Fluid flow and heat transfer in wavy microchannels

Sui, Yi; Teo, C. J.; Lee, Poh Seng; Chew, Y. T.; Chen, Shu

doi:10.1016/j.ijheatmasstransfer.2010.02.022

Cited by 477 publications

(143 citation statements)

References 43 publications

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“…What is more, the microchannels with cylinder and v-groove devices have better heat flux transfer performance, while the microchannel with protrusion devices is better from the perspective of entropy generation minimization. Based on the entropy generation theory and Equation (20), for the given working condition, the entropy generation of microchannel increases with the increase of pressure drop (reflected by Fanning friction factor) and the decrease of heat transfer (reflected by the Nusselt number). Furthermore, due to the nonlinear effect of mass flow rate, the influences of Fanning friction factor on the entropy generation for varied Re cases are obviously different from that of the Nusselt number.…”

Section: Effects Of Structuresmentioning

confidence: 99%

“…With the increases of nanofluids concentration, both the thermal conductivity of Al2O3-water nanofluids (Table 2) and Nu/Nu0 (Figure 8) increase. Then, based on the Equation (20), ST'/S'0 decreases. While, with the increases of nanofluids concentration, the density of working substances increases (Table 2), but f/f0 ( Figure 7) and mass flow rate also increase, and the change of the latter two parameters are much larger than that of former, then SF'/S'0 increases.…”

Section: Effects Of Nanofluids Concentrationmentioning

confidence: 99%

“…Khan et al [18] studied the thermal resistance and pressure drop of microchannels with various ribs in the laminar regime, and the results revealed that the lowest thermal resistance was observed in the microchannel with triangular ribs, and rectangular ribs produced the largest pressure drop. Recently, flow control technologies have also been introduced in the microchannels to achieve higher heat transfer enhancement, and the results showed strip-fins [19], wavy microchannel [20], and dimples/protrusions [21][22][23] were beneficial. Wei et al [24] introduced dimples to the heat transfer enhancement of microchannel heat sinks, but the misuse of boundary conditions may lead to some discrepancies between the simulated results and real flow.…”

Section: Introductionmentioning

confidence: 99%

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Heat Transfer Enhancement and Entropy Generation of Nanofluids Laminar Convection in Microchannels with Flow Control Devices

Xie

Zhang

et al. 2016

Entropy

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Abstract:The heat transfer enhancement and entropy generation of Al 2 O 3 -water nanofluids laminar convective flow in the microchannels with flow control devices (cylinder, rectangle, protrusion, and v-groove) were investigated in this research. The effects of the geometrical structure of the microchannel, nanofluids concentration ϕ(0%-3%), and Reynolds number Re (50-300) were comparatively studied by means of performance parameters, as well as the limiting streamlines and temperature contours on the modified heated surfaces. The results reveal that the relative Fanning frictional factor f/f 0 of the microchannel with rectangle and protrusion devices are much larger and smaller than others, respectively. As the nanofluids concentration increases, f/f 0 increases accordingly. For the microchannel with rectangle ribs, there is a transition Re for obtaining the largest heat transfer. The relative Nusselt number Nu/Nu 0 of the cases with larger nanofluids concentration are greater. The microchannels with cylinder and v-groove profiles have better heat transfer performance, especially at larger Re cases, while, the microchannel with the protrusion devices is better from an entropy generation minimization perspective. Furthermore, the variation of the relative entropy generation S 1 /S 1 0 are influenced by not only the change of Nu/Nu 0 and f/f 0 , but also the physical parameters of working substances.

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Section: Effects Of Structuresmentioning

confidence: 99%

Section: Effects Of Nanofluids Concentrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Heat Transfer Enhancement and Entropy Generation of Nanofluids Laminar Convection in Microchannels with Flow Control Devices

Xie

Zhang

et al. 2016

Entropy

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“…The optimal number of layers for the micro channel heat sink under a constant pumping power of 0.01 W to achieve the maximum heat removal was shown [4]. The heat transfer characteristics of wavy channels have been studied [5,6]. The heat transfer performance of the wavy micro channel was better than the straight one with the same cross-section, but increasing the heat transfer efficiency with a wavy micro channel will also increase the pump power relatively.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the Micro Channel Heat Sink by Combing Genetic Algorithm with the Finite Element Method

