Transient modeling of cryogenic two-phase flow boiling during chill-down process

Accurate predictions of chill-down time and propellant consumption as well as a clear understanding of the performance and characteristics of cryogenic pipeline chill-down are significant for achieving the safe and high-efficiency cryogenic propellants fueling. On the basis of available nitrogen experimental data, detailed mechanism analysis and comprehensive verification are carried out for three characteristic points and four heat transfer regimes respectively, and a group of correlations for cryogenic pipeline chill-down are proposed. Besides, an accurate chill-down model involving intricate interaction of phase change, heat transfer and fluid dynamics is established with quasi-steady state method. To further reveal the unknown mechanism and phenomena of chill-down boiling, flow regime and heat transfer performance at typical moments and wall temperature drop characteristics at typical locations are studied respectively, which provide feasibility for more efficient refueling and arouse concern for potential safety hazard.