Heat and Mass Transfer in the Melting of Frost

Mohs, William F.; Kulacki, F. A.

doi:10.1007/978-3-319-20508-3

Cited by 4 publications

(2 citation statements)

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“…Generally, during defrosting on a surface, frost melting and water permeation occur successively until the unmelted porous frost layer is saturated with water. 35,36 Afterwards, the meltwater (ice−water mixture) evolution stage (also called the accumulation stage) begins, during which some unique phenomena (such as edge curling) or self-propelled movements (such as jumping) may take place on superhydrophobic surfaces according to our recent works. 18,23 However, these stages during defrosting are not fixed, but will change with frost parameters such as the frost thickness, especially when defrosting on a vertical superhydrophobic surface.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Mohs and Kulacki mentioned in their book that the transition between the frost melting−water permeation and the meltwater evolution stages was less defined but they conjectured that the transition appeared to occur when the surface temperature is about 2.5 °C. 35 In our experiments, we measured the surface temperature variations, which is shown in Figure 7a. When the temperature is near 2 °C, there are obvious turning points, but none near other temperatures.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Frost Self-Removal Mechanism during Defrosting on Vertical Superhydrophobic Surfaces: Peeling Off or Jumping Off

Chu

Wen

2018

Langmuir

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Although a superhydrophobic surface has potentials to delay frosting, it fails finally when conditions are too harsh, so defrosting is still essential. Here, we investigated the frost self-removal mechanism during defrosting on vertical superhydrophobic surfaces. Owing to the great water repellency of the superhydrophobic surface and the water absorption of porous frost, meltwater close to the surface tends to permeate into the frost layer. As frost density is much less than water density, the frost volume shrinks during defrosting. When the frost quantity is large, the permeation effect dominates because there is much porous frost. The permeation effect separates the unmelted frost layer from the superhydrophobic surface, as a result, the frost peels off by gravity completely. When the frost quantity is little, the permeation effect is negligible, while the volume shrinkage effect works, making the thin frost layer break up into many small pieces. These small frost pieces keep irregular shapes and continue to shrink, releasing large amounts of surface energy to drive themselves jump off from the superhydrophobic surface. However, compared with the peeling off mode, the jumping off mode is not so effective that there are still small droplets adhering on the surface after defrosting. This work may provide guides for defrosting application of superhydrophobic surfaces in related engineering fields.

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