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

Abstract

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.

Foam, Fin, and Nanoparticle Thermal Management of Power Amplifiers Using Liquid Cooling

“…Data are expressed in terms of power-chip temperature as a function of dissipated thermal power. All water-cooling experimental data and CFD predictions illustrate a linear behavior, as did the air-cooling CFD predictions and experimental data of [12]; this can be very beneficial in predicting power-chip temperatures at other power levels and at other ambient-temperature environments. The numerical-model grid was made successively finer until the predictions were grid-independent.…”

“…‡ The proposed advantage to using these foams is that the porosity of the foam provides an increased amount of surface area to convectively interact with the fluid in the cooling channel. It is the goal of the current study to experimentally evaluate graphite foam with water cooling and determine how much the foam enhances the heat transfer with water cooling, as compared with air [12] cooling, and which configuration provides the best performance for the present application. The nanoparticles Al 2 O 3 and CuO were obtained from Meliorum § , with both types of particles sized at a 40 nm diameter.…”

“…The proposed experimental design employs base-plate channel cooling with water as the cooling fluid. A previous companion study [12] using air as the cooling fluid showed that the use of various cooling mechanisms significantly reduced the power-amplifier chip temperatures by as much as 47 C or more. The present work is a follow-up experimental study to explore some of the same [12] and some different cooling mechanisms but with water as the cooling fluid.…”

“…Aluminum-oxide (Al 2 O 3 ) or copper oxide (CuO) nanoparticles were dispersed at various volume percentages within the cooling fluid to determine their effectiveness in comparison with the graphite foams and copper fins. The overall objective of this study is to determine/quantify the amount of improvement in thermal management by graphite foam, copper fins, or nanoparticles with water as the cooling fluid as opposed to air [12] as the cooling fluid.…”

Review on Graphite Foam as Thermal Material for Heat Exchangers

“…This response time may be crucial for the power electronics. Williams et al [12] investigated several different channel -insert configurations as mini -heat exchangers by using both copper fins and graphite foams. The graphite foam was proved to have strong potential as a mini -heat exchanger.…”