Oxygen Transfer From Falling Water Droplets

Overall oxygen transfer coefficients are obtained for deaerated water droplets falling freely through the atmosphere with and without 50 ppm. of a synthetic detergent. Drop distances ranged from 0 to 13 ft, and droplet surface areas varied from 0.47 to 0.55 cm². Transfer coefficients are found to decrease somewhat with increasing droplet size, becoming independent of droplet size above 6.0 ppm of D.O. With detergent present, the coefficients are reduced approximately 50%. Experiments were also performed with fully aerated water droplets falling freely through a nitrogen atmosphere. For this case, droplet surface area ranged from 0.15 to 0.50 cm². Transfer coefficients are found to increase with increasing droplet size. Although no direct comparison of droplet sizes could be made, it is concluded that the rate of oxygen transfer for both inward and outward transfer from a droplet is not substantially different.