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https://ntrs.nasa.gov/search.jsp?R=19810006640 2020-05-24T01:42:00+00:00Z
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(NASA-CR-160072) PRELIMINARY DESIGN N 1 - 15155TRADE-OFFS FOR A MULTI-MISSION STONEDCRYOGEN COOLER Final Report (Lockheed.Missiles and Space: Co.) 102 P HC A06/MF ,A01 U:nclas
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TP-5096 d
REPORT NO.- LMSC/D630389
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FINAL REPORT
;
PRELIMINARY DESIGN TRADE—OFFSFOR A MULTI-MISSION STORED
CRYOGEN COOLER
LMSC/D630389Dece0er 1978
FOR THE NATIONAL AERONAUTICS AND SPACEADMINISTRATION GODDARD SPACE FLIGHT CENTER q
CONTRACT NAS 5-2428DR. ALLAN SHERMAN, TECHNICAL OFFICER
E
MATERIAL SCIENCES
LOCKHEED PALO ALTO RESEARCH LABORATORY i. LOCKHEED MISSILES & SPACE COMPANY, INCs
PALO 'ALTO, CA.
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LOCKHEED PALO ALTO RESEARCH LARORA'TORY-— _ - — -- --- 10CKNIID. M.1S311l I t 1 0 A C ( COMPANY, 1 N.t.
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TABLE OF CONTENTS Gk
Section Page
I
1.0 INTRODUCTION 1-:1
i 2.0: SUMMARY 2-1
j 3.0 PAYLOADS REVIEW 3^1
i4.0 ANALYSIS APPROACH 4-1
4.1 Development of Caroler Design 4-1
4.2 Structural Analysis 4-9
5.0 TRADE STUDY RESULTS 5-1
6.0 BASELINE COOLER 6-1"'
6.1 Baseline Cooler Description 6-1
6.1.1 Summary 6-1
6.1.2 Component Description 6-4 i
6.1.3 Thermal Analysis 6-12
6.1.4 Structural Analysis 6-17
6.2 Instrument Cooling Capabilities 6-23
6.3 'Instrument Integration and Flight Operations' 6-41
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ILLUSTRATIONS'
Figure No. Page:.
_ 2-1 Temperature Range of Solid Cryogens 2-2
2-2 Multi-Mission Cooler Configuration - 2-3
C2-3 Instrument Cooling Capability of Saseltm+ Cooler 2-4
3-1 Cryogenic Pa load Reference (Autom Payloads)y (Automated _ 3-4
3-2 Cryogenic Payload Reference (Sorties) 3_5
j 3-3i
Cooling Requirements for Automated Payloads 3-6
3-4j Cooling requirements for Space Shuttle Sortie Payloads 3-7
4.1-1 Interrelation of Computer Programs for Solid Cooler Thermal 4-2,i Design
4.1-2 Solid Cooler Optimization Program 4-6
41-3 Comparison of Actual Cooler Hardware Weights with Computer 4-7Model Predicted Weights
4.1-4 Comparison of Predicted and Measured Heat Loads 4-$
4.2- Structural Analysis Flow 4-10
5-1 Assumptions for Cooler Trade Studies 5_2
5-2 Trade Studies - Carbon Dioxide Primary - 1 Year Life 5-4
5-3 Trade Studies - Ethylene Primary - 1 Year Life 5-5
5-4 Trade Studies - Methane Primary - T Year LIfe 5-6
5-5 Trade. Studies - Nitrogen Primary - l Year Life -5-7
5-6 Trade Studies - Argon Primary - 1 Year Life 5-8
5-7 Trade Studies - Neon Primary - l Year Life 5-9
5-8 Trade Studies -'Hydrogen Primary - 1 Year Life 5-10
5-9 Trade Studies - Carbon Dioxide Primary - 2 Year Life 5-11
5-10 Trade Studies - Ethylene Primary - 2'Year Life 5-12
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ILLUSTRATIONS CONT'D
Figure No. P,e
5-11 Trade Studies Methane Primary - 2 Year Lifo 5-.13
5-12 Trade Studies - Argon Primary - 2 Year Life 5-14
5-13 Trade Studies - Neon Primary - 2 Year Life 5-15
5-14 Trade Studies - Ethylene-Primary - 3 Year Life 5-16
5-15 Trade Studies - Carbon Dioxide Primary-3 Year Life 5-17',
5-16 Trade Studies - Methane Primary - 3 Year Life 5-18
5-17 Trade Studies - nitrogen. Primary - 3 Year Life 5-19
5-18 Trade Studies - Argon Primary - 3 Year Life 5-20!
5-19 Trade Studies - Neon Primary - 3 Year Life 5-211
5-20 Trade. Studies - Hydrogen. Primary - 3 Year Life 5-22
5-21 Summary of Cooler Weight vs. Instrument Heat Load 5-23
5-22 Sununary_of Cooler Diameter vs. Instrument Heat Load 5-24'
6.1-1 Multi-Mission Baseline Cooler System Summary 6-2
$.1-2 Multi-Mission Cooler Mass Summary 6-3
6.1-3 Multi-Mission Cooler Layout 6-5
6.1-4 Cooler Plumbing Schematic 6-14
6.1-5 Beat Map of Cooler 6-15
6.1-6 Effect of Off-Loading for Various,Cryogens 6-19
6.1-7 Material Properties 6-20
6.1-8 Structural Analysis Results 6-21
6.2-1 Methane Primary-Lifetime vs. Instrument Heat Load 6-25
6.2-2 Argon Primary-Lifetime vs. Instrument Heat Load 6-26 EI
6.2-3 Nitrogen Primary-Lifetime vs. Instrument Heat Load -. 6-27,i
6.2-4 Neon Primary-Lifetime vs. Instrument Heat Load 6-28
6.2-5 Hydrogen Primary-Lifetime vs. Instrument Heat Load 6-29'a
LOCKHEED PALO ALTO RESEARCH LABORATORYi' tOCKMII o MIf }11.[f f ► AtI 2O MIAH. r . INC -° A LUIS 101A01' 01. (OC K,!!.!. UP — _6l!C I A,II C 0F0BAIION
ILLUSTRATIONS CONT' D.
Pi$u re No. _ P_ aj!
6.2-6 Secondary Cooling-Capacity-Methane Primary ^ 6-31
6.2-7 Secondary! CQol,ing Capacity - Argon Primary 6-32
. 6.2-8 Secondary Cooling Capacity - Nitrogen Primary 6-33
6.2-9 - Secondary Cooling Capacity - Neon Primary 6-34
$.2-10 Secondary Cooling Capacity - Hydrogen Primary 6-35
6.2-11 Summary of Cooling Capability for 300 •K Shell 6-38F
6.2-1Z Summary of Cooling Capability for 200°K Shell 6-39
6.2-13 Summary of Cooling Capability for 160'K Shell 6-40
6.2-14 Summary of Primary Cooling vs. 'Primary Temperature 6-41
! 6.3-1 Instrument Integration with Cooler 6-43
6.3-2 Additional Instrument Options 6-46
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This study was performed to determine the preliminary design trade-offs for
a multi-mission stored solid cryogen cooler which will have application to
both shuttle sortie and free flyer missions. This study was in response to
the statement of work, generated by INASA Goddard Space Flight Center on Mar
1977.
Extensive studies were performed in this program. They Fell into
two main categories:
1) 'grade studies which determined the optimum characteristics of various
coolers for specific temperatures, heat loads and lifetimes.
2) Selection of a baseline design from these studies (i.e. fixed
geometry) and an analysis of the instrument cooling capability of thisF
baseline when loaded with various cryogen combinations.1
1I The computer program which was utilized for these studies was modified at the
start'of the study and validated by comparison with the weights and heat rates r
of coolers which had previously been built and tested. A plotting routine
was also developed for the trade studies. aa1
_
8
Some studies were performed to determine the requirements of proposed
instruments to aid in selecting a baseline cooler, but this activity was -
limited, and existing data was utilized for the most part.
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2,0 SUMARY
Preliminary design studies have been performed for a multi-mission solid
cryogen cooler which has a wide range of application for both the shuttle
sortie and free flyer missions. This multi-mission cooler (MMC) is designed
II to be utilized with various solid cryogens to meet a wide range of instrument
cooling from 10`K (with solid hydrogen) to 90'K. The cryogens which may ba
utilized and their associated temperature capability is shown in Fig. 2-1.
The baseline cooler utilizes two stages of.solid cryogen and incorporates
an optional, higher temperature third. stage which is cooled by dither a
passive radiator or a Thermoelectric cooler. The general configuration is
shown in Fig. 2-2.
The MIC has an interface which can accommcydate a wide variety of instrument
i
configurations. A shrink fit adapter is incorporated which allows a "drop-
in" instrument integrations as shown in Fig. 2-2
Iti
The baseline system is 83 cm in diameter by 113 cm in length. Its weight
varies depending upon the cryogens utilized and is a minimum of 154 Kg
when loaded with solid H2 and solid ammonia. When loaded with the heaviesti
cryogens; Argon and carbon dioxide the loaded weight is 416 Kg The dryi
° weight of the cooler is 99 Kg.1
The cooling capability of the system is indicated in Fig. 2-3 which shows
the instrument coaling capability as a function of the instrument temperature
r' for one and three year lifetimes.- This capability is compared with the
2-1
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OF POOR QUALITY
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V, requirements of various instruments which are described in Section 3.0.
The baseline design provides cooling of approximately 1 watt over a 00-i000K f
~ temperature range and About 0.5 watts from 13 to 601K for a one year lifetime.
For low cooling loads'( O.1W) and with use of the optional radiator shield,t
cooling lifetimes As great as 8 years are predicted.
The capability of the ZINC is based on state of the art technology and does not
incorporate any features which have not been previously demonstrated. The
utilization of solid hydrogen in the cooler has not been extensively demon-
strated, however, it is not expected that any new technology will be required
E for its use.
The 101C should demonstrate excellent versatility for the instruments under
consideration and should lead to a substantial cost savings when compared to
coolers which are uniquely designed for each mission and instrument.
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3.0 PAYLOADS REVIEWf
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The cryogenic requirements of many proposed instruments are not, established
in much detail in the preliminary design pbase. Temperature requirements'
are generally known to a fair degree for the instruments, but quite often the
investigator does not recognize the impact of 5 or 10'K on the cooling system
requirements. This is particularly significant for a solid cryogen cooler
where 5 or 10'K change in temperature requirement may allow the us e of an
alternate,much more efficient cryogen...
