National Aeronautics and

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IS20

George C. Marshall Space Flight Center

Marshall Space Flight Center, Alabama

35812
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i

NASA/TP—2010–216453

December 2010

National Aeronautics and

Space Administration

Marshall Space Flight Center • MSFC, Alabama 35812

Large-Scale Demonstration of Liquid

Hydrogen Storage With Zero Boiloff

for In-Space Applications

L.J. Hastings

Alpha Technology, Inc., Huntsville, Alabama

C.B. Bryant, R.H. Flachbart, K.A. Holt, E. Johnson, A. Hedayat, and B. Hipp

Marshall Space Flight Center, Marshall Space Flight Center, Alabama

D.W. Plachta

Glenn Research Center, Cleveland, Ohio
ii

Available from:

NASA Center for AeroSpace Information

7115 Standard Drive

Hanover, MD 21076 –1320

443–757–5802

This report is also available in electronic form at

<https://www2.sti.nasa.gov>

Acknowledgments

The authors wish to extend appreciation to the test team at test stand 300 for their dedicated performance 

of the testing. Special thanks also goes to Rae Ann Meyer for her patient programmatic support; to Kenny Webster, 

Stuart Nelson, Steve Tucker, and Tony Bautista for their excellent technical support during the planning and test 

phases; to Davy Haynes for his supervisory guidance; and to Diana LaChance 

for her valuable documentation assistance.
iii

TABLE OF CONTENTS

1. INTRODUCTION ............................................................................................................. 1

2. TEST ARTICLE ELEMENTS ........................................................................................... 3

2.1 Multipurpose Hydrogen Test Bed ................................................................................. 3

2.2 Cryocooler .................................................................................................................... 4

2.3 Cryocooler Integration ................................................................................................. 6

2.4 Instrumentation and Controls ...................................................................................... 8

2.5 Test Facility and Procedures ......................................................................................... 15

3. PREDICTIONS AND TEST APPROACH ........................................................................ 21

4. COMPONENT AND SUBSYSTEM TEST RESULTS ..................................................... 22

4.1 Multipurpose Hydrogen Test Bed/Cryocooler Assembly Bench Test ............................ 22

4.2 Heater Testing ............................................................................................................... 22

5. ANALYTICAL CORRELATIONS ................................................................................... 29

6. CONCLUSIONS AND RECOMMENDATIONS ............................................................ 31

APPENDIX A—MULTIPURPOSE HYDROGEN TEST BED TANKING ........................ 32

APPENDIX B—INTEGRATION OF THE CRYOMECH GB37 CRYOREFRIGERATOR INTO THE MULTIPURPOSE HYDROGEN 

TEST BED THERMODYNAMIC VENT SYSTEM .................................. 39

APPENDIX C—LIQUID HYDROGEN HEATER ELEMENT TESTING 

FOR MULTIPURPOSE HYDROGEN TEST BED 

ZERO-BOILOFF DEMONSTRATION ..................................................... 43

C.1 Background .................................................................................................................. 43

C.2 Test Setup .................................................................................................................... 43

C.3 Test Procedures ............................................................................................................ 43

C.4 Conclusions ................................................................................................................. 45

APPENDIX D—CONTROL SYSTEM FOR MULTIPURPOSE HYDROGEN

TEST BED ZERO-BOILOFF DEMONSTRATION................................... 46

D.1 Zero-Boiloff Model ..................................................................................................... 46

D.2 Multipurpose Hydrogen Test Bed Thermal Performance ............................................. 48
iv

TABLE OF CONTENTS (Continued)

APPENDIX E—INSTRUMENTATION LIST FOR THE MULTIPURPOSE 

HYDROGEN TEST BED TANKING ZERO-BOILOFF 

DEMONSTRATION ................................................................................... 60

APPENDIX F—FLUID SYSTEM FOR THE MULTIPURPOSE HYDROGEN

TEST BED TANKING ZERO-BOILOFF DEMONSTRATION ............... 74

APPENDIX G—MULTIPURPOSE HYDROGEN TEST BED TEST

 REQUEST SHEET ..................................................................................... 77

G.1 Zero-Boiloff Cryogenic Storage/Optical Mass Gauging Sensor Testing ....................... 77

REFERENCES ...................................................................................................................... 81
v

LIST OF FIGURES

 1. NASA’s cooperative effort on ZBO storage ................................................................ 2

 2. MHTB test article ...................................................................................................... 4

 3. MHTB schematic ....................................................................................................... 5

 4. Manhole cover .......................................................................................................... 5

 5. Environmental shroud assembly ................................................................................. 6

 6. Cryocooler ................................................................................................................. 7

 7. Interfacing He lines .................................................................................................... 7

 8. Spray bar integration with cryocooler ........................................................................ 8

 9. Test facility/spray bar/cryocooler integration ............................................................. 9

10. Cryocooler integration with MHTB ........................................................................... 9

11. Installed cryocooler .................................................................................................... 10

12. Spray bar at tank bottom ........................................................................................... 10

13. Spray bar recirculation system .................................................................................... 11

14. Environmental shroud layout: (a) Top panel, (b) bottom panel, (c) side panel 

(zones 5–12), and (d) top view side panels .................................................................. 12

15. MHTB internal instrumentation rakes ....................................................................... 13

16. MHTB instrumentation specific to ZBO .................................................................... 15

17. TS300 vacuum chamber ............................................................................................. 17

18. TS300 facility flow diagram ........................................................................................ 18

19. LH2 heater test fixture ................................................................................................ 23

20. Component enclosure with coils ................................................................................ 24
vi

LIST OF FIGURES (Continued)

21. Upper enclosure with instrumentation—sensors 3.8 cm (1.5 in) 

below upper flange ..................................................................................................... 25

22. Upper enclosure with instrumentation—sensors 6.35 cm (2.5 in) 

below cooling coils .................................................................................................... 26

23. Boiloff flow rate transition to ZBO at 95% fill level ................................................... 27

24. Ullage pressure transition at 95% fill level .................................................................. 27

25. Ullage pressure at 50% fill level .................................................................................. 28

26. Ullage correlations at 95% fill level ............................................................................. 30

27. Ullage correlations at 50% fill level ............................................................................. 30

28. Schematic of control system ZBO model ................................................................... 47

28a. Schematic of ZBO recirculation line model ............................................................... 48

28b. Schematic of ZBO ullage model ................................................................................ 48

29. Schematic for MHTB ZBO demonstration ................................................................ 75

30. Schematic for cryo-refrigerator He system ................................................................. 76

31. Test matrix timeline ................................................................................................... 79
vii

LIST OF TABLES

 1. Pump power input versus flow rate ............................................................................ 11

 2. ZBO red line values ................................................................................................... 16

 3. Predicted heat leak distribution ................................................................................. 21

 4. Representative set of data for one heater element ...................................................... 23

 5. ZBO testing matrix summary—summer 2001 ............................................................ 24

 6. MHTB tanking .......................................................................................................... 32

 7. Resistance measurements for each element ................................................................ 44

 8. Data for element 1 at different voltage settings .......................................................... 44

 9. Current measurements for each element .................................................................... 45

10. MHTB thermal performance spreadsheet .................................................................. 49

11. MHTB ZBO instrumentation list .............................................................................. 61

12. MHTB ZBO test article measurements ...................................................................... 65
viii

LIST OF ACRONYMS, SYMBOLS, AND ABBREVIATONS

ACS automated control system 

AFRL Air Force Research Laboratory

ARC Ames Research Center

CFM cryogenic fluid management 

CO2 carbon dioxide

Cu copper

DSU data systems unit

GH2 gaseous hydrogen

GHe gaseous helium

GN2 gaseous nitrogen

GRC Glenn Research Center 

H2O water

He helium

HRS heat removal system

HX heat exchanger

J-T Joule-Thompson

LH2 liquid hydrogen

LN2 liquid nitrogen 

MGA missile-grade air

MHTB multipurpose hydrogen test bed

MLI multilayer insulation

MSFC Marshall Space Flight Center

N2 nitrogen

NI DAQ National Instruments data acquisition
ix

LIST OF ACRONYMS AND SYMBOLS (Continued)

O2 oxygen

OMGS optical mass gauging sensor

RGA residual gas analysis 

SCRAMNet shared common random access memory network

SLPM standard liters per minute

SOFI spray-on foam insulation

TC thermocouple

TS300 test stand 300 

TVS thermodynamic vent system

ZBO zero boiloff 
x
1

TECHNICAL PUBLICATION

LARGE-SCALE DEMONSTRATION OF LIQUID HYDROGEN STORAGE

WITH ZERO BOILOFF FOR IN-SPACE APPLICATIONS

1. INTRODUCTION

The extension of cryogenic propellant storage periods to months and years has become 

increasingly important within NASA, especially with the current emphasis on manned space 

exploration beyond Earth orbit. Furthermore, the advancement of cryocooler and passive insulation technologies in recent years has substantially improved the prospects for long-term, 

in-space storage of cryogenics with zero-boiloff (ZBO) losses. The ZBO weight benefits for 

long-term missions are substantial, particularly because the tank size and insulation weight 

grow with mission duration extension in a passive storage concept, but not with ZBO.1 Additionally, mission flexibility is significantly enhanced because delays in operations and transient space environments can be accommodated without jeopardizing propellant mass margins; 

i.e., cryogenics can be treated like storable propellants. ZBO involves the use of a cryocooler/

radiator system to balance incoming and extracted thermal energy such that boiloff and the necessity 

for venting are precluded. A cryocooler—with a power supply, radiator, and controls—is integrated 

into a traditional orbital cryogenic storage subsystem, which includes passive thermal insulation, 

a destratification mixer, instrumentation, and controls.

A cooperative effort (fig. 1) by NASA’s Ames Research Center (ARC), Glenn Research 

Center (GRC), and Marshall Space Flight Center (MSFC) was implemented to develop and 

demonstrate ZBO concepts for in-space storage of cryogenics, particularly liquid hydrogen (LH2) 

and oxygen. ARC leads the development of flight-type cryocoolers, GRC the subsystem development and small-scale testing,2 and MSFC the large-scale and integrated system-level testing. Because 

of constrained opportunities for orbital experiments, ground testing must be employed to the fullest 

extent possible. The early ground-based concept demonstrations are performed with low-cost available hardware, followed by increasingly flight-like hardware. Described herein is one element of the 

cooperative program, a large-scale ZBO system demonstration using the MSFC multipurpose hydrogen test bed (MHTB) along with a commercial cryocooler unit. 
2

Flight

GRC-ARC-MSFC

Thermal and Fluid Model 

Development 

MSFC

Advanced Demonstration

Long-Term, Full-Scale

Demonstration With FlightType Cryocoolers

ARC-AFRL

Flight-Type Cryocooler 

Development 

MSFC 

Early Large-Scale System

639-ft3 Tank, Multiple

Liquid Levels, Spray Bar

Mixer HX Concept 

Commercial Cryocoolers

GRC

Early Subscale Test

Concept Evaluation

With 50-ft3 LH2 Tank, Cooler 

in Ullage (No Mixer) 

GRC-ARC

Concept Analysis

GRC-MSFC-ARC

Integration

Analysis, Design, Tests

of Integration Components 

Figure 1. NASA’s cooperative effort on ZBO storage.
3

2. TEST ARTICLE ELEMENTS

2.1 Multipurpose Hydrogen Test Bed

The MHTB 5083 aluminum tank is cylindrical in shape with a height of 3.05 m (10 ft), 

a diameter of 3.05 m (10 ft), and 2:1 elliptical domes (figs. 2 and 3). It has an internal volume of 18.09 m3

(639 ft3) and a surface area of 35.74 m2 (379 ft2), with a resultant surface area-to-volume ratio of 

1.92 m–1 (0.58 ft–1) that is reasonably representative of a full-scale vehicle LH2 tank; e.g., a manned 

lunar lander. The tank is an American Society of Mechanical Engineers pressure vessel coded for a 

maximum operational pressure of 344 kPa (50 psid) and was designed to accommodate various cryogenic fluid management (CFM) technology and advanced concepts as updated versions become available. Major accommodations include a 60.9-cm-diameter (24-in-diameter) manhole; pressurization 

and vent ports; a fill/drain line (through the top of the tank); 15.24 and 7.5 cm (6 and 3 in) general purpose penetrations with flanges on top; the zero-gravity pressure control subsystem (thermodynamic vent subsystem) penetration provisions on the tank bottom (one each 5.08-, 3.81-, and 

1.27-cm tube) and an enclosure external to the tank; a 7.62-cm-diameter (3-in-diameter) drain at the 

tank bottom for future growth; a continuous liquid level capacitance probe; two vertical temperature 

rakes; wall temperature measurements at selected locations; ullage pressure sensors; pressure control/

relief safety provisions; internal mounting brackets for future equipment and structural ‘hard points’ 

for a temporary scaffolding and ladder; and low-heat-leak composite structural supports. Each of 

the penetrations is equipped with a heat guard to intercept heat leak, thereby enabling more accurate 

measurement of the tank insulation performance; however, the heat guards were not activated in this 

test series.

Fluid connections are welded wherever possible and all mechanical seals are the knife-edge/

copper (Cu) gasket (Conflat®) design. The exception is the primary manhole cover design, which 

incorporates a soft, crushable indium wire as a seal material and Invar® expansion collars on the 

stainless steel bolts to offset thermal expansion effects. The secondary manhole cover is equipped 

with a pumpout port (fig. 4) so that any primary seal leakage can be intercepted and routed to 

a facility vacuum pump. Appendix A contains an MHTB tanking table with information regarding 

fill height, percent liquid/ullage volume, and LH2 mass.

The MHTB tank is enclosed within an environmental shroud (fig. 5) that simulates a ground 

hold conditioning purge (similar to that in a payload bay) and enables the imposition of a range 

of uniform temperatures on the multilayer insulation (MLI) external surfaces. The shroud is 

4.57 m (15 ft) high by 3.56 m (12 ft) in diameter and contains a purge ring for distributing gaseous nitrogen (GN2). The shroud heater strips/cooling loops can impose either constant or timedependent boundary temperatures ranging from 80 to 320 K (144 to 576 °R). 

The MHTB insulation concept consists of a foam/multilayer combination. The foam element 

enables the use of a payload bay-type GN2 purge during ground hold periods. The 45-layer, double 

aluminized mylar MLI provides thermal radiation protection while at vacuum conditions on orbit. 
4

Figure 2. MHTB test article.

As reported in reference 3, which describes the insulation in more detail, the combined effects of the 

MLI variable density, large vent hole pattern, and installation technique resulted in substantial performance improvements over conventional insulation configurations. However, in this application, 

the insulation system performance was compromised by the thermodynamic vent system hardware 

installation and by degradation due to exposure to multiple test environments over a 15-yr period. 

2.2 Cryocooler

ARC selected and procured a commercial Cryomech, Inc. GB37 cryocooler unit for the 

MHTB testing (fig. 6). The Cryomech unit, a two-stage Gifford-McMahon cycle refrigerator4,5 was 

then delivered to GRC for bench testing and the design of a heat exchanger (HX) and structure for 

MHTB integration. The cryocooler rated capacity is 30 W at 20 K and requires 350 W of power 

input per watt of cooling for a 4% Carnot cycle efficiency. The first stage provides 50 W of cooling 

at 80 K. Unlike a flight-type unit, the compressor system is positioned outside the vacuum chamber 

and is linked to the cryocooler with stainless steel helium (He) lines penetrating the chamber walls, 

as shown in figure 7. The cryocooler integration procedure is described in appendix B.
5

Work Platform

Manhole Cover

Optical Sensor Port 2

Purge Ring Diffuser

Insulation Interstitial 

Pressure Probe

Tank Secondary Rake

Cryocooler HRS 

Spray Bar/HX

Cryocooler HRS 

Enclosure Pumpout

Environmental

Shroud Assembly

Lifting Eyes (×4)

Primary Instrumentation Penetration

Pressurization Penetration

Fill/Drain Penetration

Tank Vent Penetration

Tank Primary Rake

Test Tank Insulation 

SOFI: ≈3.5 cm Thick 

MLI: 45 Layers

Tank Capacitance Probe

Tank Support Legs 

Composite (×4)

Optical Emitter Port 1

Leg Tie Rods

Tank Interface 

Support Structure

Ladder

Figure 3. MHTB schematic.

Outer Cover Secondary Seal Vacuum Port

Evacuation Volume

Inner Cover Primary Seal

Vacuum

Chamber Interface

Pressure

Transducer

P

Vacuum

Isolation

Valve

Figure 4. Manhole cover.
6

Figure 5. Environmental shroud assembly.

2.3 Cryocooler Integration

The cooler integration concept involves connecting the second-stage cooling head to a HX 

inserted into an existing 5-cm-diameter recirculation line that, in turn, interfaces with the pump and 

spray bar mixer system (figs. 8–11). The spray bar recirculation system shown in figures 12 and 13 is 

designed to provide destratification independent of ullage and liquid positions in a zero-gravity environment.6 During the mixing process, fluid is withdrawn from the tank by a pump and flows through 

the spray bar positioned along, or near, the tank longitudinal axis. The fluid is then expelled radially 

back into the tank through 180 spray bar orifices 0.17 cm (0.067 in) in diameter, or a standard 51 drill 

size. The orifice diameter was selected to produce relatively uniform injection velocities for the design 

condition of a half-full tank in a normal gravity environment. If the liquid is settled in the upper half 

of the tank, then the pump can be shut down and the ullage cooled directly, thereby controlling tank 

pressure.

The inline HX is shown in diagram and schematic form in figures 8 and 9, respectively, and 

in pictorial form in figure 10. It transfers thermal energy from the fluid to the cryocooler and was
7

Figure 6. Cryocooler.

Figure 7. Interfacing He lines.
8

Concentric Tube

Vent Row (Closed)

J-T Valve (Closed)

Circulation Pump

Cryocooler Position

Bulk Liquid Inlet

LH2

Vent Exit (Closed 

for ZBO Tests)

Figure 8. Spray bar integration with cryocooler.

designed by GRC to minimize cryocooler size and power requirements. Further details regarding the 

GRC testing are presented in section 4.1.

