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Analytical Models for Variable Density Multilayer Insulation Used in Cryogenic StorageA unique multilayer insulation concept for orbital cryogenic storage was experimentally evaluated at NASA Marshall Space Flight Center (MSFC) using the Multipurpose Hydrogen Test Bed (MHTB). A combination of foam/Multi layer Insulation (MLI) was used. The MLI (45 layers of Double Aluminized Mylar (DAM) with Dacron net spacers) was designed for an on-orbit storage period of 45 days and included several unique features such as: a variable layer density and larger but fewer DAM perforations for venting during ascent to orbit. The focus of this paper is on analytical modeling of the variable density MLI performance during orbital coast periods. The foam/MLI combination model is considered to have five segments. The first segment represents the foam layer. The second, third, and fourth segments represent the three layers of MLI with different layer densities and number of shields. Finally, the last segment is considered to be a shroud that surrounds the last MLI layer. The hot boundary temperature is allowed to vary from 164 K to 305 K. To simulate MLI performance, two approaches are considered. In the first approach, the variable density MLI is modeled layer by layer while in the second approach, a semi-empirical model is applied. Both models account for thermal radiation between shields, gas conduction, and solid conduction through the separator materials. The heat flux values predicted by each approach are compared for different boundary temperatures and MLI systems with 30, 45, 60, and 75 layers.
Document ID
20010021346
Document Type
Conference Paper
Authors
Hedayat, A.
(Sverdrup Technology, Inc. Huntsville, AL United States)
Hastings, L. J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Brown, T.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Date Acquired
August 20, 2013
Publication Date
January 1, 2001
Subject Category
Engineering (General)
Meeting Information
Meeting: Cryogenic Engineering Conference and International Cryogenic Materials Conference
Location: Madison, WI
Country: United States
Start Date: July 16, 2001
End Date: July 20, 2001
Funding Number(s)
CONTRACT_GRANT: NAS8-40836
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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