Fabrication of High Conductivity Heat Pipes using Multi-Walled Carbon Nanotubes

This proposal will demonstrate the development of a composite material containing aligned carbon nanotubes with thermal conductivity far in excess of traditional copper or aluminum. A unique process for easily fabricating the aligned carbon nanotubes will be demonstrated in Phase I. This aligned Carbon Nanotube Composite (CNC) will be fabricated into a heat pipe in Phase I and demonstrated. In addition to the potential for a thermal conductivity that approaches graphite (6600 W/mK, compared to 390 W/mK for copper), the CNC heat pipe is ideal for direct chemical bonding to solid-state electronic devices, thereby eliminating interfacial thermal resistance. While existing hardware is limited to cooling heat fluxes of approximately 100 W/cm2, Mainstream has already demonstrated that technology exists to push this capability to 1,000 W/cm2 using microchannels or spray cooling, however heat pipe systems would be clearly simpler and more reliable. This Phase I effort will demonstrate the potential for a high heat flux, heat spreading, heat pipe to transfer waste heat generated in the semiconductor junction to a secondary cooling source such as sea water, while maintaining a low junction temperature. Phase I will demonstrate a high thermal conductivity composite composed of aligned carbon nanotubes with enhanced thermal conductivity. Phase I will demonstrate the capability of this heat pipe to remove heat fluxes in excess of 300 W/cm2. Phase I will include manufacturing techniques, design specifications, experimental data and cost analysis. This effort will experimentally demonstrate the performance of a simple but innovative high performance heat pipe with heat flux capability that far exceeds traditional copper or aluminum heat pipes. The proposed material would be applicable to all types of heat pipes and compatible with essentially all working fluids. In addition to the Navy applications, other potential applications include passive small-satellite thermal control, hardened radiator systems, and commercial or military electronics cooling (high-power electronics, supercomputers, electronic switch gear, and avionics ). Mainstream has performed a commercialization study and the commercial potential is tremendous.