Impacts of Gravity on Dropwise Condensation-Enhanced Heat Pipes. App.D-9-Li

Primarily consisting of evaporation and condensation sections, the heat pipe is a light, highly efficient, and durable two-phase device that transports heat over a distance with a small temperature drop and a type of primary devices in thermal control systems of satellites, space shuttles, and manned space stations. Ultrahigh-performance, long, and light-weight heat pipes are critical to future space missions (e.g. manned missions to Mars) and hence, highly desired.

Numerous efforts have been made to improve heat pipe performance by engineering the evaporation section and are nearly approaching the physical limits. However, the heat pipe condensation section that results in an order of magnitude higher thermal resistance than the evaporation one has not been well developed. It is promising if a performance leap of heat pipe technologies can be realized by enhancing the condensation section. Heat transfer rate of dropwise condensation (DWC) is 10 times higher than filmwise condensation adopted in existing heat pipe technologies. Most recently, using super-durable Ni-graphene coatings in a terrestrial environment, the Science PI’s team has successfully demonstrated 8 times higher effective thermal conductivity by promoting DWC inside heat pipes. However, the enhancement was highly sensitive to orientations.

In most space environment, due to the reduced gravity, droplets would attach on the wall and DWC could totally fail without quickly removing droplets. The objective of this proposed project is to explore a feasibility in implementing DWC for space missions. Conducting experiments in a drop tower would be the first step to verify the feasibility of wick designs in rapidly removing droplets inside heat pipes. In this proposal, condensation sections of heat pipes will be coated with the demonstrated Ni-graphene coatings. Moreover, various wicking structures will be designed to eventually realize rapid droplet removal in a microgravity environment. The gap between the Ni-graphene coated wall and wicking structures would play a critical role in maximizing DWC and hence, heat pipe performances. Heat pipes with various wicking structure designs and gaps will be evaluated before and in drop tower experiments.

This is a mature technology (TRL 7+) — the realistic path in is usually NASA's Technology Transfer Program: licensing an existing NASA patent, or a Space Act Agreement to use NASA facilities/expertise directly. NASA also runs a startup licensing program with no upfront fee for companies formed to commercialize a specific NASA technology.

None of these are guaranteed paths for this specific project — TechPort itself doesn't have an "apply" button. Reaching out to the contact(s) above with a specific question is usually the fastest way to find out what's actually open.