Experimental and numerical studies on the temperature in a pendant water droplet heated in the hot air

Abstract

Experimental and theoretical studies are carried out to broaden the modern understanding of high-temperature heating of water droplets in the gas medium. Using the optical method of planar laser-induced fluorescence and the fluorophore of Rhodamine B, experimental temperature distributions in the droplet are determined when the temperature of the outer gas medium varies up to 500 °C. A predictive mathematical model is developed based on the experimental findings. The first approximation takes into account the main heat-mass transfer processes and phase transformations within the one-dimensional statement. When comparing experimental and theoretical results, the validity and sufficiency of the use of one-dimensional statement are justified. We studied the effects of convective, conductive, radiative heat transfer in a droplet; convective, radiative, conductive heat exchange of the droplet with the gas medium; the size and material of the holder; the size of the droplet; the properties of tracers and fluorophore, etc. on the conditions and characteristics of the formation of the temperature field of the water droplet, the rate of its warming and evaporation. The dominant processes at different drop heating temperatures are highlighted. In mathematical modeling, the range of temperature variation is extended to 1000 °C to account for various high-temperature gas-vapor-droplet technologies.