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. Herstellung der modifizierten Oberflächen <ol><li> Polieren manuell das Prüfstück (hohlen Kupferzylinder mit einer 40-mm - Länge (l) in einem 25-mm Außendurchmesser (d o), und ein 18-mm - Innendurchmesser (d i)) für 15 min unter Verwendung eines # 2000 Emery unter Verwendung Papier. Reinigen Sie die polierte Oberfläche indem sie sie mit Aceton, gefolgt von DI-Wasser gespült. </li><li> Platzieren Sie das polierte Teststück in einem Ofen für 2 Stunden bei einer konstanten Temperatur von 120 ° C. </li><li> Vorbereiten einer superhydrophilen SiO 2 Nanopartikellösung die folgenden Schritte verwendet wird . <ol><li> Bereiten Lösung A durch Mischen von 1: 4 Molverhältnisse von Tetraethoxysilan und DI-Wasser. 2 Tropfen 37% konzentrierte HCl zur Lösung A hinzu und rührt 2 Stunden. </li><li> Make-Lösung B durch ein 1 Mischen: 3 Molverhältnis von Ethanol und DI-Wasser. </li><li> Mix 1 ml Lösung A und 80 ml Lösung B hinzu und rühre 2 Stunden. </li><li> Fügen Sie 32 g SiO 2 -Nanopartikel (40 nm Durchmesser) auf die vorbereitete solution und rühre 1 h. </li></ol></li><li> Tauchen des Prüfkörpers in der vorbereiteten Lösung durch die Tauchbeschichtungsvorrichtung mit einer Geschwindigkeit von 5 mm / min verwendet. Halten Sie das beschichtete Teststück in einem Ofen bei 120 ° C für 1 h. </li><li> Bereiten 2, 4, 8 und wattierte Hybridmuster mit unterschiedlichen Orientierungen entlang der axialen Richtung mit Hilfe der folgenden Schritte (wie in Abbildung 1 gezeigt). <ol><li> Maskiert den Bereich unbeschichtet sein, mit dem Isolierband entsprechend die erforderlichen Anzahl von Zwischenzeilen mit der richtigen Orientierung (für die 2-Interline-Oberfläche bei einer 0 ° Orientierung, stellen Zwischenzeilen in der Mitte und der superhydrophilen Bereich (Bereich zu beschichtende) auf die Oberseite. Andererseits seits~~POS=HEADCOMP wird für die Ausrichtung 90 °, stellt eine Zwischenzeile am oberen Ende und ein anderen am unteren Ende und für die 180 ° -Ausrichtung, superhydrophilen Bereich auf der Unterseite und die Zwischenzeilen in der Mitte eingestellt wird. in ähnlicher Weise justiert die Position der 4, 8 wattierten Oberflächen mit der verschiedenen orientation wie in Abbildung 1 gezeigt). </li><li> Tauchen des maskierten Prüfstück in der hergestellten Lösung, die durch eine Tauchbeschichtungsvorrichtung verwendet wird, bei einer hohen dip Tauchgeschwindigkeit und Anstieg bei einer langsamen Geschwindigkeit von 5 mm / min. Halten Sie das beschichtete Teststück in einem Ofen bei 120 ° C für 1 h. </li><li> Entfernen Sie das Isolierband aus dem maskierten Bereich die erforderlichen Anzahl von Zwischenzeilen mit der richtigen Orientierung zu erhalten. </li></ol></li></ol><img alt="Abbildung 1" src="/files/ftp_upload/55387/55387fig1.jpg" /> Abbildung 1. Auswahl von verschiedenen wattierte Oberflächen. (a) Schematische Darstellung der verschiedenen wattierte Flächen mit unterschiedlichen Orientierungen. Das Flächenverhältnis einer glatten Kupferoberfläche und eine superhydrophile Oberfläche ist, von 1: 1 unter allen Bedingungen. (b) Ausrichtung Auswahlkriterien. (c) isometrische Ansicht der 2 Interline 0 ° Winkel orientiert Oberfläche. Die Orientierung wird als der Winkel zwischen der Basislinie ausgewählt und BeschichtungsMittellinie des ersten hydrophilen Musters von der oberen Seite, und es wird im Uhrzeigersinn gemessen. <a href="http://ecsource.jove.com/files/ftp_upload/55387/55387fig1large.jpg" target="_blank">Bitte klicken Sie hier</a> , um <a href="http://ecsource.jove.com/files/ftp_upload/55387/55387fig1large.jpg" target="_blank">eine größere Version dieser Figur zu sehen.</a> 2. Experimentelles Verfahren <ol><li> Unter Verwendung des Isolierband, fixieren ein Glasrohr an jeder kreisförmigen Basis des beschichteten Teststücks. </li><li> Horizontal fixiert diese Baugruppe in der 140- 140- x x 160 mm-Kammer unter Verwendung von Silikonpaste nach der gewünschten Position der Zwischenzeilen (wie in Abbildung 2 gezeigt). </li><li> Legen Sie eine 550-W, 18 mm Durchmesser und 40 mm langen Heizpatrone mit einem dünnen Film aus Wärmeleitpaste auf der Umfangsfläche in das Loch des Prüflings. </li><li> Verbinden Sie die Heizpatrone in einen Gleichstrom (DC) Energieversorgungseinheit. </li><li> Ort T-Typ - Thermoelemente