2018

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Abstract:The design of a micro multi-channel heat sink to achieve the minimum thermal resistance is the purpose of this study. The numerical package is employed by using the genetic algorithm to process the heat dissipation optimization of the micro multi-channel heat sink (the genetic algorithm employs the numerical package). The variables of this optimal design include channel number, channel aspect ratio and the ratio of channel width to pitch, as well as considering the weight of this micro channel heat sink in the optimal design process. Therefore, this optimization is a multi-objective function design. The results show that the thermal resistance is decreased as 0.144 W/K, and the weight of this micro channel heat sink can be decreased, individually or simultaneously.

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“…The results here showed that the two phase pressure drop strongly depends on the mass flux and increases almost in line with an increasing exit quality at a constant mass flux. Three dimensional wavy rectangular microchannels were tested by Sui et al [11] with different wavy magnitudes. They also compared the heat transfer performance of the wavy microchannels with straight microchannels.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Microchannel Geometry on Phase Transition for Two Phase Flow in Microchannel Heat Sinks

Le¹,

Nguyen²,

Dang³

2018

IJPER

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Abstract. The effects of microchannel geometry on the phase transition between liquid and vapour for the two phase flow were investigated both numerically and experimentally. In the study the rounded edge rectangular microchannel heat sink was found to have the phase transition earlier than the rectangular one in both numerical simulation and experimental data by about 1.5 seconds. The outlet temperature and vapour quality of the rounded edge rectangular microchannel heat sink was higher than those obtained from the rectangular microchannel heat sink. Also, the phase transition curves achieved in the evaporation were parabolic in shape. The output vapour temperature achieved a steady state with the maximum value at around 2 minutes, 30 seconds. In addition the numerical results matched well with the experimental data. These numerical results have not yet been seen in literature reviews.Keywords: Microchannel, two phases, temperature, numerical simulation, experiment. IntroductionIn recent years the heat transfer behaviour of the two phase flow in microchannels has become an interesting topic. Regarding the microchannel heat transfer fields, Yun et al.[1] investigated in the boiling heat transfer coefficients and the two-phase pressure drops of rectangular microchannels. The microchannels have a hydraulic diameter of 1.36 and 1.44 mm. R410A was used as the working fluid and the heat flux obtained was from 10 to 20 kW/m2. The results showed that the boiling heat transfer coefficients in the microchannels were much higher than those in single tubes under similar test conditions. In addition, they also showed that the pressure drop accelerated with the increasing mass flux at a constant saturation temperature. Also in addition, the pressure drop decreased with an increasing saturation temperature at a given mass flux, Schilder et al.[2] studied the pressure drop and the convective heat transfer characteristics in a circular tube with a diameter of 600 µm and with the working fluid being ethanol. The experiments were carried out for both the two phase flow and single phase flow. The results showed that the mean pressure drop for two phase flow was about three times higher than that for the single phase flow. The Nusselt number for the two phase flow was not dependent on the heat flux and increased with raising the mass flux. The alternating slanted passage in the channel wall as a secondary flow was investigated by Kuppusamy et al. [3]. The results showed that when comparing the alternating slanted passage microchannel heat sink with the conventional one the overall performance of the microchannel heat sink with alternating slanted passage increased by 146% and the thermal resistance reduced to 76.8%. Ergu et al.[4] studied the pressure drop and local mass transfer of the rectangular microchannel with a hydraulic diameter of 208 µm. The microchannels have a width of 3.70 mm, a height of 0.107 mm and a length of 35 mm. Distilled water was used to measure the pressure drop and was also used as the working fluid. Reynol...

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Fluid flow and heat transfer in wavy microchannels

Cited by 477 publications

References 43 publications

Heat Transfer Enhancement and Entropy Generation of Nanofluids Laminar Convection in Microchannels with Flow Control Devices

Heat Transfer Enhancement and Entropy Generation of Nanofluids Laminar Convection in Microchannels with Flow Control Devices

Optimization of the Micro Channel Heat Sink by Combing Genetic Algorithm with the Finite Element Method

The Effects of Microchannel Geometry on Phase Transition for Two Phase Flow in Microchannel Heat Sinks

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