Heat Transer Enhancement Using Flow-Induced Vibration of a Microfin Array

2000 ◽  
Author(s):  
Jeung Sang Go ◽  
Geunbae Lim ◽  
Hayong Yun ◽  
Junghyun Lee ◽  
Inseob Song ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Flow Velocity ◽  
Surface Area ◽  
Heat Sink ◽  
High Speed ◽  
Fluid Velocity ◽  
Heat Removal ◽  
High Heat ◽  
Thermal Engineering ◽  
Flow Induced Vibration

Abstract Advanced notebook computers are facing thermal engineering challenges from both the high heat generation with rapid performance improvement and the reduction of the available heat removal surface area. Efficient and compact cooling technology is desired to provide the reliable operation of the microelectronic devices. This paper investigates the feasibility of heat transfer enhancement in laminar flow using the flow-induced vibration of a microfin array without the additional consumption of battery power or the extension of heat removal surface area. The microfins are initially bent due to the residual stress difference. A high speed motion analyzer records the flow-induced vibration of the microfin array. Increase in flow velocity provides larger vibrating deflection and higher frequency of the microfin. We measure the thermal resistances to evaluate the thermal performance of the microfin heat sink and compare them with those of the plain-wall heat sink. For the fluid velocity of 4.4m/s, the thermal resistance of the microfin array heat sink is measured to be 4.45°C/W and that of the plain-wall heat sink 4.69°C/W, which indicates 5.5% cooling enhancement. At the flow velocity of 5.5m/s, the thermal resistance of the microfin array heat sink decreases by 11.5%.

Numerical Analysis of Single Phase Multi Layered Micro-Channel Heat Sink With Inter-Connects Between Vertical Channels

2010 ◽  
Author(s):  
A. K. M. M. Morshed ◽  
Jamil A. Khan
Keyword(s):  
Thermal Resistance ◽  
Flow Velocity ◽  
Heat Sink ◽  
Cross Flow ◽  
Heat Removal ◽  
Electronics Cooling ◽  
Solid Matrix ◽  
High Heat Flux ◽  
Micro Channel ◽  
Micro Channels

Micro-channels embedded in solid matrix have already proven to be a very efficient way of electronics cooling. Traditional micro-channel heat sinks consist of single layer of parallel channels. Although micro-channel heat sink can achieve very high heat flux, its pumping requirement for circulating liquid through the channel increases very sharply as the flow velocity increases. The pumping requirement can be reduced by stacking multi layers of micro-channels. By introducing multi layers of channels, the flow velocity through each channel is reduced for the same total mass flow rate of the coolant. A novel approach to take advantage of multi layered channel is proposed in this study where the vertical channels are interconnected to allow cross flow of the coolant. The cross-flow between the channels disrupts boundary layer enhancing heat removal capacity of the heat sink. A CFD model has been developed using commercially available software package FLUENT to evaluate overall thermal performance of multi layered micro-channel heat sink. A parametric study of the flow rates and the effect of the number of layers and interconnections have been performed. Significant reduction in thermal resistance has been observed for multiple layers, it is also observed that this reduction in thermal resistance is dependent on the thermal conductivity of the heat sink material.

Experimental Investigation of Liquid Cooling Through Shallow Copperclad Cavities With Etched Pin-Fin Arrays

2018 ◽  
Author(s):  
Yin Lam ◽  
Nicole Okamoto ◽  
Younes Shabany ◽  
Sang-Joon John Lee
Keyword(s):  
Pressure Drop ◽  
Thermal Resistance ◽  
Surface Area ◽  
Flow Rate ◽  
Heat Sink ◽  
Heat Removal ◽  
Heat Sinks ◽  
Liquid Cooling ◽  
Pin Fin ◽  
Pin Fin Arrays

