A Numerical Parametric Study of Flow and Heat Transfer in Circular and Zig-Zag Square Microchannel Heat Sinks

Author(s):  
Wenming Li ◽  
Fanghao Yang ◽  
Tamanna Alam ◽  
Congcong Ren

This paper aims to study the overall performance of circular and zig-zag square microchannel heat sinks with single phase liquid flow via a numerical parametric study. Thermal resistance and pressure drop when subjected to key geometric parameters such as hydraulic diameter, orientation, and connector length is numerically investigated with Reynolds number ranging from 50 to 500. Specifically, the hydraulic diameter is varied from 100 μm to 300 μm with an increment of 100 μm; the orientation angle of 10°, 20° and 30° is studied. A figure of merit (FOM) involving both the thermal resistance and pressure drop is introduced to evaluate the performance. Results show that hydraulic diameter is critical to thermal resistance and pressure drop compared to orientation angle. Zig-zag microchannel heat sink shows better performance compared with heat sinks with circular microchannel. FOM varies considerably with the change in hydraulic diameter and flow rate.

Entropy ◽  
2018 ◽  
Vol 21 (1) ◽  
pp. 16 ◽  
Author(s):  
Daxiang Deng ◽  
Guang Pi ◽  
Weixun Zhang ◽  
Peng Wang ◽  
Ting Fu

This work numerically studies the thermal and hydraulic performance of double-layered microchannel heat sinks (DL-MCHS) for their application in the cooling of high heat flux microelectronic devices. The superiority of double-layered microchannel heat sinks was assessed by a comparison with a single-layered microchannel heat sink (SL-MCHS) with the same triangular microchannels. Five DL-MCHSs with different cross-sectional shapes—triangular, rectangular, trapezoidal, circular and reentrant Ω-shaped—were explored and compared. The results showed that DL-MCHS decreased wall temperatures and thermal resistance considerably, induced much more uniform wall temperature distribution, and reduced the pressure drop and pumping power in comparison with SL-MCHS. The DL-MCHS with trapezoidal microchannels performed the worst with regard to thermal resistance, pressure drop, and pumping power. The DL-MCHS with rectangular microchannels produced the best overall thermal performance and seemed to be the optimum when thermal performance was the prime concern. Nevertheless, the DL-MCHS with reentrant Ω-shaped microchannels should be selected when pumping power consumption was the most important consideration.


Author(s):  
Anas Alkhazaleh ◽  
Mohamed Younes El-Saghir Selim ◽  
Fadi Alnaimat ◽  
Bobby Mathew

Abstract This article discusses the mathematical modeling of a straight microchannel heat sink, embedded with pin-fins, for purposes of liquid cooling of microelectronic chips. The influence of three different geometrical parameters, pin fins’ diameter, pitch, and hydraulic diameter, on the heat sinks performance is studied. The studies are performed for Reynolds numbers varying from 250 to 2000, and the results are quantified based on thermal resistance and pressure drop. The heat sinks embedded with pin fins have better performance in terms of thermal resistance but at the same time have higher pressure drop. Studies revealed that increasing the pin fins’ diameter, pitch, and hydraulic diameter have an influence on the thermal resistance; the thermal resistance is found to be decreasing with increasing these parameters for the same Reynolds number. For the cases studied, the reduction in thermal resistance of straight microchannels embedded with pin fins varied from 18% to 60% compared with that of traditional straight microchannels for different heat sinks configurations and Reynolds number. On the other hand, the pressure drop is increasing with an increase in pin fins’ diameter and pitch, while it is found to be decreasing with increasing the hydraulic diameter.


Author(s):  
Anas Alkhazaleh ◽  
Mohamed Younes El-Saghir Selim ◽  
Fadi Alnaimat ◽  
Bobby Mathew

Abstract In this work, an investigation of the heat sink performance employing sinusoidal microchannels embedded with pin fins was conducted. The effect of the sine wave frequency, the pin fins’ diameter, and the hydraulic diameter of the microchannel are studied. The results are quantified in terms of thermal resistance and pressure drop. The study was done using Reynolds numbers varying from 250 to 2000. As Reynolds number increases, the heat sink’s thermal resistance decreased while the pressure drop increased accordingly for all scenarios. The sinusoidal microchannels showed better performance — lower thermal resistance — but with the cost of higher pressure drop compared to the straight microchannel heat sink. The heat sink’s performance was improved by increasing the frequency, diameter of pin fins, and hydraulic diameter; however, this reduction in thermal resistance was associated with an increase in pressure drop. The reduction in thermal resistance of the different configurations of the sinusoidal microchannels was between 17% and 69% compared to the straight microchannel heat sink.


2005 ◽  
Vol 2 (2) ◽  
pp. 122-131
Author(s):  
Pradeep Hegde ◽  
K.N. Seetharamu ◽  
P.A. Aswatha Narayana ◽  
Zulkifly Abdullah

Stacked microchannel heat sinks with two-phase flow have been analyzed using the Finite Element Method (FEM). The present method is a simple and practical approach for analyzing the thermal performance of single or multi layered microchannel heat sinks with either single or two-phase flow. A unique 10 noded finite element is used for the channel discretization. Two-phase thermal resistance, pressure drop and pumping power of single, double and triple stack microchannel heat sinks are determined at different base heat fluxes ranging from 150 W/cm2 to 300 W/cm2. The temperature distribution along the length of the microchannel is also plotted. It is found that stacked microchannel heat sinks with two-phase flow are thermally more efficient than two-phase single layer microchannel heat sinks, both in terms of thermal resistance and pumping power requirements. It is observed that the thermal resistance of a double stack microchannel heat sink with two-phase flow is about 40% less than that for a single stack heat sink. A triple stack heat sink yields a further 20% reduction in the thermal resistance and at the same time operates with about 30% less pumping power compared to a single stack heat sink. The effect of channel aspect ratio on the thermal resistance and pressure drop of stacked microchannel heat sinks with two-phase flow are also studied.


Author(s):  
Carlo Nonino ◽  
Stefano Savino

Abstract A numerical investigation is carried out on the effects of flow maldistribution on the temperature uniformity and overall thermal resistance in double-layered microchannel heat sinks. Different flow maldistribution models accounting for the effects of some typical header designs are considered together with different combinations of the average inlet velocity in the two layers of microchannels for a given total mass flow rate. The numerical simulations are carried out using an in-house FEM procedure previously developed by the authors for the analysis of cross-flow microchannel heat exchangers.


Author(s):  
Tannaz Harirchian ◽  
Suresh V. Garimella

Two-phase heat transfer in microchannels can support very high heat fluxes for use in high-performance electronics-cooling applications. However, the effects of microchannel cross-sectional dimensions on the heat transfer coefficient and pressure drop have not been investigated extensively. In the present work, experiments are conducted to investigate the local flow boiling heat transfer in microchannel heat sinks. The effect of channel size on the heat transfer coefficient and pressure drop is studied for mass fluxes ranging from 250 to 1600 kg/m2s. The test sections consist of parallel microchannels with nominal widths of 100, 250, 400, 700, and 1000 μm, all with a depth of 400 μm, cut into 12.7 mm × 12.7 mm silicon substrates. Twenty-five microheaters embedded in the substrate allow local control of the imposed heat flux, while twenty-five temperature microsensors integrated into the back of the substrates enable local measurements of temperature. The dielectric fluid Fluorinert FC-77 is used as the working fluid. The results of this study serve to quantify the effectiveness of microchannel heat transport while simultaneously assessing the pressure drop trade-offs.


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