Performance Of Microchannel Heat Sink Research Articles

Thermal and hydraulic performance of solid-porous compound wavy micro-channel heat sinks

In this numerical study, seven distinct three-dimensional unique models of micro-channel heat sinks have been investigated. A solid-porous compound wavy channel with optimum thickness of porous fins has been newly adapted to improve the thermal and hydraulic performance of the forthcoming micro-electronic devices. The finite volume method is used to solve the hydraulic and thermal performance of micro-channel heat sinks, and Darcy–Forchheimer flow models are applied for fluid flow through porous fins. Water is employed as a working fluid. Solid wall and porous fins are made of copper material; during analysis, Reynolds numbers vary from 50 to 300, and the effective thermal conductivity has been considered for porous fins as well as solid-porous compound fins. The effect of solid fins, porous fins, and compound fins are comprehensively determined. The result shows that as the thickness of porous fins increases in compound wavy channel, the heat transfer performance significantly increases up to 63.6% and pressure drop penalty decreases up to 55.32% as compared to the regular straight channel (solid fins) heat sinks. This is due to reduction of viscous shear stress at the place of fluid-porous interface and slip effect of fluids in the porous zone. Hence, the ability of the solid-porous compound wavy micro-channel heat sinks can effectively enhance the cooling performance of high-power electronic devices.

Performance improvement and thermodynamic assessment of microchannel heat sink with different types of ribs and cones

The present study aims to investigate the performance of microchannel heat sink via numerical simulations, based on the first and second law of thermodynamics. The heat transfer and flow characteristics of rectangular microchannel heat sinks have been improved by adding six different types of surface enhancers. The cross-sections include rectangular, triangular, and hexagonal-shaped ribs and cones. The cones have been created from the same cross-sections of ribs by drafting them at an angle of 45° orthogonal to the base, which is expected to decrease the pressure drop, dramatically. The performance of ribs and cones has been evaluated using different parameters such as friction factor, wall shear stress, entropy generation rate, augmentation entropy generation number, thermal resistance, and transport efficiency of thermal energy. The results of the present study revealed that the novel effect of coning at an angle of 45° reduces frictional losses (Maximum pressure drop reduced is 85%), however; a compromise on thermal behavior has been shown (Maximum Nusselt number reduced is 25%). Similarly, the application of coning has caused a significant reduction in wall shear stress and friction factor which can lead to reducing the pumping power requirements. Moreover, triangular ribs have more ability to transfer thermal energy than rectangular and hexagonal ribs. Furthermore, it has been examined in the present study that the trend of total entropy generation rate for triangular ribs decreases up to Re = 400 and then increases onwards which means that thermal losses are more significant than frictional losses at lower Reynolds number. However, frictional losses dominate over thermal losses at higher Reynolds numbers, where vortex generation takes place, especially in triangular ribs.

Performance improvement of rectangular microchannel heat sinks using nanofluids and wavy channels

In this article, the effect of two different methods of cooling enhancement, including the use of nanofluid as the coolant and sinusoidal wavy walls, on the performance of rectangular microchannel heat sinks (MCHSs) has been numerically investigated. Three-dimensional simulations based on the finite-volume approach are carried out using three different wave amplitudes (50, 100, and 200 µm) and wavelengths (1.3, 2, and 4 mm). Water-based nanofluid containing Al2O3 nanoparticles with volume fraction of 1% is employed as the coolant, and its influence on the hydraulic and thermal performance of the MCHS is compared with the water. The simulation of nanofluid flow is performed by both the single-phase method and the two-phase mixture method. Comparison between predicted results and experimental data from literature is carried out, which indicates the two-phase method is more precise than the single-phase method. Results showed that the enhanced microchannels with higher wave amplitudes and lower wavelengths performed better in terms of heat transfer, and among the investigated geometries, the wavelength of 1.3 mm and the amplitude of the 200 µm show the highest cooling performance. Using these optimal geometrical values in the wavy-walled microchannel heat sink (WMCHS), the amount of heat absorbed by the water-Al2O3 with volume fraction of 1% increases by 43% compared with the water flow in the straight-walled microchannel heat sink (SMCHS) at Reynolds number of 500. In addition, in a given geometry with fixed length and cross section area, employing wavy walls has a greater effect on heat transfer enhancement than using nanofluid instead of water. Employing optimal wavy walls in the MCHS, the amount of absorbed heat increases by 30% when the coolant is pure water and by 21% when the coolant is nanofluid. Whereas if nanofluid is used instead of water, the heat absorbed increases by 18% in SMCHS and 10% in WMCHS. Although both methods of cooling enhancement increase the pressure drop as well, the negative effect of the increase in pressure drop is less than the positive effect of increasing heat transfer in both methods.

