Numerical Simulations for Digitized Heat Transfer

2009 ◽  
Author(s):  
Eric Baird ◽  
Kamran Mohseni
Keyword(s):  
Heat Transfer ◽  
Thermal Management ◽  
Liquid Metals ◽  
Heat Removal ◽  
Heat Sinks ◽  
Management Technique ◽  
High Power Density ◽  
Transfer Rates ◽  
Integrated Microsystems ◽  
High Degree

This paper presents estimates of heat removal capabilities of a Digitized Heat Transfer (DHT) cooled device, a novel active thermal management technique for high power density electronics and integrated microsystems. In DHT, thermal energy is transported by a discrete array of electrostatically activated microdroplets of liquid metals, alloys or aqueous solutions with the potential of supporting significantly higher heat transfer rates than classical air-cooled heat sinks. Actuation methods for dispensing and transporting individual fluid slugs with a high degree of precision and programmability are described, and numerical results for the amount of heat flux removal a DHT device can obtain are presented.

Electrowetting Droplet Manipulation for Application in Thermal Management of Compact Microsystems

2006 ◽  
Author(s):  
Kamran Mohseni ◽  
Eric Baird
Keyword(s):  
Heat Transfer ◽  
Substrate Temperature ◽  
Liquid Metals ◽  
Heat Sinks ◽  
Active Management ◽  
Management Technique ◽  
Transfer Rates ◽  
Electrowetting On Dielectric ◽  
Micro Systems ◽  
High Degree

Digitized heat transfer (DHT), a novel active management technique for high power density electronic and integrated micro systems in which heat is transported by a discrete array of electrostatically activated microdroplets, is proposed. Liquids, especially liquid metals or alloys, support significantly higher heat transfer rates than classical air-cooled heat sinks; in addition, discrete microdroplets are shown to be actuated and controlled with a high degree of precision and programmability. As a consequence, DHT is a viable new alternative for achieving the most important objectives of electronic cooling, i.e., minimization of the maximum substrate temperature, reduction of the substrate temperature gradient and removal of substrate hot spots. Three methods of microdroplet actuation, electrowetting on dielectric (EWOD), dielectrophoresis (DEP), and continuous electrowetting (CEW), are described, with simple results for steady state velocities in terms of known parameters. The use of EWOD to transport a droplet of commercially available liquid metal is reported. In addition, preliminary considerations on the heat transfer rates of such droplets are presented, with a simple analysis leading to a generalization of the continuous Nusselt number to a discretized flow.

Additive Manufactured, Low EMI, Non-Metallic Convective Heat Spreader Design and Optimization

2019 ◽  
Author(s):  
Reece Whitt ◽  
David Huitink ◽  
Skyler Hudson ◽  
Bakhtiyar Nafis ◽  
Zhao Yuan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Thermal Management ◽  
Convective Heat ◽  
Electromagnetic Interference ◽  
Electronic Device ◽  
Heat Removal ◽  
Heat Sinks ◽  
Metallic Materials ◽  
Transfer Coefficients

Abstract With the increase of electronic device power density, thermal management and reliability are becoming increasingly important. First, increased density challenges the capability of conventional heat sinks to adequately dissipate heat. Secondly, higher frequency switching in wide bandgap power modules is introducing new issues in electromagnetic interference (EMI) in which metallic heat removal systems will couple and create damaging current ringing. Lastly, lightweight heat removal is required to meet the increasing needs of mobile power systems. In this effort we introduce an additive manufacturing pathway to produce custom-tailored heat removal systems using non-metallic materials, which take advantage of convective heat transfer to enable efficient thermal management. Herein, we leverage the precision of AM techniques in the development of 3D optimized flow channels for achieving enhanced effective convective heat transfer coefficients. The experimental performance of convective heat removal due to liquid impingement is compared with conventional heat sinks, with the requirement of simulating the heat transfer needed by a high voltage inverter. The implementation of non-metallic materials manufacturing is aimed to reduce EMI in a low weight and reduced cost package, making it useful for mobile power electronics.

Additive Manufactured Impinging Coolant, Low Electromagnetic Interference, and Nonmetallic Heat Spreader: Design and Optimization

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Reece Whitt ◽  
Skyler Hudson ◽  
David Huitink ◽  
Zhao Yuan ◽  
Asif Emon ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Additive Manufacturing ◽  
Thermal Management ◽  
Convective Heat ◽  
High Voltage ◽  
Electromagnetic Interference ◽  
Electronic Device ◽  
Heat Removal ◽  
Heat Sinks ◽  
Transfer Coefficients

Abstract With the increase of electronic device power density, thermal management and reliability are increasingly critical in the design of power electronic systems. First, increased density challenges the capability of conventional heat sinks to adequately dissipate heat. Second, higher frequency switching in high voltage, high current, wide bandgap power modules is creating intensified electromagnetic interference (EMI) challenges, in which metallic heat removal systems will couple and create damaging current ringing. Furthermore, mobile power systems require lightweight heat removal methods that satisfy the heat loads dissipated during operation. In this effort, we introduce an additive manufacturing (AM) pathway to produce custom heat removal systems using nonmetallic materials, which take advantage of impinging fluid heat transfer to enable efficient thermal management. Herein, we leverage the precision of additive manufacturing techniques in the development of three-dimensional optimized flow channels for achieving enhanced effective convective heat transfer coefficients. The experimental performance of convective heat removal due to liquid impingement is compared with conventional heat sinks, with the requirement of simulating the heat transfer needed by a high voltage inverter. The implementation of nonmetallic materials manufacturing is aimed to reduce electromagnetic interference in a low weight and reduced cost package, making it useful for mobile power electronics.

