al.  Bicomponent droplets evaporation: Temperature measurements and modelling , 2008 .

[10]  A. E. Elwardany,et al.  Multi-component droplet heating and evaporation: Numerical simulation versus experimental data , 2011 .

[11]  W. Hallett,et al.  A continuous thermodynamics model for multicomponent droplet vaporization , 1995 .

[12]  Rolf D. Reitz,et al.  A model for high-pressure vaporization of droplets of complex liquid mixtures using continuous thermodynamics , 2002 .

[13]  S. Sazhin,et al.  Convective vaporization of a fuel droplet with thermal radiation absorption , 2006 .

[14]  A. E. Elwardany,et al.  A simplified model for bi-component droplet heating and evaporation , 2010 .

[15]  S. Sazhin,et al.  Models for fuel droplet heating and evaporation: Comparative analysis , 2006 .

[16]  G. Lavergne,et al.  Combustion for aerospace propulsion Continuous thermodynamics for droplet vaporization: Comparison between Gamma-PDF model and QMoM , 2009 .

[17]  W. Hallett,et al.  The role of liquid mixing in evaporation of complex multicomponent mixtures: modelling using continuous thermodynamics , 2005 .

[18]  W. Sirignano,et al.  Unsteady, Spherically-Symmetric Flame Propagation Through Multicomponent Fuel Spray Clouds , 1991 .

[19]  Paulo L. C. Lage,et al.  The quadrature method of moments for continuous thermodynamics , 2007, Comput. Chem. Eng..

[20]  Song-Charng Kong,et al.  Vaporization modeling of petroleum–biofuel drops using a hybrid multi-component approach , 2010 .

[21]  W. Sirignano,et al.  Multicomponent Transient Droplet Vaporization with Internal Circulation: Integral Equation Formulation and Approximate Solution , 1986 .

[22]  P. Lage,et al.  Nonideal vaporization of dilating binary droplets with radiation absorption , 1995 .

[23]  D. E. Rosner,et al.  Multicomponent fuel droplet vaporization and combustion using spectral theory for a continuous mixture , 2003 .

[24]  W. Sirignano,et al.  Droplet vaporization model for spray combustion calculations , 1989 .

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

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

[27]  W. Hallett.  A simple model for the vaporization of droplets with large numbers of components , 2000 .

[28]  S. Sazhin,et al.  Models for droplet transient heating: effects on droplet evaporation, ignition, and break-up , 2005 .

[29]  D. Brüggemann,et al.  Numerical investigation of semi-continuous mixture droplet vaporization at low temperature , 2010 .

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

[31]  Rolf D. Reitz,et al.  Modeling of Multicomponent Fuels Using Continuous Distributions with Application to Droplet Evaporation and Sprays , 1997 .