Homogeneous nucleation rate measurements in supersaturated water vapor II

2009 ◽  
Vol 131 (7) ◽  
pp. 074507 ◽  
Author(s):  
David Brus ◽  
Vladimír Ždímal ◽  
Hermann Uchtmann
Keyword(s):  
Water Vapor ◽  
Nucleation Rate ◽  
Homogeneous Nucleation

How does a Homogeneous Nucleation Event respond to changes of Parameterizations of Water Activity and Saturation Vapor Pressure?

2021 ◽  
Author(s):  
Manuel Baumgartner ◽  
Martina Krämer ◽  
Christian Rolf
Keyword(s):  
Water Vapor ◽  
Water Activity ◽  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
Saturation Pressure ◽  
Cirrus Clouds ◽  
Ice Crystals ◽  
Nucleation Theory ◽  
Ice Microphysics ◽  
Water Vapor Saturation Pressure

<p>Homogeneous nucleation of ice crystals via freezing of small supercooled solution particles represents a major pathway in the formation of cirrus clouds with high ice water content at low temperatures. A reasonable physical explanation of this type of freezing is provided by Koop's nucleation theory, relating the homogeneous nucleation rate to the water activity of the solution particles. While the homogeneous nucleation rate encodes the probability of freezing of solution particles, the water activity represents the ratio of water vapor saturation pressures over the solution to that over pure water in Koop's portrayal.</p><p>By using the ice microphysics model "CLaMS-Ice", we investigate the effect of various formulations of the water activity and the water vapor saturation pressure on the resulting cirrus clouds. Although CLaMS-Ice is a two-moment bulk model, it implements a comparatively detailed ice microphysics formulated by Spichtinger and Gierens. Such a microphysics scheme is suitable to be implemented in full three dimensional atmospheric models in contrast to even more detailed bin microphysics schemes.</p><p>We performed sensitivity simulations over a wide range of temperatures and vertical velocities by using two different direct parameterizations of water activity based on thermodynamic models in addition to the one used by Koop. Also, three different formulations of the water vapor saturation pressure are applied in the simulations. The results are evaluated regarding the predicted number of ice crystals and the ice onset humidities. In particular, one major finding is that the freezing thresholds are increased compared to Koop's freezing lines.</p>

Homogeneous nucleation rate measurements in supersaturated water vapor

2008 ◽  
Vol 129 (17) ◽  
pp. 174501 ◽  
Author(s):  
David Brus ◽  
Vladimír Ždímal ◽  
Jiří Smolík
Keyword(s):  
Water Vapor ◽  
Nucleation Rate ◽  
Homogeneous Nucleation

Homogeneous nucleation of water in argon. Nucleation rate computation from molecular simulations of TIP4P and TIP4P/2005 water model

2017 ◽  
Vol 146 (8) ◽  
pp. 084309 ◽  
Author(s):  
Lucia R. Dumitrescu ◽  
David M. J. Smeulders ◽  
Jacques A. M. Dam ◽  
Silvia V. Gaastra-Nedea
Keyword(s):  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
Molecular Simulations ◽  
Water Model

Characteristics of the Initial Stage of CaCO3 Crystallization Fouling on Straight Oblique Fin Tube

2013 ◽  
Vol 671-674 ◽  
pp. 2535-2541
Author(s):  
Ping Zhao ◽  
Jian Sheng ◽  
Hua Zhang
Keyword(s):  
Growth Rate ◽  
Induction Period ◽  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
Particle Concentration ◽  
Concentration Increase ◽  
Fouling Resistance ◽  
Initial Stage ◽  
Fin Tube ◽  
Resistance Decrease

To investigate the effect of CaCO3 concentration and velocity on scaling fouling process on plain and SOFT, experiments have been done at different CaCO3 concentration and velocity on the two kind tubes. The results are that the homogeneous nucleation rate and the growth rate are both increase when CaCO3 concentration increases. This make the scaling particle concentration and foulant ions concentration increase, the former gets more scaling on tubes and the later enlarges the heterogeneous nucleation rate and growth rate. Higher velocity decreases the nucleation of scaling, scaling crystal and fouling resistance, but it can prolong the induction period. Higher velocity increases nucleation rate on SOFT first, but the induction period extends and the mass of scaling and fouling resistance decrease. SOFT has a bigger heat transfer coefficient than PT at both clean and fouling conditions and it has smaller fouling resistance even a little more scaling.

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