Thermal Management of a High Packing Density Array of Power Amplifiers Using Liquid Cooling

2007 ◽  
Vol 129 (4) ◽  
pp. 488-495 ◽  
Author(s):  
Z. A. Williams ◽  
J. A. Roux
Keyword(s):  
Base Plate ◽  
Thermal Control ◽  
Experimental Program ◽  
Electronic Systems ◽  
Transfer Coefficients ◽  
Liquid Cooling ◽  
Cfd Simulations ◽  
Heat Transfer Coefficients ◽  
Computational Fluid Dynamics Cfd ◽  
Increasing Demand

The increasing demand for smaller more compact electronic systems as well as the need to handle higher levels of power dissipation has lead to an increase in necessity for more innovative cooling designs. In recent years, computational fluid dynamics (CFD) software has been used extensively in the design of thermal control systems for electronics. In many cases, there remains a need for experimental evaluation of cooling systems in order to validate the results of the CFD simulations. The present work investigates several variations of a liquid cooled base plate channel design for an array of generic power amplifier units. Several different channel insert configurations are investigated as miniheat exchangers using both copper fins and graphite foam. Experiments were conducted measuring the chip temperatures as well as the inlet liquid temperature. CFD simulations were also conducted to guide the experimental program. Effective heat transfer coefficients were also reverse-engineered using CFD software and the experimental results.

Graphite Foam Thermal Management of a High Packing Density Array of Power Amplifiers

2005 ◽  
Vol 128 (4) ◽  
pp. 456-465 ◽  
Author(s):  
Z. A. Williams ◽  
J. A. Roux
Keyword(s):  
Thermal Management ◽  
Base Plate ◽  
Cooling Channel ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Chip Technology ◽  
Thermal Management Of Electronics ◽  
Computational Fluid Dynamics Cfd ◽  
Plate Channel ◽  
Graphite Foam

Much focus has been placed on the thermal management of electronics in recent years. An overall reduction in size of electronic components as well as advances in chip technology, leading to ever higher power dissipation, have increased the necessity for innovative cooling designs. While computational fluid dynamics (CFD) software packages have been instrumental in the design of cooling systems, it remains important to validate these CFD predictions through experimentation. The present work focuses on the experimental evaluation of several variations of an air cooled base plate channel design for an array of generic power amplifier modules. In the current study two materials, graphite foam and a microfibrous material, are investigated as mini-heat exchangers to be implemented in the cooling channel of the base plate. Computational simulations have been conducted on some of the proposed designs in order to evaluate certain parameters. Experiments were conducted measuring chip temperatures and the pressure drop across the cooling channel. Effective heat transfer coefficients were also reverse engineered.

Calibration of External Heat Transfer Coefficients During Cooling of a Partially-Filled Water Tank Using Measured Temperature-Time Data

2018 ◽  
Author(s):  
Vishal Ramesh ◽  
Sandip Mazumder ◽  
Gurpreet Matharu ◽  
Dhaval Vaishnav ◽  
Syed Ali ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Measured Temperature ◽  
Water Tank ◽  
Time Data ◽  
Transfer Coefficients ◽  
Ansys Fluent ◽  
Heat Transfer Coefficients ◽  
Computational Fluid Dynamics Cfd ◽  
Temperature Time

A combined Computational Fluid Dynamics (CFD) and experimental approach is presented to determine (calibrate) the external convective heat transfer coefficients (h) around a partially-filled water tank cooled in a climactic chamber. A CFD analysis that includes natural convection in both phases (water and air) was performed using a 2D-axisymmetric tank model with three prescribed average heat transfer coefficients for the top, side and bottom walls of the tank. The commercial CFD code ANSYS-Fluent™, along with User-Defined Functions (UDFs), were utilized to compute and extract temperature vs. time curves at five different thermocouple locations within the tank. The prescribed h values were then altered to match experimentally obtained temperature-time data at the same locations. The calibration was deemed successful when results from the simulations exhibited match with experimental data within ±2°C for all thermocouples. The calibrated h values were finally used in full-scale 3D simulations and compared to the experimental data to test their accuracy. Predicted 3D results were found to agree with experimental results within the error of the calibration, thereby lending credibility to the overall approach.