A Barber-Nichols, Inc. BNHP-08 centrifugal cryogenic pump was used for the recirculation 

process. The pump delivers 18 and 37.8 L/min with an estimated power input to the liquid of 0.04 

and 0.3 W, respectively. The pump power input versus flow rate, which must be considered in the 

tank heat leak computations, is presented in table 1. The recirculation line, pump, and cryocooler 

assembly (fig. 11) were contained within an enclosure attached to the tank bottom, as shown in 

figures 8 and 9, so that any leakage could be entrapped and pumped out without compromising 

the chamber vacuum levels. Such an enclosure would not be required in an actual application.

2.4 Instrumentation and Controls

The environmental shroud instrumentation details are shown in figure 14 and the instrumentation arrangement for each primary test article segment is summarized in this section. (A list 

of all instrumentation is presented in app. E.) The test article instrumentation consists primarily 

of thermocouple (TC) and silicon diodes to measure insulation, fluid, and tank wall temperatures. 

Typically, silicon diode (Lakeshore type DT-470-11A) temperature transducers are positioned in the 

areas of lowest temperatures because of their higher accuracy as compared with TCs. MLI temperature profiles or gradients are measured at seven positions with one silicon diode and four TCs placed 

at each of the seven measurement positions. The MLI interstitial pressure is measured at the foam/
9

Tank Internal

Tank External

Tank Internal

Tank External

Flowmeter

Back-Pressure

Orifice

Pump

Electrical Supply He Return to Compressor

He Supply From Compressor

Cylinddrical Enclosure

Cryocooler Enclosure

Axial Liquid Jets Distributed Along

the Spray Bar to Mix the Fluid

Spray Bar

Bulk Liquid Inlet

To Evacuation System, Purge

System and Controls

Vent Exit (to Vacuum Pump)

Figure 9. Test facility/spray bar/cryocooler integration.

Mixing Pump

TVS Recirculation Line

HX and

Cold-Finger 

Attach Position

Figure 10. Cryocooler integration with MHTB.

MLI interface, and a sampling port for both dewpoint level and gas species is provided. The environmental shroud is composed of 17 individual panels, each equipped with a minimum of two TCs 

attached to the inner surfaces and placed beneath the electrical heating strips. These TCs are used 

with a closed-loop control system to regulate each shroud panel temperature.
10

Figure 11. Installed cryocooler.

MHTB Lower

Penetration

Recirculation

Flow Inlet

Vent Flow Inlet

(Downstream

J-T Valve)

Concentric HX Spray Tubes (×4)

Figure 12. Spray bar at tank bottom.
11

TVS Mast

Manifold

Pressure and

Temperature

Sensors

Vent Flow Line

and Back-Pressure

Orifice

Concentric HX

Spray Tubes (×4)

Figure 13. Spray bar recirculation system.

Table 1. Pump power input versus flow rate.

Flow Frequency 

(Hz)

Pump Power 

(W)

Motor Input Power 

(W)

∆P

(L/min) (gpm) (mBar)

19 5 18 0.040 0.44 0.9

38 10 37 0.330 1.77 3.9

57 15 55 1.10 3.47 8.6

76 20 73 2.70 6.51 15.2

118 30 110 9.00 16.75 34.5

151 40 147 21.00 37.3 61.3

As shown in figure 15, the tank is internally equipped with two instrumentation rakes and 

a capacitance liquid level probe, all supported from the top of the tank. The following should be 

noted:
12

Bottom Shroud Pane Layout

0.2 to 0.23 m (8 to 9.3 in) Typical Distance Between Tapes

TCs

Top Shroud Pane Layout

0.3 m (12 in) Typical Distance Between Tapes

Side Shroud Pane Layout (Zones 5 to 12)

0.24 m (9.5 in) Typical Distance Between Tapes

Only in Zones 7 and 11

Only in Zones 7 and 11

Top Bottom

(Based on Original Design, Modifications will be Implemented During Assembly Based on Pretest Checkouts)

TCs

TCs

Zone 1 Zone 2

Zone 3

Zone 4

Zone 7 Zone 11

Zone 8 Zone 10

Zone 6 Zone 12

Zone 9

Zone 5

Top View

Side Panels

All Fluid Lines

Penetrate

Zone 15 Zone 16

Zone 13

Zone 17 Zone 14

(0 Deg)

(0 Deg) +CW

(0 Deg)

(c)

(a)

(d)

(b)

Figure 14. Environmental shroud layout: (a) Top panel, (b) bottom panel, (c) side panel 

(zones 5–12), and (d) top view side panels.

• Diode rake 2 was relocated inside the MHTB to accommodate mass gauge testing.* Rake 2 

is in a vertical position with the uppermost diode (TD13) located 24.77 cm (9.75 in) from 

the bottom surface of the inner manway flange.

• The LH2 heaters are installed such that the top of each heater is located ≈224 cm (≈88 in) 

from the bottom surface of the inner manway flange. This also places the top of each heater 

≈11.4 cm (≈4.5 in) below the 25% point level sensor.

• The Sierra Lobo instrument is installed with one diode at the 61.1% location—the TD5 diode—

with the second Sierra Lobo diode located 22.86 cm (9 in) above the 61.1% location.*

The rakes, constructed from a fiberglass epoxy channel section, are equipped with silicon 

diodes attached at 22.9 cm (9 in) intervals using nylon rod offsets and cryogenic epoxy. The instrumentation rakes provide temperature-gradient measurements within both the ullage and liquid, in 

*Piggy-Back Testing”—not a part of ZBO testing.
13

91.44 cm (36 in)

22.86 cm (9 in)

101.6 cm (40 in)

284.48 cm (112 in)

Tank Top (100% Full) Reference

22.86 cm (9 in)

22.86 cm (9 in) (Typical)

22.86 cm (9 in) (Typical)

274.32 cm (108 in)

Note: All Diodes Spaced at Intervals of 22.86 cm (9 in)

TD13

TD14

TD15

TD16

TD17

TD18

TD19

TD20

TD21

TD22

TD23

TD24

TD1

TD2

TD3

TD4

TD5

TD6

TD7

TD8

TD9

TD10

TD11

TD12

Rake No. 1

Rake No. 2

TVL4 & TVL5

Figure 15. MHTB internal instrumentation rakes.

addition to providing a backup to the continuous liquid level capacitance probe. Two of the four 

composite legs, the vent, fill/drain, pressurization, pressure sensor probe, and manhole pumpout 

penetrations are instrumented to determine the solid conduction component of heat leak. 

In a flight application, the cooler would be designed to vary the thermal extraction rate with 

the storage system heat leak. However, the thermal extraction rate of the commercial cooler could 

not be varied. Therefore, to enable balancing the total tank heat leak with the cooler extraction rate 

more precisely and efficiently, two graphite heaters were installed below the 25% fill level such that 

the heaters always remained submerged in liquid. Because graphite electrical resistance increases 

with decreasing temperature, the heaters were especially suited for cryogenic applications. Each 

heater provided zero to 50 W of power (two for redundancy) and were adjustable in increments 

of <1 W. Details on the heater bench testing are presented in appendix C.

The controller task was to maintain the tank heat leak at a value that matched the heat 

extraction capability of the cryocooler. As described earlier, the controller basically added thermal energy to the LH2 via submerged heaters as required to achieve constant ullage pressure and 

corresponding liquid saturation conditions. To check out the control system logic, the controller 

was exercised during both pretest simulation/checkout and real-time test operations to eliminate 

version differences. As detailed in appendix D, the ‘acquire data’ block read data from the TS300 

data acquisition computer using a shared common random access memory network (SCRAMNet). 
14

SCRAMNet was used to provide a low-latency, low-overhead, and high-bandwidth network for 

the transfer of large quantities of data between separate data acquisition and control computers. 

Control was applied to the heater using a National Instruments data acquisition (NI DAQ) board 

installed in the control computer. Specialized C-language software was written to transfer data from 

the data acquisition computer onto the SCRAMNet, from this network into the control computer, 

and finally from the heater power command to the NI DAQ board. This command was presented 

to a power supply (Agilent) that controlled the carbon heaters’ voltage. Before testing, the resistance 

of three carbon heaters was calibrated at LH2 temperatures (app. C). Two heaters were selected for 

installation in the MHTB LH2 tank that had the nearest match in calibration (heaters 1 and 2). The 

basic control law was a proportional-integral-derivative controller with simplified Kalman filters 

(pink blocks) used to estimate the ZBO measurements that were fed into two thermodynamic/fluid 

system models (blue blocks) of the MHTB LH2 system. The two models—ZBO recirculation line 

model and ZBO ullage model—are included in appendix D, as well as the MHTB thermal performance worksheet, which provided the ‘real time’ heat leak into the MHTB LH2 tank. Although the 

tank heat leak was a manual input, the control system could have interacted directly with the MHTB 

thermal model. The upper portion of this MATLAB/Simulink block diagram was used primarily for 

simulation but was active during test operations for ‘health’ monitoring the control system state. The 

lower portion implemented the control law and predicted the ullage pressure rise rate, which was displayed with the measured rise rate, and calculated the heater power command, which was displayed 

with the measured heater power. 

Three benefits resulted from using this control scheme:

(1) Highly accurate pressure control was obtained from ‘standard’ pressure gauges. 

(2) Significant time reductions to reach a stable liquid saturation point were achieved. Pressure 

control ±0.0003 kPa was achieved using a pressure gauge with a range of 5,000 psig, instead of having to use the more expensive delta pressure system. The latter can also be very time consuming to set 

near the saturation point of the LH2. Pretest planning indicated that many hours would be needed to 

reach saturation using a manual control procedure. Using this controller, saturation was reached in 

a matter of 30 min. Many hours of setup time were turned into useful test time and allowed testing 

at several saturation points that were not in the initial test matrix. 

(3) Interfacing the control system directly with thermal and thermodynamic analytical models enabled the use of real-time predictions to guide the controller. For future testing applications, the 

significance of successfully integrating ‘real time’ thermal/thermodynamic analytical modeling into 

the control system should not be overlooked. 

During the ZBO performance testing, the bulk liquid temperature relative to the ullage 

saturation conditions was monitored using silicon diode TD23 on rake 2 and ullage pressure sensor P1 (see sec. 2.5). TD23 is at the 11.5% fill level or 53.3 cm (21 in) above the tank bottom and 

was assumed to be representative of the bulk liquid temperature. The TD23 temperature output 

was converted to an equivalent saturation pressure (termed PSA1) and compared with ullage pressure sensor P1. P1 is an MKS Instruments, Inc. Baratron zero to 133 kPa (zero to 19 psia) absolute 

pressure transducer with an accuracy of ±0.02%. 
15

MHTB instrumentation added specifically to support ZBO is presented in figure 16. 

GD1 Gallium diode 15/310

GD2 Gallium diode 15/310

GD4 Gallium diode 15/310

GD5 Gallium diode 15/310

GD6 Gallium diode 15/310

GD7 Gallium diode 15/310

GD8 Gallium diode 15/310

GD9 Gallium diode 15/310

GD10 Gallium diode 15/310

GD11 Gallium diode 15/310

GD12 Gallium diode 15/310

SD101 Silicon diode 15/310

SD102 Silicon diode 15/310

SD103 Silicon diode 15/310

SD104 Silicon diode 15/310

SD105 Silicon diode 15/310

SD106 Silicon diode 15/310

SD107 Silicon diode 15/310

SD108 Silicon diode 15/310

HTC25 Motor heater temperature top 15/310

HTC26 Motor heater temperature bottom 15/310

PTC28 Pump M 1 inlet temperature 15/310

PTC27 Pump M 1 outlet temperature 15/310

PS10 Pump M 1 ∆P 0/0.2 psid

PS20 Pump M 1 inlet pressure 0/50 psig

PS30 Flowmeter FM 1 outlet pressure 0/50 psig

FM 1 Flowmeter 15/150 gpm

CHT1 Copper HSG surface temperature top 15/310

CHT2 Copper HSG surface temperature bottom 15/310

HT1 Cryocooler HSG wall temperature top 15/310

HT2 Cryocooler HSG wall temperature bottom 15/310

MID Description Range

Cryocooler Intrumentation

GD1 GD2

GD2

GD4

GD5 GD6 GD7 GD8

GD12

GD9

GD11 GD10

SD101

SD102

SD103

SD104

SD105

SD106

SD107

SD108

HTC25

HTC26

HT1

HT2

PTC28

PS20

PS30

FM 1

CHT1

CHT2

PS10

PTC27

Figure 16. MHTB instrumentation specific to ZBO.

Further details on all test instrumentation are presented in appendix E. The red line values 

used to protect the facility test article and test objectives are defined in table 2.

2.5 Test Facility and Procedures

2.5.1 Facility Description

Testing was performed at the MSFC east test area thermal vacuum facility, test stand 300 

(TS300). The vacuum chamber, shown in figure 17, is cylindrical in shape and has usable internal 

dimensions of 5.5 m (18 ft) in diameter and 7.9 m (26 ft) in height. Personnel access is through 

a small side-entry door, but the chamber lid is removable for the installation of large test articles. The 

chamber pumping train consists of a single-stage GN2 ejector, three mechanical roughing pumps 

(rated at 140 L/s (300 ft3/min) each) with blowers (rated at 610 L/s (1,300 ft3/min) each), and two 

1.2-m (48-in) oil diffusion pumps (rated at 95,000 L/s (200,000 ft3/min) N2 each). Liquid nitrogen 

(LN2) cold walls provide cryopumping and thermal conditioning capability and are composed 
16

Table 2. ZBO red line values.

Red Line Value Red Line Type MID No.

Ullage pressure increase 1 psi over set pressure Alarm P1

Ullage pressure decrease 1 psi under set pressure Alarm P1

Ullage high pressure cut >45 psid Automated P2

Recirculation Line Temperature

Recirculation line low temperature <15 K Alarm GD1

Mixing pump

Pump ∆P 0 psi Alarm PS10

Pump flow stabiliation Set flow 5 gpm Alarm FM1

Compressor

Compressor cooling water <2 gpm Alarm F16

Compressor ∆P low <210 psid Alarm P3143–P3144

Compressor ∆P high >270 psid Alarm P3143–P3144

Heat Exchanger

HX high temperature GD4>GD2 Alarm GD4 and GD2

HX low temperature <7 K Alarm GD4

HX motor high temperature >105 °F Alarm HTC26

HX motor low temperature <45 °F Alarm HTC26

HX enclosure pressure 1 atm Alarm TBD

Heater Shroud

HX low temperature <159 K Alarm Controller

HX high temperature >169 K Alarm Controller

20-ft Vacuum Chamber

Chamber high pressure >0.001 torr Alarm VP3010

Chamber Cold Walls

Chamber high temperature >85 K Alarm TBD

Manway Pressure

Manway pumpout flow TBD Alarm F8

of five parallel zones that totally surround the usable chamber volume with a surface emissivity of 

≈0.95. The facility systems in combination with the test article shroud enable simulation of orbit 

environmental conditions by providing vacuum levels of 10–8 torr and a temperature range of 80 to 

320 K (140 to 576 °R). 

A fluid flow schematic shown in figure 18 depicts the integration of the MHTB, with its ZBO 

hardware, into the TS300 vacuum chamber facility. 

A vacuum-jacketed fill and drain system provides cryogenic fluid servicing to and from the 

test article. All facility lines have welded construction to assure that vacuum conditions are not compromised by leakage. During the heat leak measurement phases of the testing, conditions within the 

MHTB were controlled using the following facility subsystems:
17

Figure 17. TS300 vacuum chamber.

• A tank pressure control subsystem was used to maintain the MHTB ullage pressure at the required 

steady-state conditions during the boiloff or heat leak measurement phase of testing. The system was composed of several flow control valves (located in the vent line), each of which was 

regulated through a closed-loop control system. This control loop manipulated the valve positions based on a comparison of the measured tank ullage pressure and the desired set point. 

An MKS Instruments, Inc. Baratron zero to 133 kPa (zero to 19 psia) absolute pressure transducer (accuracy of ±0.02%) and an MKS delta pressure (DP) transducer (1 torr or 133  Pa 

head with an accuracy of ±0.04%) located outside the vacuum chamber were used to measure 

ullage pressure. The system successfully maintained set points ranging from 110 to 124 kPa 

(16 to 18 psia) with a tolerance of ±0.00689 kPa (±0.001 psi) for the boiloff or simulated orbital 

heat leak test conditions.

• The LH2 boiloff flow instrumentation was located in the vent downstream of the flow control 

valves. During the on-orbit heat leak simulations, one of three mass flowmeters (MKS model 

258C, Hastings model 200, and Hastings model H-3MS) was used. These meters spanned 

flow ranges of zero to 280, zero to 50, and zero to 1 SLPM with accuracies of ±0.8%, ±1%, 

and ±1% of full scale, respectively. To prevent ambient temperature effects on measurement accuracy, the flowmeter system was placed within a containment box and equipped with 

a temperature-controlled purge, which maintained the box interior at a constant temperature, typically 306 K (550 °R). This facility element was only used to establish a baseline heat leak magnitude 

and was deactivated during the ZBO phase of testing.
18

T

T

P

P

P

20-ft Vacuum Chamber

Facility Pumping

Train

Ejector Pump

Test Article Shroud Purge

Tank Pressure

Control System

Boiled Flow Measurement

Chamber Purge

Flow Control Valve

Isolation Valve

Hand Regulator

Temperature Valve

Relief Valve

Flowmeter Valve

Pressure Valve

GN2

GHe

MGA

Facility

Services

Seal Evacuation System

Flowmeter Environmental Enclosure

Thermally Isolated With Feedback Control

Ice Bath Reference

Volume With Delta

Pressure Control System

Drain System

Fill System

Burn Stack

Vent Trailer

Supply

Diffusion Pumps

MHTB

Test

Tank

Roughing Train

Chamber LN2 Cold Walls

Figure 18. TS300 facility flow diagram.

• A seal evacuation system, MKS model 258 with a range of zero to 61 standard in3/min, captured 

and measured any gases leaked past the 61 cm (24 in) primary tank seal (fig. 4). As described 

earlier, this was used as required to prevent vacuum-level degradation; i.e., maintained 

a seal volume pressure at or below 133 Pa (1 torr). During boiloff testing, however, seal leakage 

is typically avoided by maintaining tank pressures at moderate level; i.e., in the 105 to 140 kPa 

(15 to 20 psi) range.

