Nano-capillary aluminum finned heat sink for ultra-efficient evaporative cooling

Abstract

Aluminum finned heat sinks are commonly used for cooling electronics and high-power systems through convective heat transfer, but their cooling efficiency per unit volume is a major bottleneck to further improve performance or compactness of device/system. Here we report a new strategy including surface modification and system design that for the first time allowed commercially available aluminum finned heat sinks to perform capillary-driven water evaporation from entire surface of fins for significant cooling enhancement. The capillary wicking ability was attributed to a nanostructured surface resulting from the surface modification. Experimental results showed that the passive cooling power of this nano-capillary evaporative finned heat sink (EF-HS) was about 7.8–8.4 times higher than that of a regular (unmodified) heat sink under natural convection. The new strategy can potentially reduce the fin height, cut material costs and save space without compromising heat dissipation efficiency, which is favorable for both large-scale power systems and compact devices. Using photovoltaic (PV) solar panel cooling as an example, the EF-HS with only 9 mm fin height was able to reduce the PV panel temperature by 15.5 °C (26.4%) in a windless condition and increase the energy conversion efficiency by 12.7%.