in die 8 gleich beabstandeten Löcher von 1 mm, mit abwechselnden Tiefen von 5 mm und 7 mm , wie gezeigt in Fig3 Schließen Sie sie an den Datenlogger. </li><li> Einsetzen und fixieren Widerstandstemperaturdetektoren (RTD), einen Rückflusskühler und einen Zuheizer in den auf der oberen Abdeckung vorgesehen Flächen. Fix sie über die Siedekammer. </li><li> Füllen Sie 1400 ml DI-Wasser in den Pool-Siedekammer. </li><li> Schließen Sie den Rückflußkühler in eine Kühlkammer, die bei 5 ° C gehalten wird. </li><li> Vor dem Experiment, kochen kräftig das DI-Wasser in den Pool-Siedekammer für 30 min, um die Zusatzheizung verwendet wird. </li><li> Halten Sie das DI-Wasser im gesättigten siedenden Zustand durch die Zusatzheizung verwendet wird. Anschließend schalt die Stromversorgung und einen ersten Strom von 0,1 A. </li><li> Warten für 2 min, um einen stabilen Zustand zu erreichen. Dann erhöht den elektrischen Strom in Schritten von 0,3 A. </li><li> Aufzeichnen die Temperatur an jedem Stromeingang durch den Datenlogger verwendet. Weiter das Experiment, bis ein Maximalstrom von 4 A erreicht ist. Inzwischen notieren Sie die Blasendynamik f<html> oder jeder Stromeingang von einer CCD-Kamera angeordnet vor den Pool-Siedekammer, die auf dem Teststück fokussiert wird. </li></ol><img alt="Figur 2" src="/files/ftp_upload/55387/55387fig2.jpg" /> Abbildung 2. Schematische Darstellung des Pool-Siedekammer. Glasrohre sind an beiden Seiten des hohlen Kupferzylinders mit Silikonpaste verbunden. Dies wird mit Silikonpaste zum Pool-Siedekammer befestigt. <a href="http://ecsource.jove.com/files/ftp_upload/55387/55387fig2large.jpg" target="_blank">Bitte klicken Sie hier</a> , um <a href="http://ecsource.jove.com/files/ftp_upload/55387/55387fig2large.jpg" target="_blank">eine größere Version dieser Figur zu sehen.</a> <img alt="Abbildung 3" src="/files/ftp_upload/55387/55387fig3.jpg" /> Abbildung 3. Thermoelement Positionierung. 8-Thermoelemente sind in den Bohrungen von 1 mm Durchmesser in Umfangsrichtung in dem Prüfstück Ort bei einem Durchmesser von 20 mm platziert. Die Tiefen von abwechselnden 1 mm Durchmesser Löcher werden bei 5 mm und 7 mm bzw. fixiert./files/ftp_upload/55387/55387fig3large.jpg“target =‚_ blank‘&gt; Bitte hier klicken, um eine größere Version dieser Figur zu sehen. 3. Datenreduktion <ol><li> Berechnen Sie die Wärmezufuhr (Q) durch die folgende Gleichung unter Verwendung von 19 Q = I V (1) HINWEIS: I und V ist der Eingangsstrom in Ampere und die Spannung in Volt, respectively. </li><li> Schätzen , um den Wärmeverlust (Q Verlust) von den beiden Seitenflächen mit Hilfe der Formel 19: <img alt="Gleichung 2" src="/files/ftp_upload/55387/55387eq2.jpg" /> (2) HINWEIS: k ist die thermische Leitfähigkeit von Kupfer; T 7 mm T 5 mm und sind die Mittelwerte der Temperatur in einer Tiefe von 7 mm und 5 mm sind; &amp; Dgr; x (2 mm) ist der Unterschied zwischen der Tiefe; und <img alt="Gleichung 2B" src="/files/ftp_upload/55387/55387eq2b.jpg" /> ist die Querschnittsfläche des Test p<html> IECE. </li><li> Bestimmen Sie den Wärmefluß (q ‚‘) unter Verwendung der folgenden Formel 19: <img alt="Gleichung 3" src="/files/ftp_upload/55387/55387eq3.jpg" /> (3) HINWEIS: A = π d o l ist der Umfangsbereich des Prüflings. </li><li> Berechnen der Wandüberhitzung (unter Verwendung der folgenden Gleichung 19: <img alt="Gleichung 4" src="/files/ftp_upload/55387/55387eq4.jpg" /> (4) HINWEIS: Die T m ist der Durchschnitt der T 7 mm und T 5 mm ist die Länge des Prüfkörpers, r o (12,5 mm) Außenradius des Prüfkörpers, r m (10 mm) Radius des Prüfstücks bei der Löcher zu messen und T sat die Sättigungstemperatur von DI - Wasser , wie in Abbildung 4 dargestellt. </li><li> Berechnen Sie die HTC (α) mit der folgenden Formel 19: pload / 55387 / 55387eq5.jpg“/&gt; (5) </li></ol><img alt="Abbildung 4" src="/files/ftp_upload/55387/55387fig4.jpg" /> Abbildung 4. Schematische Darstellung der Wandtemperatur - Analyse. Wandtemperatur wird unter Verwendung des gemessenen Durchschnittstemperatur und bekannten zylindrischen Wärmewiderstand errechnet. <a href="http://ecsource.jove.com/files/ftp_upload/55387/55387fig4large.jpg" target="_blank">Bitte klicken Sie hier</a> , um <a href="http://ecsource.jove.com/files/ftp_upload/55387/55387fig4large.jpg" target="_blank">eine größere Version dieser Figur zu sehen.</a>