2.5.2 Test Facility Procedures

The procedures and approaches used for test preparations, heat leak measurement, 

and post-test operations are summarized in sections 2.5.2.1 through 2.5.2.3. 

2.5.2.1 Pretest Operations. Before testing, the vacuum chamber and environmental shroud 

were purged at a trickle rate with dry GN2 for ≈5 days while the chamber and MLI dewpoint was 

maintained. Before tanking, the environmental shroud purge ring was operated at a GN2 flow rate 

of 5 kg/min (11.2 lb/min) with a dewpoint not to exceed –54 °C (–65 °F). Also, the seal evacuation 

system was activated and held steady at a level of 2×10–2 torr or less. About 2 hr before tanking, 

dry GN2 (followed by gaseous hydrogen (GH2)) with a dewpoint of –54 °C (–65 °F) was used for 

the internal purge/conditioning operations of the test tank, fill/drain line, and vent line. This purge 
19

and conditioning process was accomplished using charge-vent cycles during which the tank was 

pressurized to ≈103 kPa (≈15 psig) with GH2, held for ≈1 min, and then vented back down to near 

atmospheric pressure. This sequence was typically repeated 15–20 times before loading LH2 into 

the MHTB. The test tank is designed to withstand an internal vacuum against external atmospheric 

pressure, enabling vacuum cycling with GH2 pressurization, a much more efficient method of conditioning. However, the vacuum cycling approach was not implemented during this test program.

The vacuum chamber was pumped down to a steady-state vacuum level (10–6 torr or less), 

and the MLI allowed time to evacuate before initiating tank fill. The test article was then filled with 

LH2 to the 85% level while maintaining the ullage pressure ≈103.4 torr (≈2 psi) above the required 

set point pressure. Completion of fill to the 95% level was then accomplished with the automated 

pressure control subsystem activated to control the ullage ≈25.8 torr (≈0.5 psi) above the set point. 

Once filling was completed, the transition to the test set point pressure occurred over a period of 

10–20 min. Several hours were required to saturate and equilibrate the tanked LH2 at the set point 

pressure. 

2.5.2.2 Tank Heat Leak Testing. Boiloff testing was conducted to determine the ambient 

heat leak into the MHTB tank and to set up consistent initial conditions for each of the ZBO tests. 

Also, the additional ZBO hardware added heat leak. The heat leak test procedures are summarized 

herein and further details are presented in reference 3.

Steady-state vacuum and thermal conditions within both the chamber and MLI were achieved 

before the on-orbit heat leak test phase. The four criteria, which had to occur simultaneously, for 

steady-state thermal conditions were as follows:

(1) A vacuum chamber pressure of 10–6 torr or less was required to ensure an adequate 

vacuum within the insulation.

(2) Insulation temperatures (MLI and spray-on foam insulation (SOFI)) had to be in 

a steady-state condition with the MLI surface temperature at the prescribed set point imposed 

by the environmental shroud. Insulation equilibrium was assumed to exist once temperature 

transients of no more than 0.55 K in 6 hr occurred in any section of the insulation system. 

(3) Thermal equilibrium of the LH2 had to be maintained through precise ullage pressure 

control during the heat leak measurement test phase. Ullage pressure was maintained at a set point 

in the range of 110.316 to 124.106 kPa (16 to 18 psia) with a tolerance of ±0.00689 kPa (0.001 psi). 

The boiloff rate was recorded for 6 hr after steady state was achieved.

(4) The vented ullage gas temperature had to increase with time (have a positive slope), 

indicating that the tank dome is in thermal equilibrium; i.e., is not cooling and contributing 

to the vented gas enthalpy. 

When performing the heat leak cryogenic storage testing, either a loss of ullage pressure 

control or the chamber vacuum can significantly increase unproductive test time. Each 6.89 kPa 

(1 psi) of LH2 subcooling, due to a sudden reduction in ullage pressure, requires 30 hr for recovery 
20

to saturation (due to the low heat leak conditions). Similarly, a sudden increase in vacuum chamber 

pressure (10–4 torr or above) can dramatically alter the MLI temperatures, necessitating several days 

to recover the steady-state temperature profile. Therefore, great care was taken to ensure tight control 

of the tank ullage and vacuum chamber pressures. 

A residual gas analysis (RGA) system was used to periodically record vacuum chamber and 

MLI interstitial gas composition during steady-state orbit hold periods. RGA sampling intervals 

varied, depending on the vacuum chamber pressure stability, and assisted in determining the source 

of any chamber pressure variations; e.g., test article or chamber leakage, or outgassing. Species possibilities included H2O, N2, O2, CO2, and the foam-blowing agent CFC-11 (CCL3F molecular weight 

of 137.4).

2.5.2.3 Post-Test Operations. Chamber repressurization conditions after the ZBO tests 

were selected primarily to protect the test article and facility. Also, following a test, the MHTB 

was not held under vacuum conditions for needlessly long periods. The chamber and test article 

were warmed and repressurized within 8 to 12 hr after testing was concluded. Chamber repressurization occurred slowly (≈30 min) with dry GN2 (dewpoint –54 °C (–65 °F)) in the 4 to 27 °C 

(40 to 80 °F) temperature range. To prevent H2O condensation, repressurization was initiated 

only after the vacuum chamber cold walls and all test article insulation (SOFI/MLI) had reached 

≈15.5 °C (≈60 °F). 

Dry GN2 with a dewpoint of –54 °C (–65 °F) was used to accomplish purge and inerting 

operations for the test article volume and all service lines. These operations were designed so that the 

test article was not subjected to a positive differential pressure in excess of 344 kPa (50 psid). Typically, the GN2 shield purge remained on for 24 hr after completion of testing.
21

3. PREDICTIONS AND TEST APPROACH

The strategy was to first use the MHTB environmental shroud to establish an insulation 

warm boundary temperature of 164 K and, before turning the cooler on, to ensure a tank heat 

leak below the cooler thermal extraction capability (27 W expected). A tank heat leak of 12.9 W 

was predicted with the pump operating (table 3). About 8.3 W was expected through the insulation and penetrations, excluding the nonoperating cooler. An additional heat leak of 4.3 W was 

calculated for the nonoperating cooler using a model based on bench testing the MHTB cryocooler 

hardware. The pump was expected to add ≈0.3 W at 37.8 L/min. Then, during subsequent ZBO testing with the cooler operating, one of the internal heaters could be adjusted, based on the measured 

tank pressure transients, to balance the tank heat load and achieve steady-state pressure conditions. 

By integrating a simplified MHTB thermal/fluid analytical model into a control system algorithm 

(see sec. 2.5), the measured ullage pressure response and real-time thermal data could be used to 

automatically provide a constant tank pressure condition. Although the control scheme was necessitated by the cooler’s constant output design, the control system challenges were similar to those 

that will be encountered in actual missions. The MHTB test request sheet is presented in appendix G.

Table 3. Predicted heat leak distribution.

Source

Heat Leak 

(W)

Tank with penetrations 8.3

Nonoperating cooler 4.3

Operating pump 0.3

Total 12.9
22

4. COMPONENT AND SUBSYSTEM TEST RESULTS

4.1 Multipurpose Hydrogen Test Bed/Cryocooler Assembly Bench Test

As mentioned earlier, the inline HX was designed to transfer thermal energy from the fluid 

to the cryocooler in a manner that minimized cryocooler size and power requirements. Besides having a high conductivity, the HX design had to allow for welding to a stainless steel flange and have 

the strength to accommodate piping stress. GRC conducted a series of bench tests to verify that the 

design would perform as expected and that the assembly could be successfully integrated into the 

MHTB.

The HX was fabricated from high-conductivity Cu and then integrated with the stainless steel 

piping tee. The HX, composed of five fins, has an overall height and a base diameter of ≈17 and 

≈3 cm, respectively. The measured conductivity was ≈23 W/cm·K, which limits the temperature 

increase along the HX to just 2 K and mitigates thermal integration losses. This limited temperature 

increase, compared to the predicted difference of 3.5 K, improved the overall system efficiency and 

limited the thermal integration losses. 

The GRC bench testing proved to be very worthwhile and enabled avoidance of last-minute 

issues that would have otherwise been encountered. The testing resulted in a measured conductivity 

that was higher than expected which minimized the temperature increase between the cooler ‘cold 

finger’ and the LH2 end of the HX. The measured conductivity of ≈23 W/cm·K limited the temperature increase to just 2 K, compared to the predicted difference of 3.5 K, thereby reducing losses and 

improving the overall system efficiency. Furthermore, the bench testing assured that the cryocooler 

subsystem structural support and electrical and mechanical fittings would be easily accommodated 

by MSFC’s MHTB and test facility interfaces.

4.2 Heater Testing

Each of the carbon heater elements was secured in a fixture and solid Cu feedthrough wires 

were attached to the heating elements, as shown in figure 19. The baseline resistance of each element with the solid Cu wires attached was measured before and after installation in the cryostat. 

After cryostat fill, voltage and current readings were taken periodically as the power level was slowly 

increased to a maximum of 50 W. Table 4 presents a representative set of data for one of the three 

heater elements. The following could be concluded:

• As expected, the heater element resistance increased with decreasing temperature.

• LH2 exposure did not adversely affect the heater operation.
23

Carbon Heater Element

Figure 19. LH2 heater test fixture.

Table 4. Representative set of data for one heater element.

Applied 

Volts

Current 

(A)

Power 

(W)

1 0.8 0.8

2 1.7 3.4

3 2.6 7.8

4 3.5 14.0

5 4.4 22.0

6 5.3 31.8

7 6.2 43.4

7.5 6.6 49.5

4.2.1 First Zero-Boiloff Test Series

The ZBO testing consisted of two test series—one during the summer and a second during 

the fall of 2001. The first series (see table 5), conducted with a 95% fill level, was compromised by 

a larger-than-predicted heat leak from the component enclosure positioned around the recirculation 

line and cooler assembly. Based on measured parameters, the cryocooler net energy extraction rate 

from the LH2 was established to be 24 W. However, the internal heat generated by the cooler motor 

operation resulted in an enclosure assembly heat leak addition of 17 W. Thus, the enclosure heat 

leak combined with a measured tank heat leak of 9.5 W (including the recirculation pump input of 

0.3 W) totaled 26.5 W, exceeding the cooler extraction capability by 2.5 W. Therefore, testing was 
24

Table 5. ZBO testing matrix summary—summer 2001.

Test Scope Description

1 Establish thermal control subsystem heat leak < cooler capacity 

 @ 90%–95% fill with boiloff vent open

Steady-state boiloff with cooler and mixer off to baseline heat leak prior 

 to ZBO test; correlate predictions

2 Assure that cooler capacity > heat leak @ 90%–95% fill with 

 cooler and mixer on, vent closed

Baseline ullage pressure trend (decrease expected); correlate predictions

3 Establish constant average ullage pressure @ 90%–95% fill 

 with cooler, mixer, and heater on

Add and adjust heater input to balance total heat leak with cooler energy 

 removal; evaluate auto pressure control

4 Sustain ZBO conditions for 4 days @ 90%–95% fill Allow automatic controls to maintain constant average ullage pressure; 

 verify ZBO concept

5 Check heat leak conditions @ 25%–30% fill Perform abbreviated heat leak test

6 Repeat tests 1 and 2 @ 25%–30% fill Ullage pressure rise rate slower with larger ullage, assess effect on controls

7 Repeat test 1 and 2 @ 50%; then impose off-nominal conditions Abbreviated ZBO test @ 50% followed by assessing effects of off-nominal 

 conditions on ullage pressure and system controls

Note: Total test duration of 25 to 30 days including optical mass gauge testing.

suspended so that LN2 cooling coils could be installed around the component enclosure, shown in 

figure 20, and reduce the heat leak to acceptable levels. (Such an enclosure would not be needed in 

an actual space application.)

Figure 20. Component enclosure with coils.

In spite of the limitations, the first series was successfully used to evaluate various system 

elements and adjust operational procedures. Both intermittent and continuous pump operations at 

various flow rates were tested to evaluate impacts on pressure control and cryocooler performance. 
25

The intermittent pump operations compromised the cryocooler heat extraction process because the 

colder liquid that accumulated between operations reduced the cooler efficiency, did not benefit destratification and ullage pressure control, and added operational complexity. As the pump flow rate 

was reduced, erratic flow rate and DP across the pump indicated unstable, two-phase flow began at 

flow rates below ≈37.8 L/min. Because the pump was designed for operation at 114 L/min, the pump 

efficiency began to rapidly degrade below 38 L/min and an increased percentage of the power input 

was thermally transferred to the fluid. Ultimately, it was concluded that continuous pump operation at 

≈38 L/min was optimal for the MHTB ZBO hardware arrangement. A substantial advancement was 

that thermal/fluid analytical modeling of the MHTB system was successfully integrated into the 

control system algorithm. Measured thermal and thermodynamic parameters were used to quantify 

the various heat leak sources, anchor real-time analytical modeling, and establish confidence in the 

automated control system (ACS) algorithm.

4.2.2 Second Test Series

Using LN2 cooling coils and structural temperature sensors on the component enclosure, 

it was established that the assembly heat leak was reduced from 17 to 3.5 W (figs. 20–22). Also, 

boiloff testing confirmed that the total MHTB tank heat leak, including the operating pump, was 

reduced to 13 W, well within the measured 24 W cryocooler energy extraction rate. Testing was 

conducted primarily at fill levels of 95% and 50%, with limited testing at 25%. 

Sensors 3.8 cm (1.5 in) Below Upper Flange and 5.1 cm (2 in) Apart

Sensors 3.8 cm (1.5 in) 

Above Bottom Flange 

and 4.44 cm (1.75 in) Apart

22.54-cm (8.875-in) Distance 

Between Upper Flange and 

Lower Sensors (at Centerline 

of Sensor)

Interface Flange Between Lower

and Upper Component Housing

Lower TVS Housing With Cooling Coils Installed

Figure 21. Upper enclosure with instrumentation—sensors 3.8 cm (1.5 in) below upper flange.
26

Sensor 6.35 cm (2.5 in) Below Cooling Coils and 25.4 cm (10 in) Below Flange Surface

Sensor 4.44 cm (1.75 in)

From Bottom Flange 

Surface

32.7 cm (12.875 in) 

Distance Between 

Upper and Lower 

Sensor

56.52 cm (22.25 in) 

Distance From Upper 

Sensor on Upper 

and Lower Housing

Figure 22. Upper enclosure with instrumentation—sensors 6.35 cm (2.5 in) below cooling coils.

The transition to ZBO conditions is illustrated in figure 23, in which the measured boiloff rate versus time at the 95% fill level is presented. The boiloff rate peaked shortly after tanking. Then, the transition to steady-state temperature profiles within the MLI was expedited 

by injecting a small amount of He into the chamber. This technique accelerated the transition to stable boiloff conditions by several days. Steady-state boiloff began at ≈150,000 s, and 

≈100,000 s (28 hr) later, the cryocooler was turned on and the transition to ZBO began and was 

achieved within ≈30,000 s (8.3 hr). The corresponding ullage pressure versus time data presented 

in figure 24 demonstrate the transition from constant pressure (steady-state boiloff) at 117.3 kPa 

to a gradual drop in pressure when ZBO conditions began at ≈230,000 s, and to a constant 

114.8 kPa after the heater control algorithm was activated at 670,000 s. The ACS thereafter maintained the ullage pressure within ±0.003 kPa for over 50 hr and could have continued indefinitely. 

The total ZBO period was over 156 hr at the 95% fill level.

The automated interaction between the ullage pressure and heater input is illustrated in figure 25 for the 50% fill level. The cooler was initially operated without heater input; the ullage pressure 

therefore decreased at the beginning. As the pressure dropped below the pressure control point of 

114.8 kPa at 20,000 s, the heater was activated; then, when the pressure increased to the set point, the 

heater was deactivated. The ACS then locked on the set point and thereafter controlled the ullage 

pressure to within ±0.003 kPa for the remaining 89 hr of testing. The total ZBO period was ≈114 hr 

at the 50% fill level. Short-duration testing conducted at the 25% fill level indicated similar trends. 

The test durations were considered sufficient to demonstrate that the ZBO condition could have been 

sustained for the operating life of the cryocooler and mixer pump.
27

Tank Loading

He Injection

Cryocooler and Mixer On

Boiloff Approaches Zero

Time (s)

SLPM

400

300

200

100

0

–100

0 200,000 400,000 600,000 800,000 1,000,000

Figure 23. Boiloff flow rate transition to ZBO at 95% fill level.

Set Back-Pressure Control System to Maintain 117.3 kPa

Cryocooler Achieved ZBO LH2 Heater Control 

Algorithm Activated

Time (s)

Pressure (kPa)

120

116

112

108

104

100

96

0 200,000 400,000 600,000 800,000 1,000,000

Figure 24. Ullage pressure transition at 95% fill level.
28

Ullage Pressure

Heater Input

Time (s)

Heater Input (W)

Pressure (kPa)

16

12

8

4

0

–4

116

115.5

115

114.5

114

0 50,000 100,000 150,000 200,000 250,000 300,000 350,000

Figure 25. Ullage pressure at 50% fill level.
29

5. ANALYTICAL CORRELATIONS

	 A transient, one-dimensional analytical model was formulated by modifying an existing thermodynamic vent system (TVS) computer program to characterize integrated performance of the spray

bar recirculation, cryocooler, and heaters within the MHTB. The integrated system performance formulation comprises three combined thermal/fluid models, including the spray manifold and injector tubes, the recirculation pump, and the tank. The spray manifold and injection tube model 

determines the pressure drops within the manifold and tubes along with the spray flow rates and 

velocities leaving the injection orifices. The recirculation pump model calculates the pump head 

increase from the pump speed and the head coefficient curve provided by the pump manufacturer. The tank model is a lumped model consisting of three control volumes—the ullage, the tank 

wall, and the bulk liquid. A more detailed description of the TVS analytical model, developed by 

H. Nguyen, Rockwell Aerospace, is presented in reference 7.

With the continuous spray bar and cooler operation, the thermal energy input and energy 

extraction rates could be balanced, and the ullage and liquid were homogenous or destratified. 

Therefore, the single-node analytical representations of the ullage and liquid proved to be accurate. 

