Résumé
Defrosting of a frosted surface is a crucial part for system recovery in refrigeration and cryogenic engineering. The performances of defrosting on a horizontal surface can better reflect the defrosting and drainage characteristics of the surface itself, since the influence of gravity is almost eliminated. This work performed defrosting experiments on horizontal hydrophobic surfaces with the defrosting process divided into three stages including frost melting, meltwater breaking and meltwater shrinking. The meltwater on the hydrophobic surface finally shrinks into a droplet with a final contact angle which is called the shrink angle. A theoretical model was also developed to analyze the free energy change of the meltwater during defrosting with the shrink angle predicted and its influencing factors discussed. Based on the model, the shrink angle relates to the static contact angle, contact angle hysteresis and meltwater size. When the meltwater size is less than the capillary length, the shrink angle is only related to the surface wettability. With increasing static contact angle and reducing contact angle hysteresis, the shrink angle increases and approaches the static contact angle. The predicted shrink angles were consistent with the experimental results with a maximum difference of 7%.
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Détails
- Titre original : Defrosting on horizontal hydrophobic surfaces and the shrink angle.
- Identifiant de la fiche : 30019398
- Langues : Anglais
- Source : International Journal of Refrigeration - Revue Internationale du Froid - vol. 71
- Date d'édition : 11/2016
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Indexation
- Thèmes : Systèmes de dégivrage
- Mots-clés : Surface horizontale; Givre; Performance; Modèle; Experimentation; Dégivrage
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