Fabrication of copper-based ZnO nanopencil arrays with high-efficiency dropwise condensation heat transfer performance

RSC Advances ◽  
2016 ◽  
Vol 6 (64) ◽  
pp. 59405-59409 ◽  
Author(s):  
Mengnan Qu ◽  
Jia Liu ◽  
Jinmei He
Keyword(s):  
Heat Transfer ◽  
Zinc Oxide ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
High Efficiency ◽  
Condensation Heat Transfer ◽  
Transfer Performance ◽  
Dropwise Condensation ◽  
Condensation Heat Transfer Coefficient

A copper-based zinc oxide nanopencil array film was reported. Compared with hydrophobic flat Cu surface, it exhibits condensate microdrop self-propelling function and maximal ∼140% enhancement in dropwise condensation heat transfer coefficient.

scholarly journals Experimental investigation on effect of helical grooves on condensation heat transfer performance of vertically oriented copper tubes

2019 ◽  
Vol 128 ◽  
pp. 06001
Author(s):  
Jyothish Abraham ◽  
Venugopal G ◽  
Rajkumar M R
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Condensation Heat Transfer ◽  
Transfer Performance ◽  
Helical Groove ◽  
Helical Grooves ◽  
Condensation Heat Transfer Coefficient

An experimental investigation was conducted to study the influence of pitch of helical grooves on condensation heat transfer performance on vertically oriented copper tubes. The condensation heat transfer coefficient of bare as well as grooved copper tubes of various pitches ranging from 2.54 mm to 22.4mm were studied. The investigation revealed that copper tube with groove pitch ≤ 6.35 mm has an adverse effecton the heat transfer performance in comparison to bare copper. The helical groove with pitch > 6.35 mm showed improvement in heat transfer coefficient. The helical groove with pitch 8.47 mm showed a maximum enhancement of 68.4% in condensation heat transfer coefficient at ∆T = 40°C.

The Use of an Organic Self-Assembled Monolayer Coating to Promote Dropwise Condensation of Steam on Horizontal Tubes

1999 ◽  
Vol 122 (2) ◽  
pp. 278-286 ◽  
Author(s):  
A. K. Das ◽  
H. P. Kilty ◽  
P. J. Marto ◽  
G. B. Andeen ◽  
A. Kumar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gold Surface ◽  
Condensation Heat Transfer ◽  
Dropwise Condensation ◽  
Atmospheric Conditions ◽  
Copper Nickel ◽  
Self Assembled ◽  
Condensation Heat Transfer Coefficient

Hydrophobic coatings have been created through self-assembled monolayers (SAMs) on gold, copper, and copper-nickel alloy surfaces that enhance steam condensation through dropwise condensation. The monolayer is formed by chemisorption of alkylthiols on these metal surfaces. Due to their negligible thickness (10–15 Å), SAMs have negligible heat transfer resistance, and involve a minuscule amount of the organic material to pose any contamination problem to the system from erosion of the coating. The coating was applied directly to copper and 90/10 copper-nickel tubes, and to previously gold-sputtered aluminum tubes. The quality of the drops on SAMs, based on visual observation, was found to be similar for the three surfaces, with the gold surface showing a slight superiority. When compared to complete filmwise condensation, the SAM coating increased the condensation heat transfer coefficient by factors of 4 for gold-coated aluminum, and by about 5 for copper and copper-nickel tubes, under vacuum operation (10 kPa). The respective enhancements under atmospheric conditions were about 9 and 14. Comparatively, the heat transfer coefficient obtained with a bare gold surface (with no organic coating) was 2.5 times that of the filmwise condensation heat transfer coefficient under vacuum, and 3.4 at atmospheric conditions. [S0022-1481(00)02502-0]

Effect of Micro-Structured Surface on Dropwise Condensation Heat Transfer

2013 ◽  
Author(s):  
Atsushi Tokunaga ◽  
Masaki Mizutani ◽  
Gyoko Nagayama ◽  
Takaharu Tsuruta
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Hydrophobic Surface ◽  
Condensation Heat Transfer ◽  
Dropwise Condensation ◽  
Mems Technology ◽  
Phase Change Phenomena ◽  
The Heat Transfer Coefficient ◽  
Condensation Heat Transfer Coefficient

The micro/nano scale phase change phenomena become more and more important because the MEMS technology develops rapidly in the fields of electro- and bio-devices [1][2] and the MEMS enable us to control the surface wettability. In the dropwise condensation on the hydrophobic surface, the heat transfer coefficient is determined by the departing droplet size. In our previous paper, it was found that the droplets in radius around 7 μm made more significant contribution to the condensation heat transfer under the low-pressure conditions. That is, when the smaller droplets less than 7 μm cover the condensing surface, the higher condensing heat flux would be achieved than that of the ordinary dropwise condensation. However, it is still very difficult to keep the droplets to be continuous condensed within 7 μm at the surface. A challenging work has been conducted to fabricate a droplets exclusion structure on the condensing surface for the purpose of the enhancement of condensation heat transfer in our previous experiment [3]. By using the MEMS technology, we made the hybrid-condensing surface with hydrophobic and hydrophilic patterns in order to remove the grown droplets effectively. It was found that the hybrid-surface has a possibility to increase the condensation heat transfer coefficient but its drainage-ability of the condensate has the limitation due to the occurrence of the flooding over the surface structures. In order to reduce the flooding at the hydrophobic area, in this study, the new design of the condensing surface has been proposed and the condensation heat transfer coefficient is evaluated.

