Droplet supercooling in marine icing tests

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openAccess

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Volume Title

A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2024-03

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Mcode

Degree programme

Language

en

Pages

14

Series

Cold Regions Science and Technology, Volume 219

Abstract

Droplet supercooling in marine icing tests is studied theoretically using established correlations for convection and evaporation. The effect of freestream turbulence on heat and mass transfer is included through an empirical modification to the Nusselt and Sherwood numbers. Droplets are shown to cool following a modified exponential decay, with the trajectory length and shape determined by a thermal mixing length and a cooling exponent. The space needed for supercooling is shown to increase with (droplet diameter)1.8, and also depend on wind speed, injection speed and ambient temperature. Turbulence at realistic offshore levels shortens cooling distances by up to 50%. A reanalysis shows that previous marine icing tests have typically reached supercooling higher than 80% of cooling potential for small droplets up to 100–200 μm, and possibly up to 300–400 μm in long setups at low wind speeds if boosted by turbulence or a contracting tunnel; larger droplets have been significantly undercooled compared to field conditions.

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Publisher Copyright: © 2024 The Author

Keywords

Droplet supercooling, Marine icing test, Thermal mixing length, Turbulence, Undercooling

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Citation

Puolakka, O 2024, ' Droplet supercooling in marine icing tests ', Cold Regions Science and Technology, vol. 219, 104121 . https://doi.org/10.1016/j.coldregions.2024.104121