Analytical modeling correlations for test periods with ACS set point pressure control are presented 

in figures 26 and 27 for the 95% and 50% fill levels, respectively. The analytically modeled ullage pressures correlated almost perfectly with the measured data. 
30

Test

Model

Time (s)

Pressure (kPa)

120

116

112

108

104

100

480,000 500,000 520,000 540,000 560,000 580,000 600,000

Figure 26. Ullage correlations at 95% fill level.

Test

Model

Time (s)

Pressure (kPa)

120

116

112

108

104

100

0 50,000 100,000 150,000 200,000 250,000 300,000 350,000

Figure 27. Ullage correlations at 50% fill level.
31

6. CONCLUSIONS AND RECOMMENDATIONS

ZBO involves using a cryocooler/radiator system to intercept and reject cryogenic storage 

system heat leak such that boiloff and the necessity for venting are precluded. A cooperative effort 

by ARC, GRC, and MSFC was implemented to develop and demonstrate ZBO hardware and concepts for in-space storage of cryogenic propellants. The MHTB, a large-scale LH2 test article, was 

modified at MSFC for the integrated operation of a commercial cooler with passive insulation, 

a propellant recirculation subsystem, and pressure control subsystems. The cooler was a Cryomech 

GB37 unit with a rated cooling capacity of 30 W at 20 K. Because the cooler thermal extraction 

rate could not be directly controlled, the test procedure strategy was to first establish a heat leak 

below the thermal extraction capability of the cooler. Then an automated control algorithm was 

used to adjust an internal heater, based on the measured tank pressure to achieve steady-state 

pressure conditions; i.e., the incoming and extracted thermal energy were continually balanced.

Both intermittent and continuous pump operations at various flow rates were tested to evaluate impacts on pressure control and cryocooler performance. However, the intermittent pump operations compromised the cryocooler heat extraction process because the colder liquid that accumulated 

between operations reduced the cooler efficiency, did not benefit destratification and ullage pressure 

control, and added operational complexity. Because the pump was designed for operation at 114 L/

min, the pump efficiency began to rapidly degrade below 38 L/min and an increased percentage of 

the power input was thermally transferred to the fluid. Ultimately, it was concluded that continuous 

pump operation at ≈38 L/min was optimal for the MHTB ZBO hardware arrangement.

The MHTB/cryocooler arrangement successfully demonstrated that hydrogen can be stored 

within a large-scale vessel without boiloff losses and with tight pressure control limits. A substantial advancement was achieved with the successful integration of a thermal/fluid analytical model 

into an ACS algorithm. Measured thermal and thermodynamic parameters were used in real time 

to quantify the various heat leak sources, anchor analytical modeling, and perform troubleshooting. The control algorithm maintained the ullage pressure within ±0.003 kPa. The test durations 

at 90% and 50% fill levels (156 and 114 hr, respectively) were sufficient to demonstrate that the 

ZBO condition could have been sustained for the operating life of the cryocooler and mixer pump. 

Limited testing at a 25% fill level indicated similar trends. Also, excellent correlation of measured 

ullage pressures was achieved with a simplified analytical model. In conclusion, cryogenic storage 

technology in space entered a new era wherein hydrogen and other cryogens can eventually be stored 

in space on the order of years as opposed to a few weeks or months. 
32

APPENDIX A—MULTIPURPOSE HYDROGEN TEST BED TANKING

The liquid hydrogen fill height versus fill volume, ullage and liquid percent, and liquid mass 

for the MHTB tank is presented in table 6.

Table 6. MHTB tanking.

Height* Volume** Ullage

(%)

Liquid

(%)

Liquid Mass

(in) (cm) (ft3) (m3) (lbm) (kg)

0.00 0.00 0.00 0.0000 100.00 0.00 0.00 0.0000

0.50 1.27 0.05 0.0015 99.99 0.01 0.24 0.1087

1.00 2.54 0.22 0.0061 99.97 0.03 0.95 0.4324

1.50 3.81 0.48 0.0137 99.92 0.08 2.13 0.9673

2.00 5.08 0.85 0.0242 99.87 0.13 3.77 1.7098

2.50 6.35 1.33 0.0375 99.79 0.21 5.86 2.6560

3.00 7.62 1.90 0.0537 99.70 0.30 8.38 3.8025

3.50 8.89 2.57 0.0727 99.60 0.40 11.34 5.1453

4.00 10.16 3.33 0.0944 99.48 0.52 14.73 6.6809

4.50 11.43 4.19 0.1187 99.34 0.66 18.53 8.4055

5.00 12.70 5.15 0.1457 99.20 0.80 22.74 10.3154

5.50 13.97 6.19 0.1753 99.03 0.97 27.35 12.4068

6.00 15.24 7.32 0.2073 98.85 1.15 32.36 14.6762

6.50 16.51 8.54 0.2419 98.66 1.34 37.74 17.1198

7.00 17.78 9.85 0.2788 98.46 1.54 43.51 19.7338

7.50 19.05 11.23 0.3181 98.24 1.76 49.64 22.5146

8.00 20.32 12.70 0.3597 98.01 1.99 56.13 25.4585

8.50 21.59 14.25 0.4035 97.77 2.23 62.97 28.5618

9.00 22.86 15.88 0.4495 97.52 2.48 70.15 31.8207

9.50 24.13 17.58 0.4977 97.25 2.75 77.67 35.2316

10.00 25.40 19.35 0.5480 96.97 3.03 85.52 38.7907

10.50 26.67 21.20 0.6003 96.68 3.32 93.68 42.4943

11.00 27.94 23.12 0.6546 96.38 3.62 102.16 46.3388

11.50 29.21 25.10 0.7109 96.07 3.93 110.94 50.3204

12.00 30.48 27.16 0.7690 95.75 4.25 120.01 54.4354

12.50 31.75 29.28 0.8290 95.42 4.58 129.37 58.6801

13.00 33.02 31.46 0.8907 95.08 4.92 139.00 63.0509

13.50 34.29 33.70 0.9542 94.73 5.27 148.91 67.5439

14.00 35.56 36.00 1.0193 94.37 5.63 159.08 72.1556

14.50 36.83 38.36 1.0861 94.00 6.00 169.50 76.8821

15.00 38.10 40.77 1.1545 93.62 6.38 180.16 81.7198
33

Height* Volume** Ullage

(%)

Liquid

(%)

Liquid Mass

(in) (cm) (ft3) (m3) (lbm) (kg)

15.50 39.37 43.24 1.2243 93.24 6.76 191.06 86.6650

16.00 40.64 45.76 1.2957 92.84 7.16 202.19 91.7140

16.50 41.91 48.32 1.3684 92.44 7.56 213.55 96.8630

17.00 43.18 50.94 1.4425 92.03 7.97 225.11 102.1084

17.50 44.45 53.60 1.5179 91.62 8.38 236.88 107.4464

18.00 45.72 56.31 1.5946 91.19 8.81 248.84 112.8734

18.50 46.99 59.06 1.6724 90.76 9.24 261.00 118.3856

19.00 48.26 61.85 1.7515 90.33 9.67 273.33 123.9794

19.50 49.53 64.68 1.8316 89.88 10.12 285.83 129.6510

20.00 50.80 67.55 1.9128 89.43 10.57 298.50 135.3967

20.50 52.07 70.45 1.9949 88.98 11.02 311.32 141.2128

21.00 53.34 73.39 2.0780 88.52 11.48 324.29 147.0957

21.50 54.61 76.35 2.1620 88.06 11.94 337.40 153.0415

22.00 55.88 79.35 2.2469 87.59 12.41 350.64 159.0467

22.50 57.15 82.37 2.3325 87.12 12.88 364.00 165.1074

23.00 58.42 85.42 2.4188 86.64 13.36 377.48 171.2200

23.50 59.69 88.49 2.5059 86.16 13.84 391.06 177.3808

24.00 60.96 91.59 2.5935 85.67 14.33 404.74 183.5861

24.50 62.23 94.71 2.6818 85.19 14.81 418.51 189.8321

25.00 63.50 97.84 2.7705 84.70 15.30 432.36 196.1152

25.50 64.77 100.99 2.8598 84.20 15.80 446.29 202.4317

26.00 66.04 104.16 2.9494 83.71 16.29 460.28 208.7778

26.50 67.31 107.34 3.0394 83.21 16.79 474.32 215.1498

27.00 68.58 110.53 3.1298 82.71 17.29 488.42 221.5441

27.50 69.85 113.73 3.2204 82.21 17.79 502.56 227.9569

28.00 71.12 116.93 3.3112 81.71 18.29 516.73 234.3845

28.50 72.39 120.15 3.4021 81.21 18.79 530.92 240.8233

29.00 73.66 123.36 3.4932 80.70 19.30 545.14 247.2695

29.50 74.93 126.58 3.5843 80.20 19.80 559.36 253.7193

30.00 76.20 129.80 3.6755 79.70 20.30 573.58 260.1718

30.50 77.47 133.02 3.7666 79.19 20.81 587.80 266.6225

31.00 78.74 136.23 3.8577 78.69 21.31 602.02 273.0731

31.50 80.01 139.45 3.9489 78.19 21.81 616.24 279.5237

32.00 81.28 142.67 4.0400 77.68 22.32 630.47 285.9743

32.50 82.55 145.89 4.1311 77.18 22.82 644.69 292.4250

33.00 83.82 149.11 4.2222 76.68 23.32 658.91 298.8756

33.50 85.09 152.33 4.3134 76.17 23.83 673.13 305.3262

34.00 86.36 155.54 4.4045 75.67 24.33 687.35 311.7768

34.50 87.63 158.76 4.4956 75.17 24.83 701.57 318.2275

35.00 88.90 161.98 4.5868 74.66 25.34 715.79 324.6781

Table 6. MHTB tanking (Continued).
34

Height* Volume** Ullage

(%)

Liquid

(%)

Liquid Mass

(in) (cm) (ft3) (m3) (lbm) (kg)

35.50 90.17 165.20 4.6779 74.16 25.84 730.01 331.1287

36.00 91.44 168.42 4.7690 73.66 26.34 744.24 337.5793

36.50 92.71 171.63 4.8601 73.15 26.85 758.46 344.0300

37.00 93.98 174.85 4.9513 72.65 27.35 772.68 350.4806

37.50 95.25 178.07 5.0424 72.15 27.85 786.90 356.9312

38.00 96.52 181.29 5.1335 71.64 28.36 801.12 363.3818

38.50 97.79 184.51 5.2247 71.14 28.86 815.34 369.8325

39.00 99.06 187.73 5.3158 70.64 29.36 829.56 376.2831

39.50 100.33 190.94 5.4069 70.13 29.87 843.78 382.7337

40.00 101.60 194.16 5.4980 69.63 30.37 858.00 389.1843

40.50 102.87 197.38 5.5892 69.13 30.87 872.23 395.6350

41.00 104.14 200.60 5.6803 68.62 31.38 886.45 402.0856

41.50 105.41 203.82 5.7714 68.12 31.88 900.67 408.5362

42.00 106.68 207.03 5.8626 67.62 32.38 914.89 414.9868

42.50 107.95 210.25 5.9537 67.11 32.89 929.11 421.4375

43.00 109.22 213.47 6.0448 66.61 33.39 943.33 427.8881

43.50 110.49 216.69 6.1359 66.11 33.89 957.55 434.3387

44.00 111.76 219.91 6.2271 65.60 34.40 971.77 440.7893

44.50 113.03 223.13 6.3182 65.10 34.90 986.00 447.2400

45.00 114.30 226.34 6.4093 64.60 35.40 1,000.22 453.6906

45.50 115.57 229.56 6.5005 64.09 35.91 1,014.44 460.1412

46.00 116.84 232.78 6.5916 63.59 36.41 1,028.66 466.5918

46.50 118.11 236.00 6.6827 63.09 36.91 1,042.88 473.0425

47.00 119.38 239.22 6.7738 62.58 37.42 1,057.10 479.4931

47.50 120.65 242.43 6.8650 62.08 37.92 1,071.32 485.9437

48.00 121.92 245.65 6.9561 61.58 38.42 1,085.54 492.3943

48.50 123.19 248.87 7.0472 61.07 38.93 1,099.76 498.8450

49.00 124.46 252.09 7.1384 60.57 39.43 1,113.99 505.2956

49.50 125.73 255.31 7.2295 60.07 39.93 1,128.21 511.7462

50.00 127.00 258.53 7.3206 59.56 40.44 1,142.43 518.1968

50.50 128.27 261.74 7.4117 59.06 40.94 1,156.65 524.6475

51.00 129.54 264.96 7.5029 58.56 41.44 1,170.87 531.0981

51.50 130.81 268.18 7.5940 58.05 41.95 1,185.09 537.5487

52.00 132.08 271.40 7.6851 57.55 42.45 1,199.31 543.9993

52.50 133.35 274.62 7.7763 57.05 42.95 1,213.53 550.4500

53.00 134.62 277.83 7.8674 56.54 43.46 1,227.76 556.9006

53.50 135.89 281.05 7.9585 56.04 43.96 1,241.98 563.3512

54.00 137.16 284.27 8.0496 55.54 44.46 1,256.20 569.8018

54.50 138.43 287.49 8.1408 55.03 44.97 1,270.42 576.2525

55.00 139.70 290.71 8.2319 54.53 45.47 1,284.64 582.7031

55.50 140.97 293.93 8.3230 54.03 45.97 1,298.86 589.1537

Table 6. MHTB tanking (Continued).
35

Height* Volume** Ullage

(%)

Liquid

(%)

Liquid Mass

(in) (cm) (ft3) (m3) (lbm) (kg)

56.00 142.24 297.14 8.4142 53.52 46.48 1,313.08 595.6043

56.50 143.51 300.36 8.5053 53.02 46.98 1,327.30 602.0550

57.00 144.78 303.58 8.5964 52.52 47.48 1,341.53 608.5056

57.50 146.05 306.80 8.6875 52.01 47.99 1,355.75 614.9562

58.00 147.32 310.02 8.7787 51.51 48.49 1,369.97 621.4068

58.50 148.59 313.23 8.8698 51.01 48.99 1,384.19 627.8575

59.00 149.86 316.45 8.9609 50.50 49.50 1,398.41 634.3081

59.50 151.13 319.67 9.0521 50.00 50.00 1,412.63 640.7587

60.00 152.40 322.89 9.1432 49.50 50.50 1,426.85 647.2093

60.50 153.67 326.11 9.2343 48.99 51.01 1,441.07 653.6600

61.00 154.94 329.33 9.3254 48.49 51.51 1,455.29 660.1106

61.50 156.21 332.54 9.4166 47.99 52.01 1,469.52 666.5612

62.00 157.48 335.76 9.5077 47.48 52.52 1,483.74 673.0118

62.50 158.75 338.98 9.5988 46.98 53.02 1,497.96 679.4625

63.00 160.02 342.20 9.6900 46.48 53.52 1,512.18 685.9131

63.50 161.29 345.42 9.7811 45.97 54.03 1,526.40 692.3637

64.00 162.56 348.63 9.8722 45.47 54.53 1,540.62 698.8143

64.50 163.83 351.85 9.9633 44.97 55.03 1,554.84 705.2650

65.00 165.10 355.07 10.0545 44.46 55.54 1,569.06 711.7156

65.50 166.37 358.29 10.1456 43.96 56.04 1,583.29 718.1662

66.00 167.64 361.51 10.2367 43.46 56.54 1,597.51 724.6168

66.50 168.91 364.73 10.3278 42.95 57.05 1,611.73 731.0675

67.00 170.18 367.94 10.4190 42.45 57.55 1,625.95 737.5181

67.50 171.45 371.16 10.5101 41.95 58.05 1,640.17 743.9687

68.00 172.72 374.38 10.6012 41.44 58.56 1,654.39 750.4193

68.50 173.99 377.60 10.6924 40.94 59.06 1,668.61 756.8700

69.00 175.26 380.82 10.7835 40.44 59.56 1,682.83 763.3206

69.50 176.53 384.03 10.8746 39.93 60.07 1,697.06 769.7712

70.00 177.80 387.25 10.9657 39.43 60.57 1,711.28 776.2218

70.50 179.07 390.47 11.0569 38.93 61.07 1,725.50 782.6725

71.00 180.34 393.69 11.1480 38.42 61.58 1,739.72 789.1231

71.50 181.61 396.91 11.2391 37.92 62.08 1,753.94 795.5737

72.00 182.88 400.13 11.3303 37.42 62.58 1,768.16 802.0243

72.50 184.15 403.34 11.4214 36.91 63.09 1,782.38 808.4750

73.00 185.42 406.56 11.5125 36.41 63.59 1,796.60 814.9256

73.50 186.69 409.78 11.6036 35.91 64.09 1,810.82 821.3762

74.00 187.96 413.00 11.6948 35.40 64.60 1,825.05 827.8268

74.50 189.23 416.22 11.7859 34.90 65.10 1,839.27 834.2775

75.00 190.50 419.43 11.8770 34.40 65.60 1,853.49 840.7281

75.50 191.77 422.65 11.9682 33.89 66.11 1,867.71 847.1787

76.00 193.04 425.87 12.0593 33.39 66.61 1,881.93 853.6293

Table 6. MHTB tanking (Continued).
36

Height* Volume** Ullage

(%)

Liquid

(%)

Liquid Mass

(in) (cm) (ft3) (m3) (lbm) (kg)