scholarly journals Heat transfer enhancement of car radiator using aqua based magnesium oxide nanofluids

2015 ◽  
Vol 19 (6) ◽  
pp. 2039-2048 ◽  
Author(s):  
Hafiz Ali ◽  
Muhammad Azhar ◽  
Musab Saleem ◽  
Qazi Saeed ◽  
Ahmed Saieed
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Thermal Management ◽  
Heat Transfer Performance ◽  
Inlet Temperature ◽  
Fluid Temperature ◽  
Transfer Enhancement ◽  
Volumetric Concentration ◽  
Flow Rates ◽  
Transfer Rates

The focus of this research paper is on the application of water based MgO nanofluids for thermal management of a car radiator. Nanofluids of different volumetric concentrations (i.e. 0.06%, 0.09% and 0.12%) were prepared and then experimentally tested for their heat transfer performance in a car radiator. All concentrations showed enhancement in heat transfer compared to the pure base fluid. A peak heat transfer enhancement of 31% was obtained at 0.12 % volumetric concentration of MgO in basefluid. The fluid flow rate was kept in a range of 8-16 liter per minute. Lower flow rates resulted in greater heat transfer rates as compared to heat transfer rates at higher flow rates for the same volumetric concentration. Heat transfer rates were found weakly dependent on the inlet fluid temperature. An increase of 8?C in inlet temperature showed only a 6% increase in heat transfer rate.

High Power CPU Cooling Experiment

1995 ◽  
Author(s):  
Elizabeth B. Nadworny ◽  
T. Gary Yip ◽  
Nader Farag
Keyword(s):  
Heat Transfer ◽  
High Power ◽  
Power Dissipation ◽  
Heat Removal ◽  
Data Acquisition System ◽  
Heat Sinks ◽  
Small Scale ◽  
Heat Transfer Area ◽  
Pin Fin ◽  
Transfer Parameters

Abstract This experimental study focuses on the enhancement of the heat removal process by modifying the geometry of pin fin heat sinks, while maintaining the same effective heat transfer area. The pins are cut at an angle to reduce the blockage of air flow across the surface. To perform this study, a small scale wind tunnel facility has been designed specifically for testing high power dissipation processors and other ULSI components. The facility is fully automated and controlled by an HP3852A Data Acquisition System interfaced with a 486 based PC computer. The average surface temperature, Reynolds number, Nusselt number and other relevant heat transfer parameters were reduced from the data collected. Results from the study show that a heat sink with an angled trailing edge produces the greatest enhancement of heat removal. The mechanism for the improved heat transfer is the larger temperature gradient across the surface, which is obtained by lowering the minimum temperature on the surface.

A Study of Forced Convection Direct Air Cooling in the Downstream Vicinity of Heat Sinks

1990 ◽  
Vol 112 (3) ◽  
pp. 234-240 ◽  
Author(s):  
G. L. Lehmann ◽  
S. J. Kosteva
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Heat Sink ◽  
Convection Heat Transfer ◽  
Heat Sinks ◽  
Air Cooling ◽  
Transfer Coefficients ◽  
Packaging System ◽  
Transfer Rates ◽  
Heat Transfer Coefficients

An experimental study of forced convection heat transfer is reported. Direct air cooling of an electronics packaging system is modeled by a channel flow, with an array of uniformly sized and spaced elements attached to one channel wall. The presence of a single or complete row of longitudinally finned heat sinks creates a modified flow pattern. Convective heat transfer rates at downstream positions are measured and compared to that of a plain array (no heat sinks). Heat transfer rates are described in terms of adiabatic heat transfer coefficients and thermal wake functions. Empirical correlations are presented for both variations in Reynolds number (5000 < Re < 20,000) and heat sink geometry. It is found that the presence of a heat sink can both enhance and degrade the heat transfer coefficient at downstream locations, depending on the relative position.

Perspiration Nano-Patch for Hot Spot Thermal Management

2007 ◽  
Author(s):  
Shankar Narayanan ◽  
Andrei G. Fedorov ◽  
Yogendra K. Joshi
Keyword(s):  
Heat Transfer ◽  
Thermal Management ◽  
Hot Spot ◽  
Evaporative Cooling ◽  
Heat Removal ◽  
Heat Fluxes ◽  
Conceptual System ◽  
Sweeping Gas ◽  
Phase Change Heat Transfer ◽  
Latent Heat Of Vaporization

A novel cooling scheme utilizing evaporative cooling for an ultra-thin, spatially confined liquid film is described for meeting the challenge of hot spot thermal management aiming at locally removing heat fluxes in excess of 200 W/cm2. This work presents the conceptual system design and results of performance calculations supporting the feasibility of the proposed cooling scheme. The phase change heat transfer is one of the most efficient means of heat transfer due to an advantage offered by the significant latent heat of vaporization of liquids. Fundamentally, evaporation could be a much more efficient method of heat removal as compared to boiling if certain conditions are met. Theoretically, we demonstrate that if a stable monolayer of liquid can be maintained on the surface and fully dry sweeping gas (e.g., air) is blown at high velocity above this liquid monolayer one can dissipate heat fluxes of the order of several hundreds of Watts per cm2. We also show that a more volatile FC-72 can outperform water in evaporative cooling using stable liquid microfilms.

