An assessment of helium evolution from helium-saturated propellant depressurization in space
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Helium evolution from the transfer of heliumsaturated propellant in space is quantified to assess the impact of discharging two-phase gas/liquid flow from the supply tank, gas injection into the receiving tank, and liquid discharge from the receiving tank. To affect propellant transfer, the receiving tank is required to vent from 1827 kPa to a predetermined lower pressure. For tank venting, the maximum volumes of helium evolved are approximately 0.014 m3 for monomethylhydrazine (MMH-CH3N2H3) and 0.057 m3 for nitrogen tetroxide (NTO-N2O4). Due to lack of body force in a microgravity environment, the evolution and growth of helium bubbles from a liquid body influences its fluid dynamics. For propellant transfer [1], the volume fractions of helium evolved at line pressure are 0.1% by volume for MMH and 0.6% by volume for NTO at 11 liters per minute (1pm). The void fraction of helium evolved varies as a second order power function of flow rate, which suggests significant change in void fraction at higher flow rate (>11 1pm). The accumulation of excess helium inside the receiving tank for 941-kg transfer is insignificant; however, for 4082-kg transfer, the release of excess helium causes the receiving tank pressure to increase by 165 kPa, which can reduce its capacity to receive propellant. 2001 by The Boeing Company. Published by the American Institute of Aeronautics and Astronautics, Inc.
