A Numerical Simulation of Conjugate Heat Transfer in an Electronic Package Formed by Embedded Discrete Heat Sources in Contact With a Porous Heat Sink

1997 ◽  
Vol 119 (1) ◽  
pp. 8-16 ◽  
Author(s):  
A. G. Fedorov ◽  
R. Viskanta
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Conjugate Heat Transfer ◽  
Heat Transfer Analysis ◽  
Model Parameters ◽  
Heat Sources ◽  
Similar System ◽  
Electronic Package ◽  
Conjugate System ◽  
Discrete Heat Sources

A physical/mathematical model has been developed to simulate the conjugate heat transfer in an actively cooled electronic package. The package consists of a highly conductive substrate with embedded discrete heat sources that are in intimate contact with a porous channel through which a gaseous coolant is circulated. The flow in the porous medium is analyzed using the extended Darcy model. The nonequilibrium, two-equation model which accounts for the near wall thermal dispersion effects was used for the heat transfer analysis. The concept of the general energy equation for the entire physical domain was employed as a method of solving numerically the conjugate system. The model has been validated by comparing the predictions with available experimental data for a similar system. A parametric study has been performed to examine the effects of some of the most important model parameters on the thermal performance of porous heat sink.

Effects of Protrusions on Conjugate Heat Transfer in a Microtube or Microchannel

2010 ◽  
Author(s):  
Muhammad M. Rahman ◽  
Phaninder Injeti
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Conjugate Heat Transfer ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Heat Sources ◽  
Two Dimensional ◽  
Discrete Heat Sources ◽  
Global Performance ◽  
Tube Geometry

Effects of protrusions on heat transfer in a microtube and in a two-dimensional microchannel of finite wall thickness were investigated for various shapes and sizes of the protrusion. Calculations were done for incompressible flow of a Newtonian fluid with developing momentum and thermal boundary layers under uniform and discrete heating conditions. It was found that the local Nusselt number near the protrusions changes significantly with the variations of Reynolds number, height, width, and distance between protrusions, and the distribution of discrete heat sources. The results presented in the paper demonstrate that protrusions can be used advantageously for the enhancement of local heat transfer whereas the global performance may be enhanced or diminished based on the tube geometry.

A Multi-Grid Based Multi-Scale Thermal Analysis Approach for Combined Mixed Convection, Conduction, and Radiation Due to Discrete Heating

2005 ◽  
Vol 127 (1) ◽  
pp. 18-26 ◽  
Author(s):  
Lan Tang ◽  
Yogendra K. Joshi
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Mixed Convection ◽  
Single Step ◽  
Heat Transfer Analysis ◽  
Heat Sources ◽  
Length Scales ◽  
Multi Scale ◽  
Discrete Heat Sources ◽  
Wide Range

A multi-grid embedded multi-scale approach is presented for conjugate heat transfer analysis of systems with a wide range of length scales of interest. The multi-scale analysis involves a sequential two-step “zoom-in” approach to resolve both the large length scales associated with the system enclosure, and the smaller length scales associated with fine spatial structures of discrete heat sources contained within. With this approach, computation time is shortened significantly, compared to conventional single-step computational fluid dynamics/computational heat transfer (CFD/CHT) modeling, with a very fine mesh. Performance of the two-step multi-scale approach is further enhanced by integrating the multi-grid technique in the CFD/CHT solver. Implementation of the enhanced approach is demonstrated for thermal analysis of an array of substrate mounted discrete heat sources cooled by mixed and forced convection, with accompanying experiments performed for validation and for the assessment of the importance of mixed convection. It is found that the multi-grid embedded multi-scale thermal analysis reduces simulation run time by 90% compared to the multi-grid integrated single step solution. The computed temperatures were in good agreement with measurements, with maximum deviation of 8%.

