Theory of quasi-steady one-dimensional diffusional combustion with variable properties including distinct binary diffusion coefficients

A previously formulated variable-property theory for a class of heat and mass transfer problems, exemplified by droplet vaporization and combustion, is generalized herein such that in addition to the previous features that the specific heats C, the thermal conductivity k, and the binary diffusion coefficient D_ij are temperature dependent whereas C and k are further concentration-weighted, in the present formulation the D_ij's are also distinct for all species pairs. Explicit expressions are derived for the temperature and species profiles, the mass vaporization rate, and the flame-front standoff ratio. It is shown that oxidizer mass diffusion in the outer region and heat transport in the inner region are the dominant transport processes. A simplified model is recommended to obtain estimates of the various vaporization characteristics.