Influence of Orientation and Radiative Heat Transfer on Aluminum Foams in Buoyancy-Induced Convection.

Marijn Billiet,Henk Huisseune,Sven De Schampheleire,Michel De Paepe

doi:10.3390/ma8105340

Abstract

Two differently-produced open-cell aluminum foams were compared to a commercially available finned heat sink. Further, an aluminum plate and block were tested as a reference. All heat sinks have the same base plate dimensions of four by six inches. The first foam was made by investment casting of a polyurethane preform and has a porosity of 0.946 and a pore density of 10 pores per linear inch. The second foam is manufactured by casting over a solvable core and has a porosity of 0.85 and a pore density of 2.5 pores per linear inch. The effects of orientation and radiative heat transfer are experimentally investigated. The heat sinks are tested in a vertical and horizontal orientation. The effect of radiative heat transfer is investigated by comparing a painted/anodized heat sink with an untreated one. The heat flux through the heat sink for a certain temperature difference between the environment and the heat sink’s base plate is used as the performance indicator. For temperature differences larger than 30 C, the finned heat sink outperforms the in-house-made aluminum foam heat sink on average by 17%. Furthermore, the in-house-made aluminum foam dissipates on average 12% less heat than the other aluminum foam for a temperature difference larger than 40 C. By painting/anodizing the heat sinks, the heat transfer rate increased on average by 10% to 50%. Finally, the thermal performance of the horizontal in-house-made aluminum foam heat sink is up to 18% larger than the one of the vertical aluminum foam heat sink.

Highlights

Electronic components are omnipresent in daily life products, such as cars, computers and power converters
To avoid failures caused by elevated operating temperatures, electronic components are cooled
Due to the miniaturization of electronic devices and the resulting rise of heat fluxes [5,6], electronic devices need to be cooled by heat sinks

Summary

Introduction

Electronic components are omnipresent in daily life products, such as cars, computers and power converters. The main causes of electronics failure are over-voltage, elevated operating temperature, moisture and electrostatic discharge (ESD) [1]. To avoid failures caused by elevated operating temperatures, electronic components are cooled. Some components, such as LEDs, are more efficient at lower operating temperatures [2,3,4]. Two types of heat sinks can be distinguished: passive and active heat sinks. The passive heat sink dissipates heat by buoyancy-induced convection. The active heat sink is equipped with a fan to induce an air flow through it and thereby dissipates heat by forced convection. From an economic and ecological point of view, passive heat sinks are favorable over active heat sinks, because they are less expensive, more reliable, require less maintenance and do not use energy

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