Library Subscription: Guest
Home Archives Thermal Letter Officers Future meetings Assembly for International Heat Transfer Conferences
International Heat Transfer Conference 16

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

MODELING CRYSTALLIZATION AND HEAT TRANSFER IN AN EVAPORATING UREA-WATER DROP

Achim Bender
Institute for Technical Thermodynamics, Technische Universitat Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt, Germany

Philipp Hanichen
Institute for Technical Thermodynamics, Technische Universitat Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt, Germany

Peter Stephan
Institute for Technical Thermodynamics, Technische Universität Darmstadt, 64287 Darmstadt, Germany

Tatiana Gambaryan-Roisman
Institute of Technical Thermodynamics and Center of Smart Interfaces, Technische Universitat Darmstadt, Alarich-Weiss-Str. 10, 64287, Darmstadt, Germany

DOI: 10.1615/IHTC16.mpf.022242
pages 6679-6686


KEY WORDS: Two-phase/Multiphase flow, Boiling and evaporation, deposit formation, mass transfer, numerical simulation

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.

Purchase $25.00 Check subscription Publication Ethics and Malpractice Recommend to my Librarian Bookmark this Page