Thermal performance study of finned foam heat sinks and the effect of painting and inclination angle in natural convective heat transfer

Abstract

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.

In this study, two different types of open-cell aluminium foam samples were experimentally tested: pure metal foam fixed to a substrate (a ‘conventional’ foam heat sink) and a finned foam heat sinks (where fins are inserted in the foam to increase the effective thermal conductivity). Samples with 5, 8 and 11 fins are tested. The substrate and fins are connected to the foam by epoxy glue (k = 0.55 W/mK). 10 PPI (Pores Per linear Inch) AL1050 foam is used with a porosity of 93%. The dimensions of the substrate are the same for all samples: 102x165 mm². Temperatures of the substrate range from 50 to 90°C. Next to studying the thermal performance in a horizontal orientation, some samples are also tested vertically. Furthermore, the impact of radiative heat transfer is investigated. The ‘conventional’ foam heat sink performs best when comparing all foam samples: this is because of the increase in flow resistance in case of finned foam heat sinks. The thermal performance (heat transfer rate) of the ‘conventional’ foam heat sink is up to 15% higher compared to the worst performing finned heat sink with 11 fins. Effects of the inclination angle are (only) found to be significant for the ‘conventional’ foam heat sink (up to 15% in heat transfer rate) and painting the foam heat sink results in an increase in thermal performance up to 10.8%.