Experimental investigation on the influence of copper foam characteristics on pool boiling heat transfer

Abstract

Advancements in technology have led to electronics with higher power densities, which strains the sustainability of these devices. In this context, using metal foams in pool boiling can provide solutions by enhancing heat transfer. The porous structure of metal foams affects the boiling parameters such as critical heat flux (CHF) and boiling heat transfer coefficient (BHTC). To study these effects, copper foams of varying thicknesses and PPI were used, and they were attached to smooth silicon surfaces to simulate chip cooling. This research focused on thin foams with 1 mm thickness, which had been sparsely explored in the previous studies. In the ten samples, the CHF increased by up to 85.8 %, and the BHTC increased by up to 141.1 %. Vapor bubble dynamics on copper foam surfaces, which were affected by the foam thickness and PPI, were analyzed. The experimental results show that copper foams significantly enhance pool boiling heat transfer. However, thicker foams increase the frequency of bubble trapping, causing localized overheating which leads to deterioration of heat transfer performance. There was also an optimal PPI value for each foam thickness, which is 40 PPI for the 1 mm thickness and 30 PPI for the 3 mm thickness.