Thermal and hydraulic performances of the wavy microchannel heat sink with fan-shaped ribs on the sidewall

The innovative wavy microchannel heat sinks with a variety of geometric fan-shaped ribs are proposed. The thermal and hydraulic performances of such a microchannel are given considering the thermo-physical properties. The calculation results validate its advantage in improving the thermal performance. New insights into the flow and heat transfer mechanism are obtained based on the detailed flow field evolution. The geometry parameter of fan-shaped ribs on the friction factor, Nusselt number, and thermal performance is further investigated. Results show that the heat transfer enhancement is dependent on the geometric parameters of ribs and Re. Compared with rectangular wavy microchannel, the heat transfer is enhanced in the larger Re besides Hr/Wr = 0.05. The best thermal performance of this proposed microchannel is mainly observed at the Sr/Wr = 2, and a worse thermal performance is found for the microchannel as the Sr/Wr = 1 and 4 in the lower Re. With the increase of the flow rate, a noticeable increase in PEC is found for the heat sinks with lower Sr/Wr. The maximum value of PEC occurs more early for the channel with Sr/Wr = 0.0375, and the increase rate of PEC for such microchannel with Re is lower. The PEC is larger for Hr/Wr = 0.1125 and 0.075 in the higher Re.

Effect of fluid distribution along the channel length on the cooling performance of microchannel heat sink

Purpose The purpose of this study is to conduct research on a new kind of division microchannel heat sink (D-MCHS), which can distribute cooling water along the channel-length direction. First, the pressure drops in the D-MCHS with different division region numbers were compared. Then, the cooling performance of the D-MCHS with different division region numbers was also comparatively investigated. Finally, the temperature distribution on the bottom surface of the D-MCHS was analyzed. Design/methodology/approach First, experiments were conducted to investigate the numerical calculation method. Then, a three-dimensional steady, single-phase, laminar flow and solid-fluid conjugate heat transfer numerical model was used to research the flow and heat transfer characteristics in microchannels. Findings The pressure drop in the D-MCHS could be reduced by increasing the number of divided flow regions along the channel-length direction. The bottom average temperature of the D-MCHS could be simultaneously affected by the number of divided flow regions and the water flow rate. The thermal uniformity performance of the D-MCHS could be improved by increasing the number of division flow regions. The number of low-temperature and high-temperature areas on the bottom surface of the D-MCHS is corresponding to the division flow region number. Originality/value The D-MCHS exhibited a positive effect on the pressure drop decrease and thermal uniformity improvement. It not only keeps the electronic module working in a secure temperature environment but also consumes less pump power for a lower pressure drop.

Heat Transfer Performance and Structural Optimization of a Novel Micro-channel Heat Sink

With the advent of the 5G era, the design of electronic equipment is developing towards thinness, intelligence and multi-function, which requires higher cooling performance of the equipment. Micro-channel heat sink is promising for the heat dissipation of super-thin electronic equipment. In this study, thermal resistance theoretical model of the micro-channel heat sink was first established. Then, fabrication process of the micro-channel heat sink was introduced. Subsequently, heat transfer performance of the fabricated micro-channel heat sink was tested through the developed testing platform. Results show that the developed micro-channel heat sink has more superior heat dissipation performance over conventional metal solid heat sink and it is well suited for high power LEDs application. Moreover, the micro-channel structures in the heat sink were optimized by orthogonal test. Based on the orthogonal optimization, heat dissipation performance of the micro-channel radiator was further improved.

Thermal design of microchannel heat sinks using a contour extraction based on topology optimization (CEBTO) method

The Topology Optimization (TO) has been proved to be an effective method for designing Microchannel Heat Sinks (MCHS). However, due to the relatively high computational cost and poor numerical stability, it is still challenging to design the thermo-fluid TO under high Reynolds number (Re). In this work, we propose a Contour Extraction Based on Topology Optimization (CEBTO) method to optimize the geometry of the fins based on a threshold velocity (Ut, proportional to the maximum velocity Umax) and improve the hydrothermal performance of MCHS under high Re. The 3D conjugate heat transfer numerical models are established to study the fluid flow and heat transfer characteristics of the MCHS generated by the conventional TO method and the CEBTO method. The results showed that due to the elimination of the area of stagnation zones under high Re, the CEBTO-generated heat sinks have a better interaction of fluid with the walls and more uniform velocity distribution compared to the TO-generated ones. However, the elimination of the stagnation zones area also leads to the decrease of channel width, which increases the friction loss in CEBTO-generated heat sinks. Nevertheless, the CEBTO-generated heat sinks have better overall performance compared to the TO designs owing to the smaller total entropy generation rate. For example, the CEBTO-I (Ut=28%Umax) exhibits the best overall performance with 10.1% increment of flow entropy generation rate and 7.1% reduction of thermal entropy generation rate as compared to those of TO-I (i.e., a TO-generated heat sink with alveoli-like shape), leading to the augment entropy generation number of 0.92 (Re = 1715). Finally, the CEBTO-I (Ut=28%Umax) was manufactured by micro milling technology and its hydrothermal performance was investigated experimentally to validate the accuracy of numerical simulation. The pressure drop and temperature of the CEBTO-generated heat sink in the experiment agree well with the numerical simulation.

