Abstract
Extending the storage period for cryogenic propellant is necessary for future space exploration, such as Mars transportation. In a space mission, the heat entering from solar induces cryogenic propellant evaporation and generates the boil-off gas (BOG) from the propellant. The BOG causes self-pressurization of the storage and shorten its storage period. Therefore, a pressure regulation system is necessary for extending the storage period. The thermodynamic vent system (TVS) regulates the pressure of the storage tank by reducing BOG with active thermal management. In this study, we did experiments of jet mixing using liquid nitrogen (LN2) against the LN2 self-pressurized tank in ground gravity environment to verify pressure-regulating function by jet mixing, a component of TVS. As a result of the tests, jet mixing reduced the boil-off rate by about 98 %. On the other hand, jet mixing with a smaller supply flow rate could reduce the boil-off rate only slightly. These results showed the effectiveness of jet mixing for reducing BOG and the importance of using appropriate flow rate at actual TVS.