76.50 194.31 429.09 12.1504 32.89 67.11 1,896.15 860.0800

77.00 195.58 432.31 12.2415 32.38 67.62 1,910.37 866.5306

77.50 196.85 435.53 12.3327 31.88 68.12 1,924.59 872.9812

78.00 198.12 438.74 12.4238 31.38 68.62 1,938.82 879.4318

78.50 199.39 441.96 12.5149 30.87 69.13 1,953.04 885.8824

79.00 200.66 445.18 12.6061 30.37 69.63 1,967.26 892.3331

79.50 201.93 448.40 12.6972 29.87 70.13 1,981.48 898.7837

80.00 203.20 451.62 12.7883 29.36 70.64 1,995.70 905.2343

80.50 204.47 454.83 12.8794 28.86 71.14 2,009.92 911.6849

81.00 205.74 458.05 12.9706 28.36 71.64 2,024.14 918.1356

81.50 207.01 461.27 13.0617 27.85 72.15 2,038.36 924.5862

82.00 208.28 464.49 13.1528 27.35 72.65 2,052.58 931.0368

82.50 209.55 467.71 13.2440 26.85 73.15 2,066.81 937.4874

83.00 210.82 470.93 13.3351 26.34 73.66 2,081.03 943.9381

83.50 212.09 474.14 13.4262 25.84 74.16 2,095.25 950.3887

84.00 213.36 477.36 13.5173 25.34 74.66 2,109.47 956.8393

84.50 214.63 480.58 13.6085 24.83 75.17 2,123.69 963.2899

85.00 215.90 483.80 13.6996 24.33 75.67 2,137.91 969.7406

85.50 217.17 487.02 13.7907 23.83 76.17 2,152.13 976.1912

86.00 218.44 490.23 13.8819 23.32 76.68 2,166.35 982.6418

86.50 219.71 493.45 13.9730 22.82 77.18 2,180.58 989.0924

87.00 220.98 496.67 14.0641 22.32 77.68 2,194.80 995.5431

87.50 222.25 499.89 14.1552 21.81 78.19 2,209.02 1,001.9937

88.00 223.52 503.11 14.2464 21.31 78.69 2,223.24 1,008.4443

88.50 224.79 506.33 14.3375 20.80 79.20 2,237.46 1,014.8949

89.00 226.06 509.54 14.4286 20.30 79.70 2,251.68 1,021.3456

89.50 227.33 512.76 14.5198 19.80 80.20 2,265.90 1,027.7962

90.00 228.60 515.98 14.6108 19.30 80.70 2,280.12 1,034.2433

90.50 229.87 519.19 14.7019 18.79 81.21 2,294.33 1,040.6895

91.00 231.14 522.41 14.7929 18.29 81.71 2,308.52 1,047.1282

91.50 232.41 525.61 14.8837 17.79 82.21 2,322.69 1,053.5559

92.00 233.68 528.81 14.9743 17.29 82.71 2,336.83 1,059.9687

92.50 234.95 532.00 15.0646 16.79 83.21 2,350.93 1,066.3630

93.00 236.22 535.18 15.1546 16.29 83.71 2,364.98 1,072.7350

93.50 237.49 538.35 15.2443 15.80 84.20 2,378.97 1,079.0811

94.00 238.76 541.50 15.3335 15.30 84.70 2,392.89 1,085.3976

94.50 240.03 544.63 15.4223 14.81 85.19 2,406.74 1,091.6807

95.00 241.30 547.75 15.5105 14.33 85.67 2,420.51 1,097.9267

95.50 242.57 550.84 15.5982 13.84 86.16 2,434.19 1,104.1320

96.00 243.84 553.92 15.6852 13.36 86.64 2,447.78 1,110.2928

96.50 245.11 556.97 15.7716 12.88 87.12 2,461.25 1,116.4054

Table 6. MHTB tanking (Continued).
37

Height* Volume** Ullage

(%)

Liquid

(%)

Liquid Mass

(in) (cm) (ft3) (m3) (lbm) (kg)

97.00 246.38 559.99 15.8572 12.41 87.59 2,474.61 1,122.4661

97.50 247.65 562.99 15.9420 11.94 88.06 2,487.85 1,128.4713

98.00 248.92 565.95 16.0260 11.48 88.52 2,500.96 1,134.4171

98.50 250.19 568.89 16.1091 11.02 88.98 2,513.93 1,140.3000

99.00 251.46 571.79 16.1913 10.57 89.43 2,526.75 1,146.1161

99.50 252.73 574.66 16.2724 10.12 89.88 2,539.42 1,151.8618

100.00 254.00 577.49 16.3526 9.67 90.33 2,551.92 1,157.5334

100.50 255.27 580.28 16.4316 9.24 90.76 2,564.26 1,163.1272

101.00 256.54 583.03 16.5095 8.81 91.19 2,576.41 1,168.6394

101.50 257.81 585.73 16.5861 8.38 91.62 2,588.37 1,174.0664

102.00 259.08 588.40 16.6615 7.97 92.03 2,600.14 1,179.4044

102.50 260.35 591.01 16.7356 7.56 92.44 2,611.71 1,184.6498

103.00 261.62 593.58 16.8084 7.16 92.84 2,623.06 1,189.7988

103.50 262.89 596.10 16.8797 6.76 93.24 2,634.19 1,194.8478

104.00 264.16 598.57 16.9496 6.38 93.62 2,645.09 1,199.7930

104.50 265.43 600.98 17.0179 6.00 94.00 2,655.76 1,204.6307

105.00 266.70 603.34 17.0847 5.63 94.37 2,666.18 1,209.3572

105.50 267.97 605.64 17.1498 5.27 94.73 2,676.34 1,213.9689

106.00 269.24 607.88 17.2133 4.92 95.08 2,686.25 1,218.4619

106.50 270.51 610.06 17.2751 4.58 95.42 2,695.88 1,222.8327

107.00 271.78 612.18 17.3350 4.25 95.75 2,705.24 1,227.0774

107.50 273.05 614.23 17.3932 3.93 96.07 2,714.31 1,231.1924

108.00 274.32 616.22 17.4494 3.62 96.38 2,723.09 1,235.1740

108.50 275.59 618.14 17.5037 3.32 96.68 2,731.57 1,239.0185

109.00 276.86 619.99 17.5560 3.03 96.97 2,739.73 1,242.7221

109.50 278.13 621.76 17.6063 2.75 97.25 2,747.58 1,246.2812

110.00 279.40 623.46 17.6545 2.48 97.52 2,755.10 1,249.6921

110.50 280.67 625.09 17.7005 2.23 97.77 2,762.28 1,252.9510

111.00 281.94 626.64 17.7444 1.99 98.01 2,769.13 1,256.0543

111.50 283.21 628.11 17.7860 1.76 98.24 2,775.62 1,258.9981

112.00 284.48 629.49 17.8253 1.54 98.46 2,781.75 1,261.7790

112.50 285.75 630.80 17.8622 1.34 98.66 2,787.51 1,264.3930

113.00 287.02 632.02 17.8967 1.15 98.85 2,792.90 1,266.8366

113.50 288.29 633.15 17.9288 0.97 99.03 2,797.90 1,269.1060

114.00 289.56 634.19 17.9583 0.80 99.20 2,802.51 1,271.1974

114.50 290.83 635.15 17.9853 0.66 99.34 2,806.72 1,273.1073

115.00 292.10 636.01 18.0097 0.52 99.48 2,810.52 1,274.8319

115.50 293.37 636.77 18.0313 0.40 99.60 2,813.91 1,276.3675

116.00 294.64 637.44 18.0503 0.30 99.70 2,816.87 1,277.7103

116.50 295.91 638.01 18.0665 0.21 99.79 2,819.40 1,278.8567

117.00 297.18 638.49 18.0799 0.13 99.87 2,821.48 1,279.8030

Table 6. MHTB tanking (Continued).
38

Height* Volume** Ullage

(%)

Liquid

(%)

Liquid Mass

(in) (cm) (ft3) (m3) (lbm) (kg)

117.50 298.45 638.86 18.0904 0.08 99.92 2,823.12 1,280.5455

118.00 299.72 639.12 18.0979 0.03 99.97 2,824.30 1,281.0804

118.50 300.99 639.28 18.1025 0.01 99.99 2,825.01 1,281.4041

119.00 302.26 639.34 18.1040 0.00 100.00 2,825.25 1,281.5128

 *Height is measured from the bottom of the tank.

**Total Tank Volume: 18.10 m3 (639.34 ft3).

***LH2 Density: 70.786 kg/m3 (4.419 lbm/ft3).

Table 6. MHTB tanking (Continued).
39

APPENDIX B—INTEGRATION OF THE CRYOMECH GB37 CRYO-REFRIGERATOR 

INTO THE MULTIPURPOSE HYDROGEN TEST

BED THERMODYNAMIC VENT SYSTEM

Prepared by 

E. Johnson/TD71

Revised 02/27/01

General Notes:

(1) Cryo-refrigerator specs:

 Cryomech model GB37 w/CP25 compressor (Cryo-Refrigerator S/N GB37-500047)

 Refrigerator capacity of 25 W @ 20 K.

(2) Reference GRC drawing 58444M70A000 for cryo-refrigerator assembly and integration 

into the existing MHTB TVS plumbing.

(3) This procedure will be performed after installation of the HX spool piece (tee) drawing 

reference number A009.

(4) Exercise caution with delicate instrumentation wiring at all times during installation and 

especially when handling the HX which is heavily instrumented.

(5) During installation of fasteners, cross-torque patterns will be repeated until no movement 

is observed.

(6) MHTB instrumentation PTC27 and PTC28 to be replaced prior to installing cryorefrigerator housing.

(7) Cleanliness: 

 – Clean all surfaces prior to installation with 190 proof alcohol or other engineering 

approved solvent only. Use lint-free cloth to wipe surfaces.

 – Use lint-free gloves at all times when handling hardware.

Installation Procedure:

(1) Insulate MHTB tank bottom (within TVS enclosure) and TVS plumbing as directed by 

engineering. 
40

 (2) Install diode probes (GD1 and GD2) into spool piece A009 and tighten as follows: 

Verify that the probe end is at the centerline of the flow stream. Initially hand tighten Swagelok nuts. 

Scribe the nuts at the 6:00 position. Tighten the nuts 11/4 turn while holding the fitting body steady. 

The scribe mark on the nut will be in the 9:00 position when tight. (Verify the upstream and downstream diode are labeled and traceable back to the individual calibration curves for each diode.)

 (3) Instrumentation engineer verify that the HX instrumentation is installed and checkout 

is complete.

 (4) Use lint-free gloves to clean all residue from the HX using alcohol as required. Take 

extra precaution not to damage delicate wiring on HX.

 (5) Using Loctite primer and threadlock on the Conflat bolts, install HX (A010) onto spool 

piece (A009). Verify that the HX fins are installed such that the LH2 will flow through the fins and the 

threaded plugs are on the downstream end of the fins. Torque bolts to 144 in-lb using cross-torque 

pattern. (Note: Temporarily secure instrumentation wiring as required to prevent damage during 

mechanical installation.)

Note: An ambient leak check will be performed on the MHTB at this time to verify the integrity of 

all sealing surfaces including the TVS connections. Cryo-refrigerator installation will continue after 

this initial leak check is completed. Proceed to next step only after ambient leak check is completed.

 (6) Verify PTC28 and PTC27 have been replaced (upstream and downstream of the MHTB 

LH2 pump, respectively).

 (7) Install TVS component box A001 onto the MHTB using 0.0625-in-diameter indium 

wire. Verify orientation of A001 in accordance with drawing 58444M70A000. Torque housing bolts 

to 144 in-lb using cross-torque pattern.

 (8) Route instrumentation from HX through 8-in flange on TVS housing A001. (Note: 

Instrumentation wiring will be connected to flange feedthrough connectors at a later date.)

 (9) Verify thermocouples HTC25 and HTC26 are installed onto cryo-refrigerator motor per 

drawing 58444170S000.

(10) Using lint-free gloves, clean all cryo-refrigerator surfaces with alcohol, paying special 

attention to the first- and second-stage surfaces.

Caution: Take precautions to prevent moving the cryo-refrigerator once bolted to the HX in the following step. Movement could overstress the bolted joint.

(10A) Verify spring retainer collar (A005) is properly bolted to the cryo-refrigerator. Verify 

that bolts are tight. (Note: Cryo-refrigerator arrived from GRC with spring retainer collar attached.)

(11) Install cryo-refrigerator (A006) onto HX (A010) using indium foil between the two mating surfaces. Support the cryo-refrigerator weight during and after installation to reduce stress on 
41

bolted joint. Torque 0.635-cm (0.250-in) bolts to 140 in-lb and 0.164-in bolts to 5 in-lb using crosstorque pattern. (Note: Verify clocking of the cryo-refrigerator onto the HX before bolting to confirm 

that He supply and return lines are oriented correctly relative to the He line interface flange A008.)

(11A) Install temporary cryo-refrigerator support as directed by engineering to prevent lateral movement of cryo-refrigerator.

(12) Using lint-free gloves, insulate cryo-refrigerator as directed by engineering. (Reference 

insulation sketch provided by D. Plachta dated 02/12/01.)

(13) Install the three instrumented Cu HX straps per drawing 58444M70A000 using indium 

foil between the mating surfaces. Insulate over the Cu straps as directed by engineering. (Note: 

Indium foil is the preference but conductive grease supplied by GRC may be substituted if an adequate quantity of indium foil is not available.)

(14) Install two heater strips onto the cryo-refrigerator motor as indicated by drawing 

58444170S000. (Note: Verify the location of the seals within the cryo-refrigerator motor with the 

Cryomech manual to ensure that the heater strips are properly located.) Route thermocouple wiring, 

heater wiring, and the motor power cable to 8-in outlet flange through the gap in the spring retainer 

collar (A005) bearing in mind that the spring (A007) will be installed directly over the wiring. Place 

a tight layer of aluminized mylar directly over the heater strips and secure with mylar tape. Further 

insulate cryo-refrigerator motor as directed by engineering.

(15) Verify that MHTB LH2 pump and flowmeter wiring is routed to 20.36-cm (8-in) flange 

as required. (Note: Wiring to be connected to flange feedthrough connector at a later date.)

(16) Instrumentation perform final verification that all wiring is routed to outlet flange as 

required. Instrumentation wiring will be difficult to access once cryo-refrigerator cover A002 is 

installed.

(17) Remove temporary supports from the cryo-refrigerator and install the cryo-refrigerator cover (A002) onto the component box (A001), ensuring that the dowel pin aligns between the 

two mating surfaces. Use 0.159-cm (0.0625-in-) diameter indium wire gasket material. Torque cryorefrigerator cover bolts to 500 in-lb using a cross-torque pattern. Provide additional temporary support of the cryo-refrigerator after the cover (A002) is installed and prior to connecting the He lines 

in the following step. 

(18A) (Note: Helium supply and return line tubing which connects to refrigerator is precharged with 1,378 kPa (200 psi) He.) Check alignment of He supply and return lines (A14) from the 

refrigerator to the He interface flange (A008) by initially engaging only enough threads to hold lines 

in place on refrigerator. Place He line interface flange into position on housing cover (A002) to verify 

alignment of tubing connections. Reference drawing 58444M70A000 to verify proper installation.

(18B) After initial alignment is completed, install the He supply and return lines (A14) onto 

the cryo-refrigerator. Verify proper installation and alignment prior to tightening connections. Take 

precaution not to apply torque to cryo-refrigerator housing while tightening connections.
42

(19) (Note: The 1.9-cm (0.75-in) tubing with Aeroquip fittings is precharged with 1,378 kPa 

(200 psi) He. Proper alignment of the Aeroquip fittings before tightening is critical. Set the housing 

flange (A008) containing 3/4-in tubing near the mating flange on the housing and adjust length of 

3/4-in tubing as required to interface with the 3/4-in Aeroquip fittings inside the housing. Tighten 

Aeroquip fittings first to ensure proper alignment and then install bolts for flange A008. Torque 

Aeroquip connection to 46 ft-lb and torque A008 flange bolts to 312 in-lb using cross-torque pattern. 

Caution: If tubing connections within the housing do not align, do not bend tubing while attached 

to cryo-refrigerator as overstress of upper bolted joint may occur. 

(20) Verify that all insulation is installed per engineering direction. Clean all accessible surfaces with alcohol and lint-free cloth.

(21) Temporarily install TVS housing flange (A003) and spring (A007) to the TVS housing 

as shown in drawing 58444M70A000. (Note: Do not use indium wire at this time as cover will be 

removed after LH2 coldshock.)

Note: An LN2 and LH2 coldshock of the MHTB will be performed to verify the integrity of the 

connections when thermally cycled. The cryo-refrigerator will not be operated during this coldshock. 

Proceed to next step only after LH2 coldshock is successfully completed.

(22) After coldshock and leak check are completed, carefully remove housing cover (A003) 

and spring (A007). Install temporary transportation support per engineering direction.

(23) Verify MHTB and cryo-refrigerator hardware are properly secured for removal from the 

test cell and transportation to TS300.

Note: The following steps to be performed after MHTB has been relocated to TS300:

(24) Remove temporary shipping support from the cryo-refrigerator. Install the housing 

cover (A003) and spring (A007) using 0.159-cm (0.0625-in) indium wire gasket. Torque flange bolts 

to 500 in-lb using cross-torque pattern.

(25) When feedthrough connectors for instrumentation and controls are installed in TVS 

housing flanges, make final connections at the connectors. Perform checkouts as required to ensure 

that connections to feedthrough pins match instrumentation/controls drawings.

(26) Verify Conax flange feedthrough connector on flange A008 is tight. Perform seal weld of 

Conax fittings as directed by engineering.
43

APPENDIX C—LIQUID HYDROGEN HEATER ELEMENT TESTING 

FOR MULTIPURPOSE HYDROGEN TEST BED 

ZERO-BOILOFF DEMONSTRATION

C.1 Background

These graphite heater elements were installed in the MHTB LH2 tank to assist in maintaining 

the total heat load at a constant value. The test objectives were to (1) demonstrate that the heater elements would survive and operate effectively in LH2 and (2) calibrate the electrical resistance of the 

three heater assembly elements before and during LH2 exposure. 

C.2 Test Setup

This test was performed in the LH2 cryostat located in test cell 15 of Building 4628. The 

three heater elements were installed in fixturing to hold them in place inside the cryostat (fig. 19). Six 

strands of 14-gauge, solid Cu wire with Kapton insulation were passed through a sealed port in the 

lid of the cryostat. The solid Cu wire was attached to the connecting wires on the furnace elements 

using screw-type connectors. Stranded 14-gauge Cu wire was attached to the solid Cu wires passing 

through the lid of the cryostat. These stranded wires were run to the control room adjacent to the 

test cell where the furnace power supply was located. The power supply used was a Lambda model 

LLS9040 capable of outputting zero to 40 V dc at 20 A. 

The amount of LH2 in the cryostat was measured using two thermocouples placed above 

the height of the heater elements. The thermocouples detected when the LH2 covered the heater 

elements. This was accomplished by monitoring the readout from the TCs and watching for stabilization on the readout that represented LH2 temperatures. When the TC readout stabilized at LH2

temperatures, this indicated that the LH2 was covering the heater elements.