<ol>
	<li>Putsch, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermal+challenges+in+the+next+generation+of+supercomputers.">Thermal challenges in the next generation of supercomputers.</a> Proc. CoolCon MEECC Conference. , 1-83 (2005).</li><li>Phan, H. T., Caney, N., Marty, P., Colasson, S., Gavillet, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+wettability+control+by+nanocoating:+The+effect+on+pool+boiling+heat+transfer+and+nucleation+mechanism.">Surface wettability control by nanocoating: The effect on pool boiling heat transfer and nucleation mechanism.</a> Int. J. Heat and Mass Transfer. 52, 5459-5471 (2009).</li><li>Barber, J., Brutin, D., Tadrist, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+on+boiling+heat+transfer+enhancement+with+nanofluids.">A review on boiling heat transfer enhancement with nanofluids.</a> Nanoscale Res. Lett. 6 (1), 280 (2011).</li><li>Kim, S. J., Bang, I. C., Buongiorno, J., Hu, L. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+nanoparticle+deposition+on+surface+wettability+influencing+boiling+heat+transfer+in+nanofluids.">Effects of nanoparticle deposition on surface wettability influencing boiling heat transfer in nanofluids.</a> Appl. Phys. Lett. 89, 153107 (2006).</li><li>Berenson, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experiments+on+pool-boiling+heat+transfer.">Experiments on pool-boiling heat transfer.</a> Int. J. Heat Mass Transfer. 5 (10), 985-999 (1962).</li><li>You, S. M., Simon, T. W., Bar-Cohen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+technique+for+enhancing+boiling+heat+transfer+with+application+to+cooling+of+electronic+equipment.">A technique for enhancing boiling heat transfer with application to cooling of electronic equipment.</a> IEEE Trans. Compon. Hybrids Manuf. Tech. 15 (5), 823-831 (1992).</li><li>Li, C., Peterson, G. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Parametric+study+of+pool+boiling+on+horizontal+highly+conductive+microporous+coated+surfaces.">Parametric study of pool boiling on horizontal highly conductive microporous coated surfaces.</a> J. Heat Transfer. 129 (11), 1465-1475 (2007).</li><li>Trisaksri, V., Wongwises, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+review+of+heat+transfer+characteristics+of+nanofluids.">Critical review of heat transfer characteristics of nanofluids.</a> Renew. Sust. Energy Rev. 11 (3), 512-523 (2007).</li><li>Trisaksri, V., Wongwises, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nucleate+Pool+Boiling+Heat+Transfer+of+TiO2-R141b+nanofluids.">Nucleate Pool Boiling Heat Transfer of TiO2-R141b nanofluids.</a> Int. J. Heat Mass Transfer. 52 (5-6), 1582-1588 (2009).</li><li>Suriyawong, A., Wongwises, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nucleate+pool+boiling+heat+transfer+characteristics+of+TiO2-+water+nanofluids+at+very+low+concentrations.">Nucleate pool boiling heat transfer characteristics of TiO2- water nanofluids at very low concentrations.</a> Exp. Therm. Fluid Sci. 34 (8), 992-999 (2010).</li><li>Suriyawong, A., Dalkilic, A. S., Wongwises, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nucleate+Pool+Boiling+Heat+Transfer+Correlation+for+TiO2-Water+Nanofluids.">Nucleate Pool Boiling Heat Transfer Correlation for TiO2-Water Nanofluids.</a> J. ASTM Int. 9 (5), 1-12 (2012).</li><li>Sarangi, S., Weibel, J. A., Garimella, S. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+particle+size+on+surface-coating+enhancement+of+pool+boiling+heat+transfer.">Effect of particle size on surface-coating enhancement of pool boiling heat transfer.</a> Int. J. Heat Mass Transfer. 81, 103-113 (2015).</li><li>Kumar, C. S. S., Suresh, S., Kumar, M. C. S., Gopi, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+surfactant+addition+on+hydrophilicity+of+ZnO-Al2O3+composite+and+enhancement+of+flow+boiling+heat+transfer.">Effect of surfactant addition on hydrophilicity of ZnO-Al2O3 composite and enhancement of flow boiling heat transfer.</a> Exp. Therm. Fluid Sci. 70, 325-334 (2016).</li><li>Takata, Y., Hidaka, S., Uraguchi, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Boiling+feature+on+a+super+water-repellent+surface.">Boiling feature on a super water-repellent surface.</a> Heat Transfer Eng. 27 (8), 25-30 (2006).</li><li>Takata, Y., Hidaka, S., Masuda, M., Ito, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pool+boiling+on+a+super+hydrophilic+surface.">Pool boiling on a super hydrophilic surface.</a> Int. J. Energy Res. 27 (2), 111-119 (2003).</li><li>Takata, Y., Hidaka, S., Kohno, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+nucleate+boiling+by+super+hydrophobic+coating+with+checkered+and+spotted+patterns.">Enhanced nucleate boiling by super hydrophobic coating with checkered and spotted patterns.</a> International Conference on Boiling Heat Transfer. , (2006).</li><li>Hsu, C. C., Chiu, W. C., Kuo, L. S., Chen, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reversed+boiling+curve+phenomenon+on+surfaces+with+interlaced+wettability.">Reversed boiling curve phenomenon on surfaces with interlaced wettability.</a> AIP Advances. 4, 107110 (2014).</li><li>Jo, H., Ahn, H. S., Kang, S. H., Kim, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+study+of+nucleate+boiling+heat+transfer+on+hydrophilic,+hydrophobic+and+heterogeneous+wetting+surface.">A study of nucleate boiling heat transfer on hydrophilic, hydrophobic and heterogeneous wetting surface.</a> Int. J. Heat Mass Transfer. 54 (25-26), 5643-5652 (2011).</li><li>Mehta, J. S., Kandlikar, S. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pool+boiling+heat+transfer+enhancement+over+cylindrical+tubes+with+water+at+atmospheric+pressure,+Part+I:+Experimental+results+for+circumferential+rectangular+open+microchannels.">Pool boiling heat transfer enhancement over cylindrical tubes with water at atmospheric pressure, Part I: Experimental results for circumferential rectangular open microchannels.</a> Int. J. Heat Mass Transfer. 64, 1205-1215 (2013).</li><li>Cornwell, K., Houston, S. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nucleate+Pool+Boiling+on+Horizontal+Tubes+-+a+Convection-Based+Correlation.">Nucleate Pool Boiling on Horizontal Tubes - a Convection-Based Correlation.</a> Int. J. Heat Mass Transfer. 37, 303-309 (1994).</li><li>Holman, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Experimental Methods for Engineers. , (2007).</li></ol>

