Appendix A: Soliciting Proposals for Fluid Physics Experiments on the International Space Station in Flow Boiling to Support Cryogenic Propellant Tank Transfer Research
Step-1 Proposals Due: October 1, 2020
Subject to the availability of funds, the award for each proposal selected from this Appendix will be a maximum of approximately $247,500 per year for a total maximum award amount up to approximately $1,237,500 for a five-year period.
This Appendix to the Research Opportunities in Physical Sciences NRA NNH20ZDA012N (henceforth referred to as the Omnibus NRA) solicits research proposals for fluid physics experiments to be conducted on the International Space Station (ISS) in flow boiling to support cryogenic propellant tank transfer research.
NASA is working to establish a permanent human presence on the Moon within the next decade to uncover new scientific discoveries and lay the foundation for private companies to build a lunar economy. To support the lunar initiative, NASA and its partners are developing activities to be conducted in cislunar space, including the Lunar Gateway, a small spaceship that will placed in orbit around the Moon for astronauts, science experiments, and technology demonstrations, and also will provide access to the surface of the Moon. Another goal for cislunar activities is the development of refueling depots and servicing platforms. It is envisioned that tens of tons of cryogenic propellant (LH2, LO2, LCH4) will need to be transferred and stored with negligible losses for up to a year in cislunar space for lunar sustainability and during Mars transit.
NASA has recognized the area of cryogenic refueling as a key technological challenge. During the cryogenic propellant tank transfer process, initially warm lines between the cold supply (donor) tank and warm receiver tank will be chilled down using the liquid propellant from the donor tank. The line chilldown and transfer process is complicated by flow boiling that transitions from film to nucleate boiling before a liquid flow is established. The vapor produced will flow into the receiver tank where it will eventually be condensed or vented out. The receiver tank will also need to be chilled down through pool boiling processes. Understanding of pool and flow boiling, and condensation in the context of tank-to-tank transfer in microgravity are important for proper design and cryogenic fluid management of cryogenic propellant tanks. The fuel transfer processes of interest are intrinsically transient and may involve time-varying system pressure (which makes the saturation temperature vary) and time-varying wall temperatures for the boiling and/or condensation processes that occur, due to progressive cooling of the receiver tank structures. Investigating such transient effects would contribute to a better design of systems for accomplishing the performance objectives of the fuel transfer processes needed for future missions.
Through this Appendix, NASA is seeking research proposals to determine the best use of the new flow boiling module for the FBCE in support of in-space cryogenic propellant tank transfer research. Proposals are specifically solicited for an ISS flight experiment using the FBCE with the new boiling module.