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4
In addition, many times other elements of the instrument such as optics,
baffles or electronics may be operated at a separate, higher temperature
than the primary or lowest temperature requirement. Consideration should also
be given to provisions for intermediate temperature shields for the sole
purpose ,of reAucing the heat load to the primary. These shields may derive
their cooling from the secondrry temperature shield or from attachment to a
passive radiator shield. The working curves which have been developedi
(Section 6 . 2) allow the investigator to determine the trade-offs associated
with various temperatures,
Heat rates for proposed instruments are often estimated from the detector
heat dissipatiovt alone, which often underestimates the total heat input due
to parasitic heat loads.
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Instrument thermal design cannot be effectively accomplished without aI
thorough knowledge of how the instrument may be cooled and what the available
interfaces and thermal shielding options with the instrument are. This
study provides much of the required infotmation in these areas to aid inp
establishing efficient instrument thermal design.
A partial list of parameters which are necessary or helpful in establishing
the most efficient instrument design and cooling means are presented below.
` o rrimary Temperature Requirement and Cooling Load
Ff
o Secondary Temperature Requirement and Cooling Load
o Instrument Duty Cycle
o Vibration Environment
o Hold Time Prior to haunch
o Instrument Size and Distance from Cooler
o Required Overall Life of Cooler
o nbital Characteristics (when Passive Radiator Option i3Considered
Published documents and in-house instrument designs were reviewed, to determine
the principal requirements for future-instrument requirements.
Ref. 3-1 contained data on many instruments and was used extensively. It 1
,.
was apparent from the indicated data spread that the heat rates in many cases
were not known better than a factor of three or four or even an order ofy j'
magnitude in some eases.
3
3-2
LOCKHEED PALO ALTO RESEARCH LABORATORY1,0Cof"I10 M ISS1.11 S • SIACI CO MPAN Y, 1NCA SU•f101A ITY 01 l0CKM1iI 'D AiRClA1i CORPORATION _
Figs. 3-1 and 3-2 list the instruments for both the sortie and automated
payloads`along with their identification numbers which are summarised in z
Figs. 3-3 and 3-4.
These =figures provide a convenient way to compare the MC cooling capability
i with the instrument requirement.
I
__
Additional points in which detail thermal, designs have been made or which have
been built and tested are shown as filled points.
Although the data in these figures must be regarded as very approximate, it
forms a rough guide to the cooling requirements for a wide range of instru-
ments, and was utilized in sizing the baseline cooler parameters.
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FIGURE ^-1, C RYOGENI C PAYLOAD REFERENCE
(AUTOMATED PAYLOADS ►
*SSPD_A MI LARGE; SPACE TELESCOPE
02 LARGE X KAY TELESCOPE FACILITY
03 SYNCHRONOUS EARTH OBSERVATION SATELLITE (HE)
04 LARGE H I GH ENERGY OBSERVATO RY D05 COSMIC RAY LABORATORY
^6 LARGE SOLAR OBSERVATORY07 GRAV ITY AND RELATIV ITY SATELLITE (LEO)
18 GRAVITY AND RELATIVITY SATELLITE (SOLAR)
09 LANDSAT - D
0,10 SYNCHRONOUS EARTH OBSERVATION SATELLITE (EO)
+Y I1 APPLICATIONS EXPLORER12 TIROS 0
#13 OPERATIONAL ENVIRONMENTAL SATELLITE
01 14 FOREIGN SYNCH. MET. SATELLITE015 GEOSYNCH. OPERATIONAL ENV. SATELLITE
016 GEOSYNCH. EARTH RESOURCES SATELLITE
017 EARTH RESOURCES SURVEY OPERATIONS
018 FOREIGN SYNCHRONOUS EO5019 SE'ASAT B
020 GLOBAL EARTH AND OCEAN MON. SYSTEM
#21 ENCKE BALLISTIC FLYBY
x'22 PIONEER SATURNIURANUSITITAN PROBE
#23 MARINER MARS POLAR ORBITER
SSPDA #24 LUNAR ORBITER
OTHER #80 Limb SCANNING IR RADIOMETER (LS IR)1181 HIGH RES . X RAY SPECTROSCOPY#82 1R TELESCOPE
#83 IR TELESCOPE (GSFCI#84 EARTH RES SENSOR (GSFC).
#85 I RAS
OTHER 1186 POLLUTION MONITORING (LRC)
SPACE SHUTTLE PAYLOADS DESCRIPTION ACTIVITY
3-c!
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FIGURE 3-2, CRYOGENIC PAYLOAD REFERENCE,(Sorties)
SSPDA 025 rC1 m SHUTTLE IR TELES(:;0 4 ' FACILITY026 DEEP SKY UV SURVEY TELESCOPE027 COMETARY SIMULATION029 METEOROID SIMULATION
i 030 1 in UN000LED IR TELESCOPE031 3 in AMBIENT TEMP. IR TELESCOPE032 1,5 Km IR INTERFEROMETER033 2.5 in CRYOGENICALLY COOLED I R TELESCOPE034 COMBINED PAYLOAD EXPERIMENT035 COMBINED PAYLOAD EXPERIMENT036 ATTACHED FAR IR SPECTROMETER#37 COMBINED IR PAYLOAD038 COMBINED UV PAYLOAD039 ATTACHED FAR IR PHOTOMETER040 MAGNETIC SPECTROMETER041f HIGH RESOLUTION X RAY TELESCOPE042 ANTIPROTON MEASUREMENTS143 LIQUID "X" DETECTOR044 SOLAR FAR IR TELESCOPE, AMBIENT TEMPERATURE045 FLARE COARSE MONITORING PACKAGE046 SOLAR ACTIVITY EARLY PAYLOAD047 ATM. MAG. AND PLASMAS IN SPACE (AMPS)148 SCANNING S PECTRORAD I OMETER049 SPACE SHUTTLE CALIBRATION FACILITY050 ACTIVE AND PASSIVE CLOUD RADIANCE EXPERIMENT051 STD. EARTH OBSERVATION PACKAGE (SEOPS)#52 MULTISPECTRAL SCANNER _ COASTAL ZONE
SSPDA 053 LIQUID HELIUM RESEARCH FACILITY
OTHER 054 LASER HETERODYNE EXPERIMENT055 IR DETECTOR (MIT)056 HX - II DETECTOR
SPACE SHUTTLE PAYLOADS DESCRIPTION ACTIVITY
6
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I COOLERREQUIREMENTS
1., LIFETIME• CRYOGEN TEMPERATURES
I' • ENVELOPE• STRUCTURAL ENVIRONMENT`• EXPERIMENT HEAT LOADS
PRELIMINARY DESIGNf • ESTABLISH GENERAL CONFIGURATION
CRYSUPPRES 1• CRYOGEN TEMP.
WT. AND SIZE. VS. TEMP, HEAT LOADS, LIFE• LIFE VS. TEMPS, HEAT LOADS
' VS VENT LINE. I * MlI OPTIMIZATIONPARAMETERS 0 WT. AND SIZE VS. SUPPORT CONFIGURATION y
F^
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DETAIL DESIGN STRUCTURALANALYSIS
• FREEZE MAJOR PARAMETERS RESULTS1
THERM
R PRES o FINAL SIZE AND HEATLOADS DETERMINED
• FINAL VENT • TRANSIENT STUDIESLINE SIZING • EXPERIMENT TEMPERATURE
VARIATIONS• SENSITIVITY STUDIES
FIGURE L11.1-1 INTERRELATION OF COMM PFMP41S FOR SOLID COOLER PER'IAI.
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L Since PRES was not used during this work effort, the cryogen temperature at a't w
pressure of 0.1 torr was used as input to the CRYSUP program for all cryogen
investigated
`` THERM: Detailed design analyses are done with the thermal analyzer computer
program, THERM, on the UNIVAC 1110 computer. The cooler is
divided into a throe-dimension nodal network by the analyst and finite
t
differ ence solutions to the heat transfer equation are determined at each node.
I TITERM has the capacity to Handle well over 1000 nodes for both steady- state
`and transient analyses. T11EMI also has subroutine capability which may be
used to calculate temperature dependent properties before each iteration,
call for heat maps of selected nodes, or in general perform a wide variety of
tasks required by the analyst.
CRYSUP The CRYSUP program uses the UNIVAC 1110 computer to initially size
the support tube bundle to meet the cooler structural requirements and then
determine the.cryogen tank dimensions and system weight. The inputs are
experiment and plumbing heat loads, MLI type, layer density and thickness,
required lifetime, cryogens and boundary temperature, cryogen properties, tank
wall densities and thicknesses, vacuum tank radius, the support tubes' radii
` and length, their structural properties and the structural loads on the system.
For the MIC lifetimes of 1 2 and 3 ears were investigated^ , y g d apt :primary3
experiment heat loads of 0.02, 01, 0.3, and 1.0 watt. Secondary experiment
heat loads were assumed to be such that ,QSecondary 2 x QPrimary for all
cases.
_^..{ and tisuglas was used For each cryogen, the temperature
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was taken to be the temperature where the vapor pressure over the solid is
0.1 tore, and boundary temperatures considered were 100 •K, 1601x, 200•K and
3000x. The following mjor assumptions were made:
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o overall, cooler L/D 1.5
o cavity dimension to be
i Lcavity 40% of LPrimary
Dcavity 23% of DPrimaryx
• fiberglas support tubes sized to survive
5.45g lateral static acceleration (includes 1.65 safety factor)
• design for 20% lifetime contingency r
iThe program performs an iterative process in which the thickness of each tutee,
its deflection, and the clearance between tubes is calculated based on the
equations for a nuntilevered beam. With this infp niation the support tube
heat load is determined, and the size, weight and center of gravity location
for the cryogens are calculated. With the recalculated weight and c.g., the
support tubes are resized. The process continues until the difference In
c g. location between iterations is small. To `do the tank sizing, the heat
loads to the primary cryogen are first calculated and thereafter the tank size.
The conductivity of the support tubes and MLI is curve fit from data measured
atUISC.4_1' -2 The sizing of the secondary is begun only after the sizing of
the primary is completed since the net haat load to the secondary consists of
both the secondary heat load inputs less the cooler heat loads to the primary
and less the heat removed by the primary vent gas.. F
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A summary of the CRYSUP program is shown in figure 4,1-2. As seen, weight
and heat rates as well as cooler geometry are output as the final results.
Data on the degree of reliability that one can derive from the output, is
Indicated in Figures 4.1-3 and 4.1-4.
