Name: pool-boiling heat-transfer enhancement on cylindrical surfaces with hybrid wettable patterns
Uploaded: 2017-04-10T14:00:00
Description: Watch this Scientific Journal Video about Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns at JoVE.com

The authors gratefully acknowledge funding support from the Ministry of Science and Technology, MOST (project numbers: MOST 104-2218-E-002 -004, MOST 105-2218-E-002-019, MOST 105-2221-E-002 -107 -MY3, MOST 102-2221-E-002 -133 -MY3, and MOST 102-2221-E-002 -088 -MY3).

1. Préparation des surfaces modifiées <ol><li> Polir manuellement la pièce de test (cylindre creux en cuivre avec une longueur de 40 mm (L), un diamètre extérieur (d o), et un diamètre intérieur de 18 mm (d i) de 25 mm) pendant 15 min en utilisant un émeri # 2000 papier. Nettoyer la surface polie en le rinçant avec de l&#39;acétone puis de l&#39;eau DI. </li><li> Placer l&#39;éprouvette polie dans un four pendant 2 heures à une température constante de 120 ...

<ol>
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The main goal of this investigation was to develop a pool-boiling heat sink for high heat dissipation applications, such as nuclear reactors, boilers, and heat pipes, by introducing the hybrid wettable surface, as described in the protocol section. These surfaces can produce better pool-boiling performances than homogeneous wettable surfaces (hydrophilic and hydrophobic). The improvement in the boiling heat-transfer performance is due to an increase in active nucleation sites and the easy detachment of the formed bubbles...

Un système de maintien de flux de chaleur élevé fournissant de refroidissement dans la plage de 10 à 10 mai W / cm 2 est requise dans les domaines émergents de l&#39; électronique, de la défense, de l&#39; avionique, et le développement de l&#39; appareil nucléaire. refroidissement classique avec de l&#39;air est insuffisante pour ces applications en raison du faible coefficient de transfert de chaleur (HTC) pour les deux conditions free- et à convection forcée. Les techniques de refroidissement à base de changement de phase, tels que l&#39; ébullition de la piscine et le débit d&#39; ébullition, sont suffisamment bons pour enlever des flux de chaleur élevés de l&#39;ordre de 10 - 1 000 W / cm 2 1. Etant donné que le processus de transfert de chaleur à deux phases est isotherme, la température du dispositif refroidi est pratiquement constante sur toute sa surface. En raison de la variation négligeable de la température le long de la surface, le choc thermique du dispositif peut être éliminé. Cependant, le principal paramètre limitant à point d&#39; ébullition de transfert de chaleur est le flux de chaleur critique (CHF), ce qui provoque une élévation anormale de température 2 </sup&gt;. Au cours des dernières décennies, des recherches approfondies ont été menées pour améliorer la CHF à l&#39;aide d&#39;une modification de surface, nanofluides et revêtements de surface 3, 4, 5, 6, 7, 8, 9, 10, 11. Parmi les différentes méthodes, les revêtements de surface se trouvent être la meilleure méthode pour améliorer la CHF en raison de l&#39;augmentation substantielle de la surface. Les revêtements de surface augmentent généralement le transfert de chaleur par l&#39; action des nageoires, des effets de la porosité, et la mouillabilité de la surface 12. mouillabilité de surface joue un rôle important dans l&#39;ébullition de transfert de chaleur. Des études antérieures montrent que, à la baisse des conditions de flux de chaleur, la surface hydrophobe montre mieux HTC en raison de la nucléation précoce. Cependant, àle flux de chaleur plus élevé, le détachement des bulles formées est lente en raison de la faible affinité de l&#39;eau vers la surface. Cela conduit à la coalescence des bulles et se traduit par une faible CHF 3. D&#39;autre part, une surface hydrophile produit une CHF en hausse, en raison du détachement rapide des bulles formées, mais il donne un HTC plus faible à faible flux de chaleur, en raison du retard dans la nucléation des bulles 13. Les structures hybrides montrent une amélioration remarquable dans l&#39; ébullition de transfert thermique pour tous les flux de chaleur due à l&#39;effet combiné d&#39;hydrophobicité et d&#39; hydrophilicité 14, 15, 16. Hsu et al. produit hétérogène surface mouillable par revêtement superhydrophile Si nanoparticules sur une surface de cuivre masquée. Ils ont obtenu des rapports de mouillabilité en faisant varier le temps de revêtement. Le début de l&#39;ébullition a eu lieu plus tôt sur les surfaces hétérogènes par rapport à l&#39;homogeneous surface, ce qui réduit sensiblement la paroi 17 de surchauffe. Jo et al. -mené des études de transfert de chaleur d&#39;ébullition nucléée sur les surfaces de mouillage hydrophiles, hydrophobes, et hétérogènes. La surface de mouillage hétérogène est composée de points à motifs hydrophobes sur la surface hydrophile. Ils ont obtenu les CTH plus élevés et la même CHF pour la surface hétérogène par rapport à la surface hydrophile. Une amélioration de l&#39; ébullition de transfert de chaleur dépend directement du nombre de points sur la surface et sur les conditions d&#39;ébullition 18. Dans cette étude, les modèles hybrides mouillables axiales ont été produites sur une surface de cuivre cylindrique en utilisant la technique de revêtement par immersion. Des études de transfert de chaleur piscine d&#39;ébullition ont été réalisées pour déterminer les effets du nombre de interlignes et de l&#39;orientation du motif mouillable hybride. Ébullition flux de chaleur, HTC, et la dynamique des bulles ont été analysés pour les substrats revêtus et nous tousre par rapport au substrat en cuivre.

