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Spray Bar Zero-Gravity Vent System for On-Orbit Liquid Hydrogen StorageDuring zero-gravity orbital cryogenic propulsion operations, a thermodynamic vent system (TVS) concept is expected to maintain tank pressure control without propellant resettling. In this case, a longitudinal spray bar mixer system, coupled with a Joule-Thompson (J-T) valve and heat exchanger, was evaluated in a series of TVS tests using the 18 cu m multipurpose hydrogen test bed. Tests performed at fill levels of 90, 50, and 25 percent, coupled with heat tank leaks of about 20 and 50 W, successfully demonstrated tank pressure control within a 7-kPa band. Based on limited testing, the presence of helium constrained the energy exchange between the gaseous and liquid hydrogen (LH2) during the mixing cycles. A transient analytical model, formulated to characterize TVS performance, was used to correlate the test data. During self-pressurization cycles following tank lockup, the model predicted faster pressure rise rates than were measured; however, once the system entered the cyclic self-pressurization/mixing/venting operational mode, the modeled and measured data were quite similar. During a special test at the 25-percent fill level, the J-T valve was allowed to remain open and successfully reduced the bulk LH2 saturation pressure from 133 to 70 kPa in 188 min.
Document ID
Document Type
Technical Memorandum (TM)
Hastings, L. J. (Alpha Technology Huntsville, AL, United States)
Flachbart, R. H. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Martin, J. J. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Hedayat, A. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Fazah, M. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Lak, T. (Boeing Co. United States)
Nguyen, H. (Boeing Co. United States)
Bailey, J. W. (Sverdrup Technology, Inc. United States)
Date Acquired
August 21, 2013
Publication Date
October 1, 2003
Subject Category
Space Transportation and Safety
Report/Patent Number
Distribution Limits
Public Use Permitted.

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NameType 20040000092.pdf STI