In figure 4.1a-3 0 predicted system weights are compared to actual.weights, and
in figure 4.1-4 predicted heat rates are compared with actual heat rates for
an in-houseprototype, two stage cooler having a 200'R cooled radiator shield,
This cooler was selected because of its similarity in size and construction
to the baseline cooler. As can be seen, excellent agreement in the coolera
weights was acheived a difference of only 3%. The agreement achieved be-
tween actual and predicted heat gates was 24% (predicting low by 105 mW). This
disparity would be all but eliminated with the 20% lifetime contingency which
is utilized in the MMC. This table also indicates the comparison with THERH
which is 13%.y
By way of summary,, cooler design methodology produces a preliminary design
concept from the initial cooler requirements. From these, CRYSUP will size
the cooler tank and support tube assembly, determine weight and heat leaks into
each cryogen. in parallel, PRES would determine the vent plumbing sizes re-
quired and together with the CRYSUP results and a further input from;a
y designdetailed structure analysis (see Section 4.2) a final desi n is selected.
From these THERM is used to perform a detailed thermal analyses.
URICINAL PAGE ,IS^5 OF POOR @UALITy
LOCKHEED PALO ALTO RESEARCH LABORATORYl O C KM t t D M I S S I t a S f S I A C I. C O M/ A M Y, I N C.
-. A 3.41.SIDIAIY 01 I . 00KM 4 10 A I 1 9 0 A F I C01,?01A. I10M, ._ ,.
^ f
L
LY
^
H M;i
3 0 ►-
o g -^aEEw o►
°~-z
L.; ZCA
") z_a c g 3.
^"' Z ^ WG.1 Q
Q
!.Jl tAv a g ^„ O ^o in
CL
^z ^ WC O
l...,W
_ --p
H U. W {y^ y^j G. on N Zv --
GG ' V LL Z 'z C AN̂Cc W w Z
U.
O ^ W ^ to c^ & 2 ^O -'^4 d^ O o t^ ON0 ^m 0 = W W A^ >-^ td̂
J G» Z Z 0< 5- 5- Z ^j v i W ^iW.
ce. 00
JCA G° =` in o dcn >O V c.^ U Q 3
W IL
- A O y W;; O V m V
Qc
v^
Fig.COMPARISON OF ACTUAL COOLER
HARDWARE WEIGHTS WITH COMPUTERMODEL PREDICTED WEIGHTS
µ I Actual Weight Predicted Weightof Prototype for Actual GeometryCooler 5
Mounting Plate 48.8 30.11
{ Primary Cryogen Tank,including Foam Heat 80.8 73.2Exchanger
! Secondary Cryogen Tank 14 5.6
Primary Tank Insulation 8.1 8.1
Secondary Tank 6.5 6.2Insulation
Secondary'Cooled Shield 16 15.1
Radiator Cooled Shield 20.723.9 24.3 I
Radiator Cooled Shield 3.2Insulation
Outer Vacuum Shell 56.2 42.2 1
Fiberglas SupportBundle, Including Flanges 38.6 32.4Dry Weight w/o 202Misc _29,.3 23.7,20% Dry Weight 0 47.4-For Miscellaneous
TOTAL DRY WEIGHT 293 284.6
Primary Cryogen (Methane) 235 233.7
Secondary Cryogen (Ammonia) 30 26.1'
TOTAL LOADED WEIGHT 558 LBS
i
544 LBS
c1-7
LOCKHEED PALO ALTO RESEARCH LABORATORYL0CKNtfu 1k111 Ott'! l ihA C2 GQMrANT INb.A 4U4S101A4Y 0r t 0 C K N ( I D AIaC0Arf C04r0AAI10N
J
ii
i
Fig, 4.1-4 COMPARISON OF PREDICTED AND MEASURED HEAT LOADS
Item
Measured Predicted Predictedby CRYSUP by Thermal
An&Wer THERM)
Load• to Primary:
Support Tubes 292 301
Insulation 133' 146
Plumbing 12 11
Miscellaneous 21
PRIMARY TOTAL. HEAT LOAD 542 ^ 37
4.2 structural Analysis
The dynamic vibration analysis was performed with the BOSOR4 cc.+pater
pro&ran 4-3
The flow
the thermal design requiring several iterations before all, system re -
quirements are satisfied is necessary. The extent of the studies
performed here are shown by the dotted region.
The support tubes are sized initially with the combined thermal /structural
program CRXSUr (Section 4.1) which determines the :required wall thickness.
This support configuration is incorporated into a simplified version of
BOSOM, and vibration and buckling studies are performed in a parametric
manner. When thearametric studies are completed and consistent withp P ^
thermal requirements, a detail model of the complete cooler is made, and
final analyses are performed. These final, analysesinclude the vibration
and acceleration in both the lateral and axial direction.
_
7as
9
X1-9 Y
LOCKHEED PALO ALTO RESEARCH LABORATORYfC!_il(FI1l0 MIEAIiIA l 5IAC1 C0MPANt, 1NC,,A 1UI. :1101A I Y 00 10CWNI10 A:12CIAII C04V0 1A110M - -'
r
FIGURE 4.2-1 STRUCTURAL ANALYSIS FLOW
For Su Tubing,Port
Requirements/Parameters CRYSUP'(Sec. 4.1. )
i o General. Configurationo Vibration o Provides preliminary sizing
1 o Shock .....! o Acceleration` o Loads -
t o Material Properties DOSOR-4 ) _
o Sim ified model for para-metric studies
o Provides mode shapes' o Resonance
o Stresso Deflections
r
Thermal Studies__ r
_--^.-
BOSOR-4
o Detail model for finalanalysis
o Stresso Vibrationo Acceleration
4-10 j
LOCKHEED PALO ALTO RESEARCH LABORATORY.` SOCI(NtS0 MISSIISS A S ► ACS COM ► AMY, IN-C." A. SYAS.iDIANY LOCK141l0 AIICIAS/ COAt:ORAIION
5.0 TRADE STUDY RESULTS
Tra4e studies were conducted to determine the characteristics of various
cryogen combinations as a function of heat load and lifetime. These studies
were performed as an aid in determining the desirable characteristics of the
baseline cooler.' They also provide information on the required weight andi
size for cooler systems outside the scope of the multi-mission cooler (MMC)
and may be used to compare the performance of the MC with a cooler optimized
for a particular cooling requirement, E
I
The studies that follow show the characteristics of solid`eryo$en coolers
each of which is optimized for a specific cooling requirement. The optimum
insulation thickness is determined by a subroutine in the computer program
for each cooling condition investigated.
In order to limit the number of parameters which must be investigated certain rassumptions were made rega rding the parameters of the cooler. These assumptions_
^lA
p p providing coolers for instrumentwere bused largely on prior experience in ruvi
cooling and in fabricating these coolers. The major assumptions are summarized
in Table 5-1. One of the primary assumptions W48 that the n.qt instrument
cooling to the secondary instrument stage was twice the cooling required for
the primary,
It was also assumed that the ratio of cooler length to diameter was 1.5 and
this ratio corresponds with systems developed in the past. Experience has
indicated that the diameter of the cooler is the critical dimension, while
the length restraint is less severe. As mentioned before a 20% lifetime con-
tingency has been incorporated into the calculations to account for uncer-
tainties in predicting the heat rates.
iiThe fberglas support tubes were sized by a subroutine in the program and
j were treated structurally as cantilevered tubes with a static acceleration j
load equivalent to the dynamic environment. A check on the baseline cooler
configuration indicated very close agreement between the static andequivalent
i dynamic loading. A lateral load of 5 . 45 g's was utilized, and this includes
r the 1.65 safety factor. 1I
LOCKHEED PALO ALTO RESEARCH LABORATORYI. a C9 41 ID MII I Ik11, a IPAc.1 ioM ► A.MC 1 M C
_.. A SYaS101AlV 0/_ ... I IL, CXN110 AIICIA[I COa.tO1AiION^.r -- . ^c,^— t̂er_-^ mnsw^. •,,^^^,,.,»..., ,, ._ sca5
....t ".. .. .
FIGURE 5-1. ASSUMPTIONS FOR COOLER TRADE STUDIES
o Equivalent Acceleration: 5.45 g's
o Length to Diameter Ratio: 1.5o Insulation Type: Tissue/Double Aluminized Mylar fo ot Secondary
Stage and Cooled Shield, Double Silk Net/Double Aluminized Mylar for Primary Stage.
o Lifetime! Contingency: 20%o Instrument Cleat Cates: Secondary Cooling is Twice V imary Cooling'
o Vapor Cooling: The secondary cryogen is cooled with the
primary vent gas, the suPpores are also cooked
with both primary and secondary vent gas
o Cavity (Internal Instru-ment) Cavity length is 40t of the Piimary Tank Length.
Dimensions: Cavity 'Diameter is 23% of the Primary Tank Diu.
f
F
Ia
,f
LOCKHEED PALO ALTO RESEARCH LABORATORY10Ck41( 0 M1$11t1$ LACK 011rANV, 1140A 1UIr,101AIW Of t0CKWI1D A11CIF11 COIf0IA11004
a
F r
The principal result of this trade study is presented in Figures 5-2
thru 5- '20. In these f'ig,ures the total weight of the system is presented
as a function of primary instrument beat loud for 'lifetimes of l year'
2:years and 3 years. Knch curve corresponds to a particular primary
cryogen selection, and shows the weights fur various secondary cryogens
and radiator temperatures. Although the CO2 (1250K) and athylene (95°K) fall
somewhat above the stated temperature limits for the study, they were In-
eluded for completeness and,for possible consideration for use with gamma-
ray instruments which may operate in this temperature range. It should be
understood that the heat load to the secondary is twice the heat-load in-
dicated to the primary and in most cases this increases the-'system weight
substantially over the weight for cooling with the primary only,
F igure 5- 21 shows a summary of the cooler weights for various primary cryogens3
utilizing ammonia as the secondary for I year and 3 year lifetimes. The
results for a cooled radiator shield is not shown, it is assumed the shield
temperature is 300°K.
Figure 5-22 shows the diameter variation for the various cases. The length
as previously stated is 1.5 times the indicated diameter.
The diameters shown, in Fig. 5-22 do not include the insulation thicknessI
required on the radiator shield. This thickness may be in the order of
0,76 to 2 cm, and requires further Analysis to define.. The overall system
diameter will therefore increase above the values indicated in the figure.
3
l
li
5—R
LOCKHEED PALO ALTO RESEARCH LABORATORYL O C K N 1 t 0 M 1 1 1 1 t 1$ ► 1 ► A C I C O M f A N ► + I N{.
, -. - • %Ui11u1.A111 Of i0C1(N110 A I I C a A 0 V C06 ► ONAI10N.