The authors declare that they have no competing financial interests.

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...

Ein hoher Wärmefluß erhaltKühlSystems im Bereich von 10 bis 10 Mai W Bereitstellung / cm 2 wird in den Schwellen Bereichen Elektronik, Verteidigungs-, Avionik und Kerngeräteentwicklung erforderlich. Herkömmliche Kühlung mit Luft nicht ausreichend ist für diese Anwendungen aufgrund der geringen Wärmeübertragungskoeffizienten (HTC) sowohl für Frei und erzwungener Konvektion Bedingungen. Die Phasenänderung-basierten Kühltechniken, wie Pool Sieden und Sieden fließen, sind gut genug , um hohe Wärmeströme in der Größenordnung von 10 zu entfernen - 1.000 W / cm 2 1. Da der Zwei-Phasen-Wärmeübertragungsvorgang isotherm ist, wird die gekühlte Gerätetemperatur über seine Oberfläche nahezu konstant. Aufgrund der vernachlässigbaren Variation der Temperatur entlang der Oberfläche, kann der thermische Schock der Vorrichtung beseitigt werden. Allerdings ist die Hauptbegrenzungs Parameter in siedendem Wärmeübertragungs der kritische Wärmefluss (CHF), die einen anormalen Temperaturanstieg verursacht 2 </sup&gt;. In den letzten Jahrzehnten wurde umfangreiche Forschung durchgeführt , die CHF zu verbessern , indem die Oberflächenmodifikation unter Verwendung Nanoflüssigkeiten und Oberflächenbeschichtungen , 3, 4, 5, 6, 7, 8, 9, 10, 11. Unter den verschiedenen Methoden, Oberflächenbeschichtungen die beste Methode zur Verbesserung der CHF aufgrund der erheblichen Zunahme der Oberfläche befunden werden. Oberflächenbeschichtungen erhöhen im allgemeinen die Wärmeübertragung durch fin Aktion, Porosität Effekte und Oberflächenbenetzbarkeit 12. Benetzbarkeit der Oberfläche spielt eine bedeutende Rolle Wärmetransfer in siedendem. Frühere Studien zeigen bei niedrigeren Wärmeflussbedingungen, dass die hydrophobe Oberfläche besser HTC aufgrund der frühen Keimbildung zeigt. Doch beihöherer Wärmefluss ist die Ablösung der gebildeten Blasen langsam aufgrund der geringen Affinität von Wasser in Richtung der Oberfläche. Dies führt zu einer Blasenvereinigung und führt zu einem geringeren 3 CHF. Auf der anderen Seite erzeugt eine hydrophile Oberfläche eine höhere CHF, wegen der schnellen Ablösung der gebildeten Blase, aber es gibt eine geringere HTC bei niedrigen Wärmeflüssen, aufgrund der Verzögerung in Blasennukleierung 13. Die Hybridstrukturen zeigen eine bemerkenswerte Verbesserung Wärmeübertragung für alle Wärmeflüsse aufgrund der kombinierten Wirkung der Hydrophobie und Hydrophilie 14, 15, 16 in sieden. Hsu et al. hergestellte heterogene benetzbare Oberfläche superhydrophilen Si durch Beschichtung Nanopartikel auf einer maskierte Kupferoberfläche. Sie erreichten unterschiedliche Benetzbarkeit Verhältnisse durch die Beschichtungszeit variiert. Der Beginn des Kochens aufgetreten früher auf den heterogenen Oberflächen im Vergleich zu dem Homogeneous Oberfläche, die im wesentlichen die Wand 17 verringert hitzen. Jo et al. Blasensieden Wärmeübertragungs Studien auf hydrophile, hydrophobe und heterogenen Benetzungsflächen durchgeführt. Die heterogene Benetzungsfläche wurde aus hydrophoben gemusterten Punkten auf der hydrophilen Oberfläche bestehen. Sie haben höhere HTCs und die gleiche CHF für die heterogene Oberfläche im Vergleich zu der hydrophilen Oberfläche. Eine Verbesserung in der Siedehitze Übertragung hängt direkt von der Anzahl der Punkte auf der Oberfläche und auf die Siedebedingungen 18. In dieser Studie axiale hybrid benetzbar Muster wurden auf einer zylindrischen Kupferoberfläche unter Verwendung der Tauchbeschichtungstechnik hergestellt. Pool siedende Wärmeübertragungs Studien wurden durchgeführt, um die Auswirkungen der Reihe von Zwischenzeilen und der Orientierung des Hybrids benetzbar Muster zu bestimmen. Boiling Wärmefluss, HTC, und Blasendynamik wurden für die alle beschichteten Substrate analysiert und wirerneut gegenüber dem Kupfersubstrat.

