Development of MEMS Microchannel Heat Sinks for Micro/Nano Spacecraft Thermal Control

2002 ◽  
Author(s):  
Anthony D. Paris ◽  
Gajanana C. Birur ◽  
Amanda A. Green
Keyword(s):  
Heat Sink ◽  
Thermal Control ◽  
Hydraulic Performance ◽  
Heat Sinks ◽  
Performance Criteria ◽  
Working Fluid ◽  
High Heat Flux ◽  
Microchannel Heat Sink ◽  
Microchannel Heat Sinks ◽  
Spacecraft Thermal Control

MEMS-based microchannel heat sinks are being investigated at the Jet Propulsion Laboratory (JPL) for use in micro/nano spacecraft thermal control. The current stage of development focuses on the integration of microchannel heat sinks into spacecraft pumped cooling loops. Two microchannel heat sinks, adapted from a Stanford University Microfluidics Laboratory design, were fabricated at JPL and tested for thermal and hydraulic performance in a single-phase pumped cooling loop. The first microchannel heat sink design was demonstrated to remove heat fluxes of up to 25 W/cm2 with a maximum device temperature of less than 80 °C. Both the original and redesigned heat sinks where shown to meet hydraulic performance criteria requiring less than 1 psi pressure drop with water as the working fluid. It was concluded that the design methodology developed for this project produces microchannel heat sink devices capable of high heat flux removal in future micro/nano spacecraft thermal control architecture.

Enhanced Thermal Transport in Microchannel Using Oblique Fins

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Y. J. Lee ◽  
P. S. Lee ◽  
S. K. Chou
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Enhancement ◽  
Heat Sink ◽  
Heat Sinks ◽  
Maximum Temperature ◽  
Working Fluid ◽  
Microchannel Heat Sink ◽  
Transfer Enhancement ◽  
Microchannel Heat Sinks

Sectional oblique fins are employed, in contrast to continuous fins in order to modulate the flow in microchannel heat sinks. The breakage of a continuous fin into oblique sections leads to the reinitialization of the thermal boundary layer at the leading edge of each oblique fin, effectively reducing the boundary layer thickness. This regeneration of entrance effects causes the flow to always be in a developing state, thus resulting in better heat transfer. In addition, the presence of smaller oblique channels diverts a small fraction of the flow into adjacent main channels. The secondary flows created improve fluid mixing, which serves to further enhance heat transfer. Both numerical simulations and experimental investigations of copper-based oblique finned microchannel heat sinks demonstrated that a highly augmented and uniform heat transfer performance, relative to the conventional microchannel, is achievable with such a passive technique. The average Nusselt number, Nuave, for the copper microchannel heat sink which uses water as the working fluid can increase as much as 103%, from 11.3 to 22.9. Besides, the augmented convective heat transfer leads to a reduction in maximum temperature rise by 12.6 °C. The associated pressure drop penalty is much smaller than the achieved heat transfer enhancement, rendering it as an effective heat transfer enhancement scheme for a single-phase microchannel heat sink.

Thermal Design Criteria for Extraordinary Performance of Devices Cooled by Microchannel Heat Sink

2010 ◽  
Vol 2 (4) ◽  
Author(s):  
Dylan Farnam ◽  
Bahgat Sammakia ◽  
Kanad Ghose
Keyword(s):  
Contact Area ◽  
Heat Sink ◽  
Heat Removal ◽  
Thermal Design ◽  
Heat Sinks ◽  
Design Criteria ◽  
Microchannel Heat Sink ◽  
Device Architecture ◽  
Microchannel Heat Sinks ◽  
Thermal Solution

Increasing power dissipation in microprocessors and other devices is leading to the consideration of more capable thermal solutions than the traditional air-cooled fin heat sinks. Microchannel heat sinks (MHSs) are promising candidates for long-term thermal solution given their simplicity, performance, and the development of MHS-compatible 3D device architecture. As the traditional methods of cooling generally have uniform heat removal on the contact area with the device, thermal consequences of design have traditionally been considered only after the layout of components on a device is finalized in accordance with connection and other criteria. Unlike traditional cooling solutions, however, microchannel heat sinks provide highly nonuniform heat removal on the contact area with the device. This feature is of utmost importance and can actually be used quite advantageously, if considered during the design phase of a device. In this study, simple thermal design criteria governing the general placement of components on devices to be cooled by microchannel heat sink are developed and presented. These thermal criteria are not meant to supersede connection and other important design criteria but are intended as a necessary and valuable supplement. Full-scale numerical simulations of a device with a realistic power map cooled by microchannel heat sink prove the effectiveness of the criteria, showing large reduction in maximum operating temperature and harmful temperature gradients. The simulations further show that the device and microchannel heat sink can dissipate a comparatively high amount of power, with little thermal danger, when design considers the criteria developed herein.

