Nucleation of bubbles on a solidification front—experiment and analysis

Abstract

The heterogeneous nucleation of bubbles on an advancing solidification front during the freezing of water containing a dissolved gas has been experimentally and analytically studied. The formation of bubbles resulting from supersaturation of liquids is commonly encountered in different fields such as heat transfer, manufacturing, and bioscience. In this work, the sizes of nucleating bubbles and the concentration profiles of dissolved oxygen and carbon dioxide gases in the water ahead of the solidification front have been measured. From successful comparisons between the measured and predicted critical radii of nucleating bubbles and distributions of dissolved gas content, the phenomena of heterogeneous nucleation in a binary weak solution during the freezing process are quantitatively confirmed. The results show that an increase in gas content at the solidification front in the liquid decreases the free-energy barrier and critical radii of bubbles that are formed on the solidification front. The sizes of the critical radii decrease and the number of nucleating bubbles increase in the early stage of solidification. As the solidification rates decrease at longer times, the content of the dissolved gas in the liquid on the advancing interface decreases and the critical radii of nucleating bubbles increase.

Force of a gas bubble on a foreign particle in front of a freezing interface

“…2b). The bubble had a higher tendency to nucleate at the sphere's surface than at the ice-water interface, as stated in [15]. This bubble kept growing in size while the ice front touched the bubble at h = d b = 88 µm (Fig.…”

“…Owing to the very different gas solubilities in the water and ice phases, the dissolved gas tends to be expelled from the solidifying front and be concentrated ahead of the interface. Bubbles were noted to form at the solid-liquid interface in systems with high dissolved gas content [15,16]. The concentration profile of dissolved gas affects the surface-tension gradient around the surfaces of bubbles, hence affecting their entrapment into ice [17,18].…”

Frozen ponds: production and storage of methane during the Arctic winter in a lowland tundra landscape in northern Siberia, Lena River delta

“…The saturation of dissolved gases in this thin water layer leads to bubble nucleation. The gas concentration in the growing bubbles is in equilibrium with the dissolved gases of the surrounding water (Wei et al, 2003). As soon as the bubbles are completely entrapped within the ice cover they are sealed from further gaseous exchange so that an enrichment of dissolved gases and bubble nucleation at the freezing front starts again.…”

“…Ponding water is often found in the depressed polygon centers (intra-polygonal ponds) or along the troughs between the polygon rims above the ice-wedges (ice-wedge ponds; Fig. 2 a, Wetterich et al, 2008;Helbig et al, 2013;Negandhi et al, 2013). Both intrapolygonal ponds and ice-wedge ponds are usually very shallow, with water depths ranging from just a few centimeters to a few tens of centimeters.…”

Pore Formation from Bubble Entrapment by a Solidification Front

“…Since gas solubility in solid is usually much less than that in liquid, gas is accumulated ahead of the solidification front (Fedorchenko and Chernov, 2003). Super-saturation thus induces nucleation of bubbles on the solidification front (Wei et al 2003). The bubbles within the liquid are not often captured by the solid (Kao et al 2009).…”