Numerical modeling of cryogenic chilldown process in terrestrial gravity and microgravity

In this paper, a numerical model is developed to predict the cryogenic chilldown process of a vertical tube for both terrestrial and microgravity conditions. The flow field is covered by four distinct regions, which are single-phase vapor region, dispersed flow region, inverted annular flow region, and single-phase liquid region. Heat transfer mechanisms are dictated by the flow patters. A two-fluid model is employed to analyze the dispersed flow region and the inverted annular film boiling region. Gravity effect on the chilldown process is also investigated. Model results indicate that film boiling heat transfer decreases with decreasing gravity level for the bottom flooding condition. The model results show a good agreement with the experimental data.