Experimental Investigation of Silicon-Based Oblique Finned Microchannel Heat Sinks

2010 ◽  
Author(s):  
Yong-Jiun Lee ◽  
Poh-Seng Lee ◽  
Siaw-Kiang Chou
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Sink ◽  
Leading Edge ◽  
Secondary Flows ◽  
Heat Sinks ◽  
Fluid Mixing ◽  
Working Fluid ◽  
Microchannel Heat Sink ◽  
Silicon Based

Sectional oblique fins are employed in contrast to the continuous fins in order to modulate the flow in microchannel heat sink. Experimental investigation of silicon based oblique finned microchannel heat sink demonstrated a highly augmented and uniform heat transfer performance against the conventional microchannel. The breakage of continuous fin into oblique sections leads to the re-initialization of the thermal boundary layers at the leading edge of each oblique fin, effectively reducing the boundary-layer thickness. This regeneration of the entrance effect causes the flow to be always in a developing state thus resulting in better heat transfer. In addition, the presence of smaller oblique channels diverts a fraction of the flow into the adjacent main channels. The secondary flows thus created improve fluid mixing which serves to further enhance the heat transfer. The average Nusselt number, Nuave, for the silicon microchannel heat sink which uses water as the working fluid can increase as much as 55%, from 8.8 to 13.6. Besides, the augmented convective heat transfer leads to reduction in both maximum chip temperature and its temperature gradient, by 8.6°C and 47% respectively. Interestingly, there is only little or negligible pressure drop penalty associated with this novel heat transfer enhancement scheme in contrast to conventional enhancement techniques.

scholarly journals Thermal–Hydraulic Performance in a Microchannel Heat Sink Equipped with Longitudinal Vortex Generators (LVGs) and Nanofluid

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 231
Author(s):  
Basel AL Muallim ◽  
Mazlan A. Wahid ◽  
Hussein A. Mohammed ◽  
Mohammed Kamil ◽  
Daryoush Habibi
Keyword(s):  
Nusselt Number ◽  
Friction Factor ◽  
Heat Sink ◽  
Pure Water ◽  
Hydraulic Performance ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Working Fluid ◽  
Microchannel Heat Sink ◽  
Fanning Friction Factor

In this study, the numerical conjugate heat transfer and hydraulic performance of nanofluids flow in a rectangular microchannel heat sink (RMCHS) with longitudinal vortex generators (LVGs) was investigated at different Reynolds numbers (200–1200). Three-dimensional simulations are performed on a microchannel heated by a constant temperature with five different configurations with different angles of attack for the LVGs under laminar flow conditions. The study uses five different nanofluid combinations of Al2O3 or CuO, containing low volume fractions in the range of 0.5% to 3.0% with various nanoparticle sizes that are dispersed in pure water, PAO (Polyalphaolefin) or ethylene glycol. The results show that for Reynolds number ranging from 100 to 1100, Al2O3–water has the best performance compared with CuO nanofluid with Nusselt number values between 7.67 and 14.7, with an associated increase in Fanning friction factor by values of 0.0219–0.095. For the case of different base fluids, the results show that CuO–PAO has the best performance with Nusselt number values between 9.57 and 15.88, with an associated increase in Fanning friction factor by 0.022–0.096. The overall performance of all configurations of microchannels equipped with LVGs and nanofluid showed higher values than the ones without LVG and water as a working fluid.

