The interaction of the complex transfer processes in the phase transformations regimes of a water droplets

Abstract

In this article the phase transformations of the water droplets in humid air flow are numerically modelled. The air temperature varies from 20°C to 1000°C, and the volume fraction of water vapor reaches up to 0.4. The droplet surface temperature dynamics defined by a numerical scheme which is based on by the fastest descent method. The interaction of complex heat and mass transfer processes has been investigated in the consistently changing water droplets condensation, transit and equilibrium evaporation regimes. Determination of droplets instantaneous temperatures in the iteration cycles is controlled by calculated heat fluxes balance condition, flowing toward and from the droplet surface, which must correspond to 99.95%. The reliability of the numerical method was confirmed when comparing the calculated water droplets equilibrium evaporation temperature in humid air with the wet bulb thermometer temperature, and with the experiments data. In the case of combined heating a calculated water droplets equilibrium evaporation vapor flux correlates well with other author's experimental data and modeling results. The numerical researches are emphasized specially for cases of water vapor condensate spraying in biofuel combustion technologies. The water droplet heat transfer as well as phase transformations transit and equilibrium evaporation processes were modelled in cases of convective and combined convective-radiative heating. In semi-transparent liquid the impact of absorbed radiation flux for water droplet complex transfer processes interaction was evaluated.