%0 Journal Article
%A Zhang, Tongxin
%A O'Neal, Dennis L.
%D 2019
%I Begell House
%K hydrophobic coating, empirical correlation, dimensionless freezing time, phase change
%N 4
%P 381-397
%R 10.1615/HeatTransRes.2018019776
%T PHASE TRANSITION OF WATER DROPLETS WITH DIFFERENT STATIC CONTACT ANGLES
%U https://www.dl.begellhouse.com/journals/46784ef93dddff27,069137575e3e0439,3542c9344568318e.html
%V 50
%X The freezing process of water droplets was investigated for an uncoated and two coated aluminum surfaces subjected to the action of a forced convective environment. One of the coatings was a silicon-based conformal polymer and the other was a hydrophobic coating. Static contact angles of the droplets ranged from 74.6 deg for the uncoated aluminum to 127.1 deg for the hydrophobic coating. Air velocities ranged from 0.2 to 1.85 m/s, surface temperatures ranged from –5 to –13°C, air temperatures ranged from 4 to 24°C, and air relative humidities were varied from 24 to 54%. Droplet radii ranged from 0.4 to 1.5 mm. A digital high speed microscopy system was used to visually observe and measure the freezing in individual droplets. Empirical correlations for dimensionless freezing time as a function of three nondimensional variables (Am∞, Re∞, and Ste) were developed. These correlations could be used to estimate dimensionless freezing time over a wide range of experimental conditions. Droplets on the hydrophobic surface showed the slowest nondimensional freezing times while those on the silicon-based conformal polymer coating and uncoated surfaces were comparable. The data for the silicon-based conformal polymer coating surface were also compared to the data from a prior researcher.
%8 2018-12-12