scholarly journals A Review of Recent Advances in Superhydrophobic Surfaces and Their Applications in Drag Reduction and Heat Transfer

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 44
Author(s):  
Yu Zhang ◽  
Zhentao Zhang ◽  
Junling Yang ◽  
Yunkai Yue ◽  
Huafu Zhang
Keyword(s):  
Heat Transfer ◽  
Drag Reduction ◽  
Industrial Applications ◽  
Superhydrophobic Surfaces ◽  
Water Repellent ◽  
Fluid Viscosity ◽  
Preparation Methods ◽  
Practical Applications ◽  
Heat Transfer Efficiency ◽  
Improve Heat Transfer

Inspired by the superhydrophobic properties of some plants and animals with special structures, such as self-cleaning, water repellent, and drag reduction, the research on the basic theory and practical applications of superhydrophobic surfaces is increasing. In this paper, the characteristics of superhydrophobic surfaces and the preparation methods of superhydrophobic surfaces are briefly reviewed. The mechanisms of drag reduction on superhydrophobic surfaces and the effects of parameters such as flow rate, fluid viscosity, wettability, and surface morphology on drag reduction are discussed, as well as the applications of superhydrophobic surfaces in boiling heat transfer and condensation heat transfer. Finally, the limitations of adapting superhydrophobic surfaces to industrial applications are discussed. The possibility of applying superhydrophobic surfaces to highly viscous fluids for heat transfer to reduce flow resistance and improve heat transfer efficiency is introduced as a topic for further research in the future.

scholarly journals A review on the thermal performance of nanofluid inside circular tube with twisted tape inserts

2020 ◽  
Vol 12 (6) ◽  
pp. 168781402092489
Author(s):  
Saadah Ahmad ◽  
Shahrir Abdullah ◽  
Kamaruzzaman Sopian
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Volume Fraction ◽  
Fluid Mixing ◽  
Transfer Efficiency ◽  
Working Fluid ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Heat Transfer Efficiency ◽  
Improve Heat Transfer

Working fluid with higher thermal conductivity and tube with better fluid mixing are two crucial elements for heat transfer enhancement in heat exchanger system. Hence, several methods and techniques have been explored to improve heat transfer efficiency, including dispersing nanoparticles into conventional heat transfer fluid and inserting instruments inside the tube of the heat exchanger. Studies have shown that nanofluid can improve heat transfer efficiency of the system due to its higher thermal conductivity and drastic Brownian motion of nanoparticles while inserts within tube can improve heat transfer efficiency by increasing axial velocity of working fluid for better fluid mixing. This article summarized 109 of journals from recent research on heat transfer enhancement of nanofluid flowing inside the tube with inserts as well as discussing the significant parameters that affected the system’s efficiency such as nanoparticles’ volume fraction, Reynolds number and types and configurations of inserts. Ultimately, analysis will be carried out to determine the most suitable modification of twisted tape inserts with the most optimum value of nanoparticle volume fraction for turbulence flow regime. Finally, some problems that need to be solved for future research such as agglomeration and pressure drop are discussed.

Research on Inner Cooling Apparatus Sets in the Mold of 700mm×700mm Bloom

2011 ◽  
Vol 328-330 ◽  
pp. 1623-1626
Author(s):  
Ming Hua Bai ◽  
Jing Jing Liu ◽  
Jun Li Ge ◽  
Zhi Qiang Liu ◽  
Zhi Ming Zhang
Keyword(s):  
Heat Transfer ◽  
Casting Speed ◽  
Empirical Formula ◽  
Liquid Core ◽  
Feasibility Analysis ◽  
Equiaxed Crystal ◽  
Heat Transfer Efficiency ◽  
Improve Heat Transfer ◽  
Segregation Level ◽  
The Impact

Based on the problems emerged from market, 700mm×700mm super-large billet has been advanced. This paper calculated the casting speed and the depth of liquid core according to empirical formula for 700mm×700mm super-large billet, based on calculate and feasibility analysis acquired the appropriate casting speed is 0.2 m/min. A new mold has been advance based on mold thermoanalysis that is complex mold. Theoretically analyzed the function of setting inner cooling and deflected SEN, indicate that complex mold can improve heat transfer efficiency and equiaxed crystal ratio, reducing center segregation; level rotary flow can uniform molten steel ingredient and growth of shell, reduce the impact depth, achieve the effect of E-EMS; calculation show that reduce the depth of liquid core by applying complex mold, finally, reduce infrastructure fee of caster.

Development of the Oxygen-Enriched Burner Using Self-Induced Oscillation

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Masashi Yamaguchi ◽  
Takeshi Saito ◽  
Yasuyuki Yamamoto ◽  
Yoshiyuki Hagihara
Keyword(s):  
Heat Transfer ◽  
Radiation Heat Transfer ◽  
Oscillation Period ◽  
Tube Length ◽  
The Novel ◽  
Radiation Heat ◽  
Heat Transfer Efficiency ◽  
Combustion Technology ◽  
Improve Heat Transfer ◽  
Low Nox Emission

We have developed the novel oxygen-enriched burner using the self-induced oscillating phenomenon of jet flow which has excellent radiation heat transfer characteristics. We revealed that the flame property suitable for radiation heat transfer is obtained by extending the oscillation cycle. By optimizing the connecting tube length and diameter, we got the stable oscillating flame in 1 s-oscillation period. At this time, the relationship between the burner structure including the connecting tube and the oscillation period can be easily evaluated by the dimensionless tube length and Strouhal number. In addition, combining multi-staged combustion technology, the burner can improve heat transfer efficiency by 9.1% compared with the conventional oxygen-enriched burner. We confirmed that the burner has a low NOx emission level below 55 ppm.