Two-phase mixture simulation of the performance of a grooved helical microchannel heat sink filled with biologically prepared water-silver nanofluid: Hydrothermal characteristics and irreversibility behavior

• A novel heatsink with grooved helical microchannels is suggested. • Biologically synthesized water-Ag nanofluid is considered as the working fluid. • First and second law analysis of nanofluid flow inside the heatsink are evaluated. • Heatsink with staggered grooved helical channels has best first-law performance. • Grooving the helical channel entails an increment in the entropy generation. The present paper investigates the influence of using two grooved channel geometries on the hydrothermal performance of a helical microchannel heat sink. The results were compared with those obtained for the plain channel geometry. Based on the results, the highest flow mixing is observed for the staggered grooved configuration. Moreover, the convective heat transfer coefficient enhances by nearly 70% and 17% for the MCHS with the staggered and parallel grooved channels, respectively, as compared to that with the plain channel. The influence of Reynolds number ( Re ) escalation on the convective heat transfer coefficient is insignificant, while a 21% increase is obtained when NF concentration is increased from 0% to 1%. Furthermore, the increase of φ in the grooved configurations is more effective than that in the plain configuration. In addition, the lowest thermal resistance and temperature uniformity factors were obtained for the staggered grooved configuration. Besides, the parallel grooved configuration represents the highest frictional entropy generation rates among the three studied geometries due to the considerable reduction of the fluid flow cross-section area between the groove ribs. The highest heat transfer coefficient and pressure drop are associated with the staggered grooved configuration. For the plain, parallel grooved, and staggered grooved configurations, the increase of Re from 500 to 2000 escalates the NF pressure drop by 2730%, 4420%, and 4460%, respectively. Therefore, the highest performance evaluation criterion of more than unity was obtained for the MCHS with the staggered grooved channels for the studied range of Re (500–2000). The numerical analysis was also performed to evaluate the influence of groove pitch on the hydrothermal performance of the staggered groove channel for the pitch range of 0.15 mm to 0.75 mm. The results demonstrated that the highest PEC is associated with the groove pitch of 0.75 mm.

Influence of Heat Flux on the Thermohydraulic Performance of Microchannel Heat Sinks using Computational Fluid Dynamics

Microchannel heat sinks (MCHS) have been found to be showing better performance in terms of heat transfer rates at a penalty of pressure drop. This higher-pressure drop would contribute to the requirement of higher pumping power. In this work, an investigation is carried out on a rectangular microchannel heat sink at a constant aspect ratio (AR) of 11.44 for a cross sectional area of 0.20mm2 at different heat fluxes ranging from 20W/cm2 to 100W/cm2. It is found that the effect of variation of heat fluxes for a cross sectional area of 0.20mm2 shows significant effect on the thermohydraulic performance of MCHS. In order to solve the governing equations of fluid flow through MCHS, ANSYS-FLUENT is used. The flow is considered to be laminar, since the operating Reynolds number found to be in the range of 200 to 1000. The obtained results are validated with numerical and experimental results available in the literature. Further, grid independence studies have been performed to eliminate errors in the simulation. The hydraulic characteristics such as pressure drop, pumping power and thermal characteristics such as thermal resistance have been investigated computationally.

Experiment investigation on flow boiling heat transfer in a bidirectional counter-flow microchannel heat sink