<table border="0" cellpadding="0" cellspacing="0" width="797">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Deionized water</td>
			<td style="width:279px;"></td>
			<td style="width:203px;"></td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Silica nanopowder,40nm</td>
			<td style="width:279px;">UniRegion Bio-Tech</td>
			<td style="width:203px;">60676860</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Ethanol</td>
			<td style="width:279px;">ECHO Chemical co. Ltd</td>
			<td style="width:203px;">64175</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Hydrochloric acid</td>
			<td style="width:279px;">SHOWA Chemical co. Ltd.</td>
			<td style="width:203px;">7647010</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:201px;">Tetraethoxysilane</td>
			<td style="width:279px;">SHOWA Chemical co. Ltd.</td>
			<td style="width:203px;">78104</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="27">
			<td height="27" style="height:27px;width:201px;">Acetone</td>
			<td style="width:279px;">UNI-ONWARD CORP.</td>
			<td style="width:203px;">67641</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:201px;">Cartridge Heater</td>
			<td style="width:279px;">Chung Shun Heater &#38; Instrument Co, Ltd.</td>
			<td style="width:203px;"></td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Pyrex glass&#160;</td>
			<td style="width:279px;">Automotive Glass service , Taiwan</td>
			<td style="width:203px;"></td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Ordinary toughened glass</td>
			<td style="width:279px;">Automotive Glass service , Taiwan</td>
			<td style="width:203px;"></td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Thermal paste</td>
			<td style="width:279px;">Electrolube</td>
			<td style="width:203px;">EG-30&#160;</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:201px;">Insulation Tape</td>
			<td style="width:279px;">Chuan Chi Trading Co. Ltd</td>
			<td style="width:203px;">Kapton Tape</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Sandpaper</td>
			<td style="width:279px;">Chuan Chi Trading Co. Ltd</td>
			<td style="width:203px;">#2000</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:201px;">Heating furnace</td>
			<td style="width:279px;">Chung Chuan</td>
			<td style="width:203px;">Hong Sen HS-101</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:201px;">Electronic scales</td>
			<td style="width:279px;">A&#38;D co. Ltd</td>
			<td style="width:203px;">GX400</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Ultrasonic cleaner</td>
			<td style="width:279px;">Bransonic</td>
			<td style="width:203px;">Bransonic 3510</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Magnet stirrer</td>
			<td style="width:279px;">Yellow line</td>
			<td style="width:203px;">MST D S1</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Data logger&#160;</td>
			<td style="width:279px;">Yokogawa</td>
			<td style="width:203px;">MX-100</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">CCD camera</td>
			<td style="width:279px;">JVC</td>
			<td style="width:203px;">LY35862-001A</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Silicon paste</td>
			<td style="width:279px;">Permatex</td>
			<td style="width:203px;">599BR</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Power supply</td>
			<td style="width:279px;">Gwinstek</td>
			<td style="width:203px;">GPR-20H50D</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Teflon tape&#160;</td>
			<td style="width:279px;">Chuan Chi Trading Co. Ltd</td>
			<td style="width:203px;">CS170000</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Contact Angle Goniometer</td>
			<td style="width:279px;">Sindatek</td>
			<td style="width:203px;">Model 100SB</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:201px;">Auxiliary Heater</td>
			<td style="width:279px;">Chuan Chi Trading Co. Ltd</td>
			<td style="width:203px;"></td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">T- type thermocouples</td>
			<td style="width:279px;">Chuan Chi Trading Co. Ltd</td>
			<td style="width:203px;"></td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Reflux Condenser&#160;</td>
			<td style="width:279px;">Chuan Chi Trading Co. Ltd</td>
			<td style="width:203px;"></td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Fiber glass</td>
			<td style="width:279px;">Professional Plastics, Taiwan</td>
			<td style="width:203px;"></td>
			<td style="width:115px;"></td>
		</tr>
	</tbody>
</table>

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.

Pool siedenden Wärmeübertragungsexperimente wurden auf einer Hybrid - benetzbaren zylindrischen Oberfläche durchgeführt unter Verwendung des experimentellen Aufbaus , deren schematischen wird in 5 gezeigt. Der Pool siedende experimentelle Verfahren erläutert in Schritt 2 des Protokolls Abschnitt wurde erfolgreich durchgeführt, während die Wirkung der Anzahl von Zwischenzeilen und der Orientierung des Hybrids benetzbar Muster auf dem Pool siedende Leistung zu unter...

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

Pool siedenden Wärmeübertragungs Experimente wurden durchgeführt, um die Auswirkungen von Hybrid-Spritzmuster auf dem Wärmeübertragungskoeffizienten (HTC) zu beobachten. Die Parameter der Untersuchung sind die Anzahl der Zwischenzeilen und die Musterausrichtung der modifizierten benetzbare Oberfläche.

