DESIGNING AN EXPERIMENT AND ESTABLISHING A PROCEDURE FOR MICRODROPLET EVAPORATION IMAGING AND ANALYSIS

The goal for this work was the development and verification of an experiment on n-decane microdroplet (0.5 – 1.5 mm diameter) evaporation under various levels of convection using water as a surrogate fluid. A system was designed using a round geometry with a fan built in for providing and controlling convection, while suspending the droplet on the edge of the needle during evaporation. One major factor of the design was its usage of construction paper on the edge of the enclosure to allow the droplet to reflect that color without changing its properties. Evaporation characteristics of droplets with volumes .2 µl, .4 µl, .6 µl and .8 µl were recorded and analyzed both without convection and at airspeeds ranging from 2.2 m/s to 4.6 m/s. Along with the physical experiment, a MATLAB script was written to process the results in two phases. The first phase used the perpendicular bisectors theorem from geometry to fit a circle based on the intersection of perpendicular bisectors of two chords, which then transitions to the elliptical fit method once the droplet evaporates to conform to the geometry of the needle and is no longer circular in shape. Results show that this method can effectively monitor the evaporation over time without variation without the presence of airflow and that even with airflow the results remain within the expected range of noise. Therefore, the methods and experiment should be usable within the future goals of n-decane evaporation.