Numerical Investigations of the Effect of Flow Arrangement and Number of Layers on the Performance of Multi-Layer Microchannel Heat Sinks

2015 ◽  
Author(s):  
M. B. Effat ◽  
M. S. AbdelKarim ◽  
O. Hassan ◽  
M. Abdelgawad
Keyword(s):  
Heat Flux ◽  
Temperature Distribution ◽  
Heat Sink ◽  
Single Layer ◽  
Heat Sinks ◽  
Uniform Heat Flux ◽  
Microchannel Heat Sink ◽  
Electronic Components ◽  
Number Of Layers ◽  
Microchannel Heat Sinks

With the advance of miniaturization technology, more and more electronic components are placed onto small electronic chips. This leads to the generation of high amounts of thermal energy that should be removed for the safe operation of these electronic components. Microchannel heat sinks, where electronic chips are liquid cooled instead of the conventional air cooling techniques, were proposed as a means to improve cooling rates. Later on, double layer micro channel heat sinks were suggested as an upgrade to single layer microchannel heat sinks with a better thermal performance. In the present study the effects of increasing the number of layers of the microchannel heat sink to three-layers as well as the effect of changing the flow arrangements (counter and parallel flows) within the three channel layers on the thermal performance of the heat sink were investigated. In all investigated cases the temperature distribution over the base of the microchannel heat sink system and the total pressure drop are reported. A range of mass flow rates from 1×10−4 to 5×10−4 kg/s was considered. Uniform heat flux conditions were considered during the study. COMSOL Multiphysics finite element package was employed for the numerical analysis. Results indicate significant enhancement in the uniformity of the temperature on the processor surface when multi-layer channels were employed, compared to the single-layer case. The uniformity in the temperature distribution was accompanied by reduction of pressure drop across channels for the same mass flow rate and heat flux conditions. The counter flow arrangement showed the best temperature distribution with the uniform heat flux cases.

scholarly journals Numerical Optimization of a Microchannel Geometry for Nanofluid Flow and Heat Dissipation Assessment

2021 ◽  
Vol 11 (5) ◽  
pp. 2440
Author(s):  
Inês M. Gonçalves ◽  
César Rocha ◽  
Reinaldo R. Souza ◽  
Gonçalo Coutinho ◽  
Jose E. Pereira ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Jet Impingement ◽  
Experimental Tests ◽  
Heat Sinks ◽  
Working Fluid ◽  
Optimized Design ◽  
Nanofluid Flow ◽  
Microchannel Heat Sinks

In this study, a numerical approach was carried out to analyze the effects of different geometries of microchannel heat sinks on the forced convective heat transfer in single-phase flow. The simulations were performed using the commercially available software COMSOLMultiphysics 5.6® (Burlington, MA, USA) and its results were compared with those obtained from experimental tests performed in microchannel heat sinks of polydimethylsiloxane (PDMS). Distilled water was used as the working fluid under the laminar fluid flow regime, with a maximum Reynolds number of 293. Three sets of geometries were investigated: rectangular, triangular and circular. The different configurations were characterized based on the flow orientation, type of collector and number of parallel channels. The main results show that the rectangular shaped collector was the one that led to a greater uniformity in the distribution of the heat transfer in the microchannels. Similar results were also obtained for the circular shape. For the triangular geometry, however, a disturbance in the jet impingement was observed, leading to the least uniformity. The increase in the number of channels also enhanced the uniformity of the flow distribution and, consequently, improved the heat transfer performance, which must be considered to optimize new microchannel heat sink designs. The achieved optimized design for a heat sink, with microchannels for nanofluid flow and a higher heat dissipation rate, comprised a rectangular collector with eight microchannels and vertical placement of the inlet and outlet.

Constructal Design of Circular Multilayer Microchannel Heat Sinks

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Reza Salimpour ◽  
Ahmed T. Al-Sammarraie ◽  
Azadeh Forouzandeh ◽  
Mahsa Farzaneh
Keyword(s):  
Heat Sink ◽  
Volume Fraction ◽  
Effective Means ◽  
Solid Volume Fraction ◽  
Heat Sinks ◽  
Constructal Theory ◽  
Maximum Temperature ◽  
Microchannel Heat Sink ◽  
Triple Layer ◽  
Microchannel Heat Sinks