Computational Analysis of Conjugate Heat Transfer in Gaseous Microchannels

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Giulio Croce ◽  
Olga Rovenskaya ◽  
Paola D'Agaro
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Mach Number ◽  
Heat Sink ◽  
Conjugate Heat Transfer ◽  
Stokes Equations ◽  
Heat Transfer Analysis ◽  
Navier Stokes ◽  
Flow Conditions ◽  
Navier Stokes Equations

A fully conjugate heat transfer analysis of gaseous flow in short microchannels is presented. Navier–Stokes equations, coupled with Maxwell and Smoluchowski slip and temperature jump boundary conditions, are used for numerical analysis. Results are presented in terms of Nusselt number, heat sink thermal resistance, and resulting wall temperature as well as Mach number profiles for different flow conditions. The comparative importance of wall conduction, rarefaction, and compressibility are discussed. It was found that compressibility plays a major role. Although a significant penalization in the Nusselt number, due to conjugate heat transfer effect, is observed even for a small value of solid conductivity, the performances in terms of heat sink efficiency are essentially a function only of the Mach number.

Conjugate Heat Transfer From a Vertical Plate With Discrete Heat Sources Under Natural Convection

1989 ◽  
Vol 111 (4) ◽  
pp. 261-267 ◽  
Author(s):  
S. Lee ◽  
M. M. Yovanovich
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Conjugate Heat Transfer ◽  
Vertical Plate ◽  
Power Level ◽  
Radiation Heat Transfer ◽  
Transfer Model ◽  
Heat Sources ◽  
Radiation Heat ◽  
Discrete Heat Sources

A quasi-analytical conjugate heat transfer model is developed for a two dimensional vertical flat plate with discrete heat sources of arbitrary size and power level under natural convection. The plate is located in an extensive, quiescent fluid which is maintained at uniform temperature. The model consists of an approximate analytical boundary layer solution and a one dimensional numerical conduction analysis in which an allowance is made to account for radiation heat transfer. These fluid and solid solutions are coupled through an iterative procedure. A conjugate problem is solved when a converged temperature distribution is obtained at the plate-fluid interface, concurrently satisfying the thermal fields on both sides of the interface. Comparisons of the surface temperature variations obtained by using the present model are made with existing numerical and experimental data which were obtained for cases with two strip heat sources mounted flush with the surface of a vertical plate in air. The model is shown to be in good agreement. In addition, the convection and radiation heat flux variations are presented. The results illustrate the importance of radiation heat transfer for estimating surface temperatures of the plate.

Microfeature Heat Exchanger Using Variable-Density Arrays for Near-Isothermal Cold-Plate Operation

2016 ◽  
Vol 138 (1) ◽  
Author(s):  
Noris Gallandat ◽  
Danielle Hesse ◽  
J. Rhett Mayor
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Heat Sink ◽  
Convective Heat Transfer Coefficient ◽  
Water Flow Rate ◽  
Flow Path ◽  
Heat Sources ◽  
Cold Plate ◽  
Reduced Pressure ◽  
Discrete Heat Sources

The purpose of this paper is to demonstrate the possibility to selectively tune the convective heat transfer coefficient in different sections of a heat sink by varying the density of microfeatures in order to minimize temperature gradients between discrete heat sources positioned along the flow path. Lifetime of power electronics is strongly correlated to the thermal management of the junction. Therefore, it is of interest to have constant junction temperatures across all devices in the array. Implementation of microfeature enhancement on the convective side improves the heat transfer due to an increase in surface area. Specific shapes such as micro-hydrofoils offer a reduced pressure drop allowing for combined improvement of heat transfer and flow performance. This study presents experimental results from an array of three discrete heat sources (20 × 15 mm) generating 100 W/cm2 and positioned in line along the flow path with a spacing of 10 mm between each of the sources. The heat sink was machined out of aluminum 6061, and micro-hydrofoils with a characteristic length of 500 μm were embedded in the cold plate. The cooling medium used is water at a flow rate of 3.6–13.4 g/s corresponding to a Reynolds number of 420–1575. It is demonstrated that the baseplate temperature can be maintained below 90 °C, and the difference between the maximum temperatures of each heat source is less than 6.7 °C at a heat flux of 100 W/cm2 and a water flow rate of 4.8 g/s.

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