Analysis of Pumping Requirements for Microchannel Cooling Systems

2003 ◽  
Author(s):  
Vishal Singhal ◽  
Dong Liu ◽  
Suresh V. Garimella
Keyword(s):  
Heat Sink ◽  
Removal Rate ◽  
Heat Removal ◽  
Critical Factor ◽  
Pressure Head ◽  
Heat Sinks ◽  
Microchannel Heat Sink ◽  
Pressure Drops ◽  
Large Pressure ◽  
Microchannel Cooling

Large pressure drops, and the associated pumping requirements, are often considered the most critical factor hindering widespread commercial use of microchannel heat sinks. Analytical methods are used in the present work to arrive at the pumping requirements for any given microchannel heat sink. A graphical method to check the suitability of a pump to a microchannel heat sink application has been devised. The size of the microchannels is also optimized so that for a specified heat removal rate, the pumping requirements are minimized. A number of commercially available pumps as well as several micropumps presented in the literature are compared based on their flow rate, pressure head and physical size to assess their suitability for a specific representative cooling application.

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.

scholarly journals Experimental and Numerical Thermal Analysis of Multi-Layered Microchannel Heat Sink for Concentrating Photovoltaic Application

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 122 ◽  
Author(s):  
Idris Al Siyabi ◽  
Sourav Khanna ◽  
Senthilarasu Sundaram ◽  
Tapas Mallick
Keyword(s):  
Heat Source ◽  
Heat Sink ◽  
Heat Removal ◽  
Heat Sinks ◽  
Heat Transfer Fluid ◽  
Microchannel Heat Sink ◽  
Source Temperature ◽  
Number Of Layers ◽  
Heat Source Temperature ◽  
Heating Load

Concentrating photovoltaic has a major challenge due to the high temperature raised during the process which reduces the efficiency of the solar cell. A multi-layered microchannel heat sink technique is considered more efficient in terms of heat removal and pumping power among many other cooling techniques. Thus, in the current work, multi-layered microchannel heat sink is used for concentrating photovoltaic cooling. The thermal behavior of the system is experimentally and numerically investigated. The results show that in extreme heating load of 30 W/cm2 with heat transfer fluid flow rate of 30 mL/min, increasing the number of layers from one to four reduces the heat source temperature from 88.55 to 73.57 °C. In addition, the single layered MLM heat sink suffers from the highest non-uniformity in the heat source temperature compared to the heat sinks with the higher number of layers. Additionally, the results show that increasing the number of layers from one to four reduces the pressure drop from 162.79 to 32.75 Pa.

Stacked Microchannel Heat Sinks for Liquid Cooling of Microelectronic Components

2000 ◽  
Author(s):  
X. Wei ◽  
Y. Joshi
Keyword(s):  
Flow Rate ◽  
Heat Sink ◽  
Water Flow Rate ◽  
Heat Removal ◽  
Single Layer ◽  
Heat Sinks ◽  
Computationally Efficient ◽  
Liquid Cooling ◽  
Number Of Layers ◽  
Microelectronic Components

Abstract A novel heat sink based on a multi-layer stack of liquid cooled microchannels is investigated. For a given pumping power and heat removal capability for the heat sink, the flow rate across a stack of microchannels is lower compared to a single layer of microchannels. Numerical simulations using a computationally efficient multigrid method [1] were carried out to investigate the detailed conjugate transport within the heat sink. The effects of the microchannel aspect ratio and total number of layers on thermal performance were studied for water as coolant. A heat sink of base area 10 mm by 10 mm with a height in the range 1.8 to 4.5 mm (2–5 layers) was considered with water flow rate in the range 0.83×10−6 m3/s (50 ml/min) to 6.67×10−6 m3/s (400 ml/min). The results of the computational simulations were also compared with a simplified thermal resistance network analysis.

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.  

Performance Comparison of Microchannel Heat Sink Using Boron-Based Ceramic Materials

2021 ◽  
Vol 1163 ◽  
pp. 73-88
Author(s):  
Md Tanbir Sarowar
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Sink ◽  
Electronic Devices ◽  
Ceramic Materials ◽  
Substrate Material ◽  
Heat Sinks ◽  
Maximum Temperature ◽  
Microchannel Heat Sink ◽  
Small Surface

Microchannel heat sink plays a vital role in removing a considerable amount of heat flux from a small surface area from different electronic devices. In recent times, the rapid development of electronic devices requires the improvement of these heat sinks to a greater extent. In this aspect, the selection of appropriate substrate materials of the heat sinks is of vital importance. In this paper, three boron-based ultra-high temperature ceramic materials (ZrB2, TiB2, and HfB2) are compared as a substrate material for the microchannel heat sink using a numerical approach. The fluid flow and heat transfer are analyzed using the finite volume method. The results showed that the maximum temperature of the heat source didn’t exceed 355K at 3.6MWm-2 for any material. The results also indicated HfB2 and TiB2 to be more useful as a substrate material than ZrB2. By applying 3.6 MWm-2 heat flux at the source, the maximum obtained surface heat transfer coefficient was 175.2 KWm-2K-1 in a heat sink having substrate material HfB2.