FIGURE 5-2, TRADE STUDIES CMON DIOXIDE PRIMY -1 YEAR FIFE,
I^
{
400. 0
I
4
350.0
^t
300.0
..^ 250.0
a
200. 0
w4
r
1
150.01
1
100.0
50.0
0.00.0 0 1 0.2 - 0.3 0. 11 0.5 0.6 0.7 0.8 0.9 1.0 s
PI21.11ARY EXPERMENT 11EA LOAD (11) a
5-4
5-5
• 7W . U
650 ,0
600 ,0t1j
I f
I
550 0
500 . U
1 0.n
b 100.0
a 3,50.0-
.100.0-
3t
Ii4^{n 4 n
200.0
150.0-
V100.0-
50.0-
s... ++.^•a ,.,f, ., r =..N^ _ Ewa>.+..r..+. _ .
♦ * lt4 f,0. RnD- 00 K.1 ..2-4 RAO- 00 K
oar-PA 7,- 50: K
}fi. A^.13 T VO-. CO K
.^,.. k=<" 00 K
r
A
+vn`vr +F^i!T4+ q+rg+-.. use Vce ts:t4swc^ wr: r
r -
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1100 .0.
1000. 0 .
000 .0
000.0
FIC4JRE 5-5, TRADE STUDIES - NITROGEN PRIMARY -1 YEAR LIFE
100.0
600,0-
500.,) _
100. 0
i
^, a
30U . 0
200 . 0
100.0
k
t
T;1
t iii Rn0.
Ron-
F
00 K00 K
4 PAD- 60 K1- CH4 RAO. 00 K
'3 - C2r si 'l :G, RnJ-,PAD
00 K 60 K
^i col) S :C. PAD- 00 K
y Ri.:{1..^- .,..SIL-`.60 Ks1,- }oH^ C. R OD
d
^ f
< ft!
a ^
r
u am
•. C21A 'CC, IRMW00. KK A/01P"4 I= fRmn
0- CO2 T RAO- KCO2 SX, RAU- 60 K
- NH3 SIC, RAO. 00 K
- t N3' C. ROD- 60 K
001'r
0.0 0.1 0.2 o .s n .a__ A. AS 0 . 8 0.7 n .:R n_a r_^
..
7
5-8
FIGURE 5-7, TRADE STUDIES - NEON PRIMRY 1 YEAR LIFENEON COOLER , t YR LIFE
zgoo , Ui
cm. 0
2000.0-
law. 0
1600.0
1400.0
E v12W. 0
I1000.0-
aw .0-
r 100.0 -
400.0
200.0-
n
0.0
-
N2S.rRAo-
000r Q SE
rtt^ .:c,RRO .,Mg ,
00 K00 K
CMCN/ _.c^
- MA
'C RPZPRO.
C, RRO-
6000 KW K
- CZH^n+
Cc, RR0.cc, Rno-
00 Kso K
M. NH3 5- NH3
'c, RR0.c, RW-
00 K60 K
r
F%
5-g
FIGURE 5-80 TRADE STUDIES - HUDG91 PRIMARY - l YEAR LIFE
HYDROGEN COOLER > YR LIFE,
4000.0
3.500 .0
3000.0
-^ 2500 .0^4y
v z000.ow
15W . 0
1000.0
.0
0.0^0.0 0A 0.2 0.3. 0.4 0_,5 0.6 0.7 0.8 0.9 1.0
PRIMARY EXPERIMENT HEATLOAD (W)
GCND
- NCOtI CCKCtk1 ^C^Rf10• K
IC-01NC04 Rt1D • 00 K• Q S^ ., Rt10• K
fzS^^^ Rp•^iR!COZ ^ 'G, RfiD- 00 K
t - hii3 5'C, Rf1D- 00 K• NH3 C, R(iD• GO K
/A
z z
//'oo
^Gzs%"
711,r
. .....
5'-10
^ ^^ ^ i 7 7^^ n
:}^a0̂^
{ \\, { 60`0&o
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§ \ w 5010\ 9
\ \450/»
\ .\ 40o\4^ ..
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2.5,o
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^ \\»\ \\
«\«!5\\^\
\a
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(\- \\. :.y »00 2:
\\}^\^...
7A 0
700.0
05010
t000.0
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I 500.0
14150 .0
f
* i
FIGURE 5-10, TRADE STUDIES - ETIMHE PRI(MiRy 2 YEAR LIFE
15M. 0
A
i400.0
x 1300.0
t 11.100.0
f 1100.0
1()00.0
000.0
two
UW 700 . Q
coo . c
i
:goo . c
-100A
300
200.1
Fi t f',E 5-11,
STUDIES - P' Vtl'E PRIM . 2 YEAR LIFE
ij
t
tan?-' 00 K
00 K[SC, t,A a
""`t '.' °
ROD-.00}
, NftuK
GO K3^> ^ y .i q,^ Fyn r0 K
a
xt
1'
f
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r
1
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r..^^'^ + nn. ++rawer.
,
y
P
•j
j
_ f
• FIGURE 5-12, TRADE STUDIES ARGON PRINY 2 YEAR, LIFE
ARGON' COOLER 2 YIZ LIF'I'
VIM ,0
f tow . n
Y
1000 .0
iiI
1600 10 -
II
I1100,0
1`.'00,0
1000.0-
1.,00` .
600.0-
k
100.0
r ^. 200 .0-
0 0
0' . 0 0.1 0.2 0.3 0.11 0.5 0.6 0.7 0.0 0.9 1.011MLIRY F._l'1'L'RLAIL'VT HIVATLOAD (11)
5-14
0.0 0.1 0.2 0 .3 0.1 0 5 0.6 0.7 0 .0 0.9 1.0PRIMARY EXPERIMENT IIEATLO,AD (1r)
MAN.0
4500. 0
l
`I
I1000. 0
if :1500.0
-1r
3000.0-
U . '2500 , 0_fW
i
IF i
r2000 . 0 -
1500. 0
1000.0
500. 0
i
T 0.0
- P42 5l, ', RAO- 00 KN2 5[,
5
,, Rf1O. 60 K
00
C
t
. c"iy - cm .
- cm 5......,lxiR4
- UMC2Ki
- mi3 51,
:C, RAO-C, RRO ..C, RAO.
M,.4r ,afit)-scc, RAO.ill, RAO.
RAO .
K00 K60 X,
^ K00 K60 K00 K
m -!iQ 5:C,a 3 G, RAO . 60 K
a
or
r ^.
5-15
n
^.1100.0.
f
1000.0-
900.0
floc . 0
' 700.0-
cam.:.
^
1
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500.0-
100.0`
300.0"
2?00: _. U
1 00»0t
... 0.n
I
K- D..:^ ,\1!^ r'"^F:G' , lt•^p°
1 N113 SIT , It,i \1111' NIT , HAI
-JW lip,[W.100 K1)nit30 K
>,:, a:.^._^...^.,^. ^^<,^.. - r, ^.er
f
111 `^ ! ^+ '^.
r__..-.- .. ^, .^.^ -„• »„am1 e3
^
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c.. ^
>1^
ae,:;•r^s_:,r 'rF.x.x_,zx.,y ^
/',F
e_ zz. r:.^...+r., ., .,. xi.,T. k^.... «»e..^...^+
1 ^s
y^r
3 1
,i4.,1 rt
P
+vWa ma•ra..,.M-Y4 <ytTea Ax a.n --. ux .<svra,: 4^sW++t-FR c •+.ab X .wTC,.T :^.'°.+' a%wrc.r,vr,Sattl.nR+rzr>T.
r
1
FIGURE 5)-Ti, TWE SI IES E JlYLENE PRIM - 2 YEAR LIFE
1200 T o
1100 , 0
r
` 1000.0
{Ie r
f'
ow,0
3 000.01
700.0
600.0
R G00 . 0
I,
C,100.0
300.0
t
:?00 : b
}
i 100.0
gg
1 0,0
FIGURE 5-15, TRITE STUDIES CARBON DIOXIDE PRIMARY - 3 YEAR LIFE
CO2 COOLER , 3 YR LIFE
r
Ii
k
2000. 0
`If̂f
1000 . 0 -
i1600.0-
11 .10010- -
;reS
1.'00.0
1000.0-
600.0-
600.0
A
i
400.0
¢ki200.0-
0 0
FIGURE 5-16, TRADE STUDIES h1E RIE PRIVY 3 YEAR LIFE
AI s 7'11.4 NE G00LE.R , 3 YR LIFI
2400.0
r
t`
1
^i
1
1
i
3
0.0 0.1 0.2 0. 3 0.•1 0.5 0.6 0.7 0.8 0,0 1.0PRMIRY EA ERLW,w1'7' 11L ITLQ I D (11)
5-18
1
k
tf
V H
IM
iM RnO . 00 K
xb-
C.",«q+ coa 5.C,
*,02 5:G,
!.C, RRO-
RRJ-.RltO-:00
G0 K00 K
K- CCs 5
- lol 5.0
;C, RnO- 60 K
unq -' 60 K
s
• ^:c- e'k'X Y.K-RC€ +ewC ..: c-.MK*`^.lmFZ.epre K.Y+'+4M^.wPwM rduc 'AU.rR:t
/
zcw.wr^ . • ^ a,w+wM+rz.:,,v^ _-t,^«x-
t3 .e ,,r M ex ^ .. #.a-ra.^.._r ,,, .,«sxF• _ .w r-,s... ..•_.. .-sam>ra^.'waw+s 'sec ' +sw.q^^ • -^.+rw+•..e.e+•w,e.";+ma`e.s.r >n,....
1. 40M.
IN
.j. Q?00 r
1
1
3000. 0
2500.0-
1
a 1,000.0
I[`f ;
c'm . 0
1
1000.0-
500. 0
0.0
xLl- C1 +4 rWiDC, RR0 • ' 00 K
i - C#4 4 5a , Cr+4 a
;C. RRO.1. RnO-
60 KCO K
W, RnD_ 00 Knq ^'C Rt10=x 00 K
3 - -Imi co$C Rpo_ 60 K
a _ :'...' S :C I Rn'n- 00 KX, R113- 60 K
r,.43 g • 1 FAO-, CO Ka4113 : *Ft/ PAO. 60 K
1
iw ..-.._ . t ®xnx.0:,:^.mw a.w.irsr.Gnz. v s_+rf^'. 'wnww+r
f
oo
f
f
Jfff
^>/ f5r4lJ r
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. tirt '- .ca:n`nn.^.^:w^'s^aYiu.Ma.:Yw'^wat*€M+-.+rxr^eT rn+..+.^i+r+wiaa arw:— -.'..••^w,r+rs —.v^^ernac^...s^ ;
FIGURE 5-17: TRADE STUDIES - NITROGEN PRih'il Y - 3-YEAR LIFE
A7 TROCEIN' COOLER , 3 ref? LIFE
0.0 0.1 0.2 0.3 0.11 0.5 0.6 0.7 0.6 019 1.0fPRDLI RY :1PERL lf'.1'7' Ill 11710. t D (if)
5-19ORIGINAL' PAGE ISOF POOR QUALITY
32M.0
^EfOQ . 0
Moo. 0
.100#0
2200,0-
2000 # o
p1110010
k
1600 10-
f
j 1100 1 0
a1.00 , 0
1000.0-
two. o
600. 0 -
IOO.O
200.0-
0 0
1x ut?^q
. , ^ ... . ^ ,^:tjpEE^
^A
- c:s.r xe,carw.I ^a+cwma .. ..w..,.r.r
- 2 "` - ih a ^ £ r f',+u."Rn
Wi,} ..z♦ ..r.,arxn a »+.rs»,.........^{
fk r
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Y ^i
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t 4{t{
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tF P"'r*'^ , ?,.3awF:s^e^xlw[ew^.wMiws^x-.'}+.?3Y'm^M++..:x aWt:;r+.Y ^?.'-fveAwal+e*k^... .. .. +4.rrou:W^ta 'xwtau .. ^'.'