Heat Transfer of Springs in Oblique Crossflows

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Daniel B. Biggs ◽  
Christopher B. Churchill ◽  
John A. Shaw
Keyword(s):  
Heat Transfer ◽  
Convection Heat Transfer ◽  
Reynolds Numbers ◽  
Experimental Program ◽  
Convection Heat ◽  
Computational Tool ◽  
Cfd Simulations ◽  
Nonmonotonic Dependence ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

An experimental program is presented of heated tension springs in an external crossflow over a range of laminar Reynolds numbers, spring stretch ratios, and angles of attack. Extensive measurements of the forced convection heat transfer of helical wire within a wind tunnel reveal an interesting nonmonotonic dependence on angle of attack. Computational fluid dynamics (CFD) simulations, showing good agreement with the experimental data, are used to explore the behavior and gain a better understanding of the observed trends. A dimensionless correlation is developed that well captures the experimental and CFD data and can be used as an efficient computational tool in broader applications.

Experimental and Numerical Characterization of an Electrically Propelled Vehicles Battery Casing Including Battery Module

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Johan Anderson ◽  
Johan Sjöström ◽  
Petra Andersson ◽  
Francine Amon ◽  
Joakim Albrektsson
Keyword(s):  
Heat Transfer ◽  
Transfer Coefficients ◽  
Power Train ◽  
Fire Model ◽  
Heat Transfer Coefficients ◽  
Fire Resistance Test ◽  
Numerical Characterization ◽  
Computational Fluid Dynamics Cfd ◽  
Battery Module

This paper demonstrates the possibility to predict a battery system's performance in a fire resistance test according to the new amendment of United Nations Regulation No. 100 “Uniform Provisions Concerning the Approval of Vehicles with Regard to Specific Requirements for the Electric Power Train” (R100) based on careful measurements of the physical properties of the casing material, as well as modeling of the battery modules and computer simulations. The methodology of the work consists of estimating the heat transfer coefficients by using a gasoline pool fire model in the computational fluid dynamics (CFD) software FireDynamicsSimulator (FDS), followed by finite-element (FE) calculations of the temperatures in the battery

Flow Measurements in Metal Oxide-Nanoparticle Suspensions in a Rectangular Natural Circulation Loop

2013 ◽  
Vol 685 ◽  
pp. 145-149 ◽  
Author(s):  
Thomas Shijo ◽  
Kumar Kochunni Sarun ◽  
Choondal Balakrishnapanicker Sobhan
Keyword(s):  
Heat Dissipation ◽  
Natural Circulation ◽  
Convection Heat Transfer ◽  
Thermal Control ◽  
Transfer Coefficients ◽  
Flow Measurements ◽  
Heat Transfer Coefficients ◽  
Metal Oxide Nanoparticle ◽  
Natural Circulation Loop ◽  
Nanoparticle Suspensions

Natural circulation cooling systems, such as the thermosyphon loops are preferred as effective heat dissipation methods where a silent and vibration-free operation is desired in thermal control of devices and processes. Though anomalous enhancement in forced convection heat transfer coefficients have been reported for nanofluids, the effect of addition of nanoparticles to base fluids in natural convection circulation loops is not clearly understood. An experimental study is reported in this work, using aluminum oxide and copper oxide nanofluids with varying concentrations, in a thermosyphon loop. The flow velocity is arrived at from the measured pressure drop. At a nanoparticle concentration of 0.01% by volume Al2O3-water and CuO-water nanofluids shows 88.37% and 42.89% improvement in flow, respectively.

Comparison of Numerical Simulation and Experimental Results for Crossflow and Counterflow Microchannel Heat Exchangers

2004 ◽  
Author(s):  
A. Halbritter ◽  
U. Schygulla ◽  
A. Wenka ◽  
K. Schubert
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Exchangers ◽  
Experimental Results ◽  
Transfer Coefficients ◽  
Detailed Model ◽  
Heat Transfer Coefficients ◽  
Hydrodynamic Behaviour ◽  
Computational Fluid Dynamics Cfd ◽  
Micro Process Engineering

At the Institute for Micro Process Engineering of the Forschungszentrum Karlsruhe, micro heat exchangers are manufactured out of single foils of base metal alloys. The characterisation of the thermohydraulic properties of microchannel heat exchangers is done using water as heat transfer medium on both passages at temperatures of 10°C and 95°C. The present publication will give an overview of the numerical simulation as well as experimental results for crossflow and counterflow microchannel heat exchangers. A comparison of three crossflow heat exchangers with different microchannel structures, and two different types of counterflow microchannel heat exchangers is shown. For comparison, the heat transfer rate, the overall heat transfer coefficients and efficiencies as well as pressure drop obtained from experiment and theory is shown. For numerical simulation, two models have been used. An easily accessibly method is to use classical engineering codes based on the Nusselt theory (VDI Wa¨rmeatlas, 1994). A more detailed model is to use computational fluid dynamics (CFD) with the commercially available tool FLUENT ®, where best estimation codes have been applied for numerical simulation. Both numerical calculations are a helpful complement to predict thermal and hydrodynamic behaviour of the microchannel heat exchangers.