C.3 Test Procedures

The heater elements were installed in a fixture to hold them in place while in the cryostat and 

solid Cu feedthrough wires were attached to the heating elements (fig. 19). The baseline resistance of 

each element with the solid Cu wires attached was measured prior to installing in the cryostat. The 

fixture with the heating elements was installed in the cryostat and stranded Cu wires were attached 

to the solid Cu feedthrough wires. The resistance of each furnace/wire assembly was measured to 

determine the total initial resistance of the assemblies at room temperature. When the electrical connections were verified and the resistance measurements made, the lid was installed on the cryostat. 

The resistance measurements are provided in table 7.

LH2 was added to the cryostat until the fill level thermocouples indicated the heater elements 

were covered. The pressure supplied by the LH2 Dewars was reduced and a constant flow of LH2was 
44

Table 7. Resistance measurements for each element.

Resistance (Ω) of Heater Elements

1 2 3

Baseline 6.039 0.815 0.780

With lead wire 0.766 0.945 0.929

In LH2 before power 1.190 1.214 1.534

In LH2 after power 1.190 1.216 1.535

In LH2 after 90-min soak – 1.219 1.541

In LH2 after 105-min soak – 1.214 1.536

At 133 °F after test 0.743 0.909 0.889

maintained to keep the cryostat full. This test was performed with ≈27.6 kPa (≈4) psig back-pressure 

applied to the cryostat because of a check valve and the water pressure in the boiloff tank on the 

vent line. 

When the cryostat was full, resistance measurements were taken for each heater element. The 

power leads for one heater element were connected to the power controller. Power was slowly added 

to the heater element to a maximum of 50 W. Voltage and current readings were taken periodically 

as the power level was being increased (see table 8). While power was being added to the heating element, pressure in the cryostat was monitored carefully to ensure that the vent system could handle 

the volume of hydrogen boiled off and pressure did not exceed 103 kPa (15 psig). This turned out not 

to be an issue because pressure inside the cryostat never increased during the application of power. 

The maximum power level was held on the heater element for 60 s and then the power was shut off. 

The remaining heater elements were connected to the power controller one at a time and the test 

procedure repeated. 

Table 8. Data for element 1 at different voltage settings.

Applied

Volts

Current

(A)

Power

(W)

1 0.8 0.8

2 1.7 3.4

3 2.6 7.8

4 3.5 14.0

5 4.4 22.0

6 5.3 31.8

7 6.2 43.4

7.5 6.6 49.5
45

Heating elements 2 and 3 were evaluated after soaking 90 and 105 min in LH2 by applying 

3 and 7 V to each element and measuring the associated current and comparing it to the initial readings. These data are provided in table 9. Resistance measurements were also taken at the same time 

and compared to the initial measurements. These readings are provided in table 7. 

Table 9. Current measurements for each element.

Applied

Volts

Element 1

(A)

Element 2

(A)

Element 3

(A)

Initial run 3 2.6 2.5 2.0

Initial run 7 6.2 6.0 4.7

After 90-min soak 3 – 2.5 2.0

After 90-min soak 7 – 6.0 4.7

105-min soak 3 – 2.5 2.0

105-min soak 7 – 6.0 4.7

After the LH2 test was completed, the LH2 was boiled off and the cryostat purged with He 

gas. When the temperature of the cryostat and heating elements had stabilized at room temperature, 

heated He gas was flowed through the cryostat to bring the temperature of the heating elements up 

to 133 °F and the resistance of each element was measured again. These resistance readings are provided in table 7.

C.4 Conclusions

The following conclusions can be reached:

• The resistance of the heater elements increased with decreased temperature.

• The LH2 environment did not adversely affect the operation of the heater elements.

•The heater elements were not degraded by the short-term LH2 exposure as indicated by consistent 

current measurements from the three readings taken at different time intervals.
46

APPENDIX D—CONTROL SYSTEM FOR MULTIPURPOSE HYDROGEN TEST BED 

ZERO-BOILOFF DEMONSTRATION 

The control system used to maintain the tank heat leak at a value that matched the tank heat 

extraction capability of the cryocooler is presented. 

D.1 Zero-Boiloff Model

The ZBO cooler dynamics schematic is shown in figure 28, the recirculation line model schematic in figure 28a, and the ullage model schematic in figure 28b. 
47

1

0

0

18

25

1

xo [115.01]

1

1/7

1

s 114.99

PID

+

–

+

–

++

–

×

×

÷

++

++

xo

1

[20.9]

20.736

90.09

Zero Boil-off ModelCreated on Mar 13, 2001 22:30:08Created by Brent HippLast Modified on Oct 13, 2001 08:45:04

Temp (surr) (K)

Temp (sat) (K)

Temperature Delta

Thermal Resistance Q (rec line) (Btu/hr)

ZBO Rec Line Model

Temp Variation

Temp (Rec Line) (K)

Temp (cooler) (K)Q (Rec Line) (btu/hr)M (pump) (gpm)Temp Diff (tank-line) (K)

Resistance gpm

Heater Blanket Temperature (K) Double-Click to Load PID Parameters

Load PID Parameters

Display

Simulated

gd2

gd11

<gd2>

<gd11>

gpm/Hz

Acquire Data

Temp (Heater Blankets (K)

Voltage (Heater) (V)

Current (Heater) (A)

Temp (Rec Line) (K)

Row Rate (Pump) (Hz)

Pressure (Ullage) (kPa)

Temp (Tank) (K)

Status (Heater) On/Off

Reset PID

<p4>

<p1>

<td12>

<v1>

<v4>

Thermostat Controller

Z_n X_n

Z_n X_n

Z_n X_n

Z_n X_n

Z_n

K5

>= 18.17

X_n

–

s

–

+

–

+ ++ ×

×

×

÷

T (Rec Line) (K/s)

Temp (cooler) (K) Tank Temp

Temp Difference

Rec Line Temp

Recirculation Line Dynamics

Reset Temp Cooler

Heater Power (W)

Measured

Modelled

Tank Heater Subsystem

Voltage (realstar)

Current (Power Supply)

Voltage (Power Supply) inv HP gain Heater Power

AO White

LH2 Temp (K)Power (W)Heater (Select)

Pressure

Filtered

Model

Alpha

Simulated

p1 Preset Tank Pressure

ZBO Ullage Model

Tank Level (%)

Heat Leak (Tank) (W)

Power (Heater) (W)

Heater Select and Status

Heater Select

Flow Rate (Pump) (pgm)

Power (Heater) (W)

PID Heater Power (W)

Manual

PID Controller

Enabled

Bypass Controller

Error Sim

Ullage Pressure Set Point

Temp (Cooler) (K)Q (Ambient) (W)Flow Rate (Pump) (gpm)P (Tank) (kPa)Fill Level (Tank) (%)

P (Tank) (kPa/s)

Ullage Pressure Rise Rate (kPa/s)

P (tank) (kPa)

Rise Rate (k Pa/hr)Rise Rate (k Pa/s)

•

•

•

•

•

•

Figure 28. Schematic of control system ZBO model.
48

1

1

2

3

8.0208

4.5

1.128

4

×

×

÷

÷

÷

Zero Boil-off Ullage Pressure Model

Created on Mar 13, 2001 22:38:08

Created by Ali Hedayat

Last Modified on Oct 13, 2001 08:45:04

–

++

Heat Into

Recirculation

Line (W)

Cooler

Ambient 1/3.414

0.057

–1

3600

s/hr Product

Mass

(LH2) (lb) Density (LH2) (lb/ft3)

C Heat Capacity (LH2)

(ft3/hr)

Temperature

(Cooler) (K)

Cryo Cooler

Temperature (Cooler) (K)

Temperature

Temperature Difference

(Tank Line) (K)

Heat Rate

(Cooler) (Btu/hr)

W/Btu

Fluid

Total

T (Rec Line) (K/s)

O (Rec Line) (Btu/hr)

M (Pump) (gpm)

Pump

Figure 28a. Schematic of ZBO recirculation line model.

1

1

2

3

4

5

×

×

×

×

÷

÷

Zero Boil-off Ullage Pressure Model

Created on Mar 13, 2001 22:38:08

Created by Robin Flachbart

Last Modified on Oct 13, 2001 08:45:04

–

++

1

-K1,000

kJ/J

18.104

Volume (Tank) m3

Product

Ø

Energy Derivative (kPa-m3/kJ)

Energy Derivative (Ø)

Temperature

(Cooler) (K)

CryoCooler

Temperature

(Cooler) (K)

P

(Tank) (kPa)

Fill Level

(Tank) (%)

Power

(Cooler) (W) s/s

P (Tank) (kPa/s)

Pressure Rate (kPa/s) O (Ambient) (W)

Flow Rate

(Pump) (gpm) Frequency

(gpm)

Frequency

Pump Power (Vendor Curve Fit)

Figure 28b. Schematic of ZBO ullage model.

D.2 Multipurpose Hydrogen Test Bed Thermal Purformance

Table 10 is used to perform real time MHTB heat leak computations, which was input to the 

control system. The example data included were obtained during a representative boiloff test with 

a 305 K boundary condition imposed on the MLI external surface under high vacuum conditions.
49

Table 10. MHTB thermal performance spreadsheet.

MHTB Penetration Heat Leak Worksheet 

Test # P263952H.300

Phase Orbit Hold: Hot Boundary set to 305K

DSU Time 0.0 sec to 35000 sec

Variable Input List

Fill/Drain Line Pressurization Line Flow Meter Press/Temp

TFD2 33.9 K TPL1 75.17 K P3113 0.28 KPa G

HG6 41.51 K TPL2 99.42 K T3227 306.51 K

TFD3 46.78 K TPL3 75.98 K

TFD4 50.13 K TPL4 127.58 K Tank Ullage Vent Temp

HG6 41.51 K HG5 138.08 K TVL4 23.11 K

TVL5 23.25 K

 Vent Line Ullage Pressure Line K

TVL2 33.15 K TUP1 55.7 K Ref Volume Press

HG7 35.99 K TUP2 71.25 K P3 113.7700777 KPa

TVL6 60.66 K

TVL7 68.81 K Tank Manhole Pumpout K Tank Ref Delta Press

HG7 35.99 K TCP1 82.39 K DP1 66.36 Pa

TCP2 84.17 K

Interstitial Pressure Probe

IPP1 231.09 K Tank Leg #1 Flow Meters Used

IPP2 267.1 K TSL1 81.96 K (0 or 1)

TSL2 136.7 K F1 (alpm) 0 0

Tank Leg #3 TSL19 59.67 K F2 (alpm) 0 0

TSL3 85.62 K TSL18 102.14 K F3 (slpm) 16.12 0

TSL4 143.11 K HG1 167.75 K F4 (slpm) 19.31 1

TSL15 201.4 K TSL14 180.18 K F5 (sccm) 0 0

Heat Leak Summary

Penetrations

Fill/Drain 0.067885622 W 0.231635248 BTU/Hr

Vent 0.054455715 W 0.185810523 BTU/Hr Total Penetration Heat Leak

Int. Press 0.064030617 W 0.218481428 BTU/Hr 2.385372016 W

Legs (all 4) 1.449055468 W 4.944380126 BTU/Hr 8.139223269 BTU/Hr

Pressurization 0.706067782 W 2.409202123 BTU/Hr

Ullage 0.042407458 W 0.144700183 BTU/Hr

Manhole 0.001469353 W 0.005013639 BTU/Hr

Total Tank Heat Leak Based on Boiloff (Including Penetrations)

13.0954942 W 44.68365956 BTU/Hr 0.097063453 kg/Hr

0.376907324 W/m2 0.119475026 BTU/Hr-ft2 0.21398803 #/hr

Total Tank Heat Leak Based on Boiloff (Penetrations Subtracted)

10.71012218 W 36.54443629 BTU/Hr

0.308242902 W/m2 0.097712397 BTU/Hr-ft2
50

Table 10. MHTB thermal performance spreadsheet (Continued).

MHTB Fill/Drain Penetration Heat Leak Worksheet 

Test # P263952H.300 Note: TFD1 failed (high reading). Replaced with HG6.

Phase Orbit Hold: Hot Boundary set to 305K

Silicion Diodes on Stainless Steel

ID Location From Temperature Tube Diameter Tube Thickness

Tank Boundary (cm) (K) (cm) (mm)

TFD2 6.98 33.9 2.54 1.65

HG6 13.97 41.51

Thermocouples on SOFI Surface

ID Location From Temperature SOFI Avg Circum SOFI Avg Thick

Tank Boundary (cm) (K) (cm) (cm)

TFD3 6.98 46.78 49.53 6.6

TFD4 13.97 50.13

HG6 13.97 41.51

Heat Leak Due to Stainless Steel

Delta Temp 7.61 (K)

Average Temp 37.705 (K)

Average K 4.006483354 (W/m-K)

Length 0.0699 (m)

Cross-sectional Area 0.000123111 (m2)

Heat Leak (Power) 0.053699209 (W) 0.183229219 (BTU/hr)

Heat Leak Due to PDL Foam

Avg Temp High 45.82 (K)

Avg Temp Low 40.34 (K)

Avg Delta Temp 5.48 (K)

Avg High/Low Temp 43.08 (K)

Average K 0.009521395 (W/m-K)

Length 0.0699 (m)

Cross-sectional Area 0.019005034 (m2)

Heat Leak (Power) 0.014186414 (W) 0.048406029 (BTU/hr)

Total Heat Leak (Power) 0.067885622 (W)

0.231635248 (BTU/hr)
51

Table 10. MHTB thermal performance spreadsheet (Continued).

MHTB Ullage Line Penetration Heat Leak Worksheet 

Test # P263952H.300

Phase Orbit Hold: Hot Boundary set to 305K

Silicion Diodes on Stainless Steel

ID Location From Temperature Tube Diameter Tube Thickness

Tank Boundary (cm) (K) (cm) (mm)

TUP1 11.43 55.7 1.27 1.25

TUP2 21.59 71.25

Thermocouples on SOFI Surface

ID Location From Temperature SOFI Avg Circum SOFI Avg Thick

Tank Boundary (cm) (K) (cm) (cm)

 --- 6.98 0 0 0

 --- 13.97 0

 --- 13.97 0

Heat Leak Due to Stainless Steel

Delta Temp 15.55 (K)

Average Temp 63.475 (K)

Average K 6.162267499 (W/m-K)

Length 0.1016 (m)

Cross-sectional Area 4.4964E-05 (m2)

Heat Leak (Power) 0.042407458 (W) 0.144700183 (BTU/hr)

Heat Leak Due to PDL Foam

Avg Temp High 0 (K)

Avg Temp Low 35.625 (K)

Avg Delta Temp -35.625 (K)

Avg High/Low Temp 17.8125 (K)

Average K 0.007591261 (W/m-K)

Length 0.0699 (m)

Cross-sectional Area 0 (m2)

Heat Leak (Power) 0 (W) 0 (BTU/hr)

Total Heat Leak (Power) 0.042407458 (W)

0.144700183 (BTU/hr)
52

Table 10. MHTB thermal performance spreadsheet (Continued).

MHTB Leg #1 Penetration Heat Leak Worksheet 

Test # P263952H.300

Phase Orbit Hold: Hot Boundary set to 305K

Silicion Diodes on Fibre - Glass Epoxy

ID Location From Temperature Tube Diameter Tube Thickness

Tank Boundary (cm) (K) (cm) (mm)

TSL1 2.54 81.96 7.9375 1.58

TSL2 7.62 136.7

Thermocouples on SOFI Surface

ID Location From Temperature SOFI Avg Circum SOFI Avg Thick

Tank Boundary (cm) (K) (cm) (cm)

TSL19 -5.08 59.67 48.26 3.81

TSL18 2.54 102.14

HG1 13.97 167.75

Thermocouple on SOFI Internal to Leg

ID SOFI Plug Len. (cm) Temp (K) SOFI Plug Dia. (cm)

TSL14 10.16 180.18 7.62

Heat Leak Due to Fibre - Glass Epoxy

Delta Temp 54.74 (K)

Average Temp 109.33 (K)

Average K 0.359138188 (W/m-K)

Length 0.0508 (m)

Cross-sectional Area 0.000386152 (m2)

Heat Leak (Power) 0.149437965 (W) 0.50990326 (BTU/hr)

Heat Leak Due to Exterior SOFI Interior SOFI

Avg Temp High 92.05 (K) 180.18 (K)

Avg Temp Low 43.835 (K) 28 (K)

Avg Delta Temp 48.215 (K) 152.18 (K)

Avg High/Low Temp 67.9425 (K) 104.09 (K)

Average K 0.011420592 (W/m-K) 0.014181827 (W/m-K)

Length 0.0762 (m) 0.1016 (m)

Cross-sectional Area 0.013826697 (m2) 0.004560363 (m2)

Heat Leak External 0.099915815 (W) 0.34092675 (BTU/hr)

Heat Leak Internal 0.096871385 (W) 0.330538728 (BTU/hr)

Total Heat Leak (Power) 0.346225166 (W)

1.181368737 (BTU/hr)
53

Table 10. MHTB thermal performance spreadsheet (Continued).

MHTB Pressurization Line Penetration Heat Leak Worksheet 

Test # P263952H.300

Phase Orbit Hold: Hot Boundary set to 305K

Silicion Diodes on Stainless Steel

ID Location From Temperature Tube Diameter Tube Thickness

Tank Boundary (cm) (K) (cm) (mm)

TPL1 3.81 75.17 2.54 1.65

TPL2 7.62 99.42

Thermocouples on SOFI Surface

ID Location From Temperature SOFI Avg Circum SOFI Avg Thick

Tank Boundary (cm) (K) (cm) (cm)

TPL3 7.62 75.98 38.1 3.56

TPL4 15.24 127.58

HG5 15.24 138.08

Heat Leak Due to Stainless Steel

Delta Temp 24.25 (K)

Average Temp 87.295 (K)

Average K 7.949508229 (W/m-K)

Length 0.0381 (m)

Cross-sectional Area 0.000123111 (m2)

Heat Leak (Power) 0.622908267 (W) 2.125450213 (BTU/hr)

Heat Leak Due to PDL Foam

Avg Temp High 132.83 (K)

Avg Temp Low 87.7 (K)

Avg Delta Temp 45.13 (K)

Avg High/Low Temp 110.265 (K)

Average K 0.014653523 (W/m-K)

Length 0.0762 (m)

Cross-sectional Area 0.009582074 (m2)

Heat Leak (Power) 0.083159515 (W) 0.283751909 (BTU/hr)

Total Heat Leak (Power) 0.706067782 (W)

2.409202123 (BTU/hr)
54

Table 10. MHTB thermal performance spreadsheet (Continued).

