Development of Compact Thermal-Fluid Models at the Electronic Equipment Level

The introduction of compact thermal models (CTM) into CFD codes has significantly reduced computational requirements when representing complex, multi-layered, 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, and a commercially available thermal network analyzer has been implemented to produce the CTFM and optimize an objective function to minimize discrepancies between detailed and compact solutions. It was determined that CTFM nodal temperatures could predict the corresponding area averaged temperatures from the detailed CFD model to within 6% (Celsius scale) over the intended boundary condition range. Results also highlight the necessity to subdivide the compact thermal model into the largest possible isothermal nodal elements to retain the useful features of the CTFM. The approach presented has the potential to reduce CFD requirements for multi-scale electronic systems, such as in the design of aircraft avionics bays, and also has the ability to integrate experimental data in the latter product design stages.Copyright © 2011 by ASME