Modeling the evaporation of sessile multi-component droplets

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:487

Article

Diddens, C.¹  Kuerten, J. G. M.^1,2  van der Geld, C. W. M.³  Wijshoff, H. M. A.^1,4 

[1] Eindhoven Univ Technol, Dept Mech Engn, POB 513, NL-5600 MB Eindhoven, Netherlands

[2] Univ Twente, Fac EEMCS, POB 217, NL-7500 AE Enschede, Netherlands

[3] Eindhoven Univ Technol, Dept Chem Engn & Chem, POB 513, NL-5600 MB Eindhoven, Netherlands

[4] OceTechnol BV, POB 101, NL-5900 MA Venlo, Netherlands

关键词: Droplets;    Lubrication approximation;    Multi-component flow;    Evaporation;    Marangoni flow;   

DOI  :  10.1016/j.jcis.2016.10.030

来源: Elsevier

【 摘 要 】

We extended a mathematical model for the drying of sessile droplets, based on the lubrication approximation, to binary mixture droplets. This extension is relevant for e.g. inkjet printing applications, where ink consisting of several components are used. The extension involves the generalization of an established vapor diffusion-limited evaporation model to multi-component mixtures. The different volatilities of the liquid components generate a composition gradient at the liquid-air interface. The model takes the composition-dependence of the mass density, viscosity, surface tension, mutual diffusion coefficient and thermodynamic activities into account. This leads to a variety of effects ranging from solutal Marangoni flow over deviations from the typical spherical cap shape to an entrapped residual amount of the more volatile component at later stages of the drying. These aspects are discussed in detail on the basis of the numerical results for water-glycerol and water-ethanol droplets. The results show good agreement with experimental findings. Finally, the accuracy of the lubrication approximation is assessed by comparison with a finite element method. (C) 2016 Elsevier Inc. All rights reserved.

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