Numerical Prediction of Flow and Heat Transfer Rates in Metal Based Microchannels Using Lattice Boltzmann Method

2008 ◽  
Author(s):  
Pritish R. Parida ◽  
Srinath V. Ekkad
Keyword(s):  
Heat Transfer ◽  
Lattice Boltzmann ◽  
Heat Dissipation ◽  
Transfer Problem ◽  
High Heat ◽  
Lattice Boltzmann Model ◽  
Channel Height ◽  
High Heat Transfer ◽  
Viscous Heat ◽  
Micro Channels

Metal-based Microchannel Heat Exchangers (MHEs) are of current interest due to the combination of high heat transfer performance and improved mechanical integrity. In the present work, a simple two-dimensional thermal lattice Boltzmann model without viscous heat dissipation and pressure compressible work has been developed to simulate the heat transfer phenomenon in Cu- and Al-based micro-channels. A 2D fluid-solid conjugate heat transfer problem is solved using LBM and Fluent. For the Cu specimen, the height of the channel considered was 204 μm and the top and bottom wall thickness was taken to be same as the channel height. The LBM results were compared with 3D and 2D fluent models. The study also compares the numerically computed velocity profile with the analytical results and compares the Nusselt number values predicted by LBM and Fluent with the experimental data. Owing to the simplicity of the thermal LB model, promising results were obtained from the LBM predictions.

scholarly journals WEDM of Copper for the Fabrication of Large Surface-Area Micro-Channels: A Prerequisite for the High Heat-Transfer Rate

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 173 ◽  
Author(s):  
Naveed Ahmed ◽  
Mohammad Pervez Mughal ◽  
Waqar Shoaib ◽  
Syed Farhan Raza ◽  
Abdulrhman M. Alahmari
Keyword(s):  
Heat Transfer ◽  
Surface Area ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
High Heat ◽  
Critical Feature ◽  
Maximum Heat ◽  
High Heat Transfer ◽  
Maximum Heat Transfer ◽  
Micro Channels

To get the maximum heat transfer in real applications, the surface area of the micro-features (micro-channels) needs to be large as possible. It can be achieved by producing a maximum number of micro-channels per unit area. Since each successive pair of the micro-channels contain an inter-channels fin, therefore the inter-channels fin thickness (IFT) plays a pivotal role in determining the number of micro-channels to be produced in the given area. During machining, the fabrication of deep micro-channels is a challenge. Wire-cut electrical discharge machining (EDM) could be a viable alternative to fabricate deep micro-channels with thin inter-channels fins (higher aspect ratio) resulting in larger surface area. In this research, minimum IFT and the corresponding machining conditions have been sought for producing micro-channels in copper. The other attributes associated with the micro-channels have also been deeply investigated including the inter-channels fin height (IFH), inter-channels fin radius (IFR) and the micro-channels width (MCW). The results reveal that the inter-channels fin is the most critical feature to control during the wire electrical discharge machining (WEDM) of copper. Four types of fin shapes have been experienced, including the fins: broken at the top end, deflected at the top end, curled bend at the top, and straight with no/negligible deflection.

Heat Dissipation Beyond 1 kW/cm2 With Low Pressure Drop and High Heat Transfer Coefficient for Flow Boiling Using Open Microchannels With Tapered Manifold

2016 ◽  
Author(s):  
Ankit Kalani ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Heat Dissipation ◽  
Flow Boiling ◽  
Low Pressure ◽  
High Heat ◽  
High Heat Transfer ◽  
High Heat Transfer Coefficient

Heat dissipation beyond 1 kW/cm2 accompanied with high heat transfer coefficient and low pressure drop using water has been a long-standing goal in the flow boiling research directed toward electronic cooling application. In the present work, three approaches are combined to reach this goal: (a) a microchannel with a manifold to increase critical heat flux (CHF) and heat transfer coefficient (HTC), (b) a tapered manifold to reduce the pressure drop, and (c) high flow rates for further enhancing CHF from liquid inertia forces. A CHF of 1.07 kW/cm2 was achieved with a heat transfer coefficient of 295 kW/m2°C with a pressure drop of 30 kPa. Effect of flow rate on CHF and HTC is investigated. High speed visualization to understand the underlying bubble dynamics responsible for low pressure drop and high CHF is also presented.