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pool-boiling heat-transfer enhancement on cylindrical surfaces with hybrid wettable patterns

In this study, pool-boiling heat-transfer experiments were performed to investigate the effect of the number of interlines and the orientation of the hybrid wettable pattern. Hybrid wettable patterns were produced by coating superhydrophilic SiO2 on a masked, hydrophobic, cylindrical copper surface. Using de-ionized (DI) water as the working fluid, pool-boiling heat-transfer studies were conducted on the different surface-treated copper cylinders of a 25-mm diameter and a 40-mm length. The experimental results showed that the number of interlines and the orientation of the hybrid wettable pattern influenced the wall superheat and the HTC. By increasing the number of interlines, the HTC was enhanced when compared to the plain surface. Images obtained from the charge-coupled device (CCD) camera indicated that more bubbles formed on the interlines as compared to other parts. The hybrid wettable pattern with the lowermost section being hydrophobic gave the best heat-transfer coefficient (HTC). The experimental results indicated that the bubble dynamics of the surface is an important factor that determines the nucleate boiling.

Expériences de transfert de chaleur extérieure à point d&#39; ébullition ont été réalisées sur une surface cylindrique mouillable hybride à l&#39; aide du dispositif expérimental dont le schéma est représenté sur la figure 5. La procédure expérimentale piscine à point d&#39;ébullition expliqué à l&#39;étape 2 de la section de protocole a été effectuée avec succès tout en étudiant l&#39;effet du nombre de interlignes et de l&#39;orientation du mot...

Watch this Scientific Journal Video about Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns at JoVE.com

Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns

Des expériences de transfert de chaleur-piscine à point d&#39;ébullition ont été pour observer les effets des modèles hybrides mouillable sur le coefficient de transfert de chaleur (HTC). Les paramètres de recherche sont le nombre d&#39;interlignes et l&#39;orientation du motif de la surface mouillable modifiée.

Piscine d&#39;ébullition Amélioration de transfert de chaleur sur des surfaces cylindriques avec des modèles hybrides mouillables

In this study, pool-boiling heat-transfer experiments were performed to investigate the effect of the number of interlines and the orientation of the ...

