The effect of surface modification on initial ice formation on aluminum surfaces

Rahimi, Maral; Afshari, Alireza; Fojan, Peter; Gurevich, Leonid

doi:10.1016/j.apsusc.2015.06.201

Cited by 14 publications

(10 citation statements)

References 36 publications

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“…The exact temperature at which sublimation and ice formation begins (and also the morphology of a formed ice layer) will depend on surface chemistry, surface structure, and the relative humidity. 31 One question is obviously how the formation of an ice layer will affect the surface wettability. Observations of the contact angle of water on ice have in previous studies shown that it was increasing by decreasing the water droplet temperature.…”

Section: ■ Discussionmentioning

confidence: 99%

Effect of Aluminum Substrate Surface Modification on Wettability and Freezing Delay of Water Droplet at Subzero Temperatures

Rahimi

Afshari

Thormann

2016

ACS Appl. Mater. Interfaces

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In this study, we have investigated the freezing delay of a water droplet on precooled substrates of an aluminum alloy that is commonly used for heat-exchanger fins. The surfaces of the substrates were modified to obtain surfaces with different hydrophilicity/hydrophobicity and different surface chemistry but without significantly modifying the surface topography. The freezing delays and water contact angles were measured as a function of the substrate temperature and the results were compared to the predictions of the heterogeneous ice nucleation theory. Although the trends for each sample followed the trend in this theory, the differences in the extents of freezing delays were in apparent disagreement with the predictions. Concretely, a slightly hydrophilic substrate modified by (3-aminopropyl) triethoxysilane (APTES) showed longer freezing delays than both more hydrophilic and more hydrophobic substrates. We suggest that this is because this particular surface chemistry prevents ice formation at the interface of the substrate, prior to the deposition of the water droplet. On the basis of our results, we suggest that not only wettability and topography but also the concrete surface chemistry plays a significant role in the kinetics of the ice formation process when a water droplet is placed on a precooled substrate.

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Section: ■ Discussionmentioning

confidence: 99%

Effect of Aluminum Substrate Surface Modification on Wettability and Freezing Delay of Water Droplet at Subzero Temperatures

Rahimi

Afshari

Thormann

2016

ACS Appl. Mater. Interfaces

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“…However, most of them have been aimed at condensing and solidifying water droplets instead of desublimation. Most of the studies investigated water vapor desublimation on pre-treated surfaces with distinct contact angles, from hydrophilic to hydrophobic [63][64][65][66][67][68]. Generally, the researchers have reported that the hydrophobic surface delayed the onset of frost formation while the hydrophilic one presented a thinner and denser frost thickness.…”

Section: Thermophysical Propertiesmentioning

confidence: 99%

Evaporator Frosting in Refrigerating Appliances: Fundamentals and Applications

et al. 2021

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Modern refrigerators are equipped with fan-supplied evaporators often tailor-made to mitigate the impacts of frost accretion, not only in terms of frost blocking, which depletes the cooling capacity and therefore the refrigerator coefficient of performance (COP), but also to allow optimal defrosting, thereby avoiding the undesired consequences of condensate retention and additional thermal loads. Evaporator design for frosting conditions can be done either empirically through trial-and-error approaches or using simulation models suitable to predict the distribution of the frost mass along the finned coil. Albeit the former is mandatory for robustness verification prior to product approval, it has been advocated that the latter speeds up the design process and reduces the costs of the engineering undertaking. Therefore, this article is aimed at summarizing the required foundations for the design of efficient evaporators and defrosting systems with minimized performance impacts due to frosting. The thermodynamics, and the heat and mass transfer principles involved in the frost nucleation, growth, and densification phenomena are presented. The thermophysical properties of frost, such as density and thermal conductivity, are discussed, and their relationship with refrigeration operating conditions are established. A first-principles model is presented to predict the growth of the frost layer on the evaporator surface as a function of geometric and operating conditions. The relation between the microscopic properties of frost and their macroscopic effects on the evaporator thermo-hydraulic performance is established and confirmed with experimental evidence. Furthermore, different defrost strategies are compared, and the concept of optimal defrost is formulated. Finally, the results are used to analyze the efficiency of the defrost operation based on the net cooling capacity of the refrigeration system for different duty cycles and evaporator geometries.

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“…The hydrophobic wetting state also plays an important role when the fin surface is subjected to frosting and defrosting [15]-particularly the hydrophobic wetting state, which influences the amount of water retention from surfaces during the defrosting [16]. Similar arguments also become relevant to the hydrophobic wetting state of the metallic surfaces [17]. Moreover, the fin surfaces with hydrophobic wetting state can be utilized to minimize the fouling rates in heating and cooling applications of surfaces, since they result in dust repelling of the dust particles from surfaces [18].…”

Section: Introductionmentioning

confidence: 96%

“…Thermal performance of cooling systems incorporating fins with various configurations was studied earlier [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Although fins interrupt the flow in the cooling system, proper arrangement of fin configuration, such as non-uniform fin distribution, improves the performance of the thermal systems [1].…”

Section: Introductionmentioning

confidence: 99%

“…Although flow over hydrophobic surfaces and influence of slip velocity on the frictional drag and heat transfer was studied previously [16][17][18], the main focus was to improve the heat transfer rates and pressure drop on flat surfaces. In addition, the heat transfer enhancement and cooling effectiveness for extended surfaces, such as fin, are studied earlier [31], the main challenge was to minimize the pressure drop either by introducing the fin geometric modifications [9] or utilizing the porous structures on the fin surfaces [32].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of Hydrophobic Fin Configuration in Thermal System in Relation to Electronic Device Cooling Applications

2020

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In this study, heat and flow analysis of the cooling system incorporating fins with hydrophilic and hydrophobic wetting surfaces has been considered in relation to electronic cooling applications. Temperature and velocity fields in the solution domain are simulated for various fin numbers and sizes. A temperature parameter is introduced to assess the thermal performance of the system. Fin count is introduced to formulate the number of fins in the solution domain. The Nusselt number and pressure drop between the inlet and exit ports due to different fin configurations of the cooling system for various fin counts are presented. It is found that the temperature parameter attains high values for large sizes and small fin counts, which is more pronounced for low Reynolds numbers. Increasing number of fins results in almost uniform flow distribution among the fin, which is more pronounced for the hydrophobic fin configuration. The Nusselt number attains larger values for the hydrophilic fin configuration than that corresponding to the hydrophobic fin, and it attains a peak value for certain arrangement of fin count, which differs with the Reynolds number. The pressure drop between the inlet and exit ports reduces for hydrophobic fin; hence the slip velocity introduced for hydrophobic fin improves the pressure drop by 6% to 16% depending on the fin counts in the cooling system.

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The effect of surface modification on initial ice formation on aluminum surfaces

Cited by 14 publications

References 36 publications

Effect of Aluminum Substrate Surface Modification on Wettability and Freezing Delay of Water Droplet at Subzero Temperatures

Effect of Aluminum Substrate Surface Modification on Wettability and Freezing Delay of Water Droplet at Subzero Temperatures

Evaporator Frosting in Refrigerating Appliances: Fundamentals and Applications

Influence of Hydrophobic Fin Configuration in Thermal System in Relation to Electronic Device Cooling Applications

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