Thermodynamic vent system (TVS) is deemed as an efficient pressure control technique for long-term on-orbit storage of cryogenic propellants through fluid mixing and a combination of throttling and heat exchanging before venting. Three control strategies have been proposed to automate the mixing mode and venting mode of the TVS. The effects of these control strategies on liquid temperature

stratification and mass loss are investigated on a TVS simulator

which works at room temperature with R141b as the working fluid. The results show that the TVS can not only achieve a significant vent loss but also lower liquid temperatures and weaker stratification when one of the strategies is applied whose mixing mode operates based on ullage pressure and the vent mode is controlled based on both the ullage pressure and the bulk liquid temperature. This investigation provides guidance for the design and operation of cryogenic TVS.