Improving the critical heat flux (CHF) and avoiding dry out downstream are the keys to enhance the two-phase cooling performance of microchannel heat sinks. In this work, a novel type of bidirectional counter-flow (BCF) microchannels with 600 μm depth and 300μm width, giving a hydraulic diameter of 400μm, is fabricated in an oxygen-free copper base. Flow boiling experiments are conducted in bidirectional counter-flow microchannels and conventional unidirectional parallel-flow (UPF) microchannels, with the deionized water being used as the working fluid. Cases under six mass fluxes ranging from 118 kg/m2·s to 370 kg/m2·s and three inlet subcoolings of 30 ℃, 50 ℃, and 70 ℃ are tested. Two-phase flow behaviors in microchannels are simultaneously captured by a high-speed camera. It is found that, unlike conventional UPF microchannels, the location for the onset of nucleate boiling (ONB) in BCF microchannels is moved from downstream to the middle region. The downstream dry-out, which is usually occurred in UPF microchannels, can be well avoided in BCF microchannels due to the substantial feeding of liquid in adjacent microchannels. The CHF in BCF microchannels can be increased by 33.8∼57.2% compared with the conventional UPF microchannels. Under the combined effect of expanded nucleate boiling region and shortened subcooling region, the average heat transfer coefficient (HTC) in BCF microchannels can be increased by 36.6%∼56.7%. More interestingly, the improvement of heat transfer performance is found to be accompanied by a significant reduction in pressure drop for BCF microchannels in all the experiment cases. In addition, two-phase instabilities in terms of wall temperature and pressure drop oscillations can be significantly suppressed by using BCF microchannels instead of the conventional UPF microchannels. This study proposes a more efficient microchannel heat sink design scheme to deal with the microelectronic cooling challenges.

Thermal and Hydraulic Performances of Porous Microchannel Heat Sink Using Nanofluids

Abstract Microchannel heat sink is an effective method in compact and faster heat transfer applications. This paper numerically investigates thermal and hydraulic characteristics of a porous microchannel heat sink (PMHS) using various nanofluids. The effect of porosity (γ = 0.32–0.60), inlet velocity (win = 0.5–1.5 m/s), and nanoparticle concentration (ϕ=0.0025 – 0.05) on thermal-hydraulic performance is systematically examined. The result shows a significant temperature increase (40 °C) of the coolant in the porous zone. The pressure drop reduces by 35% for γ = 0.32 compared to the non-porous counterpart, and this reduction of pressure significantly continues when γ further increases. The pressure drop with win is linear for PMHS with nanofluids, and the change in pressure drop is steeper for nanofluids compared to their base fluids. The average heat transfer coefficient increases about 2.5 times for PMHS, and a further increase of 6% in h¯ is predicted with the addition of nanoparticles. The average Nusselt number Nu¯ increases nonlinearly with Re for PMHS. The friction factor reduces by 50% when γ increases from 0.32 to 0.60, and the effect of nanofluid on friction factor is insignificant beyond the mass flowrate of 0.0004 kg/s. Whilst Cu and CuO nanoparticles help to dissipate the larger amount of heat from the microchannel, Al2O3 nanoparticle appears to have a detrimental effect on heat transfer. The thermal-hydraulic performance factor strongly depends on the nanoparticles, and it slightly decreases with the mass flowrate. The increase of nanoparticle concentration, in general, enhances both h¯ and ΔP linearly for the range considered.

Computational Study of Hydrothermal Performance of Microchannel Heat Sink With Trefoil Shape Ribs

Traditional cooling technologies are now become inadequate for electronic chips cooling due to size reduction and increase in generated heat flux. Microchannel heat sink (MCHS) is promising candidate due to its superior cooling performance than its competitors. The aim of this study is to investigate the hydrothermal performance of MCHS with novel trefoil shape ribs. The three configurations of trefoil shape ribs are: MC-AWTR (all wall trefoil ribs), MC-SWTR (side wall trefoil ribs), and MC-BWTR (base wall trefoil ribs). The performance of microchannel is evaluated on the basis of thermal enhancement factor, thermal resistance, transport efficiency and entropy generation at Re=100-1000. The results predict that addition of trefoil ribs to walls of smooth microchannel significantly improve its thermal performance at cost of pressure penalty. Nusselt number and average heat transfer coefficient tends to increase with rise in Reynolds number while thermal resistance and entropy generation reduces. Highest pressure drop occurs for MC-AWTR configuration due to more obstruction of the fluid flow. MC-SWTR configuration has highest thermal enhancement factor among all configurations while MC-AWTR has lowest due to large pressure drop penalty at all Reynold number. So, overall MC-SWTR shows superior performance than any other considered trefoil rib configuration.

Simulation of hybrid nanofluid flow within a microchannel heat sink considering porous media analyzing CPU stability

Current article aims to numerically scrutinize and compare the forced convection in three different configurations of a 3D heat sink. Two models of porous were designed aiming to evaluate the effects of nanomaterial and metallic foam to the conventional solid heat sink on thermal performance. In these two models, porous material with the same volume fraction was located in two different positions to have different contact areas with the solid. MWCNT-Fe 3 O 4 hybrid nanofluid has been utilized as coolant working fluid. Validations were carried out in the critical case of 47 W for pure water through comparison with previous experimental work in which the whole surface of the CPU is covered with porous media. According to the results, at the constant Reynolds number, the heat sinks, which are consist of metallic foam, have better cooling performance and are able to decrease the surface temperature of heat sink more. • Microchannel heat sink performance has been studied. • Multi-wall carbon nanotube-Fe3O4 hybrid nanofluid has been utilized. • Validations were carried out with comparison with previous experimental article. • The thermal resistance of model 2 is 2% lower than that of model 1.