MHTB Manhole Pump-Out Line Penetration Heat Leak Worksheet 

Test # P263952H.300

Phase Orbit Hold: Hot Boundary set to 305K

Silicion Diodes on Stainless Steel

ID Location From Temperature Tube Diameter Tube Thickness

Tank Boundary (cm) (K) (cm) (mm)

TCP1 106.68 82.39 2.083 0.254

TCP2 121.92 84.17

Thermocouples on SOFI Surface

ID Location From Temperature SOFI Avg Circum SOFI Avg Thick

Tank Boundary (cm) (K) (cm) (cm)

 --- 6.98 0 0 0

 --- 13.97 0

 --- 13.97 0

Heat Leak Due to Stainless Steel

Delta Temp 1.78 (K)

Average Temp 83.28 (K)

Average K 7.662086394 (W/m-K)

Length 0.1524 (m)

Cross-sectional Area 1.64189E-05 (m2)

Heat Leak (Power) 0.001469353 (W) 0.005013639 (BTU/hr)

Heat Leak Due to PDL Foam

Avg Temp High 0 (K)

Avg Temp Low 42.085 (K)

Avg Delta Temp -42.085 (K)

Avg High/Low Temp 21.0425 (K)

Average K 0.007837994 (W/m-K)

Length 0.0699 (m)

Cross-sectional Area 0 (m2)

Heat Leak (Power) 0 (W) 0 (BTU/hr)

Total Heat Leak (Power) 0.001469353 (W)

0.005013639 (BTU/hr)
55

Table 10. MHTB thermal performance spreadsheet (Continued).

MHTB Leg #3 Penetration Heat Leak Worksheet 

Test # P263952H.300

Phase Orbit Hold: Hot Boundary set to 305K

Silicion Diodes on Fibre - Glass Epoxy

ID Location From Temperature Tube Diameter Tube Thickness

Tank Boundary (cm) (K) (cm) (mm)

TSL3 2.54 85.62 7.9375 1.58

TSL4 7.62 143.11

Thermocouples on SOFI Surface

ID Location From Temperature SOFI Avg Circum SOFI Avg Thick

Tank Boundary (cm) (K) (cm) (cm)

 --- 2.54 0 0 0

 --- 10.16 0

 --- 13.97 0

Thermocouple on SOFI Internal to Leg

ID SOFI Plug Len. (cm) Temp (K) SOFI Plug Dia. (cm)

TSL15 10.16 201.4 7.62

Heat Leak Due to Fibre - Glass Epoxy

Delta Temp 57.49 (K)

Average Temp 114.365 (K)

Average K 0.370017233 (W/m-K)

Length 0.0508 (m)

Cross-sectional Area 0.000386152 (m2)

Heat Leak (Power) 0.161699555 (W) 0.551741521 (BTU/hr)

Heat Leak Due to Exterior SOFI Interior SOFI

Avg Temp High 0 (K) 201.4 (K)

Avg Temp Low 71.555 (K) 28 (K)

Avg Delta Temp -71.555 (K) 173.4 (K)

Avg High/Low Temp 35.7775 (K) 114.7 (K)

Average K 0.008963572 (W/m-K) 0.014992304 (W/m-K)

Length 0.0762 (m) 0.1016 (m)

Cross-sectional Area 0 (m2) 0.004560363 (m2)

Heat Leak External 0 (W) 0 (BTU/hr)

Heat Leak Internal 0.116687198 (W) 0.398153055 (BTU/hr)

Total Heat Leak (Power) 0.278386753 (W)

0.949894576 (BTU/hr)
56

Table 10. MHTB thermal performance spreadsheet (Continued).

MHTB Vent Penetration Heat Leak Worksheet 

Test # P263952H.300 Note: Problems with TVL1swapped with HG7

Phase Orbit Hold: Hot Boundary set to 305K

Silicion Diodes on Stainless Steel

ID Location From Temperature Tube Diameter Tube Thickness

Tank Boundary (cm) (K) (cm) (mm)

TVL2 7.62 33.15 5.08 1.65

HG7 15.24 35.99

Thermocouples on SOFI Surface

ID Location From Temperature SOFI Avg Circum SOFI Avg Thick

Tank Boundary (cm) (K) (cm) (cm)

TVL6 7.62 60.66 59.69 6.98

TVL7 15.24 68.81

HG7 15.24 35.99

Heat Leak Due to Stainless Steel

Delta Temp 2.84 (K)

Average Temp 34.57 (K)

Average K 3.728467236 (W/m-K)

Length 0.0762 (m)

Cross-sectional Area 0.000254775 (m2)

Heat Leak (Power) 0.035403865 (W) 0.120802943 (BTU/hr)

Heat Leak Due to PDL Foam

Avg Temp High 52.4 (K)

Avg Temp Low 46.905 (K)

Avg Delta Temp 5.495 (K)

Avg High/Low Temp 49.6525 (K)

Average K 0.010023455 (W/m-K)

Length 0.0762 (m)

Cross-sectional Area 0.026357668 (m2)

Heat Leak (Power) 0.01905185 (W) 0.06500758 (BTU/hr)

Total Heat Leak (Power) 0.054455715 (W)

0.185810523 (BTU/hr)
57

Table 10. MHTB thermal performance spreadsheet (Continued).

MHTB Interstitial Pressure Probe Penetration Heat Leak Worksheet 

Test # P263952H.300

Phase Orbit Hold: Hot Boundary set to 305K

Silicion Diodes on Stainless Steel

ID Location From Temperature Tube Diameter Tube Thickness

Tank Boundary (cm) (K) (cm) (mm)

IPP1 3.81 231.09 5.08 0.0381

IPP2 8.89 267.1

Thermocouples on SOFI Surface

ID Location From Temperature SOFI Avg Circum SOFI Avg Thick

Tank Boundary (cm) (K) (cm) (cm)

 --- 6.98 0 0 0

 --- 13.97 0

 --- 13.97 0

Heat Leak Due to Stainless Steel

Delta Temp 36.01 (K)

Average Temp 249.095 (K)

Average K 14.86674607 (W/m-K)

Length 0.0508 (m)

Cross-sectional Area 6.07592E-06 (m2)

Heat Leak (Power) 0.064030617 (W) 0.218481428 (BTU/hr)

Heat Leak Due to PDL Foam

Avg Temp High 0 (K)

Avg Temp Low 133.55 (K)

Avg Delta Temp -133.55 (K)

Avg High/Low Temp 66.775 (K)

Average K 0.011331409 (W/m-K)

Length 0.0699 (m)

Cross-sectional Area 0 (m2)

Heat Leak (Power) 0 (W) 0 (BTU/hr)

Total Heat Leak (Power) 0.064030617 (W)

0.218481428 (BTU/hr)
58

Table 10. MHTB thermal performance spreadsheet (Continued).

MHTB Penetration Heat Leak Summary

Test # P263952H.300

Phase Orbit Hold: Hot Boundary set to 305K

Fill/Drain Line 0.067885622 W

0.231635248 BTU/Hr

Pressurization Line 0.706067782 W

2.409202123 BTU/Hr

Vent Line 0.054455715 W

0.185810523 BTU/Hr

MLI Interstitial Pressure Probe 0.064030617 W

0.218481428 BTU/Hr

Tank Manhole Pump-Out Line 0.001469353 W

0.005013639 BTU/Hr

Ullage Pressure Line 0.042407458 W

0.144700183 BTU/Hr

Support Leg #1 0.346225166 W

1.181368737 BTU/Hr

Support Leg #3 0.278386753 W

(Only Fibre-Glass Epoxy Component) 0.949894576 BTU/Hr

Average Leg Heat Leak For All 4 Legs 1.449055468 W

4.944380126 BTU/Hr

Total MHTB Tank Heat Leak 2.385372016 W

8.139223269 BTU/Hr
59

Table 10. MHTB thermal performance spreadsheet (Continued).

MHTB Boiloff Heat Leak Evaluation Worksheet

Test # P263952H.300

Phase Orbit Hold: Hot Boundary set to 305K

Flow Meter Data

Meter ID Used Flow Rate Units Flow Rate

( 0 or 1) (kg/hr) English Units

F1 0 0 ALPM 0 0 #/hr

F2 0 0 ALPM 0 0 #/hr

F3 0 16.12 SLPM 0 0 #/hr

F4 1 19.31 SLPM 0.097063453 0.21398803 #/hr

F5 0 0 SCCM 0 0 #/hr

Total Flow Rate(kg/hr) 0.097063453 0.21398803 #/hr

Flow Meter Press P3113 0.28 KPa Gauge 0.04061064 psid

Flow Meter Temp T3227 306.51 K 551.718 R

Tank Ullage Vent Temp TVL4 23.11 K 41.598 R

Tank Ullage Vent Temp TVL5 23.25 K 41.85 R

Average Tank Ullage Vent Temp 23.18 K 41.72 R

Flow Meter Line Pressure 101605 Pa Absolute 14.74 psia

GH2 Density at Flow Meters based on P and T 0.080361212 kg/m3

GH2 ideal gas constant 4125 (N-m)/(kg-K) 766.67 lb-ft/#-R

GH2 standard density 0.0837765 kg/m3 0.00523 #/ft3

Reference Volume Pressure P3 113.7700777 KPa Absolute 0.01650 psia

Delta P tank to reference vol DP1 66.36 Pa 0.00962 psi

Tank Ullage pressure (calculated) 113836.4377 Pa Absolute 16.51 psia

LH2/GH2 Calculated Properties (from curve fits) 

Density of Saturated Vapor 1.48250406 kg/m3 0.09 #/ft3

Density of Saturated Liquid 70.34763604 kg/m3 4.39 #/ft3

Enthaply of Saturated Vapor 191806.3494 J/kg 82.46 BTU/#

Enthaply of Vent Gas (use temps TVL4&5) 224045 J/kg 96.32 BTU/#

Latent Heat of Vaporization 443905.7234 J/kg 190.85 BTU/#

Heat Leak Component Calculations 

mdot*hfg*(densatliq/ mdot*(hvent-hsatvap) Total Tank Heat Leak

(densatliq-densatvap))

44014.58436 J/hr 3129.194744 J/hr 47143.7791 J/hr

12.22627343 W (J/sec) 0.869220762 W (J/sec) 13.0954942 W (J/sec)

0.376907324 W/m2

41.71775663 BTU/hr 2.965902932 BTU/hr 44.68365956 BTU/hr

0.119475026 BTU/hr-ft2
60

APPENDIX E—INSTRUMENTATION LIST FOR THE MULTIPURPOSE HYDROGEN 

TEST BED TANKING ZERO-BOILOFF DEMONSTRATION

Table 11 shows the facility instrumentation list and table 12 shows the test article measurements for the MHTB ZBO testing. The MHTB test article list is further subdivided into the standard 

MHTB test instrumentation and specifically added for the ZBO demonstration. 
61

Table 11. MHTB ZBO instrumentation list.

20-FT CHAMBER FACILITY MEASUREMENTS

MID LINK SIU CH J-BOX Measurement Description Xducer Serial No. Range UNITS CAL DUE

CFA2 1 6 Chamber temp 3 m above floor Type E 15 / 310 KELVIN NONECFA3 1 7 Chamber temp 4.6 m above floor Type E 15 / 310 KELVIN NONEDEW1 1 8 MLI gas system dew point Endress Hauser -80 / 20 CELCIUS NONEDEW2 1 9 Heater shroud dew point Endress Hauser -80 / 20 CELCIUS NONE

1 101 11

F1 1 12 LH2 Vent flow rov 20-671 Flow Tech 2402000 593 / 5410 ALPM 2/3/03F2 1 13 LH2 Vent flow rov 20-672 Flow Tech. 1606628 519 / 1688 ALPM 2/3/03F3 1 14 LH2 Vent flow rov 20-673 Hastings-Ray. 10879 14 / 550 SLPM 2/13/03F4 1 15 LH2 Vent flow rov 20-674 MKS 179A 226281 0 / 61.9 SLPM 3/5/03F5 1 16 LH2 Vent flow rov 20-675 MKS 179A 396971 0 / 1000 SCCM 3/3/03F8 1 17 Manway pump out flow MKS 179A 1.08 / 8.573 SLPM 3/13/03P3105 1 18 LN2 PUMP LINE PRESSURE TABER 226 860548 0 / 2068.43 KPAG 5/19/02IP1 1 19 MLI interstitial pressure HPS 953 107261 10-3 to 1000 TORR 3/5/03IP2 1 CALC MLI interstitial pressure - semi-log scale HPS 953 107261 -2 to -8 log TORR 3/5/03IP4 1 20 MLI interstitial pressure MKS 390 M62375 0 / 1000 TORR 5/11/03IPC2 1 21 MLI interstitial pressure - millivolt reading HPS 953 107261 0 / 6000 MV 3/5/03IPD2 1 CALC MLI interstitial pressure - linear scale HPS 953 107261 0 / 10,000 UTORR 3/5/03F16 1 22 CRYOMECH CP25 COMP. COOLING H2O COX 8-6 50001 2.3 / 17.29 LPM 8/23/02F17 1 23 TVS ENCLOSURE PUMP-OUT LINE FLOW MKS 179A 92108 0 / 5000 SCCMD1 1 24 MILLIVOLTS DPP1 CSPV0002030001 93861-G (-48) / (24) MV NONEPP1 1 25 MILLIVOLTS PPA1 CSPV0002030001 93861-D (0) / (300) MV NONEPS1 1 26 MILLIVOLTS PSB1 CSPV0002030001 93861-E (-3) / (267) MV NONEDPP1 1 CALC TVS PUMP DELTA PRESSURE KPAD NONEPPA1 1 CALC TVS PUMP INLET PRESSURE KPA NONEPSB1 1 CALC TVS FLOWMETER PRESSURE KPA NONEPSA1 1 CALC MHTB TANK LIQ. VAPOR PRESS. SAT KPA NONE

1 271 281 291 30

P3097 1 31 2nd stage firex STATHAM PG347 15 0 / 6894.76 KPAG 5/17/02P3104 1 32 LN2 Tank pressure TABER 254 931251 0 / 689.47 KPAG 5/17/02BAD CH 1 33P3107 1 34 GN2 Supply pressure MB ELECTRONICS 151 41029 0 / 689.476 KPAG 5/17/02
62

20-FT CHAMBER FACILITY MEASUREMENTS

MID LINK SIU CH J-BOX Measurement Description Xducer Serial No. Range UNITS CAL DUE

P3108 1 35 Air manifold TABER 2105 888102 0 / 34,473.8 KPAG 5/18/02P3109 1 36 Repress stage two DYNISCO PT119 27686 0 / 10,342 KPAG 5/19/02P3110 1 37 Repress stage one TABER 226 930869 0 / 6894.76 KPAG 5/19/02P3111 1 38 LH2 F/D trailer fill TABER 254 880705 0 / 689.476 KPAG 5/17/02P3112 1 39 LH2 Vent sytem TABER 254 781316 0 / 689.476 KPAG 5/17/02P3113 1 40 LH2 Vent sytem @ pressure control valves TABER 254 931250 0 / 689.476 KPAG 5/17/02P3114 1 41 LN2 Supply system rov 20-1700 TABER 254 891412 0 / 689.476 KPAG 5/17/02P3115 1 42 GH2 Upstream DLR - 803 TABER2105 932076 0 / 41,368.6 KPAG 5/18/02P3116 1 43 GH2 Downstream DLR - 803 STELLAR TECH GT200 941210 0 / 6,894.8 KPAG 5/17/02P3117 1 44 GH2 Feed line TABER 226 950379 0 / 3,447.4 KPAG 5/19/02P3120 1 45 GN2 Downstream DLR-2082 TABER 226 890938 0 / 13,789.5 KPAG 5/19/02P3140 1 46 Tank pressurization TABER 226 890934 0 / 13,789 KPAG 5/19/02T3226 1 47 LH2 VENT LINE @ CHAMBER PENETRAT TYPE E 15 / 310 KELVIN NONET3247 1 48 LN2 RETURN ROV 20-1707 TYPE E 15 / 310 KELVIN NONET3248 1 49 LN2 RETURN ROV 20-1706 TYPE E 15 / 310 KELVIN NONET3205 1 50 LN2 RETURN LINE TEMP. TYPE E 15 / 310 KELVIN NONET3206 1 51 LN2 Cold wall zone 1A Type E 33.15 / 300 KELVIN NONET3207 1 52 LN2 Cold wall zone 1B Type E 33.15 / 300 KELVIN NONET3208 1 53 LN2 Cold wall zone 2A Type E 33.15 / 300 KELVIN NONET3209 1 54 LN2 Cold wall zone 2B Type E 33.15 / 300 KELVIN NONET3210 1 55 LN2 Cold wall zone 3A Type E 33.15 / 300 KELVIN NONET3211 1 56 LN2 Cold wall zone 3B Type E 33.15 / 300 KELVIN NONET3212 1 57 LN2 Cold wall zone 4A Type E 33.15 / 300 KELVIN NONET3213 1 58 LN2 Cold wall zone 4B Type E 33.15 / 300 KELVIN NONET3214 1 59 LN2 Cold wall zone 5A Type E 33.15 / 300 KELVIN NONET3215 1 60 LN2 Cold wall zone 5B Type E 33.15 / 300 KELVIN NONET3217 1 61 Diff pump #1 water outlet Type K 200 / 533 KELVIN NONET3219 1 62 Diff pump #2 water outlet Type K 200 / 533 KELVIN NONET3220 1 63 Diff pump #1oil Type K 200 / 533 KELVIN NONET3221 1 64 Diff pump #2 oil Type K 200 / 533 KELVIN NONET3222 1 65 LH2 F/D rov 20-601 Type E 15 -310 KELVIN NONET3227 1 66 LH2 Vent line flow box Type E 15 -310 KELVIN NONET3249 1 67 LN2 heat exchanger rov 20-1704 Type E 15 -310 KELVIN NONET3250 1 68 LN2 supply rov 20-1700 Type E 15 -310 KELVIN NONET3252 1 69 LH2 vent heat xchr water discharge temp Type E 15 -310 KELVIN NONE

