Influence of Relative Air Humidity on Evaporation of Water–Ethanol Solution Droplets

Evaporation of droplets of water–ethanol solutions with different concentrations has been experimentally studied at different relative humidities of ambient air. High-speed micrography has been employed to monitor the dynamics of variations in the sizes of the evaporating droplets. It has been found that relative humidity of the ambient air significantly affects variations in the diameters of water–ethanol solution droplets. Infrared thermography has been used to study variations in the temperature of the evaporating droplets. It has been shown that the temperature of the evaporating droplets decreases with an increase in ethanol concentration at all studied relative air humidities. The minimum values of evaporating droplet surface temperature and evaporation time increase with relative air humidity. The performed generalization of the obtained experimental data may be used when calculating the heat and mass transfer of evaporating droplets of water–ethanol solutions.