scholarly journals Characteristic of heat transfer nanofluid of Al2O3 improved by ZrO2 addition

2021 ◽  
Vol 882 (1) ◽  
pp. 012018
Author(s):  
Dani Gustaman Syarif ◽  
Jakaria Usman ◽  
Yofi Ike Pratiwi ◽  
Muhammad Yamin ◽  
Arie Hardian
Keyword(s):  
Heat Transfer ◽  
Particle Size ◽  
Crystallite Size ◽  
Xrd Analysis ◽  
Heat Transfer Efficiency ◽  
The World ◽  
Improve Heat Transfer ◽  
The Stability ◽  
Heat Transfers ◽  
The Heat Transfer Coefficient

Abstract Efforts to replace conventional fluids as coolants for heat transfers with new fluids are continuously being made to improve heat transfer efficiency. Nanofluids are currently widely studied around the world as candidates for conventional fluids substitutes. In this research, the synthesis of Al2O3-ZrO2 nanocomposites for heat transfer nanofluid applications was carried out. The synthesis of the nanoparticles was conducted by the hydrothermal method. Here, we used ZrO2 to improve the characteristics of Al2O3. The results of XRD analysis showed that the nanocomposite had an Al2O3 gamma structure. The Al2O3 nanoparticles and Al2O3-ZrO2 nanocomposite have a crystallite size of 7.41 nm and 6.84 nm, respectively. The addition of 0.1 % ZrO2 decreased the crystallite size and BET particle size and increased the zeta potential, hence the stability of the nanofluids. The increase of stability increased the heat transfer coefficient of the Al2O3 nanofluids, making them suitable for heat transfer.

Heat Transfer Enhancement of Double-Tube-Type Heat Exchanger by Petal-Shaped Tube (Study on Optimum Tube Shape)

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Toshihiko Shakouchi ◽  
Yusuke Matsumoto ◽  
Koichi Tsujimoto ◽  
Toshitake Ando
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
High Heat ◽  
Practical Applications ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Tube Shape ◽  
Tube Type ◽  
Wetted Perimeter ◽  
Fin Tube

Abstract Heat exchangers are used widely in many fields, and various kinds of exchanger have been developed according to the requirement of the practical applications. Recently, heat exchangers that are highly efficient or compact have become more desirable from the viewpoint of energy conservation, and several new types have been developed, such as a compact fin tube type and a double tube type having an inner pipe with a special geometry. In this study, the flow and heat transfer characteristics of a petal-shaped double tube with a large wetted perimeter of six and five petals and five shallow petals and the effect of tube shape on the heat transfer and heat transfer efficiency were examined experimentally. The heat transfer of the double tube with a petal-shaped inner tube was increased because of the large wetted perimeter, but the pressure loss by friction increased. The optimal shape of the petal-shaped double tube with a high heat transfer performance and the greatest efficiency is discussed.

Heat Transfer and Flow Characteristics of Liquid Nitrogen Laminar Fulling Films in Cryogenic Heat Transfer

2011 ◽  
Vol 148-149 ◽  
pp. 1514-1518
Author(s):  
Zhi Li ◽  
Zhong Min Li ◽  
Jun Guo
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Liquid Nitrogen ◽  
Convection Heat Transfer ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Heat Transfer Efficiency ◽  
Improve Heat Transfer ◽  
The Impact ◽  
Film Flows

This paper studies the characteristics of both the dynamic heat and mass transfer of liquid nitrogen thin film which have vital significance to improve heat transfer efficiency and optimize the cryogenic heat exchanger. Liquid nitrogen laminar film flows in the brazed cryogenic heat exchanger with 2.3mm distance between plates. Relationship between the dimensionless thickness and the coefficient of heat convection of liquid nitrogen film is derived. And the impact of rate of vapor content, intensity of interfacial convection heat transfer and Reynolds numbers are calculated and analyzed.

scholarly journals Electrospinning Technique as a Powerful Tool for the Design of Superhydrophobic Surfaces

2020 ◽  
Author(s):  
Pedro J. Rivero ◽  
Adrian Vicente ◽  
Rafael J. Rodriguez
Keyword(s):  
Surface Engineering ◽  
Dye Sensitized Solar Cells ◽  
Polymeric Materials ◽  
Industrial Applications ◽  
Electrospinning Process ◽  
Superhydrophobic Surfaces ◽  
Water Repellent ◽  
Functionalized Surfaces ◽  
Composition Structure ◽  
Highly Hydrophobic

The development of surface engineering techniques to tune-up the composition, structure, and function of materials surfaces is a permanent challenge for the scientific community. In this chapter, the electrospinning process is proposed as a versatile technique for the development of highly hydrophobic or even superhydrophobic surfaces. Electrospinning makes possible the fabrication of nanostructured ultra-thin fibers, denoted as electrospun nanofibers (ENFs), from a wide range of polymeric materials that can be deposited on any type of surface with arbitrary geometry. In addition, by tuning the deposition parameters (mostly applied voltage, flow rate, and distance between collector/needle) in combination with the chemical structure of the polymeric precursor (functional groups with hydrophobic behavior) and its resultant viscosity, it is possible to obtain nanofibers with highly porous surface. As a result, functionalized surfaces with water-repellent behavior can be implemented in a wide variety of industrial applications such as in corrosion resistance, high efficient water-oil separation, surgical meshes in biomedical applications, or even in energy systems for long-term efficiency of dye-sensitized solar cells, among others.

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