Development of Heat Sinks for Air Cooling and Water Cooling Using Lotus-Type Porous Metals

2011 ◽  
Author(s):  
H. Chiba ◽  
T. Ogushi ◽  
H. Nakajima
Keyword(s):  
Heat Transfer ◽  
Porous Materials ◽  
Heat Sink ◽  
High Heat ◽  
Heat Sinks ◽  
Air Cooling ◽  
Water Cooling ◽  
Cooling Performance ◽  
High Heat Transfer ◽  
Micro Channels

In recent years, since heat dissipation rates and high frequency electronic devices have been increasing, a heat sink with high heat transfer performance is required to cool these devices. Heat sink utilizing micro-channels with several ten microns are expected to provide an excellent cooling performance because of their high heat transfer capacities due to small channel. Therefore, various porous materials such as cellular metals have been investigated for heat sink applications. However, heat sink using conventional porous materials has a high pressure drop because the cooling fluid flow through the pores is complex. Among the described porous materials, a lotus-type porous metal with straight pores is preferable for heat sinks due to the small pressured drop. In present work, cooling performance of the lotus copper heat sink for air cooling and water cooling is introduced. The experimental data for air cooling show 13.2 times higher than that for the conventional groove fins. And, the data for the water cooling show 1.7 times higher than that for the micro-channels. It is concluded that lotus copper heat sink is the most prospective candidate for high power electronics devices.

THERMAL LATTICE BOLTZMANN MODEL WITH VISCOUS HEAT DISSIPATION IN THE INCOMPRESSIBLE LIMIT

2006 ◽  
Vol 17 (08) ◽  
pp. 1131-1139 ◽  
Author(s):  
ZHI-WEI TIAN ◽  
CHUN ZOU ◽  
H. J. LIU ◽  
Z. H. LIU ◽  
Z. L. GUO ◽  
...  
Keyword(s):  
Lattice Boltzmann ◽  
Heat Dissipation ◽  
Lattice Boltzmann Model ◽  
Incompressible Limit ◽  
Material Derivative ◽  
Computation Cost ◽  
Viscous Heat ◽  
Derivative Term ◽  
Thermal Lattice Boltzmann ◽  
Boltzmann Model

A novel thermal lattice Boltzmann (LB) model is proposed to obtain the viscous heat term expediently. Unlike the existing thermal LB models, this model is entirely based on the framework of the LB method and directly derived from the macro temperature equation. Moreover, the computation cost decreases because the computation of complicated material derivative term has been avoided successfully. To testify the simulation capability of this model, the thermal Couette flow is simulated and the results indicate agreement with the analytical solutions.

High Efficiency Heat Sinks from Polycrystalline Diamond Grown by CVD Method

2006 ◽  
Vol 956 ◽  
Author(s):  
Oleg A. Voronov ◽  
Gary S. Tompa ◽  
Veronika Veress
Keyword(s):  
Heat Transfer ◽  
Semiconductor Lasers ◽  
High Efficiency ◽  
Heat Removal ◽  
High Heat ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Measuring System ◽  
High Heat Transfer ◽  
Micro Channels

ABSTRACTWhile absolute power levels in microelectronic devices are relatively modest (a few tens to a few hundred watts), heat fluxes can be significant (through 50 W/cm2 in current electronic chips and up to 2000 W/cm2 in semiconductor lasers). Diamond heat sinks enable heat transfer rates well above what is possible with standard thermal management devices. We have fabricated heat sinks using diamond, which has the highest temperature thermal conductivity of any known material. Polycrystalline diamonds manufactured by chemical vapor deposition (CVD) are machined by laser and combined with metallic or ceramic tiles. Cooling by fluid flow through micro-channels enhances heat removal. These unique attributes make diamond based heat sinks prime contenders for the next generation of high heat load sinks. Such devices could be utilized for efficient cooling in a variety of applications requiring high heat transfer capability, including semiconductor lasers, microprocessors, multi-chip modules in computers, laser-diode arrays, radar systems, and high-flux optics, among other applications. This paper will review test designs, heat flux measuring system, and measured heat removal values.

AN IMPROVED THERMAL LATTICE BOLTZMANN MODEL FOR FLOWS WITHOUT VISCOUS HEAT DISSIPATION AND COMPRESSION WORK

2008 ◽  
Vol 19 (01) ◽  
pp. 125-150 ◽  
Author(s):  
Q. LI ◽  
Y. L. HE ◽  
Y. WANG ◽  
G. H. TANG
Keyword(s):  
Distribution Function ◽  
Lattice Boltzmann ◽  
Heat Dissipation ◽  
Lattice Boltzmann Model ◽  
Two Dimensional ◽  
Bgk Model ◽  
Function Lattice ◽  
Viscous Heat ◽  
Boltzmann Model ◽  
Benchmark Solutions

An improved lattice Boltzmann model is proposed for thermal flows in which the viscous heat dissipation and compression work by the pressure can be neglected. In the improved model, the whole complicated gradient term in the internal energy density distribution function model is correctly discarded by modifying the velocity moments' condition. The corresponding macroscopic energy equation is exactly derived through Chapman–Enskog expansion. In particular, based on the improved thermal model, a double-distribution-function lattice BGK model is developed for two-dimensional Boussinesq flow, which is a typical flow with negligible viscous heat dissipation and compression work. A two-dimensional plane flow and the natural convection of air in a square cavity with various Rayleigh numbers are simulated by using the double-distribution-function lattice BGK model. It is found that there is excellent agreement between the present results with the analytical or benchmark solutions.