:t
t FIGURE 5-18, TRAPS STUDIES ARGON PRIMLY - 3 YEAR LIFE
,n
P. 0.0 0 .1 0:2 0.a 0.4 05 0.a 0.7 ^O^.A 'o. 1.0
PPLUA RY 11EATLOAD 005-20
7000 .0
650010—
I 6wo.0
t 5500.0
n 500000—
i
3 "'°1
1500.0—'J
1000. 4
;vw 3500.0
3000, 0
2500.0-
2000.0-
1500.0-
1000.0
f50010-
tIWoo
. Rt30-' 00 Ktry '11' ', RRp- 00 K.^ c
1 «t st y ^«
RnC- OO KRPD- 0O K
4«+i at +y« On!)- 60 K 1
Sl ,`^+ rc, RnD- 60 K1 ,«,^ c ,'^ R(+,o O0 K
^. t 4 ,^,7t^+«) • Fib K
a
, t zz
r
l
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3
.-+-+H..wwN 4x^ . .... ^. .M/twi.r.r.+w++lsihwrtiw^.sw4"V11 ..1...•.w.a+^eww: • l.+M ^... .,
FINE 5-19, TRU STMIES - NE-04 PRIVY 3 YEAR LIFENE O N COOL ER, 3 YR LIFE
n 0.0 0.1 0.2 0. 3I 0.q 0.5 0,8 0.7 0.8 0.9 1.0PIMIARY EXPERBIENT IIEATLOAD (11)
a
5-21
re .w^
I
4
I
j
t FIGURE 5-20s TRADE STUDIES - I-lYDDROGEN PRIMARY - 3 YEAR LIFE
HYDROGEN COOLER, 3 YR LIFE
o }14.0
y 13.0
4
1210
i
11.0
i10`.0
I 9.0
6.0
V 7.0
Wi^
6.0
5.0
4.0
3.0
2.0
1 . 0
^c 010
Ll Gm
- NCON 'CC, Rf10- K- NCON CG, Rno. K• NCON EC, (tA0 . 60 K
N2 SC
SE• N2 S- x.02
co .C;'"R
+^ ROU-
-
RAO-:G RnO-
,C, RHO.
00 K
00 K00 K
60 K
c- NtO 5- NH3- NH3 S.0
.C, R10-C, RnO-
, RR0.
00 K00 K60 K
1-:-7
y
r Aa
^IH ZO
P
21ij W3 , U. WU Z ! JDG oC
►^ v °C
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•
6.0 BASELINE COOLER
6.1 Baseline Cooker Description
6.1.1 Suamary
The cooler trade studies described in Section-5, together with
Instrument cooling requirements presented in Section 3, wars
utilized to select a baseline configuration-, The physical
parameters of a cooler which,provides 1W of primary and'2W
of secondary cooling to the instrument for a lifetime of one
year with a methane primary (60•K) and ammonia secondary (150'x)
was selected for the baseline cooler studies.
A summary of the mechanical and thermal characteristics of
this baseline cooler is presented in Figure 6.1-1. As _can be
seen, vapor cooling is used extensively to help reduce the heat
load to the primary and secondary cryogen6, as well as to reduce
the heat load to the boundary temperature radiator shield.
The primary resonance is 7.2 Hz when loaded with noon and ammonia;
which is substantially below the 50 Hz design goal.
To give the one year design lifetime for the CHI` /NH3 cooler at a
primary experiment heat load of 1.0 Watt and secondary load of 2
Wattr, a 140.9 liter primary tank and 65.7 liter secondary tank isi
required. The dry mass of the cooler including a 10.% margin is
99.2 Kg. A more detailed breakdown of the cooler mass by component
is given in Figure 6.1-2. Included in this table is the mass of
6-1
LOCKHEED PALO ALTO 'RESEARCH LABORATORYL C9M'i!'0 MI%fIll j a 4 ► ACY COMPAW VINf.,
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Fig. 6.1-1. 14tUI;rlW 1SS1QN BASELINE COOLER SYSTEM SUMMARY
t
Mechanical i
• Elivelope (inel vacuum 811011) $3.2 coi dianiotor by 112.7 cm long• Primary tank volume 14$. a liter0 Secooda►iy tau► k volume 65.7 liter0 Dry wa ss (incl 10% margin) 99.2 kg P
• Primary resonance 7.2 Hz l'
• Support tubes dosign criteria Survive qualification random levelwith 3 (r probability using neon asprimary cryogen.
Thermal
• Vapor GooLng of Secondary with. Primary Vent Gas• Vapor Cooling of Print y Support Tubes• Vapor cooling of 11adi:ito • Shield with bout Primacy and Secondary
Cryogen Vent Gas
• ` Issuglas/Double Aluminized Mylar over Secondary Twik and RadiatorShield
10 Silk Net/Double Aluminized Mylar over Primary Tank
F
6-2
F
t
Fig. 6.1-2. MULTIMISSION COOLER MASS SUMMARY
Dry Cooler Massµ
Item_ Mass k Wei ht 10
Primary Cryogen Tan)c 21.0 46.3
Socoodary Cryogen Tank 9.3 20.4
Secondary Shield 4.9 10Itadiator Shield 5.1 11.2;
w Vacuum Shell 12.9 28.5
Mounting Pluto 15.4 34.0
Support 'pubes 10.9 24.0
Multilayer Insulation 6.5 14.3
Plumbing 2.7 6.0
Vacion Pump ( incl magnets) 0.5 1110
Mist Hardware 1.0 ^2.2
Total Dry Mass 90.2 198.8
10% Margin 9.0 119.9
Dry Mass with 10% Margin 99.2 218.7
Cryogen Mass
Primary Secondary
Cryogen Mass k Weigh t Mass kg Weight lb
Hydrogen 12.0 26. 6 5.3 11.7
Neon 193.2 425.9 85. 3 188.0
Argon 217.0 478.5 95.8 211.1
Nitrogen 131.2 289.2 57.9 127.6
Methane 67.0 147.8 29.6 65.2
Carbon Dioxide 100.0 220.4Ammonia 43.2 95.1Ethylene 43.2 95.1
6-3
the various cryogens considered in this study in both the secondary,
and, where applicable, the primary cryogen tank. The lightest
system would be the tit/N113 cooler which would have a loaded mass of
154.4 Kg. Th(i heaviest system would be the Ar/CO2 cooler which
would have a mass of 416.2 Kg.
6.1.2 Component Description
A layout of the multimission-cooler is shown in Figure 6.1-3. Each of the
major cooler subassemblies shown in the layout is described in more detail
in the following paragraphs.
^iafi
r
i`
6.1.2.a Experiment Interface
At the base of the cylindrical recession in the primary cryogen
tank is the cooler/experiment interface. Instrument cooling at
three distinct temperatures (primary, secondary, and radiator shield)
is available,and,for any given mission, any combination of one, two
or three temperatures may be utilized. This flexibility in the design
also allows for different combinations to be selected for any one
cooler during different missions.
The interface at each of the temperatures, consists of a shrink fit {
assembly of dissimilar materials. The female member of each shrink
fit is a removable "bolt-on" member which connects to the cooler
assembly. The male member which slips into the shrink fit while at
M ambient temperature couples directly to the experiment. These types
of shrink fit cooler interfaces have been used on previous flight6-1,6-2
cooler' programs and have proven to be an excellent structural
and thermal interface ,aith very small thermal resistance.
f
6-4
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The test instrument mounting surface located on the cooler main
plate can be blanked-off to allow cooler testing without need of
the experimentor's hardware. Ukewise, the modular "drop-in"
experimentors package can be cooled for testing independent of the
cooler Assembly. During integration, the experimentors package
is "dropped in" the cooler while at ambient temperature. Align -
ment of the package is referenced to the test instrument mounting
surface which is part of the experimentor's package. To maintain
alignment when cold and also to mechanically decouple the cooler
from the experiment during launch, a flexible braid is used on
the experimentor side of the male shrink fit member. These braids
which have been used in the past will transmit as little as
0.250 Kg per centimeter of relative motion (i.e., a negligible
load) -to the experiment.
6.1.2.b Aluminum Foam Heat Exchanger
Inside both the primary and secondary cryogen tanks is a heata
exchanger, whose function is to provide good thermal contact
between the heat transfer assembly and the solid cryogen. The
heat exchanger used is a 2% dense aluminum foam which is machined
to size and then bonded to the inner wall of both tanks. Without
i_ a
6-6
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any heat exchanger in the tanks, the cryogen will sublime away
from the conduction surfaces creating a vapor gap which supports
an every increasing temperature gradient. This foam has been
utilized on prior solid cooler programs at LMSC and has been found
to be a most efficient design.
6.12.c Primary Cryogen Tank
C^ The tank containing the primary cryogen is a vacuum tight, 148.9
I __liter, 6061 T6 aluminum enclosure. Manufacture of the tank is
made in three separate components: a spun-formed spheroidali
end and contoured top piece as well as _a machined, central cylindri-
cal section. Assembly of the tank is achieved by epoxy bonding
'along two lap joints at both ends of the cylindrical section.
! Special features ofthe primary tank include the addition of
three uniformly spaced 0, 51 cm wide by -1.02 cm high integrallyA
machined internal ring stiffeners along the crylindrical section
and a 24 . 9 cm diameter by 36.3 cm long cylindrical recession in
the top cover.
-Along the recession, the folded fiberglas support tube assembly is j
t
bonded into place, and at the basei attachmentto the experiment r
is made through a shrink fit union.a
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On the inside portion of the recession, an aluminum tube is
bonded to the tank and extends down to the spheroidal end dove
to provide support to the flat recession base.