Abstract Based on the constructal theory concepts, an investigation is carried out to optimize circular multilayer microchannels embedded inside a rectangular heat sink with different numbers of layers and flow configurations. The lower surface of the heat sink is uniformly heated, while both pressure drop and length of the microchannel are fixed. Also, the volume of the heat sink is kept fixed for all studied cases, while the effect of solid volume fraction is examined. All the dimensions of microchannel heat sinks are optimized in a way that the maximum temperature of the microchannel heat sink is minimized. The results emphasize that using triple-layer microchannel heat sink under optimal conditions reduces the maximum temperature about 10.3 °C compared to the single-layer arrangement. Further, employing counter flow configuration in double-layer microchannel improves its thermal performance, while this effect is less pronounced in the triple-layer architecture. In addition, it is revealed that the optimal design can be achieved when the upper channels of a multilayer microchannel heat sink have bigger diameters than the lower ones. Finally, it is observed while using two layers of microchannels is an effective means for cooling improvement, invoking more layers is far less effective and hence is not recommended.

A Three-Dimensional Simulation Analysis of Fluid Flow and Heat Transfer in Microchannel Heat Sinks with Different Structures

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jienan Shen ◽  
Xiuxiu Li ◽  
Yongsheng Zhu ◽  
Boya Zhang ◽  
Hang Guo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Heat Sink ◽  
Simulation Analysis ◽  
Heat Sinks ◽  
Mixing Efficiency ◽  
Microchannel Heat Sink ◽  
Flow And Heat Transfer ◽  
Microchannel Heat Sinks

Abstract Numerical studies have been performed to analyze the fluid flow and heat transfer characteristics of nine microchannel heat sinks (MCHS) with different shapes and different arrangements of the ribs and cavities on the sidewalls, using three common shapes (square, triangle, and circular) of ribs or cavities as the basic structure in this work. The boundary conditions, governing equations, friction factor (f), Nusselt number (Nu), and performance evaluation criteria (ξ) were considered to determine which design was the best in terms of the heat transfer, the pressure drop, and the overall performance. It was observed that no matter how the circular ribs or cavities were arranged, its heat sink performance was better than the other two shapes for Reynolds number of 200–1000. Therefore, circular ribs or cavities can be considered as the best structure to improve the performance of MCHS. In addition, the heat sink performance of the microchannel heat sink with symmetrical circular ribs (MCHS-SCR) was improved by 31.2 % compared with the conventional microchannel heat sink at Re = 667. This was because in addition to the formation of transverse vortices in the channel, four symmetrical and reverse longitudinal vortices are formed to improve the mixing efficiency of the central fluid (low temperature) and the near-wall fluid (high temperature). Then, as the Reynolds number increases, the heat sink performance of MCHS-SCR dropped sharply. The heat sink performance of microchannel heat sinks with staggered ribs and cavities (MCHS-SCRC, MCHS-STRC, and MCHS-SSRC) exceeded that of MCHS-SCR. This indicated that the microchannel heat sink with staggered ribs and cavities was more suitable for high Reynolds number (Re > 800).

scholarly journals Influence of moist air in copper heat sinks: Analysis through the entropy generation minimization criterion

2015 ◽  
Vol 35 (3) ◽  
pp. 44-52 ◽  
Author(s):  
Jorge Mario Cruz ◽  
Iván Mauricio Amaya ◽  
Carlos Rodrigo Correa
Keyword(s):  
Heat Transfer ◽  
Relative Humidity ◽  
Heat Sink ◽  
Bulk Material ◽  
Heat Transfer Process ◽  
Heat Sinks ◽  
Working Fluid ◽  
Microchannel Heat Sink ◽  
Rectangular Microchannel ◽  
Humidified Air

Many factors affect heat transfer during the cooling of modern electronic devices. Today, knowledge accrues from modeling, simu-lation, and experimentation. This allows predicting and calculating features of heat transfer phenomena, to some extent. Examples include the amount of heat generated and removed, the required physical properties of the working fluid, and the required material properties of the heat sink, among other parameters. This article describes some simulation results of using air with a given relative humidity (10 %, 50 % and 90 %). Its influence on the heat transfer process was also analyzed. Results show a measurable effect of using humidified air instead of dry air and copper as a bulk material. The heat transfer rate increased about 20 % when using air with 90 % relative humidity passing through a rectangular microchannel heat sink made of copper.

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