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Interfacial Phenomena and Heat Transfer
ESCI SJR: 0.146

ISSN Imprimer: 2169-2785
ISSN En ligne: 2167-857X

Open Access

Interfacial Phenomena and Heat Transfer

DOI: 10.1615/InterfacPhenomHeatTransfer.2018026166
pages 37-74

PHYSICAL INTERPRETATION OF ICE CONTACT ANGLES, FITTED TO EXPERIMENTAL DATA ON IMMERSION FREEZING OF KAOLINITE PARTICLES

Olaf Hellmuth
Leibniz Institute for Tropospheric Research (TROPOS), Leipzig, D-04318, Germany
A. K. Shchekin
St. Petersburg State University, Department of Statistical Physics, St. Petersburg, 198594, Russian Federation
R. Feistel
Leibniz Institute for Baltic Sea Research (IOW), Rostock–Warnemünde, D-18119, Germany
Jürn W. P. Schmelzer
Rostock University, Institute of Physics, Polymer Physics Group, Rostock, D-18051, Germany
Alexander S. Abyzov
National Science Center–Kharkov Institute of Physics and Technology, Kharkov, 61108, Ukraine

RÉSUMÉ

Previous cloud chamber experiments on freezing of supercooled cloud droplets with single immersed, size-selected 400 nm and 800 nm kaolinite particles revealed a sigmoidal increase of the fraction of frozen cloud droplets with decreasing temperature in the range from 243 to 236 K. Assuming uniformity of the particle composition and horizontal homogeneity of the phase compatibility, applying classical nucleation theory (CNT), and fitting the microscopic "ice contact angle" to these experimental freezing probabilities disclosed a negative temperature coefficient of the ice contact angle, revealing an apparent increase of the cryophobia of the freezing catalyzer. On the basis of Derjaguin's thermomechanic concept of the disjoining pressure, a conceptual model is proposed that links the semi-empirical ice contact angle to its generating molecular interaction forces by extrapolating macroscopic relations to microscopic scales. Within the framework of a closure study with consideration of a comprehensive set of physical constraints for the water/ice/kaolinite system, this model is used to determine the residual molecular interaction force, which is necessary to reproduce the experimentally derived ice contact angles. The residual interaction force is on the order of magnitude of steric oscillation forces at the kaolinite/ice interfacial layer and corresponds to a temperature-dependent negative line tension of −(5−28) pN. The line tension behavior is discussed in the light of previous findings on heterogeneous water nucleation on solid surfaces and computer simulations of the water/ice/kaolinit system. Uncertainties originating from the employed model assumptions, especially interference due to interparticle variability are analyzed. Finally, observational requirements for a conclusive discrimination between inter- and intraparticle effects are discussed.