Within the tank, the 2% dense Aluminum foam heat exchanger and a
cryogenic fluid (N or lie) cooling coil are attached to the tank
walls.k
i
tour feedthrus are provided on the top of the tank for the cryogen
fill and vent lines and auxiliary cooling loop lines.
6.1.2.d Secondary Tank and Shield_
The tank containing the secondary cryogenis a vacuum tight,
i
65.7 liter, 6061 T6 aluminum enclosure. The tank, which takes a
the Form of a toroid, is spun -formed in two halves and assembled
at a common lap joint with epoxy. i
Attached to the outer.diameter of the secondary tank is a 6061-T6
aluminum shield. This .shield, located 3 .02 cm from the primary^F
x
tank shell, extends completely around the primary tank and insula-
tion system to provide a uniform intermediate buundary temperature
for reduction of the parasitic heat leak into the primary cryogen. _ z;t
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The cooling line is routed through the tank and thermally grounded
to the secondary tank wall at the feedthru,Jtank interface. In
total, four £eedthrus are provided on the bottom of the tank and
five on the tank top. Two each are used for the cooling loop line
and two each are required for the primary fill and vent line.
The extra feedthru on the tank top is required for the secondary
fill/vent line. The 2% dense aluminum 'foam heat exchanger to
also employed within the secondary.
6.1.2.e Radiator Shield
s
IA shield which acts as the warm temperature boundary to the second-
ary cryogen system is provided. This shier can be left "uncoupled"
to any outside temperature sinks, in which case it would act as a
floating shield, maintaining an equilibrium temperature slightly
less than the local ambient. Alternatively, an external cooling
source such as a space radiator or thermoelectric cooler may be
coupled tq the thermal link which is attached to the top of the
n shield and drive the shield temperature lower, By lowering the
radiator shield temperature, longer secondary lifetimes and/or
higher secondary experiment heat loads can be realized. Heat rates
to the primary cryogen would be unaffected by a change in the
radiator shield temperature. The shield is supported by an alumin-
um cylinder which is bonded to the aluminum ring that connects
support tubes number l and 2. {
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33
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6-9
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6.1.2. f Vacuum Shell
The vacuum shell consists of a 6061-T6 aluminum integrally
machined-ring stiffened cylinder with spheroidal dome. The 0.51
cm wide by 1.02 cm high rings are spaced 5.5 cm apart along; the
entire 85 .0 cm length of the crylindrical shell.- On the base of
the cylindrical section is a mounting flange which contains an
0-ring groove and a mounting bolt hole pattern. The addition of
the spheroid dome makes the total length of the vacuum shell 112.7
cm.
6.1.2.8 Support Tubes
The support tube assembly consists of four concentric, folded, low
conductivity, high strength fiberglas tubes. Tubes 1 and 2, 3 and
4, and at the opposite end tubes 2 and 3 are ;Jointed at their ends
by epoxy bonding to an aluminum machined end fitting.
The end of the tube 1 mounts to the main plate forming the warm
temperature boundary. At the end of tube 2, where tubes 2 and 3
are coupled, the secondary tank is epoxy bonded in place. The
primary tank is .Likewise epoxy bonded in place at the end of
tube 4. The geometry of each tube is summarized as follows:
(Dia - Inner Dia and Length _ Unsupported Length).
6-10
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Tube No. Dim ) Thickness (cm) Length (cm)_
1 15.67 0,254 61.39
2 17.70 0.191 46.86
3 19.69 0.191 46.86
3 21.13 0.152 18.97
6.1.2.h Insulation
About the primary tank, secondary tank and shield and
i radiator shield will be a multilayer insulation blanket of
double-aluminized mylar. Spacer material used in the blanket
about the primary tank will be silk net:, while at all other
Locations - tisuglas will be used. Each layer of insulation
will be wrapped individually, such that a layer density of
15 layers/cm results in the silk. net system and 43 layers/cm di
in the tisuglas system will be achieved. The thickness of the
wrap will be 3.02 cm about the primary, 3.96 cm about the
secondary tank and 2.39 em about the radiator shield,
6.1.2.1 Vapor Coolingi
Vent gas cooling will be utilized in various locations to help
in reducing- the parasitic heat load to the cooler. These
techniques have been utilized in previous coolers and have been3
studied on company funded programs. At the first location, a
thermal link will be attached to the primary cryogen vetitt line.
This thermal link will be coupled to a point Along the primary
support tube #3. The primary vent line will also be grounded
6-11
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to the secondary tank so that vapor cooling willioccur.
t An additional location where vent gas cooling will be utilised
will be at the todlator shield. The primary and secondary vent
lines will both be thermally grounded to the radiation shield so
as to allow vent gas cooling of the shield from both cryogens.
6.1.2.,E Cooled Plumbing
The cooler plumbing consists of both the primary and secondary fill/
vent lines and the cryogenic fluid (LN2 or We) cooling loop line.
x,
Two identical fill and vent lines are provided to the primary to
provide flexibility in either filling with a liquid (requiring
two lines) or filling with gas (requiring a single line). A
single fill./vent :line is provided to the secondary tank.
1wi
All lines are 1.27 cm diameter convoluted stainless having a 0.013
cm wall thickness. Stainless was selected because of its low
thermal condectivity, _1_owv permeability, and good Flexibility in
mechancally`decoupling structures that will realize relative
motion in a launch environment. In addition, coated fiberglas
tube sections are utilized in series to reduce the heat loads.
The cryogenic fluid cooling loop line also employes the same con-gj
voluted stainless-fiberglas tubing wherever a temperature transi-
tion is 'encountered within the cooler. On the mounting plate, the
6-12
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vacuum feedthru includes a stainless steel tubing standoff to
Insure no tooling of the main plate occurs during the chilldown
process.
A schematic of the cooler plumbing system is shown in Figure
6.1.-4.
6.1.2.k Main Plate
The main plate acts as the supporting structure for the cooler,
as well as the vacuuminterface for the vacuum shell. It is
planned that the main plate also act as the primary support for
the experiment and satellite vehicle interface.
On the plate will be four 2.5 cm dia Cryolab valves. Three valves
will be the terminators for the fill/vent lines and the remaining one
will be a vacuum access port for rough pumpdown. An interface to
an 81 A Varian vacion pump is also provided for maintaining low-
pressure in the insulation space during ground testing.
Access to the radiator shield thermal link and to the cryogen
fluid cooling loop is also provided on the main plate as is a
hermetically sealed electrical feedthru for thermometry Instru-
mentation.
6.1.3 Thermal Analysis
A heat map of the baseline cooler, utilizing CIL/M at primary
1.0 watt
and Qsecondary 20 w is shown in Figure 6.1-5. , are the effects
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2.5-cm CRYOLAO VALUESCOOLING—LOOPLINE SEAL-OFF VALVE
8,(/s VACIONPUMP ELECTRICAL
RADIATOR
PEED THRU SHIELD ACCESS
PRIMAR Y ^...,,
CRYOGENVENT LINE
SECONDARYCRYOGENFILL/VENTLINE
SECONDARYCRYOGENTANK
—VACUUM_—SHELL
RADIATOR.__SHIELD
COOLING-LOOP SUPPORTLINE -------, TU BE
ASSEMBLY
PRIMARYCRYOGEN
SECONDARY
'iAN K __ RADIATIONSHIELD-
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of double aluminized mylar insulation systems, miscellaneous cooler plumbing
lines, and the primary and secondary support tube assembly.
No -external cooling of the radiator shield was assumed and for the baseline
the temperature was fixed at 300 0K, the local ambient. In actuality, the shield
will maintain an equilibrium temperature somewhat less than the local ambient.
This will occur because (1) both the primary and secondary vent lines are tied
to the radiator shield providing some amount of vapor cooling and(2) the shield
is supported from an intermediate point along the secondary support tubes.
"These effects were not cocsidered in the analysis and will tend to make the
predicted heat loads more conservative.
The multimission cooler utilizes vapor cooling at both the secondary cryogen ,.
tank and along the primary support tube. As shown in Figurer 6.1.5, vapor cooling
removes 265 mw from the secondary and an additional 70 mw along the support
tubes. These figures represent a 42% reduction in the.parasitic heat load to
both stages of the cooler, but only 6.4% and 12.4% of the total primary and
secondary heat load, respectively when the instrument load is included.
At lower primaryexperiment heat loads, the lower mass flow rates will decrease
the absolute effect of the ventas cooling at both locations as well as theg g ^
percentage change in the secondary cooling. The relative cooling effect at
the support tube, however, will increase. For example, if the primary experii' r
k
ment heat load to the baseline cooler were dropped to 20 mW, the percentage of
heat removed through the support tube compared to the total primary heat load
will increase from 6.4% to 14%. At the-same time, vapor cooling of the second-
6-16
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ary when compared to the net secondary heat load will decrease from 12.4% to
The effect of vent gas cooling is greater when other cryogen combinations are
utilized in the "baseline cooler". On a percentage basis, the largest benefit
is seen to occur for a Ne/C 2114-cooler at a primary experiment heat load of 1.0
watt. In this cooler, 49% of the net secondary heat load of 1.68 watts is
removed by the primary vent gas. Vent gas cooling of the support tubes removes
only 67 of the total primary heat load in this cooler, but the heat leak
realized through the support tubes is only 064% of the total primary heat load.
6.1 Structural Analysis
6.1.4.a Support Tubes
In designing the support tube assembly, it is found that use of
different cryogens in the primary and secondary tanks leads to a
support tube thickness which varies by as much as 507. In selectingS
one particular design which accommodates all cryogens with no major
penalty, two approaches were investigated. In the first approach, the
supports are sized for a lighter cryogen and to survive launch
stresses using the heavier cryogens, the cooler would only be partially,
filled The second approach is to overdesign the supports to x
accommodate the heavier cryogens, accepting the higher heat loads over
6-17
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3. A 5UGS101AfT Of L C K N I10 A I I C I AFf. CONPORAS10N
that from an optimum design with the less dense cryogena.
As a "reference point, the baseline CEi4/NJI cooler is used. Support
tubes were sized to survive a static 5.?i_Sg lateral acceleration in-
cluding a safety factor of 1.65. Maximum fill percentage giving rise
to equivalent static stresses within the tubes were then computed for
cryogens having higher density than methane. In this analysis, two
cases need to be investigated - that with the secondary above, the
primary daring fill and that with the secondary below the primary dur-
ing fill. These cases are distinct because of the location of the
center-of-mass of the cryogen within the cooler during a partial fill
condition. In figure 6.1-6 the maximum fill percentage of the primary
tank as a Function of the cryogen density is shown using methane as
the reference cryogen.
As can be seen,.neon ( 1.44 k /liter) can onlyP ^ y be filled to between{
28% to 45% of maximum capacity - depending on whether the tank is E
filled with the secondary above: or below the primary ., respectively.
