Design of Spray Cooling Systems for Chilldown of Propellant Tanks

In-orbit cryogenic propellant transfer is a key enabling technology for future long duration space exploration missions. Tank chilldown will be one of the primary challenges to be overcome to achieve refueling in space. nbsp;It is envisioned that tank cooling will be facilitated by the use of spray injection nozzles, achieving high heat removal rates through phase change. Tank filling protocols such as charge-vent-hold and vented-chill-non-vented-fill are being investigated to improve the probability of successful refueling while minimizing propellant boil-off. In this collaborative effort between the Univ of Connecticut and CRAFT Tech, experimental visualization and diagnostic measurements of a sub-scale tank are being used to understand the complex heat-transfer interaction modes between the spray and the ullage as well as the spray and the tank walls.nbsp; Validation datasets are being collected and used in the development of a specialized spray cooling models within a comprehensive high-fidelity Multiphysics simulation framework. The simulation framework can be used for design support, analyzing tank filling protocols and prediction of chilldown times and propellant loss as part of the refueling process in a microgravity environment.