The overall goal of this experiment is to investigate the effect of the number and orientation of axial wettable patterns on pool-boiling heat-transfer. This method can help answer key questions in the field of pool-boiling heat transfer such as the effect of hybrid variability on the boiling heat transfer coefficient and bubble dynamics. The main advantage of this technique is that it can accurately measure the pool-boiling heat-transfer coefficient and bubble dynamics of hybrid wettable surface.To begin, manually polish a hollow copper cylinder for 15 minutes using number 2, 000 emery paper. Clean the polished surface by rinsing it with acetone followed by deionized water. Place the polished test piece in an oven for two hours at a constant temperature of 120 degrees Celsius.To prepare a superhydrophilic silicon dioxide nanoparticle solution, first prepare solution A by mixing tetraethoxy silane and deionized water. Then add two drops of 37%concentrated HCl to solution A and stir for two hours. Next, make solution B by mixing ethanol and deionized water.Then mix one milliliter of solution A and 80 milliliters of solution B and stir for two hours. And 32 grams of silicon dioxide nanoparticles to the prepared solution and stir for one hour before immersing the test piece as described in the text protocol. Next, prepared two interlined hybrid patterns with different orientations along the axial direction of the test piece, by masking the area to be uncoated using the insulation tape according to the required number of interlines with the proper orientation.For the two interlined surface at a zero degree orientation adjust interlines at the center and the superhydrophilic area on the top side. Conversely, for the 180 degree orientation, adjust the superhydrophilic area at the bottom and the interlines at the center. Similarly adjust the position of the four and eight interlined surfaces with the different orientations.Next, immerse the masked test piece in the prepared solution by using a dip coating apparatus at a high dipping velocity and rise at a slow velocity of five millimeters per minute. Keep the coated test piece in an oven at 120 degrees for one hour. Finally, remove the insulation tape from the masked area to obtain the required number of interlines with the proper orientation.Using insulation tape, fix one glass tube at each circular base of the coated test piece. Horizontally fix this assembly to the chamber using silicon paste according to the required position of interlines. Place a cartridge heater with a thin film of thermal paste on the circumferential area into the hole of the test piece.Connect the cartridge heater to a direct current power supply unit. Place T-type thermocouples into the eight equally spaced one millimeter holes with alternate depths of five millimeters and seven millimeters. Then, connect them to the data logger.Insert and fix resistance temperature detectors, a reflux condenser and an auxiliary heater in the spaces provided on the top cover. Fix them over the boiling chamber. Next, fill 1.4 liters of deionized water into the pool-boiling chamber.Connect the reflux condenser to a cooling chamber that is maintained at five degrees Celsius. Prior to the experiment, vigorously boil the deionized water in the pool-boiling chamber for 30 minutes using the auxiliary heater. Keep the deionized water at the saturated boiling condition by using the auxiliary heater.Subsequently, switch on the power supply and give an initial current of 0.1 amps. Meanwhile, record the bubble dynamics for each power input by using a CCD camera that is placed in front of the pool-boiling chamber and focused on the test piece. After waiting for two minutes to reach a steady-state, increase the electric current with increments of 0.3 amps.Record the temperature at each power input by using the data logger. Continue the experiment until a maximum current of four amps is reached. Finally, perform Data Reduction as described in the text protocol.Shown here are pool-boiling performances of plain copper surface, fully superhydrophilic surface, and hybrid surfaces with different numbers of interlines at zero degree orientation. The effect of various surfaces on pool-boiling curves is shown, as well as the variation of the heat transfer coefficient, or HTC with respect to heat flux. Eight interlined surfaces show better HTC as compared to other surfaces for particular heat flux, but two and four interlined surfaces have almost the same HTC.The effect of orientation on pool-boiling curves of two interlined hybrid surfaces, four interlined hybrid surfaces, and eight interlined hybrid surfaces are shown. The leftward shift in pool-boiling curves is obtained for the two interlined surface for zero degrees, the four interlined surface at 90 degrees, and the eight interlined surface at 45 degrees. Also shown is the effect of orientation on the heat transfer coefficient for two interlined hybrid surfaces, four interlined hybrid surfaces, and eight interlined hybrid surfaces.HTC of the two interlined surface at zero degrees, the four interlined surface at 90 degrees, and the eight interlined surface at 45 degrees show the highest values. Once mastered this technique can done in ways if it is performed properly. For learning this procedure, analysis of pool-boiling heat-transfer coefficient and bubble dynamics can be performed to investigate the effect of hybrid variability on pool-boiling.Don't forget that, working with nanoparticles and chemicals can be hazardous and precautions such as wearing gloves and masks should always be taken while performing this procedure.

Research

JoVE Journal

Engineering

Micropunching Lithography for Generating Micro- and Submicron-patterns on Polymer Substrates

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Conducting polymers have attracted great attention since the discovery of high conductivity in doped polyacetylene in 19771. They offer the advantages of ...

Recherche

Ingénierie

Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

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High-speed Particle Image Velocimetry Near Surfaces

Particules à haute vitesse vélocimétrie par image de près de surfaces

Multi-dimensional and transient flows play a key role in many areas of science, engineering, and health sciences but are often not well understood. The ...

Monolayer Contact Doping of Silicon Surfaces and Nanowires Using Organophosphorus Compounds

Monocouche Contactez-dopage du silicium Surfaces et nanofils utilisant des composés organophosphorés

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra ...

Evanescent Field Based Photoacoustics: Optical Property Evaluation at Surfaces

Evanescent terrain Photoacoustique base: évaluation de la propriété optique au niveau des surfaces

Here, we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. ...

The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight

L&#39;évolution de la silice Nanoparticules polyester revêtements sur les surfaces exposées au soleil

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, ...

Measurements of Local Instantaneous Convective Heat Transfer in a Pipe - Single and Two-phase Flow

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This manuscript provides step by step description of the manufacturing process of a test section designed to measure the local instantaneous heat transfer ...

Fabricating Reactive Surfaces with Brush-like and Crosslinked Films of Azlactone-Functionalized Block Co-Polymers

Fabrication de Surfaces réactives avec brosse-comme et Films réticulés de copolymères bloc Azlactone fonctionnalisés

In this paper, fabrication methods that generate novel surfaces using the azlactone-based block co-polymer, poly (glycidyl methacrylate)-block-poly (vinyl ...

Uncoupling Coriolis Force and Rotating Buoyancy Effects on Full-Field Heat Transfer Properties of a Rotating Channel

Découplante Force de Coriolis et rotation effets de flottabilité sur plein champ thermique transfert des propriétés d’un canal rotatif

An experimental method for exploring the heat transfer characteristics of an axially rotating channel is proposed. The governing flow parameters that ...