This reduction in fill percentage translates directly to a reductiona
In cooler lifetime.
To assess the influence of a support tube designed for the heaviest
cryogen on cooler performance, a more rigorous analysis into the sup-
port tube sizing was performed. In this analysis, a dynamic vibration
analysis considering both material and buckling failures were con-
6-18
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ASVWISd 40 1114 967 ,
Fig. 601-7 MATERIAL PROPERTIES
Shear modulus:r
G = 750000 psi
Shear modulus; G = 750000 psi
h Elasticity modulus;
Axial:_
E - 2.14 x 106 psi
Circumferential: Ey = 5.55-X 100 psi
Poisson's ratio: vXy = 0.0956
Cloth thielmess per layer; 0.010 in rUltimate strength, axial direction: 26.4 ksi
Proportional limit, axial direction; 5.7 ksiUltimate strength, hoop direction: 119 ksi
Proportional limit, hoop direction: 72 ksi
ENWRONMENT
Ultin atc static lateral acceleration: 4 g
Lateral acceptance vibration 'level;
Frequency,-Uz Level, g-pk
5-40 0.540-80 0.0125 x fiz80-200 1.0
Random vibration acceptance level:
f rreg4.ency, IIz
20-130 6 dB/Oct
130-1000 0. 18 g2 AN1000 — 2000 -3 dD/Oct
Level: 16.7 g-rms
i
6-20
it
t
Fig. 6.1-8. STRUCTURAL ANALYSIS RESULTS
Required Support Tube Thicknesses (cm)
C1`14/NN3 CI-I4/NH3 Ne/NH3Tube (Static Analysis) (Vibration Analysis) (Vibration Analysis)
1 0. i55 cm 0.178 0.2542 0.132 0.132 0.1913 0.132 0.132 0.191
4 0.094 0.102- 0.152
Primary Resonance 9.5 Hz 7.2 Hz
sidered for a CH4 /NH 3 and Ne/NII3 cooler. The baseline cooler support
tune assembly was analyzed in addition to the Ne/N113cooler to verify
the_statts analysis performed in the trade studies.
This dynamic vibration analysis was performed with the BOSOT computer
program which is described in Section 4.2,
The material properties of the fiberglass epoxy tubes and the design
environment is shown in Figure 6.1-7. The structural analysis results 3
are'shown in Figure 6.1-8. As can be seen, excellent agreement exists 1
between the static and dynamic analysis sizing the tubes for the
CH4 /NL 3 cooler. To support the Ne/NH3 cooler, the required thicknesses
are increased by 50% -for all tubes.
To assess the impact that the thicke• : support tubes have on cooler
lifetime, it is recalled that for a.primary experiment heat load greater
V
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than 150 mW, the contribution of the support tubes to the total heat
load is less than 10%. As a result, the maximum influence of increas-
ing the thickness of tube #4 from 0.094 cm `to 0.152 cm would be to
reduce the lifetime a maximum of 6% from that achieved using the thinner
support tube. The worst case occurs at the 20 mW primary experiment
heat load case whfjre an 18% maximum reduction in lifetime would
result.
Comparing the two options, the data shows a better choice is
to design the support tubes for a neon primary cryogen. This choice:
would result in a worst case 18 % reduction in lifetime for off-design
systems, as opposed to a 57 % to '72% reduction in lifetime which would
be experienced should the tubes be designed to support CH 40
The lifetimes shown ir.figures 6 . 2-1 to 6. ,-5 are the lifetimes
expected with tubes sized for neon. The very low percentage of the
primary heat load that results from the support tube is true, in
general, for all the cryogen combinations examined at a primary
experiment heat load of 1.0 watt. It is also true, in general, thatI
only until the primary experiment heat load is reduced to —. 150 mW
does the contribution from the support tube begin to contribute
as much as 107 of the total primary heat load, and 30% when the primary
experiment heat load is 20 mW.
h CrV
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6.1.4.b Retractable Support
Figure 6.1-8 also shows the primary resonance of the Ne/NH3
cooler to be 7.2 fiz, considerably less than the minimum 50 Hz
desired. In an attempt to increase the primary resonance, a
retractable support concept was analyzed. The retractable
support consists of an actuator which slides into a recession
of the cantilever side of the cooler primary tank. During
launch this support is engaged to provide the cooler with a
pin-type of support in addition to the fixed boundary cantilever
support. Once in orbit, this actuator is removed to eliminate
the heat leak from this relative short to ambient.
The results of the analysis showed the primary resonance to
increase to 19 Hz still considerably less than the 50 Hz
minimum. The additional complexity of this support coupled
with the marginal gains indicates that either the cpnstraint
should be relaxed or other support mechanisms be analyzed.
6.2 Instrument Cooling Capabilities
in order to determine the multimission cooling capabilities for a particular
instrument the following primary parameters of the-instrument must be specified.
1) Temperature requirement of the coldest element of the instrument
(primary temperature requirement)
2) Temperature requirement of other elements, if any (secondary tempera-
ture requirement)
3) Cooling load for the primary
4) Cooling load for the secondary
A
5) Desired system lifetime
The cooling capability curves which will be described allow the investigator
to determine the utility of the 10M in terms of the above parameters.
Figures 6.2-1 thru 6.2-5 indicate the cooler lifetime as a function of the
instrument primary heat load for various secondary cryogens. Although a unique
choice of secondary cryogen will give the maximum cooler lifetime for a specific
primary cryogen, other choices are shown since instrument requirements may dictate
the use of a different secondary to attain the necessary temperature*
Figures 6.2-1 thru 6.2-5 also indicate the requirements or benefits of utilizing
a passive radiator for cooling of the guard shield. Figure 6.2-1 which is for a
methane primary indicates the-radiator-temperature "cut off" point as follows:
6-24
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FIGURE 6,2-1 METWE PRIMARY-LIFETIME VS, INSTItI VIT HEAT LOAD_a
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O MAXIMUM LIFETIME UTILIZING200 K RADIATOR
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FIGURE 6,2-2 ARCM PRIMY—LIFETIMEVSa INSTRUTi'IT HE=AT LMD
NITROGEN PRIMARY
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O MAXIMUM LIFETIME WITH• e 300 K CUTER TEMPERATURE
D MAXIMUM LIFETIME UTILIZING200 K RADIATOR
4000
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FIGURE 6,2-3 NITROGEN PRIM RY-LIFETIPE VS, INSTWIN HEAT LOAD
s
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FIGURE 6,2-11 N0111 PPMY--LIFETIME VS, INSTRIT'EI' T MEAT LOAD
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4000 NEON PRIMARY ♦
0 MAXIMUM LIFETIME WITH300 K OUTER 'TEMPERATURE
D MAXIMUM LIFETIME UTILIZING200 , K iRADIATOR
o 3000 A MAXIMUM LIFETIME UTILIZING,
r 160 K RADIATORu,
Q MAXIMUM LIFETIME UTILIZINGW 100 K RADIATOR
ct*, eef^_ r., r4a ._..
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PRIMARY INSTRUMENT HEAT LOAD (W)
{4 . ^
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FIGURE 6,2-5 IM04.14 PRUAR - IFETIPE VS, IE TRIMIT FIST LOM
2004
^1^Of1,r
8 8 M 8 u _ ^..- f .., t .. t s E f .. .. t r i- y.. ,. ., Yy a 8 ^:: . A s ;. t
t µ HYDROGEN PRIMARY
O MAXIMUM LIFETIME WITH300 K OUTER TEMPERATURE
El MAXIMUM LIFETIME UTILIZING200 K RADIATOR SHIELD
A MAXIMUM LIFETIME UTILIZING160 K RADIATOR
d MAXIMUM LIFETIME UTILIZING_100 K RADIATOR
r ,,{
At a primary instrument heat load of 0.56W with an ethylene_(C? 2) secondary
a lifetime of 700 days is -indicated. This lifetime may be achieved with a
300'K external boundary as indicated by the symbol. To the left of this point
the vent gas flow rate is lower, due to the lower heat load and this results
in less vent gas cooling of the secondary cryogen. and consequently reduces the`
4
f. secondary stage lifetime to less than theprimary life (700 days). In order to ,
increase the secondary lifetime to match the increased primary lifetime (at
lower primary heat loads) it is necessary to reduce the secondary heat load.
` This may be done by reducing the cooled shield boundary temperature below 300°K z
by mcans'of the passive radiator or.thermo-electric cooler option.• At O.1W
primary heat load with a C2 H4
secondary a lifetime of 2800 days can be achieved r...
for both primary and secondary cryogen stages by utilization mf a 200`K
radiator, as shown in Figure 6.2-1. For heat rates between the example points `3
•a radiator temperature between 300°K and 200°K-is needed, the required value
being obtained by interpolation. These radiator "cut-off" points are indicated,
for the various primary and secondary combinations in curves 6.2-1 thru 6.2-5.
These curves do not indicate the secondary cooling capacity which is availableq
to the instrument if this is required. The curves 6.2--6 thru 6.2-10 can be
utilized to determine the secondary stage cooling available. These curves a
indicate the conditions for matching the secondary cryogen life with the primary
life, and allow the determination of the parameters which will satisfy a given
secondary instrument cooling load. The following example illustrates the use
of these curves„ i
6-30
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FIGURE 6,2-E SECHARY COOLING CAPACITY NITROG91 PRIM
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FIGURE 6,2-9 SECONMARY COOLING CAPACITY - NEON PRIMARY
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FIGURE 6,2-10 SECONDARY COOLIM CAPACITY MROGM PRIM
Ci For a primary cooling requirement of 0.56W with methane and the use of an
ethylene secondary Figure 6.2-6 indicates a secondary cooling capability of
zero for a 300°K shield temperature. At this condition the secondary cryogen
sa
t
will be depleted at the same time as the primary. In order to provide neti
If
instrument cooling for the secondary for the 0.56W primary load the outer
shield must be cooled by radiator or T/E cooler. Fig. 6.2-6 shows that if the }
shield is cooled to 200 0K then the instrument cooling by_the secondary is 0.37W.1
1If ammonia is used as the secondary then the secondary cooling available for a
300°K boundary and 0.564J`primary cooling is 0.92W.