Heat removal is an increasing engineering challenge for higher-density packaging of circuit components. Microchannel heat sinks with liquid cooling have been investigated to take advantage of high surface-to-volume ratio and higher heat capacity of liquids relative to gases. This study experimentally investigated heat removal by liquid cooling through shallow copperclad cavities with staggered pin-fin arrays. Cavities with pin-fins were fabricated by chemical etching of a copperclad layer (nominally 105 μm thick) on a printed-circuit substrate (FR-4). The overall etched cavity was 30 mm wide, 40 mm long, and 0.1 mm deep. The pins were 1.1 mm in diameter and were distributed in a staggered arrangement. The cavity was sealed with a second copperclad substrate using an elastomer gasket. This assembly was then connected to a syringe pump delivery system. Deionized water was used as the working fluid, with volumetric flow rate up to 1.5 mL/min. The heat sink was subjected to a uniform heat flux of 5 W on the underside. Performance of the heat sink was evaluated in terms of pressure drop and the convection thermal resistance. Pressure drop across the heat sinks was less than 10 kPa, dominated by wall surface area rather than the small surface area contributed by cylindrical pins. At low flow rate, caloric thermal resistance dominated the overall thermal resistance of the heat sink. When compared to a microchannel without pins, the pin-fin microchannel reduced convective thermal resistance of the heat sink by approximately a factor of 4.

THERMAL AND HYDRODYNAMIC PERFORMANCE OF A MICROCHANNEL HEAT SINK COOLED WITH CARBON NANOTUBES NANOFLUID

2016 ◽  
Vol 78 (10-2) ◽  
Author(s):  
Nik Ahmad Faiz Nik Mazlam ◽  
Normah Mohd-Ghazali ◽  
Thierry Mare ◽  
Patrice Estelle ◽  
Salma Halelfadl
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
Operating Temperature ◽  
Heat Removal ◽  
Hydrodynamic Performance ◽  
Spherical Particles ◽  
Microchannel Heat Sink ◽  
Pumping Power ◽  
Rectangular Microchannel ◽  
Aspect Ratios

The microchannel heat sink (MCHS) has been established as an effective heat removal system in electronic chip packaging. With increasing power demand, research has advanced beyond the conventional coolants of air and water towards nanofluids with their enhanced heat transfer capabilities. This research had been carried out on the optimization of the thermal and hydrodynamic performance of a rectangular microchannel heat sink (MCHS) cooled with carbon nanotube (CNT) nanofluid, a coolant that has recently been discovered with improved thermal conductivity. Unlike the common nanofluids with spherical particles, nanotubes generally come in cylindrical structure characterized with different aspect ratios. A volume concentration of 0.1% of the CNT nanofluid is used here; the nanotubes have an average diameter and length of 9.2 nm and 1.5 mm respectively. The nanofluid has a density of 1800 kg/m3 with carbon purity 90% by weight having lignin as the surfactant. The approach used for the optimization process is based on the thermal resistance model and it is analyzed by using the non-dominated sorting multi-objective genetic algorithm. Optimized outcomes include the channel aspect ratio and the channel wall ratio at the optimal values of thermal resistance and pumping power. The optimized results show that, at high operating temperature of 40°C the use of CNT nanofluid reduces the total thermal resistance by 3% compared to at 20°C and consequently improve the thermal performance of the fluid. In terms of the hydrodynamic performance, the pumping power is also being reduced significantly by 35% at 40°C compared to the lower operating temperature.  

scholarly journals Cooling Performance of a Novel Circulatory Flow Concentric Multi-Channel Heat Sink with Nanofluids

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 647 ◽  
Author(s):  
Ravindra Jilte ◽  
Mohammad H. Ahmadi ◽  
Ravinder Kumar ◽  
Vilas Kalamkar ◽  
Amirhosein Mosavi
Keyword(s):  
Heat Sink ◽  
Volume Fraction ◽  
Removal Rate ◽  
Heat Removal ◽  
High Heat ◽  
Operating Conditions ◽  
Bottom Surface ◽  
Outlet Temperature ◽  
Cooling Performance ◽  
Heat Rejection

Heat rejection from electronic devices such as processors necessitates a high heat removal rate. The present study focuses on liquid-cooled novel heat sink geometry made from four channels (width 4 mm and depth 3.5 mm) configured in a concentric shape with alternate flow passages (slot of 3 mm gap). In this study, the cooling performance of the heat sink was tested under simulated controlled conditions.The lower bottom surface of the heat sink was heated at a constant heat flux condition based on dissipated power of 50 W and 70 W. The computations were carried out for different volume fractions of nanoparticles, namely 0.5% to 5%, and water as base fluid at a flow rate of 30 to 180 mL/min. The results showed a higher rate of heat rejection from the nanofluid cooled heat sink compared with water. The enhancement in performance was analyzed with the help of a temperature difference of nanofluid outlet temperature and water outlet temperature under similar operating conditions. The enhancement was ~2% for 0.5% volume fraction nanofluids and ~17% for a 5% volume fraction.

