scholarly journals COST-EFFECTIVE FABRICATION OF WETTABILITY GRADIENT COPPER SURFACE BY SCREEN PRINTING AND ITS APPLICATION TO CONDENSATION HEAT TRANSFER

2016 ◽  
Vol 42 ◽  
pp. 1660181
Author(s):  
TZONG-SHYNG LEU ◽  
HUNG-MING HUANG ◽  
DING-JUN HUANG
Keyword(s):  
Heat Transfer ◽  
Surface Modification ◽  
Screen Printing ◽  
Cost Effective ◽  
Copper Surface ◽  
Condensation Heat Transfer ◽  
Copper Tube ◽  
Tube Surface ◽  
Surface Modification Techniques ◽  
Roller Screen

In this paper, wettability gradient pattern is applied to condensation heat transfer on a copper tube surface. For this application, the vital issue is how to fabricate gradient patterns on a curve tube surface to accelerate the droplet collection efficiently. For this purpose, novel fabrication processes are developed to form wettability gradient patterns on a curve copper tube surface by using roller screen printing surface modification techniques. The roller screen printing surface modification techniques can easily realize wettability gradient surfaces with superhydrophobicity and superhydrophilicity on a copper tube surface. Experimental results show the droplet nucleation sites, movement and coalescence toward the collection areas can be effectively controlled which can assist in removing the condensation water from the surface. The effectiveness of droplet collection is appropriate for being applied to condensation heat transfer in the foreseeable future.

Boiling and condensation heat transfer and pressure drop characteristics of grooved small copper tube.

2017 ◽  
Vol 2017.70 (0) ◽  
pp. 107
Author(s):  
Yuta ICHINOSE ◽  
Yasuhiro KUDO ◽  
M.Khairul Bashar ◽  
Syoutaro NOZAKI ◽  
Keishi KARIYA ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Condensation Heat Transfer ◽  
Copper Tube

Condensation Heat Transfer on a Partially Hydrophobic Surface

2014 ◽  
Author(s):  
Ramana Saketh Vanga ◽  
Sunwoo Kim
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Copper Surface ◽  
Copper Sample ◽  
Heterogeneous Surface ◽  
Condensation Heat Transfer ◽  
Transfer Coefficients ◽  
Heterogeneous Sample ◽  
Heat Transfer Coefficients

Renewable energy systems operated by a thermal energy resource such as geothermal power plants and solar thermal power systems are demanding improvement in their condensation performance [Kutscher & Costenaro, 2009]. While their energy resources are naturally obtained at almost no cost, heat rejecting components become relatively expensive to maintain and operate. In this research, a heterogeneous condensing surface is proposed to enhance the condensation heat transfer coefficient in vapor-to-liquid heat exchangers. On its surface, parallel stripes with hydrophobic feature and ones without it alternate. The effect of the partially hydrophobic condensing surface on the dropwise condensation heat transfer of saturated steam on the flat plate copper surface is experimentally investigated. A vertical flat plat condenser is constructed to evaluate the performance of the heterogeneous condensing surface in comparison with a plain copper sample and a homogeneous hydrophobic-treated copper sample. Experimental results show that condensation heat transfer of steam on the homogeneous hydrophobic-treated sample is superior to that on the plain copper surface despite the fact that both the surfaces stably promote dropwise condensation. The heat transfer coefficients for the heterogeneous surface at lower subcooling temperatures, when its stripes situate horizontally, are as high as the heat transfer coefficients for the homogeneous hydrophobic-treated surface. The enhancement for the horizontal heterogeneous sample over the plain copper sample is approximately 100%. The heat transfer coefficient for the heterogeneous sample with its stripes being vertical at 4 K subcooling is 25% greater than that of the plain copper sample. Higher heat transfer coefficients are observed at lower subcooling temperatures for all the samples. The results and observations of this project suggest that the heterogeneous surface has the potential to enhance the heat transfer coefficients.

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.

Experimental Study of Refrigerant (R-134a) Condensation Heat Transfer and Retention Behavior on Paraffin-Coated Vertical Plates and Fin Structures

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Hong-Qing Jin ◽  
Sophie Wang
Keyword(s):  
Heat Transfer ◽  
Copper Surface ◽  
Condensation Heat Transfer ◽  
Retention Behavior ◽  
Conduction Model ◽  
Maximum Increase ◽  
Liquid Retention ◽  
Transfer And Retention ◽  
Coated Surface ◽  
R 134A

Abstract Condensation of refrigerant R-134a is experimentally investigated on a paraffin-coated copper surface and compared to condensation on a plain copper surface. Heat transfer and visualization experiments are conducted for vertical-plate samples and for two different fin structures at various degrees of subcooling. A one-dimensional heat conduction model is used to interpret the condensation heat transfer measurements, while liquid retention behavior is quantified with the aid of image processing. The experimental results on vertical plates show that the heat transfer is enhanced on the coated surface with a maximum increase of 27% in the condensing heat transfer coefficient. On fin structures, the liquid retention was reduced by up to 28% on a coated surface. The heat transfer and retention behavior vary with surface material, degree of subcooling, and fin geometry.

Effect of Polymer Coating on Vapor Condensation Heat Transfer

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Mete Budakli ◽  
Thamer Khalif Salem ◽  
Mehmet Arik ◽  
Barca Donmez ◽  
Yusuf Menceloglu
Keyword(s):  
Heat Transfer ◽  
Saturation Pressure ◽  
Copper Substrate ◽  
Copper Surface ◽  
Vapor Condensation ◽  
Condensation Heat Transfer ◽  
Condensation Process ◽  
Limiting Factor ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

Abstract Condensation heat transfer coefficients (HTCs) are rather low compared to thin film evaporation. Therefore, it can be a limiting factor for designing heat transfer equipment. In this work, heat transfer characteristics of water vapor condensation phenomena were experimentally studied on a vertically aligned smooth copper substrate for a range of pressures and temperatures for two different liquid wettability conditions. The heat transfer performance is dominated by the phase change process at the solid–vapor interface along with the liquid formation mechanism. Compared to heat transfer results measured at an untreated copper surface, heat transport is augmented with a thin layer of perfluoro-silane coating over the same substrate. In this work, the effect of saturation pressure on the condensation process at both surfaces has been investigated by analyzing heat transfer coefficients. The results obtained experimentally show an increase in contact angle (CA) with the surface coating. A heat transfer augmentation of about 26% over uncoated surfaces was obtained and surfaces did not show any degradation after 40 h of operation. Finally, current results are compared with heat transfer values reported in open literature.

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