Investigations on the Condensation Heat Transfer Performance of Stainless Steel Edge-Shaped Finned Tubes

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Zhen-ping Wan ◽  
Xiao-wu Wang ◽  
Xiao-xia Zhang ◽  
Yong Tang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Temperature Difference ◽  
Heat Transfer Performance ◽  
Three Dimensional ◽  
Condensation Heat Transfer ◽  
Transfer Performance ◽  
Shell Side ◽  
Finned Tubes

The third-generation enhanced heat transfer technologies, such as three-dimensional fin and dimple, are still important means of improving energy efficiency. This paper analyzes the condensation heat transfer performances of three edge-shaped finned tubes that were fabricated using the plowing–extruding process. Experimental results show that the shell-side heat transfer coefficient decreases with increases of heat flux and temperature difference between wall and vapor. The edge-shaped finned tubes exhibit better heat transfer performance than smooth tubes. At the identical temperature difference between the wall and the vapor, the shell-side heat transfer coefficient of the edge-shaped finned tubes is approximately 1.7–2.6 times larger than that of the smooth tubes. At the identical temperature difference between the wall and the vapor, the shell-side heat transfer coefficient of edge-shaped finned tubes is also higher than the reported value in the literature. The excellent performance of the edge-shaped finned tubes comes from the coordination of enhancement from the three-dimensional fins, dimples, and grooves. Finned tubes with grooves fabricated along the left direction have higher and thinner fins and therefore show better heat transfer performance. The shell-side heat transfer coefficients of edge-shaped finned tubes increase with plowing–extruding depth and feed increasing.

Production Process and Heat Transfer Performance of 10/316 Clad Tube

2014 ◽  
Vol 1081 ◽  
pp. 270-274
Author(s):  
Zui Xian Yu ◽  
Xue Sheng Wang ◽  
Qin Zhu Chen
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Heat Transfer Coefficient ◽  
Carbon Steel ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Steel Tube ◽  
Stainless Steel Tube ◽  
Transfer Performance ◽  
Clad Tube

A new preparation technique of carbon steel/stainless steel clad tube was introduced, and the contact surface was well combined. Meanwhile, with the using of tube heat exchanger, the experiment on the heat transfer performance of the clad tube was done. Comparing the 10/316 clad tube and the 316 stainless steel tube, the effects on the heat transfer performance of 316 stainless steel tube attached to carbon steel was evaluated. It is showed that overall heat transfer coefficient of 10/316 clad tubes is higher than that of stainless steel tube. The average heat transfer coefficient of 10/316 clad tubes is about 18.7%~34.4% higher than that of stainless steel tube. Experimental investigation indicates that, by brazing and cold drawing, the 10/316 clad tube was well combined and the thermal conductivity was better than that of stainless steel tube.

Heat Transfer Performance of Different Nanofluids Flows in a Helically Coiled Heat Exchanger

2013 ◽  
Vol 832 ◽  
pp. 160-165 ◽  
Author(s):  
Mohammad Alam Khairul ◽  
Rahman Saidur ◽  
Altab Hossain ◽  
Mohammad Abdul Alim ◽  
Islam Mohammed Mahbubul
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Transfer Performance

Helically coiled heat exchangers are globally used in various industrial applications for their high heat transfer performance and compact size. Nanofluids can provide excellent thermal performance of this type of heat exchangers. In the present study, the effect of different nanofluids on the heat transfer performance in a helically coiled heat exchanger is examined. Four different types of nanofluids CuO/water, Al2O3/water, SiO2/water, and ZnO/water with volume fractions 1 vol.% to 4 vol.% was used throughout this analysis and volume flow rate was remained constant at 3 LPM. Results show that the heat transfer coefficient is high for higher particle volume concentration of CuO/water, Al2O3/water and ZnO/water nanofluids, while the values of the friction factor and pressure drop significantly increase with the increase of nanoparticle volume concentration. On the contrary, low heat transfer coefficient was found in higher concentration of SiO2/water nanofluids. The highest enhancement of heat transfer coefficient and lowest friction factor occurred for CuO/water nanofluids among the four nanofluids. However, highest friction factor and lowest heat transfer coefficient were found for SiO2/water nanofluids. The results reveal that, CuO/water nanofluids indicate significant heat transfer performance for helically coiled heat exchanger systems though this nanofluids exhibits higher pressure drop.

Research on Heat Transfer Performance of Water Film for Outside the Tubes of the Microscale Evaporative Condenser

2009 ◽  
Author(s):  
Minghui Hu ◽  
Dongsheng Zhu ◽  
Jialong Shen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Water Film ◽  
Transfer Performance ◽  
Air Velocity ◽  
Microscale Heat Transfer ◽  
High Heat Transfer ◽  
Spray Density

It is requested to develop a microscale and high performance heat exchanger for small size energy equipments. The heat transfer performance of the water film on the condensing coils of the microscale evaporative condenser was studied for a single-stage compressed refrigeration cycle system. Under various operation conditions, the effects of the spray density and the head-on air velocity on the heat transfer performance of the water film were investigated. The results show that the microscale heat transfer coefficient of the water film αw increases with the increase of spray density and decreases with the increase of head-on air velocity. The results indicate that the key factor affecting the microscale heat transfer of the water film is the spray density. As the results, it is measured that the present device attained high heat transfer quantity despite the weight is light. In addition, via regression analysis of the experimental data, the correlation equation for calculating the microscale heat transfer coefficient of the water film was obtained, its regression correlation coefficient R is 0.98 and the standard deviation is 7.5%. Finally, the correlations from other works were compared. The results presented that the experimental correlation had better consistency with the correlations from other works. In general, the obtained experimental results of the water film heat transfer are helpful to the design and practical operation of the microscale evaporative condensers.

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