Optimization Under Uncertainty of Manifold Microchannel Heat Sinks

2012 ◽  
Author(s):  
Suchismita Sarangi ◽  
Karthik K. Bodla ◽  
Suresh V. Garimella ◽  
Jayathi Y. Murthy
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Heat Sink ◽  
Heat Sinks ◽  
Optimization Under Uncertainty ◽  
Microchannel Heat Sink ◽  
Probabilistic Optimization ◽  
Manifold Microchannel

Conventional microchannel heat sinks provide good heat dissipation capability but are associated with high pressure drop and corresponding pumping power. The use of a manifold system that distributes the flow into the microchannels through multiple, alternating inlet and outlet pairs is investigated here. This manifold arrangement greatly reduces the pressure drop incurred due to the smaller flow paths, while simultaneously increasing the heat transfer coefficient by tripping the thermal boundary layers. A three-dimensional numerical model is developed and validated, to study the effect of various geometric parameters on the performance of the manifold microchannel heat sink. Apart from a deterministic analysis, a probabilistic optimization study is also performed. In the presence of uncertainties in the geometric and operating parameters of the system, this probabilistic optimization approach yields an optimal design that is also robust and reliable. Uncertainty-based optimization also yields auxiliary information regarding local and global sensitivities and helps identify the input parameters to which outputs are most sensitive. This information can be used to design improved experiments targeted at the most sensitive inputs. Optimization under uncertainty also provides a quantitative estimate of the allowable uncertainty in input parameters for an acceptable uncertainty in the relevant output parameters. The optimal geometric design parameters with uncertainties that maximize heat transfer coefficient while minimizing pressure drop for fixed input conditions are identified for a manifold microchannel heat sink. A comparison between the deterministic and probabilistic optimization results is also presented.

Next Generation Devices for Electronic Cooling

2003 ◽  
Author(s):  
Ralph L. Webb
Keyword(s):  
Heat Sink ◽  
New Technology ◽  
Heat Removal ◽  
Cost Effective ◽  
Heat Sinks ◽  
Working Fluid ◽  
Two Phase ◽  
Conventional Technology ◽  
Removal Technology ◽  
R Value

Conventional technology to cool desktop computers and servers is that of the “direct heat removal” heat sink, which consists of a heat sink/fan mounted on the CPU. Although this is a very cost effective solution, it is nearing its end of life. This is because future higher power CPUs will require a lower R-value than can be provided by this technology, within current size and fan limits. This paper discusses new technology that uses “indirect heat removal” technology, which involves use of a single or two-phase working fluid to transfer heat from the hot source to an ambient heat sink. This technology will support greater heat rejection than is possible with the “direct heat removal” method. Further, it will allow use of higher performance air-cooled ambient heat sinks than are possible with the “direct heat removal” heat sink. A concern of the indirect heat removal technology is the possibility that it may be orientation sensitive. This paper identifies preferred options and discusses the degree to which they are (or or not) orientation sensitive. It should be possible to attain an R-value of 0.12K/W at the balance point on the fan curve.

Design of a Microscale Breather for Two-Phase Thermal Management Devices

2008 ◽  
Author(s):  
B. R. Alexander ◽  
E. N. Wang
Keyword(s):  
Phase Change ◽  
Removal Rate ◽  
Heat Removal ◽  
Design Guidelines ◽  
Heat Sinks ◽  
Two Phase ◽  
Cross Sectional ◽  
Optical Visualization ◽  
Gas Removal ◽  
Microchannel Heat Sinks

Two-phase microchannels promise an efficient method to dissipate heat from high performance electronic systems by utilizing the latent heat of vaporization during the phase-change process. However, phase-change in microchannel heat sinks leads to challenges that are not present in macroscale systems due to the increasing importance of surface tension and viscous forces. In particular, flow instabilities often occur during the boiling process, which lead to liquid dry-out in the microchannels and severely limits the heat removal capabilities of the system. We propose a microscale breather device consisting of an array of hydrophobic breather ports which allow vapor bubbles to escape from the microchannels to improve flow stability. In this study, we use the combination of microfabricated structures and surface chemistry to separate vapor from the liquid flow. We designed test devices that allow for cross-sectional optical visualization to better understand the governing parameters of a breather design with high vapor removal efficiencies and minimal liquid leakage. We examined breather devices with average liquid velocities ranging from 0.5 cm/s to 4 cm/s and breather vacuum levels between 1 kPa and 9 kPa on the maximum gas removal rate through the breather. We demonstrated successful breather performance. In addition, a model was developed that offers design guidelines for future integrated breathers in microchannel heat sinks. The breathers also have significant promise for other microscale systems, such as micro-fuel cells, where liquid-vapor separation can significantly enhance system performance.

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.

Numerical Study of Forced Convection of Nanofluids in a Microchannel Heat Sink

2008 ◽  
Author(s):  
Parisa Vaziee ◽  
Omid Abouali
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Sink ◽  
Volume Fraction ◽  
Numerical Study ◽  
Heat Removal ◽  
Al2o3 Nanoparticles ◽  
Microchannel Heat Sink ◽  
Particle Volume ◽  
Volume Fractions

Effectiveness of the microchannel heat sink cooled by nanofluids with various particle volume fractions is investigated numerically using the latest theoretical models for conductivity and viscosity of the nanofluids. Both laminar and turbulent flows are considered in this research. The model of conductivity used in this research accounts for the fundamental role of Brownian motion of the nanoparticles which is in good agreement with the experimental data. The changes in viscosity of the nanofluid due to temperature variation are considered also. Final results are compared with the experimental measurements for heat transfer coefficient and pressure drop in microchannel. Enhancement in heat transfer is achieved for laminar flow with increasing of volume fraction of Al2O3 nanoparticles. But for turbulent flow an enhancement of heat removal was not seen and using higher volume fractions of nanoparticles increases the maximum substrate temperature. Pressure drop is increased with using nanofluids because of the augmentation in the viscosity and this increase is more noticeable in higher Reynolds numbers.

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