Transient Evaporation and Combustion of a Fuel Droplet Near Its Critical Temperature

Abstract Recently obtained exact solutions for the transport-controlled lifetime of an isolated sphere of arbitrary density and “solubility” in a quiescent, constant-property fluid are exploited to predict the corresponding behavior of a fuel droplet evaporating (with or without vapor phase combustion) into a surrounding dense gas. Emphasis is placed on (i) systematic errors associated with the familiar quasi-steady (QS) approximation when applied to the vaporization of droplets which are not much denser than their surroundings, (ii) the chamber pressure-droplet temperature conditions under which the droplet will be driven to a subcritical (wet-bulb) temperature, or to its thermodynamic critical temperature, and (iii) the effects of gas/liquid solubility on the predicted lifetime of a fuel droplet. Illustrative calculations are included for the case of a kerosene-like (x-dodecane) droplet evaporating into compression-heated air, as encountered in diesel engine cylinders.

[1]  A. Crespo,et al.  A Theoretical Model for the Combustion of Droplets in Super-critical Conditions and Gas Pockets1 , 1972 .

[2]  Combustion of Fuel Vapor in a Hot, Stagnant Oxidizing Environment , 1972 .

[3]  G. M. Faeth,et al.  Supercritical bipropellant droplet combustion , 1969 .

[4]  D. Kassoy,et al.  Variable Property Effects on Liquid Droplet Combustion , 1968 .

[5]  Effects of product condensation on reaction-enhanced vaporization rates and on the transition from homogeneous to heterogeneous reaction in high-temperature metal oxidation , 1972 .

[6]  Note on the diffusion controlled growth and evaporation of droplets , 1973 .

[7]  J. S. Vrentas,et al.  Heat or mass transfer-controlled dissolution of an isolated sphere , 1971 .

[8]  D. B. Spalding,et al.  Theory of Particle Combustion at High Pressures , 1959 .

[9]  P. R. Wieber.  Calculated temperature histories of vaporizing droplets to the critical point , 1963 .

[10]  D. E. Rosner.  On liquid droplet combustion at high pressures. , 1967 .

[11]  D. Spalding.  Some Fundamentals of Combustion , 1955 .

[12]  R. L Matlosz,et al.  Investigation of liquid drop evaporation in a high temperature and high pressure environment , 1972 .

[13]  G. M. Faeth,et al.  Fuel droplet burning rates in a combustion gas environment , 1971 .

[14]  Gary L. Borman,et al.  Calculations of steady state droplet vaporization at high ambient pressures , 1969 .

[15]  Dudley Brian Spalding,et al.  Convective mass transfer : an introduction , 1963 .

[16]  G. S. Parks,et al.  Selected Values of Physical and Thermodynamic Properties of Hydrocarbons and Related Compounds. , 1954 .

[17]  W. Strahle.  A Transient Problem on the Evaporation of a Reactive Fuel , 1969 .