SIMULATION OF FLOW AND HEAT TRANSFER IN LIQUID-HYDROGEN TANK WITH THERMODYNAMIC VENT SYSTEM
For long term storage of cryogens in a space mission, the thermal gradients result in excessive tank pressure rise and the formation of undesirable liquid-vapor mixtures within the bulk liquid in the tank. Because the ullage location in microgravity environments is no longer always at the top of the tank as in normal gravity environment and is not easily predictable, direct gaseous venting to reject heat is not available in space. An indirect venting manner through using a thermodynamic vent system (TVS) has been developed to effectively control the rise of excessive tank pressure and prevent the formation of undesirable liquid-vapor mixtures produced by evaporation in the bulk liquid and in relevant transfer tubes in microgravity environments. The TVS concept defined by Rockwell International consists of a recirculation pump and a simple heat exchanger mounted on a spray injection system. As a core problem of the TVS, the function of the spray bar in the tank and the effects of the liquid spray injection on the flow and temperature fields in the tank are the most interested issues which are critically concerned by engineers designing spray-bar in TVS for space and other industrial applications involving long term storage of the sub-critical cryogenics. A numerical simulation for the time histories of the tank temperature and pressure fields induced by the liquid spray through the spray bar has been performed using FLUENT. The results show that the spray injection of the recirculated liquid is effective for the tank pressure control. It has been also revealed that the recirculated liquid spray is more efficient to control the ullage pressurization in microgravity than in normal gravity. The numerical simulation can give the density, temperature, velocity vector, stream function, and pressure fields at any predetermined time, which are very useful for understanding of the function and operation of the spray bar in a TVS.
DAVID F.CHAO JOHN M.SANKOVIC BRIAN J.MOTIL NENGLI ZHANG
NASA Glenn Research Center at Lewis Field, Cleveland, OH 44135, USA Ohio Aerospace Institute at NASA Glenn Research Center at Lewis Field, Cleveland, OH 44135, USA
国际会议
The 22nd International Congress of Refrigeration(第22届国际制冷大会)
北京
英文
2007-08-21（万方平台首次上网日期，不代表论文的发表时间）