NUMERICAL STUDY ON THE THERMAL PERFORMANCE OF MICROCHANNEL HEAT SINK WITH COMPOSITE ELLIPTICAL PIN FIN

NUMERICAL STUDY ON THE THERMAL PERFORMANCE OF MICROCHANNEL HEAT SINK WITH COMPOSITE ELLIPTICAL PIN FIN

Numerical Study on Heat Transfer Characteristic of the Plate-Fin Microchannel Heat Sink for Water-Based Thermal Management of CPU Chip

For effective water-based thermal management of high heat generating CPU chip, a series of numerical simulation has been conducted to study the effects of heat flux, fin height and flow rate on convective thermal performance of the plate-fin microchannel heat sinks. The characteristics of heat transfer and flow resistance have been quantificationally discussed and <i>JF</i> factor is employed to evaluate the comprehensive efficiency of convective heat transfer of microchannel heat sink. Results show that the increase in fin height and flow rate of cooling water is helpful to decrease the maximum temperature of CPU chip. Large flow rate and heat flux and short fin height are benefit to improve Nusselt number <i>Nu</i>, but they lead to large resistance coefficient <i>fRe</i> simultaneously. Analysis of <i>JF</i> factor shows that the microchannel with short fins shows better convective thermal performance when the thermal power of the CPU chip is small. The fins should be heightened when the CPU is operating at higher thermal power. The employment of <i>JF</i> factor in the present work shows its pertinence and convenience in the application of design of microchannel heat sink.

INVESTIGATIONS ON THE THERMOHYDRAULIC PERFORMANCE OF NOVEL ITSCEB MICROCHANNEL HEAT SINK USING Al2O3 NANOFLUID

INVESTIGATIONS ON THE THERMOHYDRAULIC PERFORMANCE OF NOVEL ITSCEB MICROCHANNEL HEAT SINK USING Al2O3 NANOFLUID

Hydrodynamic and Thermal Performance of In-Line Strip-Fin Manifold Microchannel Heat Sink

Hydrodynamic and Thermal Performance of In-Line Strip-Fin Manifold Microchannel Heat Sink

Numerical Investigation of Various Twisted Tapes Enhancing a Circular Microchannel Heat Sink Performance

Numerical Investigation of Various Twisted Tapes Enhancing a Circular Microchannel Heat Sink Performance

Numerical study on two-phase boiling heat transfer performance of interrupted microchannel heat sinks

Numerical study on two-phase boiling heat transfer performance of interrupted microchannel heat sinks

Thermal performance of a central-jetting microchannel heat sink designed for a high-power laser crystal

Thermal management has become one of the critical problems in high-power laser systems. The laser crystal, which dissipates a heat flux over 150 W/cm2, is the most challenging component when solving the thermal problem. In this work, a specialized central-jetting microchannel heat sink (MCHS) is proposed purposely for a small-size laser crystal with high heat fluxes. Considering the space constraint and installation restriction, the MCHS has a narrow width to fit with the laser crystal, while its length is extended to enhance the heat dissipation capability. The MCHS is integrated by welding the two layers completely through a vacuum brazing method. Central-jetting impingement is introduced to enhance the cooling efficiency. Coolant is flushed vertically into the microchannel layer toward the central heating region where the heating source is attached at the central bottom of the MCHS. We conduct a parametric study on the thermal performance of the MCHS by experiments. The overall heat transfer coefficient of the MCHS achieves 50 × 103 W/(m2•K), and the average heat transfer coefficient of the microchannel reaches 21.5 × 103 W/(m2•K). The surface temperature of the heating head is controlled below 65 °C, and the temperature variation is less than 5 °C. In the solid bottom of the MCHS, thermal resistance in vertical direction is over 1.8 times of that in the horizontal direction, ensuring an efficient heat dissipation in the extended volume. The local heat transfer characteristics are further examined through additional numerical simulations. The wall temperature of the microchannel and the local heat transfer coefficient have a high plateau in the heating region, and then drop significantly along the flow direction. Due to heat transfer enhancement by jet impingement, the heat transfer coefficient in the central region is generally 15% higher than that averaged on the full microchannel.