0515 Heat Transfer Enhancement by Using Vortex Generator (Relationship between Arrangement of Wings and Heat Transfer Characteristics)

In this paper, the silicon-based corrugated microchannels used for the heat transfer enhancement were fabricated by MEMS technology for the first time. Both the flow and convective heat transfer characteristics of the deionized water through these corrugated microchannels were investigated experimentally, and comparisons were performed between corrugated microchannels and straight microchannels with the same cross-sectional aspect ratio (height-to-width ratio) and same hydraulic diameter. Experimental results showed that both the flow friction and Nusselt number in corrugated microchannels increased considerably compared with those in straight microchannels, and this increase became enlarged with the increase in the Reynolds number. With the same pumping power, using corrugated microchannels instead of straight microchannels caused the reduction in the total thermal resistance. The heat transfer enhancement mechanism of the corrugated microchannels was discussed. The results presented in this paper help to design the high efficiency integrated chip cooling system.

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Flow and Heat Transfer Characteristics in Channels With Groove–Protrusions and Combination Effect With Ribs

Journal of Heat Transfer ◽

10.1115/1.4031077 ◽

2015 ◽

Vol 138 (1) ◽

Cited By ~ 1

Author(s):

Lu Zheng ◽

Yonghui Xie ◽

Di Zhang ◽

Haoning Shi

Keyword(s):

Heat Transfer ◽

Heat Transfer Enhancement ◽

Rectangular Channel ◽

Leading Edge ◽

Small Scale ◽

Combination Effect ◽

Transfer Enhancement ◽

Heat Transfer Characteristics ◽

Transfer Characteristics ◽

Flow And Heat Transfer

Passive flow control and heat transfer enhancement technique has become an attractive method for device internal cooling with low resistance penalty. In the present paper, the flow and heat transfer characteristics in the small scale rectangular channel with different groove–protrusions are investigated numerically. Furthermore, the combination effect with ribs is studied. The numerical results show that on the groove side, the flow separation mainly occurs at the leading edge, and the reattachment mainly occurs at the trailing edge in accordance with the local Nusselt number distribution. On the protrusion side, the separation mainly occurs at the protrusion back porch and enhances the heat transfer at the leading edge of the downstream adjacent groove. The rectangle case provides the highest dimensionless heat transfer enhancement coefficient Nu/Nu0, dimensionless resistance coefficient f/f0, and thermal performance (TP) with the highest sensitivity of Re. When ribs are employed, the separation bubble sizes prominently decrease, especially inside the second and third grooves. The Nu/Nu0 values significantly increase when ribs are arranged, and the one-row case provides the highest heat transfer enhancement by ribs. Besides, the two-row case provides the highest Nu/Nu0 value without ribs, and the three-row case shows the lowest Nu/Nu0 value whether ribs are arranged or not.

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Laminar Flow and Heat Transfer Characteristics of Colloid Suspensions in Water: A Numerical Study

Volume 2: Theory and Fundamental Research; Aerospace Heat Transfer; Gas Turbine Heat Transfer; Computational Heat Transfer ◽

10.1115/ht2009-88214 ◽

2009 ◽

Author(s):

Khalid N. Alammar ◽

Lin-wen Hu

Keyword(s):

Heat Transfer ◽

Laminar Flow ◽

Heat Transfer Enhancement ◽

Volume Fraction ◽

Numerical Study ◽

Volume Flow Rate ◽

Transfer Enhancement ◽

Heat Transfer Characteristics ◽

Transfer Characteristics ◽

Flow And Heat Transfer

Numerical analysis is performed to examine axisymmetric laminar flow and heat transfer characteristics of colloidal dispersions of nanoparticles in water (nanofluids). Effect of volume fraction on flow and heat transfer characteristics is investigated. Four different materials, Alumina, Copper, Copper Oxide, and Graphite are considered. Heat transfer and property measurements were conducted previously for Alumina nanofluid. The measurements have shown that nanofluids can behave as homogeneous mixtures. It is found that oxide-based nanofluids offer the least heat transfer enhancement compared to elements-based nanofluids. When normalized by friction pressure drop, it is shown that graphite can have the highest effective heat transfer enhancement. For a given volume flow rate, all nanofluids exhibited linear increase in heat transfer enhancement with increasing colloids volume fraction, up to 0.05.

