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Liquid Nitrogen Zero Boiloff TestingCryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) are a part of NASAs future space exploration due to their high specific impulse for rocket motors of upper stages suitable for transporting 10s to 100s of metric tons of payload mass to destinations outside of low earth orbit and for their return. However, the low storage temperatures of LH2 and LO2 cause substantial boil-off losses for missions with durations greater than several months. These losses can be eliminated by incorporating high performance cryocooler technology to intercept heat load to the propellant tanks and modulating the cryocooler to control tank pressure. The active thermal control technology being developed by NASA is the reverse turbo-Brayton cycle cryocooler and its integration to the propellant tank through a distributed cooling tubing network coupled to the tank wall. This configuration was recently tested at NASA Glenn Research Center, in a vacuum chamber and cryo-shroud that simulated the essential thermal aspects of low Earth orbit, its vacuum and temperature. Testing consisted of three passive tests with the active cryo-cooler system off, and 7 active tests, with the cryocooler powered up. The test matrix included zero boil-off tests performed at 90 full and 25 full, and several demonstrations at excess cooling capacity and reduced cooling capacity. From this, the tank pressure response with varied cryocooler power inputs was determined. This test series established that the active cooling system integrated with the propellant tank eliminated boil-off and robustly controlled tank pressure.
Document ID
20170001537
Acquisition Source
Glenn Research Center
Document Type
Technical Publication (TP)
Authors
Plachta, David
(NASA Glenn Research Center Cleveland, OH United States)
Feller, Jeffrey
(NASA Ames Research Center Moffett Field, CA United States)
Johnson, Wesley
(NASA Glenn Research Center Cleveland, OH, United States)
Robinson, Craig
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
February 10, 2017
Publication Date
February 1, 2017
Subject Category
Fluid Mechanics And Thermodynamics
Propellants And Fuels
Report/Patent Number
NASA/TP-2017-219389
E-19295
GRC-E-DAA-TN35381
Funding Number(s)
WBS: WBS 448887.01.03
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Keywords
Cryogenic fluid management
Zero boil-off
Reverse turbo-Brayton cycle cryocooler
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