scholarly journals CONCEPTUALIZATION, THERMAL ANALYSIS, AND MANUFACTURING OF NANO-TEXTURED MICRO-STRUCTURED SURFACES FOR ENHANCED CONDENSATION HEAT TRANSFER

2021 ◽  
pp. 867-889
Author(s):  
Mete BUDAKLI
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Condensation Heat Transfer ◽  
Structured Surfaces

20315 Condensation Heat Transfer on Micro Structured Surfaces

2014 ◽  
Vol 2014.20 (0) ◽  
pp. _20315-1_-_20315-2_
Author(s):  
Tomohiro YABE ◽  
Hiromu OHNO ◽  
Hiroyasu OHTAKE ◽  
Koji HASEGAWA
Keyword(s):  
Heat Transfer ◽  
Condensation Heat Transfer ◽  
Structured Surfaces

Study on Condensation Heat Transfer on Micro Structured Surfaces (Effect on Condensation Heat Transfer of Metal Sputtering Surfaces)

2013 ◽  
Author(s):  
Kohei Yamazaki ◽  
Hiroyasu Ohtake ◽  
Koji Hasegawa
Keyword(s):  
Heat Transfer ◽  
Metal Film ◽  
Copper Surface ◽  
Thin Metal Film ◽  
Thin Metal ◽  
Condensation Heat Transfer ◽  
Dropwise Condensation ◽  
Transfer Coefficients ◽  
Structured Surfaces ◽  
Heat Transfer Coefficients

The present study was intended to examine how the condensation heat transfer, especially the dropwise condensation, was affected by modifying the surface nature. In the present study, condensation heat transfer experiments for steam were performed by using mirror-finished copper surface and some very thin metal-film surfaces by using sputtering on mirror-finished copper block. That is, the effects on pattern of condensation heat transfer, i.e., dropwise or film-wise condensation, of metal-sputtered surfaces were examined experimentally and qualitatively. The present experimental results showed that the condensation on sputtered metal surfaces of Copper (Cu), Chromium (Cr) and Lead (Pb), became dropwise condensation. The heat transfer coefficients were ten times higher than the Nusselt equation. The condensation on sputtered metal surface of Titanium (Ti) became filmwise condensation. High contact angle was trended to be dropwise condensation on very thin metal-film surfaces by using sputtering.

Study on Condensation Heat Transfer of Micro Structured Surfaces

2009 ◽  
Author(s):  
Hiroyasu Ohtake ◽  
Yasuo Koizumi ◽  
Soichiro Miyake
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Film ◽  
Copper Surface ◽  
Heat Fluxes ◽  
Condensation Heat Transfer ◽  
Silicon Surfaces ◽  
Copper Surfaces ◽  
Structured Surfaces ◽  
Mems Technology

Condensation heat transfer experiments for steam were performed by using mirror-finished copper surfaces, mirror-finished silicon surfaces and silicon surfaces with micro grooves or micro pins on it. The micro-grooves and the micro-pins were created by the MEMS technology. The film- and also the drop-wise condensation were observed on the copper surface. The film-wise condensation heat flux was in good agreement with the values of the Nusselt equation. It was approximately one-tenth of the drop-wise condensation heat flux. The condensation on the mirror-finished silicon surface was the drop-wise condensation. The heat flux was approximately one-tenth of the drop-wise condensation heat flux on the copper surface. The condensation on the micro-grooved and the micro-pin silicon surfaces was film-wise. The condensation heat fluxes were approximately one-tenth of the copper surface film-wise condensation heat flux. When the contact angle was smaller than 70 degree, the condensation was film-wise and when larger than the value, drop-wise. It seemed that the hollow parts of the micro-grooved or the micro-pin surface were filled with condensate first after the condensation was initiated. It made the surface hydrophilic and the condensation film-wise.

Study on Condensation Heat Transfer of Micro Structured Surfaces (Effect on Condensation Heat Transfer of Metal-Spattering Surfaces)

2011 ◽  
Author(s):  
Takeru Komatsu ◽  
Hiroyasu Ohtake ◽  
Yasuo Koizumi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Silicon Surface ◽  
Copper Surface ◽  
Metal Films ◽  
Thin Metal ◽  
Condensation Heat Transfer ◽  
Silicon Surfaces ◽  
Thin Metal Films ◽  
Structured Surfaces

The present study was intended to examine how the condensation heat transfer, especially the drop-wise condensation, was affected by modifying the surface nature. In the present study, condensation heat transfer experiments for steam were performed by using mirror-finished copper surface, mirror-finished silicon surface and some mirror-finished silicon surfaces with very thin metal films by using spattering. The silicon surfaces with the thin metal films were created by the MEMS technology. The film- and also the drop-wise condensation were observed on the copper surface. The filmwise condensation heat flux was in good agreement with the values of the Nusselt’s equation. It was approximately one-tenth of the drop-wise condensation heat flux. The condensation on the mirror-finished silicon surface was the drop-wise condensation. The heat flux was approximately one-tenth of the drop-wise condensation heat flux on the copper surface. The condensation on silicon surfaces with thin Copper (Cu), Chromium (Cr), Lead (Pb) and Gold (Au) films were drop-wise. The condensation on silicon surfaces with thin Nickel (Ni), Titanium (Ti) and Aluminum (Al) films were filmwise.

Effect of Mini/Micro/Nanostructures on Filmwise Condensation of Low-Surface-Tension Fluids

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Ablimit Aili ◽  
QiaoYu Ge ◽  
TieJun Zhang
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Condensation Heat Transfer ◽  
Structured Surfaces ◽  
Nanostructured Surfaces ◽  
Hydrophobic Coating ◽  
Pin Fins ◽  
Solid Friction ◽  
Solid Liquid ◽  
The Impact

Micro/nanostructured surfaces have been widely explored to enhance condensation heat transfer over the past decades. When there is no flooding, micro/nanostructures can enable dropwise condensation by reducing solid-droplet adhesion. However, micro/nanostructures have mixed effects on filmwise condensation because the structures can simultaneously thin the condensate film and increase the fluid–solid friction. Although oil infusion of structured surfaces has recently been shown to render filmwise condensation dropwise in many cases, challenges remain in the case of extremely low-surface-tension fluids. This work aims to provide a unified experimental platform and study the impact of mini/micro/nanostructures on condensation heat transfer of low-surface-tension fluids in a customized environmental chamber. We first investigate the effect of microstructures, hydrophobic coating, as well as oil infusion on the filmwise condensation of a low-surface-tension fluid, e.g., refrigerant, on microporous aluminum surfaces. And we show that for low-surface-tension condensates, microstructures, hydrophobic coating, or oil infusion do not play a considerable role in enhancing or deteriorating heat transfer. Next, we study how the addition of nanostructures affects the condensation performance of the refrigerant on copper mini-fin structures. It is found that nanostructures slightly deteriorate the condensation performance due to the dominance of solid–liquid friction, although the performance of these mini-fins with nanostructured surfaces is still better than that of the mini-pin-fins. These results provide guidelines of designing mini/micro/nanoscale surface structures for enhanced condensation applications.

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