520: Actively Sealed Cryogenic Coupler

The connection between a fuel depot and space vessel is secured with a coupler that prevents leakage, limits boil-off and protects cryogenic fuels. NASA relies on effective coupling to supply cryogenic fuel to space vessels to continue deep space exploration. Through collaborations with industry professionals, we designed, modeled, built and tested a cryogenic coupler to facilitate a successful connection for fueling. We optimized the seal locations to decrease leakage and boil off, which is the main weakness of current designs. The coupler will be actively sealed, meaning that it is always closed except when the halves come together to allow for fuel transfer. We researched the materials used on the coupler for their unique properties: stainless steel for its strength, machinability and thermal properties, Teflon for its resilience at cryogenic temperatures, and Omniseal® 103A for its effective sealing in current NASA applications. We selected affordable spring-energized seals that resemble the Omniseal’s properties for this project. We conducted a water leakage test to improve the coupler design before cryogenic fluid testing and used environmental correction factors to obtain flow/leakage rates. Testing using liquid nitrogen allowed us to check the effectiveness of our springs and seals at low temperatures. 

Our testing confirms the coupler can be used in deep space missions or applications involving cryogenic fuel transfer by minimizing leakage and maximizing lifetime. By maximizing the fuel transferred, NASA is now saving on the cost of fuel lost during the connection process to leakage and boil-off. The coupler’s ability to retain fluid at the ideal temperatures confirms our finalized design results in an improved coupler.