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Numerical Study on the Flow and Heat Transfer Characteristics in Rectangular Channels With Grooves and Different Protrusions

Volume 5A: Heat Transfer ◽

10.1115/gt2017-63737 ◽

2017 ◽

Cited By ~ 1

Author(s):

Feng Zhang ◽

Xinjun Wang ◽

Jun Li ◽

Daren Zheng ◽

Junfei Zhou

Keyword(s):

Heat Transfer ◽

Heat Transfer Enhancement ◽

Thermal Performance ◽

Pressure Loss ◽

Numerical Study ◽

Transfer Enhancement ◽

Heat Transfer Characteristics ◽

Transfer Characteristics ◽

Flow And Heat Transfer ◽

Rectangular Channels

The present work represents a numerical study on the flow and heat transfer characteristics in rectangular channels with protrusion-grooved turbulators. The Reynolds averaged Navier-Stokes equations, coupled with SST turbulence model, are adopted and solved. In this paper, six geometric protrusion shapes (circular, rectangular, triangular, trapezoidal, circular with leading round concave and circular with trailing round concave) are selected to perform the study. The flow structure, heat transfer enhancement, friction factor as well as thermal performance factor of the rectangular channel fitted with combined groove and different protrusions have been obtained at the Reynolds number ranging from 5000 to 20000. The results indicate that the protrusion shapes affect the velocity distribution near the groove surface. The case of circular protrusion with leading round concave provides the highest overall heat transfer enhancement, while it also causes the highest pressure loss penalty. The case of rectangular protrusion has the lowest overall heat transfer enhancement with high pressure loss penalty. The case of circular protrusion has similar overall heat transfer enhancement with cases of trapezoidal protrusion as well as circular protrusion with trailing round concave, but the pressure loss penalty of the case of circular protrusion is the lowest. In addition, the best overall thermal performance can be observed for circular protrusion-grooved channel.

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Heat Transfer Characteristics of an Impinging Air Jet Laden with Solid Particles Recirculating in an Enclosure. 2nd Report. Heat Transfer Characteristics and Heat Transfer Enhancement.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B ◽

10.1299/kikaib.62.1511 ◽

1996 ◽

Vol 62 (596) ◽

pp. 1511-1516

Author(s):

Jie WANG ◽

Yasuo KUROSAKI ◽

Isao SATOH

Keyword(s):

Heat Transfer ◽

Heat Transfer Enhancement ◽

Solid Particles ◽

Transfer Enhancement ◽

Heat Transfer Characteristics ◽

Transfer Characteristics ◽

Air Jet

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Large Eddy Simulation of Turbulent Flow and Heat Transfer Characteristics in Rectangle Channel With Vortex Generators

2010 14th International Heat Transfer Conference, Volume 1 ◽

10.1115/ihtc14-22072 ◽

2010 ◽

Author(s):

Juan Wen ◽

Li Yang ◽

Cheng Ying Qi

Keyword(s):

Heat Transfer ◽

Boundary Layer ◽

Heat Transfer Enhancement ◽

Coherent Structure ◽

Vortex Generator ◽

Vortex Generators ◽

Transfer Enhancement ◽

Heat Transfer Characteristics ◽

Eddy Simulation ◽

Large Eddy

The flow structures and heat transfer characteristics of rectangle channel with the new type of vortex generators are obtained using large eddy simulation (LES) and by the application of the hydromechanics software FLUENT6.3. The bevel-cut half-elliptical column vortex generators, which is one model of the passive heat transfer enhancement, are laid on the three-dimensional rectangle channel. The instantaneous characteristic and the variational law of various parameters, such as the velocity, the temperature, the pressure and the vorticity magnitude, is analyzed to find out the temperature stripe structure that is similar with the velocity stripe in the temperature field. A turbulent boundary layer interacting with the disturbance of the vortex generators, is investigated using a “coherent structure” type of approach. The coherent structure and the streak structure of turbulent boundary layer flow are showed and the characteristic of vortex induced by vortex generator and its influence on turbulent coherent structure are analyzed. The control of the coherent structure induced by vortex generator plays more important role in heat transfer enhancement and drag reduction. And this fow configuration is of interest in terms of both heat transfer and skin friction control. The result of simulation indicates that the turbulence coherent structure directly affects the temperature gradient at the wall and the heat transfer enhancement mechanism of vortex generator is explained. Then we can seek suitable form of vortex generator and structure parameters, in order to achieve enhanced heat transfer and flow of drag reduction.

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