Effect of structural characteristics on the natural convective heat transfer performance of copper foam

Abstract

• Copper foam with highly controllable structure was manufactured. • The relationship between structure and heat transfer performance was studied. • When the porosity is > 78%, the heat transfer performance drops sharply. • The optimal porosity and pore size for convective heat transfer have been found. • Side-heated foams exhibit better heat transfer than the bottom-heated foams. The effects of porosity, pore diameter and heating direction on the heat transfer performance of copper foam under natural convection were experimentally investigated. The open cell copper foam with highly controllable porosity ranging from 65% to 85% and mean pore diameters of 330 μm, 560 μm, 850 μm and 1200 μm were manufactured using a space holder method. The natural convective heat transfer coefficient of the copper foam was measured using a purpose-designed device. The influence mechanism of porosity, pore diameter and heating direction on heat transfer was analysed and discussed. The results showed that when the porosity is less than 75%, the effect of porosity on heat transfer is not significant, but as the porosity increases further, the heat transfer performance decreases significantly. The optimal pore size was found to be 850 μm, while the heat transfer performance of other pore sizes depends on the porosity. It was also found that the samples heated from the side generally showed better heat transfer performance than the samples heated from the bottom. The influence of porosity and pore size on natural convective heat transfer performance is mainly caused by changes in thermal conductivity and permeability. This research provides important guidance for the design of future heat sinks.