Determination of Cryogenic Pool Boiling and Subsurface Helium Pressurization Characteristics in Reduced Gravity

PI: Jacob Chung, University of Florida - Gainesville, Samuel Darr (Co-I), The Aerospace Corporation

Zero-gravity boiling data is needed to predict propellant boiloff losses. Tank pressurization directly into the liquid may occur in zero gravity, generating boiloff and affecting the pressurization efficiency. Insufficient data on cryogenic subsurface pressurization is available, and heat/mass transfer rates are unknown. This experiment is designed to yield data for combining with computational fluid dynamics (CFD) simulations to back out heat and mass transfer rates.

Technology Areas (?)
  • TA02 In-Space Propulsion Technologies
Problem Statement

For cryogenic propulsion elements, pool boiling of cryogenic liquids at the wetted tank internal surfaces, caused by heat leakage from the environment, is inevitable. Also, in a reduced gravity environment, the pressurization gas may be injected directly into the liquid propellant if the inlet is submerged in liquid. The incoming helium causes immediate boiloff of the propellant which subcools the liquid, a necessity for propellant transfer. Data to understand these dynamics are limited and do not reflect the characteristics of tanks used in flight (e.g., surface roughness and shape). This experiment is designed to collect data for both phenomena and will inform vehicle tank thermodynamic simulations to estimate heat and mass transfer rates and expected boiloff losses.

Technology Maturation

The primary purpose of this project is to gain experimental data on reduced gravity cryogenic pool boiling, and the secondary purpose is to gain experimental data on reduced gravity subsurface pressurization in a cryogenic liquid. Models generated from this data will enable accurate tank thermal and pressurization system design by minimizing uncertainty in propellant boiloff losses.

Future Customers

In-space cryogenic propulsion will play a vital role in NASA’s return to the moon. Several, if not all, of the NASA lunar architecture elements will require storage and pressurization of cryogenic propellants, specifically the space tug and propellant tanker stages. Other vehicles in the lunar architecture such as the ascent and descent stages may also contain cryogenic propellants.

Technology Details

  • Selection Date
    TechFlights19 (Oct 2019)
  • Program Status
  • Current TRL (?)
    Successful FOP Flights
  • 0 Parabolic

Development Team

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