scholarly journals Experimental Study of Three-Dimensional Natural Convection High-Rayleigh Number

1984 ◽  
Vol 106 (2) ◽  
pp. 339-345 ◽  
Author(s):  
M. S. Bohn ◽  
A. T. Kirkpatrick ◽  
D. A. Olson
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Flow Visualization ◽  
Three Dimensional ◽  
Experimental Program ◽  
Transfer Coefficients ◽  
Bulk Fluid ◽  
Heat Transfer Coefficients ◽  
Experimental Apparatus ◽  
Rayleigh Numbers

Natural convection in buildings is characterized by three-dimensional flow at high Rayleigh numbers (Ra ∼ 1010). At present, little is known about natural convection heat transfer in this regime, although a better understanding would allow more energy efficient usage of buildings. This paper presents results from the first phase of an experimental program aimed at improving our understanding of heat transfer and air flow in buildings. The experimental apparatus consists of a cubical enclosure filled with water in which each wall may be heated or cooled in a controlled manner. A transparent, adiabatic top and bottom provide flow visualization capability. Average heat transfer coefficients for the walls have been measured for several configurations of heating and cooling of the vertical isothermal walls. A unified Nu-Ra correlation has been computed which collapses the heat transfer coefficients of the various configurations to within 5.7 percent. The heat transfer and flow visualization results indicate that even at Rayleigh numbers as high as 6 × 1010, the heat transfer mechanism is laminar boundary-layer convection from one wall to the bulk fluid.

Scaled Experiments and CFD Simulations Supporting the Design of the Spallation Neutron Source Mercury Target

2000 ◽  
Author(s):  
W. David Pointer ◽  
Mark W. Wendel ◽  
Jason M. Crye ◽  
Arthur E. Ruggles ◽  
David K. Felde ◽  
...  
Keyword(s):  
Neutron Source ◽  
Cfd Simulation ◽  
Complete Characterization ◽  
Experimental Program ◽  
Working Fluid ◽  
Spallation Neutron Source ◽  
Cfd Simulations ◽  
Liquid Mercury ◽  
Computational Fluid Dynamics Cfd

Abstract A combination of experimental and computational methods is necessary to adequately characterize the flow patterns in the liquid mercury target of the Spallation Neutron Source (SNS). Since liquid mercury is completely opaque and corrosive to many materials, the use of liquid mercury as the working fluid makes complete characterization of the flow field by experiment difficult. Furthermore, flow asymmetries and quasi-periodic instabilities that are observed in early target flow experiments are difficult to capture in computational fluid dynamics (CFD) simulations of the system. Therefore, an experimental program using several scaled experiments is combined with CFD simulation for the design and development of the SNS mercury target.

scholarly journals CFD SIMULATION OF VERTICAL SEVEN-ROD BUNDLE COOLED WITH SUPERCRITICAL FREON-12

2014 ◽  
Vol 3 (01) ◽  
pp. 17-28 ◽  
Author(s):  
X. Huang ◽  
K. Podila ◽  
Y.F. Rao
Keyword(s):  
Heat Transfer ◽  
Cfd Simulation ◽  
Turbulence Models ◽  
Flow Conditions ◽  
Transfer Coefficients ◽  
Cfd Simulations ◽  
Ansys Fluent ◽  
Heat Transfer Coefficients ◽  
Rod Bundle ◽  
Flow And Heat Transfer

In this paper, a seven-rod bare bundle was simulated using ANSYS Fluent 6.3.26 to accurately predict the fluid flow and heat transfer behaviour under supercritical flow conditions. Seven turbulence models were compared to identify the appropriate model to predict the experiments performed at the Institute of Physics and Power Engineering on a vertically oriented seven-rod bare bundle cooled with supercritical Freon-12. It was found that predictions of wall temperatures and heat transfer coefficients are sensitive to the choice of turbulence model as well as to the near-wall treatment. Overall, the CFD simulations were able to predict the measured sheath temperature profiles along the length of the bundle within reasonable accuracy.

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