Pool-Boiling Wärmeübertragung Enhancement auf zylindrischen Oberflächen mit Hybrid Benetzbare 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 ...

pool-boiling-heat-transfer-enhancement-on-cylindrical-surfaces-with

Research

JoVE Journal

Engineering

8.9K Aufrufe.  National Taiwan University.  Pool siedenden Wärmeübertragungs Experimente wurden durchgeführt, um die Auswirkungen von Hybrid-Spritzmuster auf dem Wärmeübertragungskoeffizienten (HTC) zu beobachten. Die Parameter der Untersuchung sind die Anzahl der Zwischenzeilen und die Musterausrichtung der modifizierten benetzbare Oberfläche. 

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

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

Conducting polymers have attracted great attention since the discovery of high conductivity in doped polyacetylene in 19771. They offer the advantages of low weight, easy tailoring of properties and a wide spectrum of applications2,3. Due to sensitivity of conducting polymers to environmental conditions (e.g., air, oxygen, moisture, high temperature and chemical solutions), lithographic techniques present significant technical challenges when working with these materials4. For example, current photolithographic methods, such as ultra-violet (UV), are unsuitable for patterning the conducting polymers due to the involvement of wet and/or dry etching processes in these methods. In addition, current micro/nanosystems mainly have a planar form5,6. One layer of structures is built on the top surfaces of another layer of fabricated features. Multiple layers of these structures are stacked together to form numerous devices on a common substrate. The sidewall surfaces of the microstructures have not been used in constructing devices. On the other hand, sidewall patterns could be used, for example, to build 3-D circuits, modify fluidic channels and direct horizontal growth of nanowires and nanotubes.
A macropunching method has been applied in the manufacturing industry to create macropatterns in a sheet metal for over a hundred years. Motivated by this approach, we have developed a micropunching lithography method (MPL) to overcome the obstacles of patterning conducting polymers and generating sidewall patterns. Like the macropunching method, the MPL also includes two operations (Fig. 1): (i) cutting; and (ii) drawing. The "cutting" operation was applied to pattern three conducting polymers4, polypyrrole (PPy), Poly(3,4-ethylenedioxythiophen)-poly(4-styrenesulphonate) (PEDOT) and polyaniline (PANI). It was also employed to create Al microstructures7. The fabricated microstructures of conducting polymers have been used as humidity8, chemical8, and glucose sensors9. Combined microstructures of Al and conducting polymers have been employed to fabricate capacitors and various heterojunctions9,10,11. The "cutting" operation was also applied to generate submicron-patterns, such as 100- and 500-nm-wide PPy lines as well as 100-nm-wide Au wires. The "drawing" operation was employed for two applications: (i) produce Au sidewall patterns on high density polyethylene (HDPE) channels which could be used for building 3D microsystems12,13,14, and (ii) fabricate polydimethylsiloxane (PDMS) micropillars on HDPE substrates to increase the contact angle of the channel15.

A micropunching lithography approach is developed to generate micro- and submicron-patterns on top, sidewall and bottom surfaces of polymer substrates. It overcomes the obstacles of patterning conducting polymers and generating sidewall patterns. This method allows rapid fabrication of multiple features and is free of aggressive chemistry.

Micropunching Lithographie zur Erzeugung von Mikro-und Submikron-Muster auf Polymersubstrate

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

Forschung

Ingenieurwesen

Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM, other properties such as local electronic states, ion diffusion coefficient and surface potential can also be investigated17-22. In this work, electrochemical measurements, Raman spectroscopy, and SPM were used in conjunction with a novel test electrode platform that consists of a Ni mesh electrode embedded in an yttria-stabilized zirconia (YSZ) electrolyte. Cell performance testing and impedance spectroscopy under fuel containing H2S was characterized, and Raman mapping was used to further elucidate the nature of sulfur poisoning. In situ Raman monitoring was used to investigate coking behavior. Finally, atomic force microscopy (AFM) and electrostatic force microscopy (EFM) were used to further visualize carbon deposition on the nanoscale. From this research, we desire to produce a more complete picture of the SOFC anode.

We present a unique platform for characterizing electrode surfaces in solid oxide fuel cells (SOFCs) that allows simultaneous performance of multiple characterization techniques (e.g. in situ Raman spectroscopy and scanning probe microscopy alongside electrochemical measurements). Complementary information from these analyses may help to advance toward a more profound understanding of electrode reaction and degradation mechanisms, providing insights into rational design of better materials for SOFCs.

Sondieren und Mapping-Elektrode Oberflächen in Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen ...

Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas allows the deposition of metal oxides with tunable morphology, structure, density and stoichiometry by a proper control of the plasma plume expansion dynamics. Such versatility can be exploited to produce nanostructured films from compact and dense to nanoporous characterized by a hierarchical assembly of nano-sized clusters. In particular we describe the detailed methodology to fabricate two types of Al-doped ZnO (AZO) films as transparent electrodes in photovoltaic devices: 1) at low O2 pressure, compact films with electrical conductivity and optical transparency close to the state of the art transparent conducting oxides (TCO) can be deposited at room temperature, to be compatible with thermally sensitive materials such as polymers used in organic photovoltaics (OPVs); 2) highly light scattering hierarchical structures resembling a forest of nano-trees are produced at higher pressures. Such structures show high Haze factor (&gt;80%) and may be exploited to enhance the light trapping capability. The method here described for AZO films can be applied to other metal oxides relevant for technological applications such as TiO2, Al2O3, WO3 and Ag4O4.

