Freezing of sessile water droplets on surfaces with various roughness and wettability

Abstract

This paper focus on the freezing delay time and the freezing time of sessile droplet on smooth, micro-structured and micro/nano-structured surfaces, and the whole freezing process are comparatively studied. The freezing delay time of the smooth surfaces with roughness smaller than the size of the critical ice nuclei is found to be much longer than superhydrophobic surfaces with hierarchical structures. Experimental data and theoretical analysis show that the surface roughness plays a very crucial role in nucleation. The freezing delay time could not be extended further on rough surface with more superhydrophobic for sessile droplet. In addition, decreased roughness can increase the free energy barrier for heterogeneous nucleation, result in significant freezing delay. On the contrary, the freezing time from the start of nucleation to the completion of freezing increases with the contact angle. In addition, surfaces with hierarchical roughness are found to have the longest freezing time.

Is Ice Nucleation from Supercooled Water Insensitive to Surface Roughness?

“…Studies of the freezing of water droplets on superhydrophobic surfaces have either reported no influence of surface topography 29 , or the conclusions are uncertain due to the difficulty of separating topographical from chemical effects. 30 Here, we describe an investigation into the influence of surface topography on nucleation from the melt. We focus on the freezing of water, since this of great importance to a diverse range of phenomena, ranging from cryopreservation and freezing damage to ice formation in the atmosphere.…”

On Modulating Interfacial Structure towards Improved Anti-Icing Performance

“…Robust anti-icing solutions are needed for both dynamic (aircraft wings) and static (power lines) applications [21]. The effect of surface energy and roughness on adhesion has been studied by various groups [46,56,70,73,132,133], with varying conclusions. Campbell et al [133] found experimentally insignificant dependence of nucleation of supercooled water droplets on surface roughness, for glass, silicion and mica surfaces.…”

Modelling the dynamics of the flow within freezing water droplets

“…Hao et al [5] found that t f was dependent on the size of the contact area, A and the thermal conductivity of the surface. A smaller A, i.e.…”

“…on wind turbines, airplane wings, and roads, calls for a better understanding of the freezing process for water droplets on cold surfaces. Previous research has identified a number of factors important to the freezing process such as the temperature of the cooling surface, T p [1], the size of the droplet [2] the impact of free and forced convection [3,4], the roughness and wettability of a surface [5], the freezing on superhydrophobic surfaces, e.g. [6], the effect of an inclined surface [7][8][9], internal heat transfer [10,11] and internal flow [12].…”