Microscale heat transfer enhancement using thermal boundary layer redeveloping concept

Xu, Jinliang; Gan, Yunhua; Zhang, D.C.; Li, X.H.

doi:10.1016/j.ijheatmasstransfer.2004.12.008

Cited by 204 publications

(64 citation statements)

References 13 publications

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“…This is true even for no seed bubble cases. The slightly negative temperature gradients are similar to those reported in Xu et al (2005).…”

Section: Heat Transfer Enhancement By Seed Bubblessupporting

confidence: 87%

Seed bubbles trigger boiling heat transfer in silicon microchannels

Yang

2009

Microfluid Nanofluid

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The smooth channel surface of microsystems delays boiling incipience in heated microchannels. In this paper, we use seed bubbles to trigger boiling heat transfer and control thermal non-equilibrium of liquid and vapor phases in parallel microchannels. The test section consisted of a top glass cover and a silicon substrate. Microheater array was integrated at the top glass cover surface and driven by a pulse voltage signal to generate seed bubbles in time sequence. Each microheater corresponds to a specific microchannel and is located in the microchannel upstream. Five triangular microchannels with a hydraulic diameter of 100 lm and a length of 12.0 mm were etched in the silicon substrate. A thin platinum film was deposited at the back surface of silicon chip with an effective heating area of 4,500 9 1,366 lm, acting as the main heater for the heat transfer system. Acetone liquid was used. With the data range reported here, boiling incipience was not initiated if wall superheats are smaller than 15°C without seed bubbles assisted. Injection seed bubbles triggers boiling incipience and controls thermal non-equilibrium between liquid and vapor phases successfully. Four modes of flow and heat transfer are identified. Modes 1, 2, and 4 are the stable ones without apparent oscillations of pressure drops and heating surface temperatures, and mode 3 displays flow instabilities with apparent amplitudes and long periods of these parameters. The four modes are divided based on the four types of flow patterns observed in microchannels. Seed bubble frequency is a key factor to influence the heat transfer. The higher the seed bubble frequency, the more decreased non-equilibrium between two phases and heating surface temperatures are. The seed bubble frequency can reach a saturation value, at which heat transfer enhancement attains the maximum degree, inferring that a complete thermal equilibrium of two phases is approached. The saturation frequency is about a couple of thousand Hertz in this study.

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“…This is true even for no seed bubble cases. The slightly negative temperature gradients are similar to those reported in Xu et al (2005).…”

Section: Heat Transfer Enhancement By Seed Bubblessupporting

confidence: 87%

Seed bubbles trigger boiling heat transfer in silicon microchannels

Yang

2009

Microfluid Nanofluid

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“…They concluded that the new arrangement showed improved thermal performance at optimum ranges of parameters and Re. Xu et al (2005) divided the whole flow length of microchannel heat sink into several independent zones, in which the thermal boundary-layer redeveloped periodically. They observed enhanced overall heat transfer along with decreased pressure drops for the newly proposed method compared to the conventional microchannel heat sink.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Interrupted Rectangular Microchannel Heat Sink with High Aspect Ratio

Kamal

Dewan

2017

JAFM

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A computational modelling of microchannel heat sinks with high aspect ratio has been performed to compare the geometrical features in the plane parallel to the heating surface and to determine the optimum configuration for the best heat transfer characteristics. A periodic thermal development of flow can cause significant heat transfer enhancement. A consensus on a particular geometrical configuration that provides the best heat transfer characteristics has not been reached in the literature, although many novel ideas have been proposed recently. Firstly the validity and applicability of microchannel sink modelling is presented followed by an optimization of parameters of interrupted microchannel heat sink. Consequences of the multichannel effect due to the introduction of transverse microchamber are also presented. It has been shown that the average Nusselt number of the microchannel heat sink increases by the introduction of a transverse microchamber with the additional advantage of a lower pressure drop. There exists an optimum width for the transverse microchamber for which the interrupted microchannel heat sink shows optimum characteristics.

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“…Usually, these types of heat sinks have several cuts, termed cross-cuts in the present study, perpendicular to the direction of the fluid flow. Xu et al [13] demonstrated a new silicon micro channel heat sink composed of longitudinal micro channels and several transverse micro channels that divide the entire flow path into several independent zones. Experiments for strip fin heat sinks were performed and empirical correlations were proposed to predict the Nusselt number and pressure drop [14,15].…”

Section: Introductionmentioning

confidence: 99%

Experimental and CFD analysis of heat sinks with base plate for CPU cooling

Mohan¹,

Govindarajan²

2011

J Mech Sci Technol

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Experimental and theoretical investigations of the thermal performance of a variety of heat sinks have been made. The heat sinks investigated were: straight finned, elliptical finned, small pin finned, circular disc finned, elliptical disc finned, frustum finned and double base straight finned. Realistic, manufacturable geometries are considered for minimizing thermal resistance at low velocity. The experimental results of several of the simple geometry heat sinks have been compared to those predicted by a commercially available computational fluid dynamics code fluent. The parameters such as fin geometry, fin pitch and fin height are optimized primarily in this paper and a second task is carried out to optimize base plate thicknesses, base plate materials and modify design of heat sink for improving the thermal performance in the next generation. Although the performance of heat sink is good, the temperature of heat sink at center is high. In this research work, the best heat sink geometry is selected and modified in order to reduce maximum temperature distribution and hot spots of heat sink at center by changing the geometry design and adding one more base. It is observed that flow obstructions in the chassis and the resulting air recirculation affect the heat sink temperature distribution.

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Microscale heat transfer enhancement using thermal boundary layer redeveloping concept

Cited by 204 publications

References 13 publications

Seed bubbles trigger boiling heat transfer in silicon microchannels

Seed bubbles trigger boiling heat transfer in silicon microchannels

Analysis of Interrupted Rectangular Microchannel Heat Sink with High Aspect Ratio

Experimental and CFD analysis of heat sinks with base plate for CPU cooling

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