We describe the experimental method to deposit nanostructured oxide thin films by nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas. By using this method Al-doped ZnO (AZO) films, from compact to hierarchically structured as nano-tree forests, can be deposited.

Herstellung von transparenten leitenden Oxide durch Pulsed Laser Deposition Nano-engineered

Nanosecond Pulsed  Laser Deposition (PLD) in the presence of a background gas allows the deposition  of metal oxides with tunable morphology, structure, ...

High-speed Particle Image Velocimetry Near 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 complex nature of these flows may be studied using particle image velocimetry (PIV), a laser-based imaging technique for optically accessible flows. Though many forms of PIV exist that extend the technique beyond the original planar two-component velocity measurement capabilities, the basic PIV system consists of a light source (laser), a camera, tracer particles, and analysis algorithms. The imaging and recording parameters, the light source, and the algorithms are adjusted to optimize the recording for the flow of interest and obtain valid velocity data. 
Common PIV investigations measure two-component velocities in a plane at a few frames per second. However, recent developments in instrumentation have facilitated high-frame rate (&gt; 1 kHz) measurements capable of resolving transient flows with high temporal resolution. Therefore, high-frame rate measurements have enabled investigations on the evolution of the structure and dynamics of highly transient flows. These investigations play a critical role in understanding the fundamental physics of complex flows.
A detailed description for performing high-resolution, high-speed planar PIV to study a transient flow near the surface of a flat plate is presented here. Details for adjusting the parameter constraints such as image and recording properties, the laser sheet properties, and processing algorithms to adapt PIV for any flow of interest are included.

A procedure for studying transient flows near boundaries using high-resolution, high-speed particle image velocimetry (PIV) is described here. PIV is a non-intrusive measurement technique applicable to any optically accessible flow by optimizing several parameter constraints such as the image and recording properties, the laser sheet properties, and analysis algorithms.

High-Speed-Particle Image Velocimetry Nahe 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

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra shallow and sharp doping profiles at the nanometer scale. In MLCD process the dopant source is a monolayer containing dopant atoms.
In this article a detailed procedure for surface doping of silicon substrate as well as silicon nanowires is demonstrated. Phosphorus dopant source was formed using tetraethyl methylenediphosphonate monolayer on a silicon substrate. This monolayer containing substrate was brought to contact with a pristine intrinsic silicon target substrate and annealed while in contact. Sheet resistance of the target substrate was measured using 4 point probe. Intrinsic silicon nanowires were synthesized by chemical vapor deposition (CVD) process using a vapor-liquid-solid (VLS) mechanism; gold nanoparticles were used as catalyst for nanowire growth. The nanowires were suspended in ethanol by mild sonication. This suspension was used to dropcast the nanowires on silicon substrate with a silicon nitride dielectric top layer. These nanowires were doped with phosphorus in similar manner as used for the intrinsic silicon wafer. Standard photolithography process was used to fabricate metal electrodes for the formation of nanowire based field effect transistor (NW-FET). The electrical properties of a representative nanowire device were measured by a semiconductor device analyzer and a probe station.

A detailed procedure for surface doping of Silicon interfaces is provided. The ultra-shallow surface doping is demonstrated by using phosphorus containing monolayers and rapid annealing process. The method can be used for doping of macroscopic area surfaces as well as nanostructures.

Monolayer Kontakt Dotierung von Silizium-Oberflächen und Nanodrähte Mit Phosphororganische Verbindungen

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

Here, we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. Optical property evaluation of thin films and the surfaces of bulk materials is an important step in understanding new optical material systems and their applications. The method presented can estimate thickness, refractive index, and use absorptive properties of materials for detection. This metrology system uses evanescent field-based photoacoustics (EFPA), a field of research based upon the interaction of an evanescent field with the photoacoustic effect. This interaction and its resulting family of techniques allow the technique to probe optical properties within a few hundred nanometers of the sample surface. This optical near field allows for the highly accurate estimation of material properties on the same scale as the field itself such as refractive index and film thickness. With the use of EFPA and its sub techniques such as total internal reflection photoacoustic spectroscopy (TIRPAS) and optical tunneling photoacoustic spectroscopy (OTPAS), it is possible to evaluate a material at the nanoscale in a consolidated instrument without the need for many instruments and experiments that may be cost prohibitive.

Here we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. This technique evanescent field-based photoacoustics can be used to create a photoacoustic metrology system to estimate materials&#39; thicknesses, bulk and thin film refractive indices, and explore their optical properties.

Abklingende Feld Basierend Photoakustik: Optische Objektbewertung an Oberflächen

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

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, building and food industries, amongst others. Polyester and coatings containing both polyester and silica nanoparticles (SiO2NPs) have been widely used to protect steel substrata from corrosion. In this study, we utilized X-ray photoelectron spectroscopy, attenuated total reflection infrared micro-spectroscopy, water contact angle measurements, optical profiling and atomic force microscopy to provide an insight into how exposure to sunlight can cause changes in the micro- and nanoscale integrity of the coatings. No significant change in surface micro-topography was detected using optical profilometry, however, statistically significant nanoscale changes to the surface were detected using atomic force microscopy. Analysis of the X-ray photoelectron spectroscopy and attenuated total reflection infrared micro-spectroscopy data revealed that degradation of the ester groups had occurred through exposure to ultraviolet light to form COO&#903;, -H2C&#903;, -O&#903;, -CO&#903; radicals. During the degradation process, CO and CO2 were also produced.

