Bender, Achim ; Hänichen, Philipp ; Stephan, Peter ; Gambaryan-Roisman, Tatiana (2018)
Modeling Crystallization and Heat Transfer in an Evaporating Urea-Water Drop.
In: IHTC 16 - International Heat Transfer Conference 16 Digital Libary, August 10-15, Beijing, China
doi: 10.1615/IHTC16
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

Evaporation and deposit formation of a pinned urea-water drop on an initially smooth surface are modeled. Water evaporates from the two-component drop into the surrounding gas phase containing a non-condensable gas. This leads to an increase of the urea concentration inside the drop. At the three-phase contact line high evaporation rates lead to a significant increase of the urea concentration. As a result, the heterogeneous nucleation and growth of urea crystals take place in the vicinity of the three-phase contact line. The model utilizing the Finite Element Method is implemented in the software COMSOL Multiphysics. The deformation of the liquid-gas interface is resolved using an Arbitrary-Lagrangian-Eulerian Method (ALE) in a moving mesh framework. The deposit shape and the influence of the deposit on the transport processes in the drop are accounted for. The drop volume evolution agrees well with experimental data on urea-water drops evaporating in a controlled environment. A qualitative agreement between model and experiment regarding the deposit formation is achieved. The wall temperature affects the evaporation rate and exerts a strong influence on the time at which the deposit formation is observed. Once the deposit formation has started, the deposit growth rate increases with time.

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