Optimization Design the Configuration Sizes of Multi-Layer Rectangle Micro-Channel Heat Sink

2013 ◽  
Vol 444-445 ◽  
pp. 1101-1106
Author(s):  
Li Feng Wang ◽  
Bao Dong Shao ◽  
He Ming Cheng ◽  
Ying He
Keyword(s):  
Pressure Drop ◽  
Thermal Resistance ◽  
Heat Sink ◽  
Optimization Design ◽  
High Heat ◽  
Micro Channel ◽  
Compact Structure ◽  
Total Thermal Resistance ◽  
High Heat Transfer ◽  
High Heat Transfer Coefficient

The configuration sizes of multi-layer rectangle micro-channel heat sink are optimized, which has been widely used to cool electronic chip for its high heat transfer coefficient and compact structure. Taking the thermal resistance and the pressure drop as goal functions, a binary-objective optimization model was proposed for the multi-layer rectangle micro-channel heat sink based on Sequential Quadratic Programming (SQP) method. The number of optimized micro-channel in width n1 and that in height n2 are 24 and 3, the width of optimized micro-channel Wc and fin Wf are 360 and 55μm, the height of optimized micro-channel Hc is 1000μm, and the corresponding total thermal resistance of the whole micro-channel heat sink is 1.5429 °C/W. The corresponding pressure drop is about 2.3454 Pa. When the velocity of liquid is larger than 0.3 m/s, the effect of change of velocity of liquid on the thermal resistance and pressure drop can be neglected.

Hydrocarbon Fuel Cooling Technologies for Advanced Propulsion

1997 ◽  
Vol 119 (2) ◽  
pp. 344-351 ◽  
Author(s):  
D. R. Sobel ◽  
L. J. Spadaccini
Keyword(s):  
Heat Sink ◽  
High Speed ◽  
Hydrocarbon Fuel ◽  
High Heat ◽  
Operating Conditions ◽  
Zeolite Catalysts ◽  
Reaction Products ◽  
Fuel Conversion ◽  
Heat Exchanger Design ◽  
Tube Reactor

Storable hydrocarbon fuels that undergo endothermic reaction provide an attractive heat sink for future high-speed aircraft. An investigation was conducted to explore the endothermic potential of practical fuels, with inexpensive and readily available catalysts, under operating conditions simulative of high-speed flight applications. High heat sink capacities and desirable reaction products have been demonstrated for n-heptane and Norpar 12 fuels using zeolite catalysts in coated-tube reactor configurations. The effects of fuel composition and operating condition on extent of fuel conversion, product composition, and the corresponding endotherm have been examined. The results obtained in this study provide a basis for catalytic-reactor/heat-exchanger design and analysis.

Experimental Characterization of Two-Phase Cooling of Power Electronics in Thermosiphon and Forced Convection Modes

2021 ◽  
Vol 143 (3) ◽  
Author(s):  
Fabio Battaglia ◽  
Farah Singer ◽  
David C. Deisenroth ◽  
Michael M. Ohadi
Keyword(s):  
Heat Flux ◽  
Thermal Resistance ◽  
Power Electronics ◽  
Forced Convection ◽  
Heat Removal ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Two Phase ◽  
Total Thermal Resistance