Two types of surfaces, polyester-coated steel and polyester coated with a layer of silica nanoparticles, were studied. Both surfaces were exposed to sunlight, which was found to cause substantial changes in the chemistry and nanoscale topography of the surface.

Die Evolution der Silica-Nanopartikel-Polyester-Beschichtungen auf Oberflächen Sonnenlicht ausgesetzt

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

This manuscript provides step by step description of the manufacturing process of a test section designed to measure the local instantaneous heat transfer coefficient as a function of the liquid flow rate in a transparent pipe. With certain amendments, the approach is extended to gas-liquid flows, with a particular emphasis on the effect of a single elongated (Taylor) air bubble on heat transfer enhancement. A non-invasive thermography technique is applied to measure the instantaneous temperature of a thin metal foil heated electrically. The foil is glued to cover a narrow slot cut in the pipe. The thermal inertia of the foil is small enough to detect the variation in the instantaneous foil temperature. The test section can be moved along the pipe and is long enough to cover a considerable part of the growing thermal boundary layer.
At the beginning of each experimental run, a steady state with a constant water flow rate and heat flux to the foil is attained and serves as the reference. The Taylor bubble is then injected into the pipe. The heat transfer coefficient variations due to the passage of a Taylor bubble propagating in a vertical pipe is measured as function of the distance of the measuring point from the bottom of the moving Taylor bubble. Thus, the results represent the local heat transfer coefficients. Multiple independent runs preformed under identical conditions allow accumulating sufficient data to calculate reliable ensemble-averaged results on the transient convective heat transfer. In order to perform this in a frame of reference moving with the bubble, the location of the bubble along the pipe has to be known at all times. Detailed description of measurements of the length and of the translational velocity of the Taylor bubbles by optical probes is presented.

This manuscript describes methods aimed at measuring the local instantaneous convective heat transfer coefficients in a single or two-phase pipe flow. A simple optical method to determine the length and the propagation velocity of an elongated (Taylor) air bubble moving at a constant velocity is also presented.

Messungen der lokalen momentane konvektive Wärmeübertragung in einem Rohr - Einzel- und zwei-Phasen-Strömung

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

In this paper, fabrication methods that generate novel surfaces using the azlactone-based block co-polymer, poly (glycidyl methacrylate)-block-poly (vinyl dimethyl azlactone) (PGMA-b-PVDMA), are presented. Due to the high reactivity of azlactone groups towards amine, thiol, and hydroxyl groups, PGMA-b-PVDMA surfaces can be modified with secondary molecules to create chemically or biologically functionalized interfaces for a variety of applications. Previous reports of patterned PGMA-b-PVDMA interfaces have used traditional top-down patterning techniques that generate non-uniform films and poorly controlled background chemistries. Here, we describe customized patterning techniques that enable precise deposition of highly uniform PGMA-b-PVDMA films in backgrounds that are chemically inert or that have biomolecule-repellent properties. Importantly, these methods are designed to deposit PGMA-b-PVDMA films in a manner that completely preserves azlactone functionality through each processing step. Patterned films show well-controlled thicknesses that correspond to polymer brushes (~90 nm) or to highly crosslinked structures (~1-10 &#956;m). Brush patterns are generated using either the parylene lift-off or interface directed assembly methods described and are useful for precise modulation of overall chemical surface reactivity by adjusting either the PGMA-b-PVDMA pattern density or the length of the VDMA block. In contrast, the thick, crosslinked PGMA-b-PVDMA patterns are obtained using a customized micro-contact printing technique and offer the benefit of higher loading or capture of secondary material due to higher surface area to volume ratios. Detailed experimental steps, critical film characterizations, and trouble-shooting guides for each fabrication method are discussed.

Surface fabrication methods for patterned deposition of nanometer thick brushes or micron thick, crosslinked films of an azlactone block co-polymer are reported. Critical experimental steps, representative results, and limitations of each method are discussed. These methods are useful for creating functional interfaces with tailored physical features and tunable surface reactivity.

Herstellung von reaktiven Oberflächen mit Pinsel-Like und querverbunden Filme von Azlactone funktionalisiert Block-Copolymere

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

An experimental method for exploring the heat transfer characteristics of an axially rotating channel is proposed. The governing flow parameters that characterize the transport phenomena in a rotating channel are identified via the parametric analysis of the momentum and energy equations referring to a rotating frame of reference. Based on these dimensionless flow equations, an experimental strategy that links the design of the test module, the experimental program and the data analysis is formulated with the attempt to reveal the isolated Coriolis-force and buoyancy effects on heat transfer performances. The effects of Coriolis force and rotating buoyancy are illustrated using the selective results measured from rotating channels with various geometries. While the Coriolis-force and rotating-buoyancy impacts share several common features among the various rotating channels, the unique heat transfer signatures are found in association with the flow direction, the channel shape and the arrangement of heat transfer enhancement devices. Regardless of the flow configurations of the rotating channels, the presented experimental method enables the development of physically consistent heat transfer correlations that permit the evaluation of isolated and interdependent Coriolis-force and rotating-buoyancy effects on the heat transfer properties of rotating channels.

Here, we present an experimental method for decoupling the interdependent Coriolis-force and rotating-buoyancy effects on full-field heat transfer distributions of a rotating channel.

Abkoppeln Corioliskraft und rotierenden Auftrieb Auswirkungen auf Vollfeld Heat Transfer Eigenschaften eines rotierenden Kanals

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