Design of Spray Cooling Systems for Chilldown of Propellant Tanks

In-space cryogenic propellant transfer is a key enabling technology for future long duration space exploration missions. However, successfully refueling tankage with cryogenic propellants in space presents significant challenges related to the chilldown of nbsp;the receiving tank. There is a limited supply of propellant in space depots and the cold propellant itself has to be used for chilldown purposes utilizing non-vented filling procedures while maintaining the pressure in the receiving tank below a prescribed threshold. Although filling protocols such as pulsed-injection and charge-vent-hold have been developed to optimally achieve high fill-levels during the refueling process, the success of attaining high fill refuel levels is largely dependent on the cooling efficiency of the tank walls and the ullage. It is envisioned that tank cooling will be facilitated by spray injection nozzles that remove thermal energy rapidly from the system minimizing boil-off, propellant loss and chilldown time. The innovation described in this proposal is a collaborative effort between CRAFT Tech and the University of Connecticut that involves detailed experimental visualization and diagnostic measurements involving the interaction of spray nozzles with tank environments and utilizing these observations for the development of specialized spray cooling models in a high-fidelity multiphysics simulation framework.