Laminar Natural Convection Heat Transfer From a Horizontal Circular Cylinder to Liquid Metals

1991 ◽  
Vol 113 (1) ◽  
pp. 91-96 ◽  
Author(s):  
K. Sugiyama ◽  
Y. Ma ◽  
R. Ishiguro
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Circular Cylinder ◽  
Liquid Metals ◽  
Convection Heat Transfer ◽  
Boussinesq Approximation ◽  
Large Temperature ◽  
Transfer Rates ◽  
Laminar Natural Convection ◽  
Horizontal Circular Cylinder

The objective of the present study is to clarify the heat transfer characteristics of natural convection around a horizontal circular cylinder immersed in liquid metals. Experimental work concerning liquid metals sometimes involves such a degree of error that it is impossible to understand the observed characteristics in a measurement. Numerical analysis is a powerful means to overcome this experimental disadvantage. In the present paper we first show that the Boussinesq approximation is more applicable to liquid metals than to ordinary fluids and that the present analysis gives accurate heat transfer rates, even for a cylinder with a relatively large temperature difference (>100 K) between the heat transfer surface and fluid. It is found from a comparison of the present results with previous work that the correlation equations that have already been proposed predict values lower than the present ones.

scholarly journals Numerical study for heat transfer enhancement using CuO water nanofluids through mini-channel heat sinks for microprocessor cooling

2020 ◽  
Vol 24 (5 Part A) ◽  
pp. 2965-2976 ◽  
Author(s):  
Muhammad Anwar ◽  
Hussain Tariq ◽  
Ahmad Shoukat ◽  
Hafiz Ali ◽  
Hassan Ali
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Numerical Study ◽  
Heat Removal ◽  
Maximum Flow ◽  
Heat Sinks ◽  
Base Temperature ◽  
Transfer Enhancement ◽  
Percentage Difference ◽  
Fin Spacing

Water cooled heat sinks are becoming popular due to increased heat generation inside the microprocessor. Timely heat removal from microprocessor is the key factor for better performance and long life. Heat transfer enhancement is reached either by increasing the surface area density and/or by altering the base fluid properties. Nanoparticles emerge as a strong candidate to increase the thermal conductivity of base fluids. In this research, the thermal performance of mini-channel heat sinks for different fin spacing (0.2 mm, 0.5 mm, 1 mm, and 1.5 mm) was investigated numerically using CuO-water nanofluids with volumetric concentration of 1.5%. The numerical values computed were than compared with the literature and a close agreement is achieved. We recorded the minimum base temperature of chip to be 36.8?C for 0.2 mm fin spacing heat sink. A reduction of 9.1% in base temperature was noticed using CuO-water nanofluids for 0.2 mm fin spacing as compared to previously experimental estimated value using water [1]. The drop percentage difference in pressure between water and CuO-water nanofluids was 2.2-13.1% for various fin spacing heat sinks. The percentage difference in thermal resistance between water and CuO-water nanofluids was computed 12.1% at maximum flow rate. We also observed uniform temperature distribution for all heat sinks.

Design Optimization of Micro-channel Heat Exchanger embedded in LTCC

2012 ◽  
Vol 2012 (1) ◽  
pp. 000857-000865
Author(s):  
Aparna Aravelli ◽  
Singiresu S. Rao ◽  
Hari K. Adluru
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Management ◽  
Optimization Technique ◽  
Thermal Design ◽  
Transfer Rates ◽  
Design Variables ◽  
Micro Heat Exchanger ◽  
Micro Systems ◽  
Silver Metal

Increase in the density of electronic packaging leads to the investigation of highly efficient thermal management systems. The challenge in these micro-systems is to maximize heat transfer per unit volume. In the author's previous work, experimental and computational analysis has been performed on LTCC substrates using embedded silver vias. This novel technique of embedding silver vias along with forced convection resulted in higher heat transfer rates. The present work further investigates into the optimization of this model. A Multi-objective optimization problem has been formulated for the heat transfer in the LTCC model. The Log Mean Temperature Difference (LMTD) method of heat exchangers has been used in the formulation. Optimization is done based on maximization of the total heat transferred and minimization of the coolant pumping power. Structural and thermal design variables are considered to meet the manufacturability and energy requirements. Demanded pressure loss and volume of the silver metal are used as constraints. The classical optimization technique Sequential Quadratic Programming (SQP) is used to solve the micro-heat exchanger problem. The optimal design is presented and sensitivity analysis results are discussed.

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