CFD Analysis in a Liquid-Cooled Carbon Nanotube Based Micro-channel Heatsink for Electronic Cooling

Abstract

In this paper, the 2D and 3D CFD simulations have been carried out in liquid-cooled carbon nano tube based (CNT) micro-fin cooling architectures. The effect of heat transfer due to fluid velocity, pressure difference in the micro-fin assembly and thermal expansion due to temperature rise in the cooling assembly have been analyzed in this paper. The analysis indicates that fluid speed is the key factor of heat transfer and 2D carbon nanotube fin array shows greater thermal performance than that of 1D carbon nanotube fin array. The pressure drop between inlet and outlet of the cooling device is an important cause to limit the fluid speed. I. I NTRODUCTION Carbon nanotubes (CNTs) were discovered in 1991. They are allotropes of carbon with a nanostructure that have a length-to-diameter ratio greater than 1000000. Figure 1 shows the structure of single-walled carbon nanotubes (SWNTs). A CNT is formed when the two-dimensional sheet of graphene is rolled into a seamless cylinder. CNTs can range from ~1 nm to ~100 nm in diameter and have lengths in the micrometer range. Based on the chemical arrangement of carbon atoms, a discrete number of unique CNTs can be formed. CNTs are made from cylindrical carbon molecules which are very special in thermal, electrical and mechanical properties. A thermal conductivity up to 6600W/m·K has been reported (1). Copper, silver and gold, which are some of the best known thermally conductive materials, have thermal conductivities of 400 W/m·K, 430 W/m·K and 320 W/m·K at room temperature respectively. As a new material, CNTs are attracting more and more attention, and they are potentially very useful in nanotechnology, electronics, optics and aeronautics. CNTs can be manufactured by Chemical Vapor Deposition (CVD) at suitable temperature. During the CVD process, process gas (such as ammonia, nitrogen, hydrogen, etc.) and carbon-containing gas (such as acetylene, ethylene, ethanol, methane, etc.) are demanded as reactors, and catalyst particles such as nickel, cobalt and iron are also needed. Therefore, to promote a good thermal contact on the interfaces between the multi-walled CNTs and their growth