Experimental Investigation on Pressure-Control Characteristics of Liquid Hydrogen Tank Based on Active and Passive Thermodynamic Venting System Technology

Pressure control while minimizing the mass loss of liquid hydrogen is one of the key technologies required for the long-term storage of cryogenic propellants in microgravity in space, and the use of a thermodynamic venting system (TVS) has been considered as an effective means to solve this problem. In order to investigate the characteristics of pressure control by TVS technology, a cryogenic test platform for liquid hydrogen that integrated active and passive TVS was set up, a spray-bar exchanger and vapor-cooling screen were used to eliminate thermal stratification and realize the reuse of cold energy. Ten pressure-control tests using passive TVS (PTVS), mixing and active TVS (ATVS) strategies with heating powers of 0 W, 40 W and 80 W, were carried out. The single cycle time under different strategies, the effect of heating power on single cycle time, and the comparison of volume of the venting GH(2) in different tests were analyzed in detail, the research showed that TVS technology could accurately control the pressure of cryogenic storage tanks within a predetermined range. An additional evaporation test was carried out using a direct venting method to compare with the above PTVS and ATVS tests, and the results showed that the venting volume of GH(2) in unit time by the direct-venting method was close to that of the PTVS test with the heating power of 40 W, and the venting volume in unit time by the ATVS strategy was decreased by 87.3% compared to the direct-venting test.