The effect of disjoining pressure on the shape of condensing films in a fin-groove corner

Download
2019-08-01
Akdag, Osman
Akkus, Yigit
Dursunkaya, Zafer
Thin film condensation is commonly present in numerous natural and artificial processes. Phase-change driven passive heat spreaders such as heat pipes, which are widely used in electronics cooling, employ a continuous condensation process at the condenser region. When the wick structure of a heat pipe is composed of grooves, the top surfaces of the walls (fins) located between consecutive grooves function as the major source of condensation and the condensate flows along the fin top into the grooves. Modeling of this condensation problem is vital for the proper estimation of condensation heat transfer, which constitutes the basis for the overall performance of a heat pipe together with the evaporation process. In the current study, a solution methodology is developed to model the condensation and associated liquid flow in a fin-groove system. Conservation of mass and momentum equations, augmented Young-Laplace equation and Kucherov-Rikenglaz equation are solved simultaneously to calculate the film thickness profile. The model proposed enables the investigation of the effect of disjoining pressure on the film profile by keeping the fin-groove corner, where the film becomes thinnest, inside the solution domain. The results show that dispersion forces become effective for near isothermal systems with sharp fin-groove corners and the film profile experiences an abrupt change, a slope break, in the close proximity of the corner. The current study is the first computational confirmation of this behavior in the literature.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES

Suggestions

Investigation of structural and optical characteristics of thermally evaporated Ga2Se3 thin films
Isik, M.; Hasanlı, Nızamı (2020-09-01)
Ga2Se3 thin films were prepared by thermal evaporation technique and structural, optical characteristics of the deposited thin films were investigated in the present study. X-ray diffraction pattern of the thin film exhibited one intensive and sharp peak associated with (111) plane of cubic crystalline structure of the compound. Energy dispersive spectroscopic analyses pointed out the atomic compositional ratio of the constituent elements as consistent with chemical formula of Ga2Se3. The optical characteri...
Modeling of fluid -vapor interface in the condensation zone of a grooved heat pipe
Alipour, Mobin; Dursunkaya, Zafer; Department of Mechanical Engineering (2017)
Condensation in grooved heat pipes involves several simultaneous phenomena including vapor-liquid boundaries whose shapes are unknown a priori, fluid flow due to capillary and dispersion pressure gradients and condensation over ultra thin films. In grooved heat pipes, the majority of condensation occurs on fin tops due to the thinner liquid film, having a lower thermal resistance, compared to inside the groove where the fluid is substantially thicker. Majority of the studies in the literature assume an appr...
Structural and optical properties of Zn-In-Te thin films deposited by thermal evaporation technique
Gullu, H. H.; Bayrakli, O.; CANDAN, İDRİS; COŞKUN, EMRE; Parlak, Mehmet (2013-07-25)
Annealing effects on structural and optical properties of the thermally evaporated Zn-In-Te(ZIT) thin films have been investigated. The structural and the compositional analyses were carried out by means of X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDXA). The as-grown and annealed ZIT films had polycrystalline structure and the preferred orientation changed from (220) to (112) direction with increasing annealing temperature. The optical properties and constants were determined by transmi...
Investigation of structural and optical parameters of Cu-Ag-In-Se thin films deposited by thermal evaporation method
Gullu, H. H.; CANDAN, İDRİS; COŞKUN, EMRE; Parlak, Mehmet (2015-01-01)
Annealing effect on the structural and optical properties of the quaternary Cu-Ag-In-Se thin film deposited by the thermal evaporation has been investigated. The evaporation source was prepared by using vertical Bridgman-Stockbarger crystal growth system. Structural analysis indicated that annealing the films following to the deposition resulted in the changes from amorphous to polycrystalline phase with the preferred orientation along (1 1 2) direction. In order to determine the optical properties of the t...
The role of pore structure in sound absorption performance of lime based plasters
Meric Nursal, Işın; Tavukçuoğlu, Ayşe; Çalışkan, Mehmet (The Institute of Noise Control Engineering of the USA, Inc.; 2015-08-09)
Sound absorption performance is directly related to the pore structure of materials. The effect of materials' pore characteristics on sound absorption performance has been examined in detail, especially for materials like mineral wool, foamed metals, porous concrete, sand and soils. However, there is scarcity of knowledge in literature on relationships between sound absorption characteristics of lime-based plasters used as finishing layer(s) in buildings and their pore structure. In this study sets of lime-...
Citation Formats
O. Akdag, Y. Akkus, and Z. Dursunkaya, “The effect of disjoining pressure on the shape of condensing films in a fin-groove corner,” INTERNATIONAL JOURNAL OF THERMAL SCIENCES, pp. 357–365, 2019, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/34981.