Abstract In this paper, we present the results of an experimental study involving low thermal resistance cooling of high heat flux power electronics in a forced convection mode, as well as in a thermosiphon (buoyancy-driven) mode. The force-fed manifold microchannel cooling concept was utilized to substantially improve the cooling performance. In our design, the heat sink was integrated with the simulated heat source, through a single solder layer and substrate, thus reducing the total thermal resistance. The system was characterized and tested experimentally in two different configurations: the passive (buoyancy-driven) loop and the forced convection loop. Parametric studies were conducted to examine the role of different controlling parameters. It was demonstrated that the thermosiphon loop can handle heat fluxes in excess of 200 W/cm2 with a cooling thermal resistance of 0.225 (K cm2)/W for the novel cooling concept and moderate fluctuations in temperature. In the forced convection mode, a more uniform temperature distribution was achieved, while the heat removal performance was also substantially enhanced, with a corresponding heat flux capacity of up to 500 W/cm2 and a thermal resistance of 0.125 (K cm2)/W. A detailed characterization leading to these significant results, a comparison between the performance between the two configurations, and a flow visualization in both configurations are discussed in this paper.

Multi-Objective Optimization Design of Multi-Layer Rectangle Micro-Channel Heat Sink for Single-Phase Flow and Heat Transfer

2013 ◽  
Vol 709 ◽  
pp. 286-291 ◽  
Author(s):  
Li Feng Wang ◽  
Bao Dong Shao ◽  
He Ming Cheng
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Thermal Resistance ◽  
Heat Sink ◽  
Optimization Design ◽  
High Heat ◽  
Micro Channel ◽  
Compact Structure ◽  
Total Thermal Resistance ◽  
High Heat Transfer

The purpose of this paper is to optimize the structural sizes of multi-layer rectangle micro-channel heat sink, which has been widely used to cool electronic chip for its high heat transfer coefficient and compact structure. Taking the thermal resistance and the pressure drop as goal functions, a binary-objective optimization model was proposed for the multi-layer rectangle micro-channel heat sink based on Sequential Quadratic Programming (SQP) method. The number of optimized micro-channel in width n1 and that in height n2 are 21 and 7, the width of optimized micro-channel Wc and fin Wf are 340 and 130μm, the height of optimized micro-channel Hc is 415μm, and the corresponding total thermal resistance of the whole micro-channel heat sink is 1.3354 °C/W. The corresponding pressure drop is about 1.3377 Pa. When the velocity of liquid is larger than 0.3 m/s, the effect of change of velocity of liquid on the thermal resistance and pressure drop can be neglected.

Numerical Prediction of Flow and Heat Transfer in an Impingement Heat Sink

1997 ◽  
Vol 119 (1) ◽  
pp. 58-63 ◽  
Author(s):  
S. Sathe ◽  
K. M. Kelkar ◽  
K. C. Karki ◽  
C. Tai ◽  
C. Lamb ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Heat Removal ◽  
Computational Method ◽  
Forced Flow ◽  
Thermal Engineering ◽  
Uniform Heat Flux ◽  
Analysis And Design ◽  
Flow And Heat Transfer ◽  
Ceramic Base

Forced flow of air over extended surfaces offers a simple, reliable, and effective heat removal mechanism and is often employed in electronic equipment. The IBM 4381 heat sink, used in production IBM computers, utilizes this cooling technique. This heat sink consists of a ceramic substrate on which fins made of an aluminum-copper alloy are arranged in a regular array. Cooling air enters the fin array from a nozzle. Extensive experiments have been carried out to characterize the performance of this heat sink at the Advanced Thermal Engineering Laboratory at IBM Endicott. This paper presents computational analysis of the three-dimensional flow and heat transfer in this device for two different air flow rates through the nozzle. The heat dissipated by the electronic components is conducted into the fins through the ceramic base. In the present study the ceramic base is assumed to be subjected to a uniform heat flux at the bottom. The computational method incorporates a special block-correction procedure to enable iterative solution of conjugate heat transfer in the presence of large differences in thermal conductivities of the air and the fin material. The results of computations reproduce the flow pattern in the fin array that is observed experimentally. The part of the ceramic base directly below the nozzle is well cooled with the temperatures gradually increasing from the center towards the corner. The predicted pressure drop and most of the local temperatures at the base and the tip of the fins agree well with the experimental observations. This study illustrates the utility of computational flow analysis in the analysis and design of electronic cooling techniques.

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