These two sets of curves for a particular primary cryogen selection may be
utilized to determine the instrument cooking capability of the 11MC in several
different ways. For example, when the primary and secmdary temperature re-
quirements are selected the allowable cooling load for a specified Lifetime
may be determined. Or if the instrument cooling loads and temperature are
established, the lifetime capability may be established. The effect of the
_instrument temperature requirements on cooler lifetime may be determined by
comparing various secondaries and primary cryogen choices with their associated
temperatures. JJ
J
Figures 6.2-11 thru 6.2-13 were plotted from the previous curves to provide
summaries of the cooling capabilities. In these curves the secondary which
yields the largest system lifetime was selected and a set of curves was made
for each radiator temperature studied. On each figure the secondary and
primary cryogen along with and the associated weight of the loaded cooler
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optimum secondary changes from one to another. At these points the cooling
capability of the secondary is zero while away from these points the secondary
cooling is positive and can be determined from the curves 6.2-6 thru 6.2-16.
The lower temperature capabilities of the primary cryogens are indicated on the
figure.
Another presentation of the cooling capability of the MMC is shown in Figure 6.2-14
in which tlie primary cooling load is shown as a function of the primary tempera-
ture for various lifetimes of interest. This curve shows the effect of the rad-
iator temperature onrp imary cooling load. It should be emphasized that the
primary advantage of the radiator or cooled shield is increasing the cooling
capability of the secondary stage. The curve shows a small benefit of the .
radiator temperature at the one year lifetime, however, as the lifetime increases
to three and five years the 'benefits become substantial, in some cases more than
doubling the primary cooling capability.
r
It is felt that the curves which have been presented will allow the instrument`I *.
developer to determine all the parameters of interest which may be provided by
the MC. These predictions have been based on prior experience with coolersI
which have been developed and flown in orbit. As previously mentioned these
predictions include a 207. life'ime contingency. It is anticipated, that as the
development of the MC progresses measurements of the actual performance for
several combinations of cryogens will be made and the predicted capabilityi
curves shown can be replaced by the actual measurements so the instrument develop-
I" er will know the orbital performance to be expected with great confidence.'1
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6.3 Instrument Integration and Flight Operation
It is believe, that the MMCrovides a very versatile approach for integratingP Y rP 6 B
a wide range of instruments. The thermal attachgiont to the cooler is made
through shrink fit connections , whose configuration is described in Section
6.1. This type of connection has been demonstrated and proven on many
coolers including flight qualified units and 1148 proven to be a vereatiie x
and efficient coupling. The MC may incorporate as many as three cooling p
links between the instrument and the cooler; one to the primary, one to the
secondary and one to the cooled shield. Any combination of these links ma y
be utilized dependingupon instrument temperature and thermal shielding re-
quirements. _, 1
Several basic arrangements of the instrument/cooler integration are possibleS S P
and have been considered. The more ordinary types of integration are schemati-
cally indicated in Fig. 6.3-1. The three approaches are designated Type I,
Il and III. In the Type I Approach the cooled elements are placed within
the cooler instrument cavity and the room temperature instrument elements are
located on the cooler mounting plate outside the cooler. These elements might
be primary optical elements or electronics or any elements which may be con-
veniently located on the mounting plate. This approach is limited to the c
size of the instrument cavity, which for the present baseline configuration -
is 65 cm long by 14.6 cm in diameter. These dimensions can be altered to some
extont in the final design if desirable and the instrument can extend outside
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6-112
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6-43
the cooler if necessary. This approachs has been utilized on the solid
cryogen coolers utilized on the Nimbus 6 and Nimbus 7 satellites and is a proven
approach.
In;add:ition to the Type I integration the Type It and III approaches have been
proven on actual hardware and can easily be incorporated. In these approaches
the cooled instrument elements are located outside the cooler and are there-
fore not limited in size as the first approach was. The Type II approach
consists of mounting the cooled elements on the mounting plate of the cooler aid
transferring the cooling to the_eryogens by means of a thermal link which may
consist of a metal rod or in extreme cases where heat loads are high and the
instrument temperature is very close to the cryogen temperature by heat pipe.
The Type 11 approach with a solid copper link was utilized on a single stage6-1
solid CO2 cooler which provided orbital coaling of a Y.-ray instrument in 1971
Acother approach which may be necessary because of instrument viewing require-
ments or unique physical parameters is 'illustrated as Type III. All of the-
instrument elements are located some distance away from the mounting plate and
are attached to a separateto structure. In this approach flexible connections
in the thermal links and the outer vacuum tube may be required so that instru-
ment alignment may be maintained separate from the cooler. In addition, it may
be necessary to utilize a heat pipe to maintain small temperature gradientsz
between the cooler and instrument. A cooler has been built and tested at
LMSC which incorporated this approach utilizing an oxygen heat pipe to provide
instrument cooling at a distance of 76 cm from the cooler.
'6"
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It is believed that these three types of instrument integration will satisfy
the majority of instrument requirements, however, there are other options which
appear to be perfectly feasible but have not been demonstrated completely with
actual hardware. These ate shown in 6.3-2.
The first approach illustrates multiple eooling of several instruments. It
appears to be perfectly feasible to cool several instruments with the MNC by
utilizing several thermal links. The instruments could be cooled to either
the primary or secondary temperature. In cases where several instruments must
be located at substantial distances it ,Pay again be necessary to utilize heat
pipes. Many variations are possible.
4The other illustration while; not indicating -a different type of integration
1 indicates another option in utilizing the WIC. If the parasitic heat load from
the instrument is quite high and the duty cycle is low, then a thermal switchi
could be incorporated to extend mission lifetime by reducing cryogen usage.
A thermal switch has been developed at LMSC specifically for this use and
could substantially reduce cryogen depletion rates for favorable duty cycles
iand high parasitic instrument heat rates.
In determining the instrument heat Toads to the cooler the heat load associated
with whatever thermal link configuration is utilized must be included. This
F,
' heat load is not considered to be part of the cooler parasitic heat load, since
each instrument configuration will have a unique link configuration, and hence
unique heat load.
,.6-LI5
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An additional consideration is that tht cooled regions of the instrument must be
vacuum sealed on the ground so that condensible gases do not cryopump. This
can be achieved with a permanent vacuum window or by a vacuum cover which is
removable in orbit for cases where a permanent window or cover is not feasible.
Venting of the ga pes in orbit is achieved in most cases by venting directly
through a line which is opened in orbit by an explosive valve. The vent line
sizes which are shown on the baseline cooler are of sufficient size to
allow the cryo$ens to operate near their minimum temperature. The final tem-
perature "trimming" for a particular instrument can be accomplished in a
simple manner by simply "bolting" on the required external plumbing line3
size to provide the desired Pressure above the cryogen. This pressure ad.-
justment provides for a very sensitive adjustment of the cryogen temperature.
The vent gases in general do not contribute a significant thrust to the
spacecraft, however, it is usually desirable to direct the vented gases away
from the instrument field of view and normal to the roll axis of the vehicle to
minimize any thrust effects from this source.
z
The cooler has been designed to the vibration specification provided in the
work statement which is representative of the space shuttle. If more severe
environments _ are encountered due to different boosters or other changes, it
may be necessary to off-load the cryogen tanks somewhat to maintain stresses
within safe limits. This can be easily incorporated.
i
6-47
LOCKHEED PALO ALTO RESEARCH LABORATORYo C K N t! D MISS 1 l C S ! S A C[ t O M A N r, t N C,
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Limited calculations were perfbrmed to determine the ground hold capability of
the MC. For the calculation it was assumed that the MMC was loaded with
methane and ammonia and that the instrument provided heat loads of 1W
to the methane and 214 to the ammonia. Calculations indicated that if the solid.
cryogens were cooled with LN2 to 80 K and then cooling was discontinued,
the methane would warm up to the melting point (90•K) in seventeen days and the
1 ammonia would be well below the 195 'K melting point (105•K) at the end of^
seventeen days,ti
i
The hold time for this case, that is the duration between re-cooling periods to
t
maintain the cryogens solid, is therefore 17 days.is
L
For lower instrument heat loads the hold time would be proportionately greater
' or if the instrument heat load consists of a significant fraction of heat genera
tion, which could be turned off during ground hold, this period would be
increased.1
i
Several, other: options may be considered in extending the groundhold period , One is '.
the use of cold helium gas for sub-cooling the cryogens to lower temperatures.
The use of cold helium will be required for ;ground hold operations when hydrogen
or neon are utilized, so that this cooling mode' is consistent with the normal
requirements.
A second option which is available for consideration is to provide LN2
cooling of the radiator shield on a continuous basis during ground hold
6-4S
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operations. If the instrument is shielded by a link to the radiator shield then
the cryogens could be maintained indefinitely without a temperature increase..
This operation is safer than cooling the cryogens directly because when cooling4
the cryogens directly, arc interruption or depletion of the cooling flud could +
resu lt'ul:C in rapid. warming of the cryogens And possible unexpected venting.[ i
Although not considered a primary option for ground hold, it provides an additional
degree of flexibility in the ground hold operations and may be used to advantage
in some operations.
e
A third option is-to utilize a mechanical refrigerator to provide ,{
coaling of the cooled sfUeld on the ground, and also during orbit if desired
1 The coupling Flange to the cooled shield provides easy access for "bolting" onJ,
a mechanical refrigerator.
As thes e option s show, the cooked shield. adds an extra dimension to the versa-
tility of the WIC.
i
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6-49
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hREFERENCES }
3-1 J. P. Wright and,D E. Wilson, "Development of Thermal Control Methodsfor Specialized Components and Scientific Instruments at Very Low Teen--Iperatures, Final Report for Contract NAS 5-31324, by Spacs'DivisionRockwell International for George C. Marshall Spaceflight Center, May1976.
4-1 W. G. Foster, L. A Naes, and C. B, Barnes, "Thermal Conductivity Mea-surements of Fiberglas/Epoxy Structural Tubes from 40K to 320OK9 " AIA11
iPaper 75.711, pres;nted. at Tharmophysics Specialist Conforenae, May 1975. n
4-2 G. A. Bell, T. C. Nast, R. K. Wedel, "Thermal Performance of MultilayerInsulation Applied to Small Cryogenic Tankage," Advances in CryogenicEngineering, Vol. 22, Plenum Publishing Corporation 1977, pg. 272-282.
4-3 D. Bushnell, "Stress, Stability, and Vibration of Complex 'Branched Shellsof Revolution: Analysis and Users Manual for BOSOR 4" NASA LangleyResearch Center, NASA CR-2116,
6-1 T. C. Nast, G.A. Bell, and R. K. Wedel, "Orbital Performance of aSolid Cryogen Cooling System for a Gamma Ray Detector," Advances inCryogenic Engineering, Vol. 21, Plenum Publishing Corporation 1976,pg. 435-442.
6-2 T. C. Nast, C.B. Barnes, R. K. Wedel, "Development and Orbital Operation 3;
of a Tao--Stage Solid Cryogen; Cooler," Journal of Spacecraft and Rockets,Vol. 15, No. 2, liar-Apr 1978, pg 85-91.
z
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