Water droplet evaporation in atmospheric air stream

Evaporation of the water droplet in the air is a natural phenomenon that causes the droplet and air properties to change over time. In this paper, time dependent variation of air and water droplet properties in a flow is examined with the developed numerical model, in the range of conditions that concern air-conditioning and respiratory-based medical events and applications. An experimental setup is built and model is validated with experiments carried out for 27 cases. Input parameters are chosen as inlet air temperature, relative humidity, droplet temperature and diameter, and air-water mass mixing ratio. Output properties are determined as the outlet air temperature, relative humidity, mass droplet ratio and droplet temperature to define the application case in simplest way. Model results of 432 different cases are used to develop correlations with R2 values above 0.984, to present the effects of co-variation of input parameters. The results show that the latent heat demand of droplet evaporation is the main factor in the decrease of air temperature, while droplet temperature has almost no effect. As the air becomes saturated with moisture, evaporation almost stops, and that causes droplets being carried with air flow without being disappeared. The droplet diameter affects only the process speed, by reducing the processing time by the square of the reduction ratio. The developed numerical model and correlations allow the rapid determination of properties change in air-water stream over time, so it will provide great convenience to researchers dealing with water droplet evaporation in atmospheric air stream.