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Research Papers

# Development of Compact Thermal–Fluid Models at the Electronic Equipment Level

[+] Author and Article Information
Jason Stafford

Ronan Grimes, David Newport

Mechanical, Aeronautical and Biomedical Engineering Department,  Stokes Institute, University of Limerick, Limerick, Ireland

J. Thermal Sci. Eng. Appl 4(3), 031007 (Jul 16, 2012) (14 pages) doi:10.1115/1.4006715 History: Received September 05, 2011; Revised March 26, 2012; Published July 16, 2012; Online July 16, 2012

## Abstract

The introduction of compact thermal models (CTM) into computational fluid dynamics (CFD) codes has significantly reduced computational requirements when representing complex, multilayered, and orthotropic heat generating electronic components in the design of electronic equipment. This study develops a novel procedure for generating compact thermal–fluid models (CTFM) of electronic equipment that are independent over a boundary condition set. This boundary condition set is estimated based on the information received at the preliminary design stages of a product. In this procedure, CFD has been used to generate a detailed model of the electronic equipment. Compact models have been constructed using a network approach, where thermal and pressure-flow characteristics of the system are represented by simplified thermal and fluid paths. Data from CFD solutions are reduced for the compact model and coupled with an optimization of an objective function to minimize discrepancies between detailed and compact solutions. In turn, an accurate prediction tool is created that is a fraction of the computational demand of detailed simulations. A method to successively integrate multiple scales of electronics into an accurate compact model that can predict junction temperatures within 10% of a detailed solution has been demonstrated. It was determined that CTFM nodal temperatures could predict the corresponding area averaged temperatures from the detailed CFD model with acceptable accuracy over the intended boundary condition range. The approach presented has the potential to reduce CFD requirements for multiscale electronic systems and also has the ability to integrate experimental data in the latter product design stages.

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## Figures

Figure 11

Enclosure temperature distribution with hR,L=200 W/m2 K, hR,R=200 W/m2 K, and T∞=25 °C

Figure 12

Compact thermal–fluid network for the electronics enclosure (sinda /fluint layout)

Figure 13

Complexity of a compact model with increasing node count if each node has a relationship with every other node in the model

Figure 5

Compact model layout

Figure 6

Successive integration of reduced order models at various electronic levels

Figure 7

A comparison between the predicted fully developed adiabatic Nusselt number for preliminary and reduced order models

Figure 8

Predicted component junction temperatures using the preliminary and optimized compact models for ReLx=6300 and T∞=27 °C

Figure 9

Temperature field around PBGA components in two channels with different heating configurations (ReLx=10,850, T∞=25 °C)

Figure 10

Enclosure temperature distribution with hR,L=0 W/m2 K, hR,R=0 W/m2 K, and T∞=25 °C

Figure 1

The typical phases in virtual product design, including the proposed approach for the detailed design phase

Figure 2

Multiple components mounted to a printed circuit board

Figure 3

Vented electronics enclosure with numerous components mounted to printed circuit boards

Figure 4

A thermal–fluid process expressed using a simple network

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