Channel Height and Jet Spacing Effect on Heat Transfer and Uniformity Coefficient on an Inline Row Impingement Channel

2010 ◽  
Author(s):  
Mark Ricklick ◽  
Roberto Claretti ◽  
J. S. Kapat
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Cross Flow ◽  
High Heat ◽  
Channel Height ◽  
Transfer Coefficients ◽  
Uniformity Coefficient ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Side Walls

Future high performance turbine airfoils will likely be cooled in a near wall configuration, potentially employing a combination of narrow, distributed internal cooling channels and impingement. In such applications, the jets impinge against a target surface, and then exit along the channel formed by the jet plate, target plate, and side walls. Local convection coefficients are the result of both the jet impact, as well as the channel flow produced from the exiting jets and the complex interaction between the jet and the cross flow. Numerous studies have explored the effects of jet array and channel configurations on both target and jet plate heat transfer coefficients, yet with little consideration of thermal stress related effects. A detailed study on the uniformity coefficient that these jets and cross flow generate on the surface is carried out. It is important to maintain a high uniformity coefficient while still having a high heat transfer coefficients to reduce thermal stresses. It is also important to use as little flow as possible while maintaining a high heat transfer coefficient. The study presented experimentally investigates the effects of wall height, jet Reynolds number, and jet spacing on the Nusselt number and uniformity of a narrow inline row impingement channel. The channel height was set at 1, 3, and 5 diameters, jet spacing was 5 and 15 diameters, and the channel width was kept constant at 4 diameters. Although heat transfer coefficients are highly sensitive to the jet Reynolds number and channel height, the uniformity of the distribution is mainly governed by the channel height and jet spacing. A channel height of 3 jet diameters tended to produce the best uniformity coefficients, regardless of the jet to jet spacing; with side walls out performing target surfaces.

Heat Transfer and Friction Loss Characteristics of Pin Fin Cooling Configurations

1984 ◽  
Vol 106 (1) ◽  
pp. 246-251 ◽  
Author(s):  
Yao Peng
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
High Surface ◽  
High Heat ◽  
Friction Loss ◽  
Channel Height ◽  
Pin Fin ◽  
High Heat Transfer ◽  
High Heat Transfer Rate

Pin fin or full cross pin cooling configurations have long been of interest to the turbine cooling designer because of their potentially high heat transfer characteristics and high surface area density, as well as their structural and castability advantages. The pin fin cooling configurations consist of flow channels with circular pins extending from the walls into the channel flow. The pin fins function as turbulators to produce high heat transfer rate; however, their geometric arrangement must be optimized to avoid high friction loss. Experimental tests have been conducted to investigate the effects of pin heights, spacings, and channel height to length ratios to the heat transfer and friction loss characteristics of the pin fin cooling configurations. The test results indicate that the pin fin configuration provides a means to reduce the flow friction loss and yet to maintain a reasonably high heat transfer rate as compared to the cross pin configuration. The pin spacing in the test range shows less effects on the pin fin performance than the pin height.

Thermal Analysis of Plastic Serpentine-Type Microchannel Evaporators

2007 ◽  
Author(s):  
Boris Kosoy ◽  
Mehmet Arik
Keyword(s):  
Heat Transfer ◽  
Removal Rate ◽  
Flow Characteristics ◽  
Heat Removal ◽  
High Heat ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
High Heat Transfer ◽  
Micro Channels

Recently, microchannel liquid cooling technology showed very high heat transfer coefficients enabling high heat fluxes at allowable wall temperatures. It promises to be a potential solution to high flux electronics. This paper presents result of two related areas in the field of microchannel heat transfer. First, experimental results of serpentine-type fluoroplastic evaporated thermosyphons for microchannel applications are presented. R11 and R113 were used as working fluid, and it was shown that R11 has higher heat removal rate than R113. Flow distribution and flow characteristics (liquid, vapor, mixture etc) are discussed. Later discussion is extended towards key issues in mini and micro channels, and proposed correlations will be discussed. It is our great honor to contribute to Prof. Sadik Kakac symposium to celebrate his 75th birthday. We feel privileged knowing him and learning from his scientific books, papers, and personal discussions. We wish him a happy, healthy, and long life.

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