Non-condensable helium effect on heat and mass transfer characteristics inside a liquid hydrogen tank.

Abstract

Existence of non-condensable helium in cryogenic tank ullage may affect the interfacial heat and mass transfer characteristics and also the pressurization performance. In the present paper, helium effect on heat and mass transfer inside a hydrogen tank as well as the associated pressurization performance is studied, and a computational fluid dynamic (CFD) approach is introduced. In the CFD computations, species transfer between helium and propellant vapor is considered, and a modified phase change model accounting for helium effect on heat and mass transfer is also involved. A series of successive pressurization operations are simulated, and the tank pressure evolutions and field distributions are calculated to assist the analysis. The results show that existing of helium in tank ullage could facilitate the mass transfer from liquid to vapor, and a combined effect of more evaporated vapor and non-condensable helium inside ullage could suppress the pressure reduction during vehicle launching process.