Table 11. MHTB ZBO instrumentation list (Continued).
63

20-FT CHAMBER FACILITY MEASUREMENTS

MID LINK SIU CH J-BOX Measurement Description Xducer Serial No. Range UNITS CAL DUE

T3253 1 70 Tank pressurization line temperature Type E 15 -310 KELVIN NONET3254 1 71 Flowbox temperature - feedback Type E 15 -310 KELVIN NONET3255 1 72 Ice bath reference pressure vessel temp Type E 15 -310 KELVIN NONET3256 1 73 DP1 hoffman box temperature Type E 15 -310 KELVIN NONET3265 1 74 Tank pressurization ROV20-1809 Type E 15 / 310 KELVIN NONE

1 75

TPT1 1 76 TEMP. PRESSURE TRANSDUCER TVS TYPE E 15 / 310 KELVIN NONETD23 1 77 RAKE 2 11.5% FILL DT-470-BO-11A 15 / 310 KELVIN NONE

1 781 79

VP3000 1 80 Manway pump out 2nd level MKS390 G85195 0 / 1000 TORR 2/22/03VP3003 1 81 15 Foot Chamber foreline GP275 none 10-3 /760 TORR 3/3/03VP3004 1 82 LN2 TANK VACUUM JACKET GP275 none 10-3 / 760 TORR 3/3/03VP3005 1 83 LH2 F/D vac jacket @ rov 1502 GP275 25210 10-3 / 760 TORR 3/3/03VP3007 1 84 Chamber wall box MKS 390 73995-2A 0 / 1000 MICRONS 3/22/03VP3008 1 85 Chamber wall box MKS 122A M645228 0 / 1000 TORR 3/15/03VP3009 1 86 Pump one foreline (outside pump house) GP275 25211 10-3 / 760 TORR 3/15/03VR3010 1 87 MILLIVOLTS FOR VP3010 MKS 290 94081226A 300 / 5300 MV 3/15/03VR3011 1 88 MILLIVOLTS FOR VP3011 VARIAN BA2C 4003 2000 / 8000 MV 3/15/03VR3012 1 89 MILLIVOLTS FOR VP3012 GP303 482 1000 / 7000 MV 3/15/03VR3014 1 90 MILLIVOLTS FOR VP3014 VARIAN BA2C 4002 2000 / 8000 MV 3/15/03VP3010 1 CALC Internal chamber pressure .01 / 1000 UTORR NONEVP3011 1 CALC Chamber wall box .01 / 1000 UTORR NONEVP3012 1 CALC Internal chamber pressure .01 / 1000 UTORR NONEVP3014 1 CALC RGA Pressure .01 / 1000 UTORR NONEVP3015 1 91 Chamber wall box - pirani HPS 953 107263 10-3 / 1000 Torr 3/15/03BAD CH 1 92VP3016 1 93 CHAMBER WALL BOX-COLD CATHODE-mv HPS 953 107263 0/6000 MV 3/15/03VP3018 1 94 20 Foot chamber foreline GP275 10-3 / 760 Torr 3/303VP3019 1 95 TVS enclosure pressure 3rd level GP275 10-3 / 760 Torr 3/3/03VPC3016 1 CALC Chamber wall box - cold cathode - semi-log HPS 953 107263 10-8 / 10-2 Torr NONEVPD3016 1 CALC Chamber wall box - cold cathode - lin.scale HPS 953 107263 .01 / 1000 uTorr NONET3266 1 96 JUSTAK SIGHT GLASS VENT TEMP. TYPE E 15 / 310 KELVIN NONET3267 1 97 PRESSURANT SUPP. TEMP,E10 FLANGE TYPE E 15 / 310 KELVIN NONET3268 1 98 HEATER SHROUD LN2 SUPPLY TYPE E 15 / 310 KELVIN NONE

Table 11. MHTB ZBO instrumentation list (Continued).
64

20-FT CHAMBER FACILITY MEASUREMENTS

MID LINK SIU CH J-BOX Measurement Description Xducer Serial No. Range UNITS CAL DUE

T939 1 99 COMPRESS DISCHARGE WATER TEMP. TYPE E 15 / 310 KELVIN NONEP3143 1 100 CRYO-COOLER HELIUM SUPPLY TABER 226 810917 0 / 3,447.3 KPAGP3144 1 101 CRYO COOLER HELIUM RETURN TABER 226 810922 0 / 3,447.3 KPAGDP4344 1 CALC P3143 / P3144 DELTA PRESSURE 0 / 3,447.3 KPAD NONEP3145 1 102 PRESSURANT SUPP.PRESS. E10 FLANG TABER 226 890893 0 / 1,378.9 KPAGVP3020 1 103 TVS PUMP-OUT D/S ROV 20-1500 GP275 10-3 / 760 TORR 3/3/03VR3021 1 104 MILLIVOLTS FOR VP3021 GP375 0 / 7000 MV 3/35/03VP3021 1 CALC TVS PUMP-OUT LVL-2 10-3 / 760 TORR NONEVP3022 1 105 CRYO COOLER HELIUM PANEL GP275 10-3 / 760 TORR 3/3/03VP3024 1 106 MHTB MANWAY PUMP-OUT PRESS GP275 10-3 / 760 TORR 3/3/03

NOTES: 6/1/01 - Added T3247, T3248, T3205, F176/11/01 - Deleted: VAV3, VAV4, VAV5, VAV6, VAV7, T3269, VP3017. Added: T939, T3226.6/12/01 - Added: V1, V2, V3, V4, E1, ,E2, I1, I2, I5, I6, I7.6/14/01 - Moved V1, V2, V3, V4, E1, E2, I1, I2, I5, I6, I7 to Real Star, SIU-0. Added calculated measurements DPP1, PPA1, PSB1, PSA1, and associated inputs, PP1, PS1, TPT1, TD23. 

 Moved D1 to another CH.

6/15/01 - Deleted F12, no longer used, not used on last MHTB Test, not a requirement. Moved P3105, VP3016 due to bad CH.6/18/01 - Changed VP3010 to VR3010, VP3011 to VR3011, VP3012 to VR3012, VP3014 to VR3014, and made VP3010, VP3011, VP3012, VP3014 to calculated measurements.7/2/01 - DP1, P1, P2, P3, P4, Moved to Real Star System. Added DP4344, VR3021.

Table 11. MHTB ZBO instrumentation list (Continued).
65

Table 12. MHTB ZBO test article measurements.

TEST ARTICLE MEASUREMENTS

MID LINK SIU CH J-BOX Measurement Description Xducer Serial No. Range UNITS CAL DUEHG1 0 0 Heat guard leg #1 Diode 15 / 310 Kelvin NoneHG3 0 1 Heat guard leg #3 Diode 15 / 310 Kelvin NoneHG5 0 2 Heat guard pressurization line DT-470-BO-11A D02247 15 / 310 Kelvin NoneHG6 0 3 Heat guard fill/drain line DT-470-BO-11A D02256 15 / 310 Kelvin NoneHG7 0 4 Heat guard vent line DT-470-BO-11A D02258 15 / 310 Kelvin NoneHS18 0 5 Inner volume 0.6 m above bottom Type E 15 / 310 Kelvin NoneHS19 0 6 Inner volume 1.2 m above bottom Type E 15 / 310 Kelvin NoneHS20 0 7 Inner volume 1.8 m above bottom Type E 15 / 310 Kelvin NoneHS21 0 8 Inner volume 2.4 m above bottom Type E 15 / 310 Kelvin NoneHS22 0 9 Inner volume 3 m above bottom Type E 15 / 310 Kelvin None

0 100 11

HS75 0 12 Zone 7 4 cm right of HS74A Type E 15 / 310 Kelvin NoneHS76 0 13 Zone 7 8 cm right of HS74A Type E 15 / 310 Kelvin NoneHS77 0 14 Zone 7 12 cm right of HS74A under cooling Type E 15 / 310 Kelvin NoneHS78 0 15 Zone 7 12 cm left of HS711B under cooling Type E 15 / 310 Kelvin NoneHS79 0 16 Zone 7 8 cm left of HS711B Type E 15 / 310 Kelvin None

0 17

HS114 0 18 Zone 11 12 cm right of HS113B Type E 15 / 310 Kelvin NoneHS116 0 19 Zone 11 bottom center Type E 15 / 310 Kelvin NoneHSA1 0 20 Zone 1 top panel under heater Type E 15 / 310 Kelvin NoneHSA2 0 21 Zone 2 top panel under heater Type E 15 / 310 Kelvin NoneHSA3 0 22 Zone 3 top panel under heater Type E 15 / 310 Kelvin NoneHSA4 0 23 Zone 4 top panel under heater Type E 15 / 310 Kelvin NoneHSA5 0 24 Zone 5 left 22.5 deg Type E 15 / 310 Kelvin NoneHSA6 0 25 Zone 6 left 67.5 deg Type E 15 / 310 Kelvin NoneHSA74 0 26 Zone 7 left side under heater Type E 15 / 310 Kelvin NoneBAD CH 0 27HSA9 0 28 Zone 9 left under heater Type E 15 / 310 Kelvin NoneHSA10 0 29 Zone 10 left under heater Type E 15 / 310 Kelvin NoneHSA111 0 30 Zone 11 left side under heater Type E 15 / 310 Kelvin None
66

TEST ARTICLE MEASUREMENTS

MID LINK SIU CH J-BOX Measurement Description Xducer Serial No. Range UNITS CAL DUEHSA12 0 31 Zone 12 left under heater Type E 15 / 310 Kelvin NoneHSA13 0 32 Zone 13 under heater Type E 15 / 310 Kelvin NoneHSA14 0 33 Zone 14 under heater Type E 15 / 310 Kelvin NoneHSA15 0 34 Zone 15 under heater Type E 15 / 310 Kelvin NoneHSA16 0 35 Zone 16 under heater Type E 15 / 310 Kelvin NoneHSB1 0 36 Zone 1 top panel under heater Type E 15 / 310 Kelvin NoneHSB2 0 37 Zone 2 top panel under heater Type E 15 / 310 Kelvin NoneHSB3 0 38 Zone 3 top panel under heater Type E 15 / 310 Kelvin NoneHSB4 0 39 Zone 4 top panel under heater Type E 15 / 310 Kelvin NoneHSB5 0 40 Zone 5 right 22.5 deg Type E 15 / 310 Kelvin NoneHSB6 0 41 Zone 6 right 67.5 deg Type E 15 / 310 Kelvin NoneHSB7 0 42 Zone 7 right side under heater Type E 15 / 310 Kelvin NoneHSB8 0 43 Zone 8 right under heater Type E 15 / 310 Kelvin NoneHSB9 0 44 Zone 9 right under heater Type E 15 / 310 Kelvin NoneHSB10 0 45 Zone 10 right under heater Type E 15 / 310 Kelvin NoneHSB11 0 46 Zone 11 right side under heater Type E 15 / 310 Kelvin None

0 47

HSB13 0 48 Zone 13 under heater Type E 15 / 310 Kelvin NoneHSB14 0 49 Zone 14 under heater Type E 15 / 310 Kelvin NoneHSB15 0 50 Zone 15 under heater Type E 15 / 310 Kelvin NoneHSB16 0 51 Zone 16 under heater Type E 15 / 310 Kelvin NoneHSA17 0 52 Zone 17 under heater Type E 15 / 310 Kelvin None

0 53

IPP1 0 54 Interstitial penet. 3.8 cm from SOFI surface Type E 15 / 310 K Kelvin NoneIPP2 0 55 Interstitial penetration 5 cm from IPPT1 Type E 15 / 310 K Kelvin NoneISS1 0 56 Leg #1 interface support structure Type E 15 / 310 K Kelvin NoneISS3 0 57 Leg #3 interface support structure Type E 15 / 310 K Kelvin NoneLL1 0 58 Tank liquid level Cryomagnetics 0-2.75 Meters NoneV1 0 59 TVS pump on/off status DISCRETE VDC 0/28 VDC Vdc NoneV2 0 60 Tank heater element #1, on/off DISCRETE VDC 0/28 VDC Vdc None

Table 12. MHTB ZBO test article measurements (Continued).
67

TEST ARTICLE MEASUREMENTS

MID LINK SIU CH J-BOX Measurement Description Xducer Serial No. Range UNITS CAL DUEV3 0 61 Tank heater element #2, on/off DISCRETE VDC 0/28 VDC Vdc NoneV4 0 62 TVS pump controller set point ANALOG VOLTS 2 / 10 VDC Hz NoneE1 0 63 Heater voltage Vdc NoneE2 0 64 Heater voltage Vdc NonePUP1 0 65 TVS pump on/off indication 0 / 1000 ofn NoneHSA8 0 66 Zone 8 left under heater TYPE E 15 / 310 Kelvin NoneTL19 0 67 Leg #1 45TH MLI layer TYPE E 15 / 310 Kelvin NoneTM4 0 68 MLI Shield 1 Profile 4 TYPE E 15 / 310 Kelvin NoneTMI2 0 69 MLI Shield 10 Profile 2 TYPE E 15 / 310 Kelvin NoneTMO7 0 70 MLI Shield 45 Profile 7 TYPE E 15 / 310 Kelvin NoneI1 0 71 Heater current Amps NoneI2 0 72 Heater current Amps NoneI5 0 73 TVS pump phase current Amps NoneI6 0 74 TVS pump phase current Amps NoneTD1 0 75 Rake 1 95.4% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD2 0 76 Rake 1 88.1% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD3 0 77 Rake 1 79.2% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD4 0 78 Rake 1 70.1% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD5 0 79 Rake 1 61.1% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD6 0 80 Rake 1 52.0% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD7 0 81 Rake 1 42.9% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD8 0 82 Rake 1 33.9% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD9 0 83 Rake 1 24.8 % fill DT-470-BO-11A 15 / 310 Kelvin NoneTD10 0 84 Rake 1 15.8% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD11 0 85 Rake 1 7.6 % fill DT-470-BO-11A 15 / 310 Kelvin NoneTD12 0 86 Rake 1 1.8 % fill DT-470-BO-11A 15 / 310 Kelvin NoneTD13 0 87 Rake 2 98.0% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD14 0 88 Rake 2 92.0% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD15 0 89 Rake 2 83.7% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD16 0 90 Rake 2 74.6% fill DT-470-BO-11A 15 / 310 Kelvin None

Table 12. MHTB ZBO test article measurements (Continued).
68

TEST ARTICLE MEASUREMENTS

MID LINK SIU CH J-BOX Measurement Description Xducer Serial No. Range UNITS CAL DUETD17 0 91 Rake 2 65.6% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD18 0 92 Rake 2 56.5% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD19 0 93 Rake 2 47.5% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD20 0 94 Rake 2 38.4% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD21 0 95 Rake 2 29.3% fill DT-470-BO-11A 15 / 310 Kelvin NoneTD22 0 96 Rake 2 20.3% fill DT-470-BO-11A 15 / 310 Kelvin NoneI7 0 97 TVS pump phase current Amps NoneTD24 0 98 Rake 2 4.3 % fill DT-470-BO-11A 15 / 310 Kelvin NoneTFD1 0 99 Fill/Drain penetration 2.54 cm from tank wall DT-470-SD-11A D01845 15 / 310 Kelvin NoneTFD2 0 100 Fill/Drain penetration 7cm from TFD1 DT-470-SD-11A D01844 15 / 310 Kelvin NoneTFD3 0 101 Fill/Drain penetration on SOFI above TFD2 Type E 15 / 310 Kelvin NoneTFD4 0 102 Fill/Drain penetration on SOFI above HG6 Type E 15 / 310 Kelvin NoneTM7 0 103 MLI Shield 1 Profile 7 Type E 15 / 310 Kelvin None

0 104

TL13 0 105 Leg 1 1st MLI layer Type E 15 / 310 Kelvin NoneTL14 0 106 Leg #1 45th MLI layer Type E 15 / 310 Kelvin NoneTL15 0 107 Leg #1 10th MLI layer Type E 15 / 310 Kelvin NoneTL16 0 108 Leg #1 18th MLI layer Type E 15 / 310 Kelvin NoneTL17 0 109 Leg #1 25th MLI layer Type E 15 / 310 Kelvin NoneTL18 0 110 Leg #1 36th MLI layer Type E 15 / 310 Kelvin NoneBAD CH 0 111TLA18 0 112 Leg #1 36th MLI layer Type E 15 / 310 Kelvin NoneTLB1 0 113 Leg #1 Boundary Type E 15 / 310 Kelvin NoneTLB3 0 114 Leg #3 Boundary Type E 15 / 310 Kelvin NoneTM1 0 115 MLI Shield 1 Profile 1 Type E 15 / 310 Kelvin NoneTM2 0 116 MLI Shield 1 Profile 2 Type E 15 / 310 Kelvin NoneTM3 0 117 MLI Shield 1 Profile 3 Type E 15 / 310 Kelvin NoneBAD CH 0 118TM5 0 119 MLI Shield 1 Profile 5 Type E 15 / 310 Kelvin NoneTM6 0 120 MLI Shield 1 Profile 6 Type E 15 / 310 Kelvin None

Table 12. MHTB ZBO test article measurements (Continued).
69

TEST ARTICLE MEASUREMENTS

MID LINK SIU CH J-BOX Measurement Description Xducer Serial No. Range UNITS CAL DUEBAD CH 0 121TMH1 0 122 Manhole outer flange (180) by TMH1 Type E 15 / 310 Kelvin NoneTMH2 0 123 Manhole outer flange (0) opp. TCMH1 Type E 15 / 310 Kelvin NoneTMI1 0 124 MLI Shield 10 Profile 1 Type E 15 / 310 Kelvin NoneBAD CH 0 125TMI3 0 126 MLI Shield 10 Profile 3 Type E 15 / 310 Kelvin NoneTMI4 0 127 MLI Shield 10 Profile 4 Type E 15 / 310 Kelvin NoneTMI5 0 128 MLI Shield 10 Profile 5 Type E 15 / 310 Kelvin NoneTMI6 0 129 MLI Shield 10 Profile 6 Type E 15 / 310 Kelvin NoneTMI7 0 130 MLI Shield 10 Profile 7 Type E 15 / 310 Kelvin NoneTMM1 0 131 MLI Shield 25 Profile 1 Type E 15 / 310 Kelvin NoneTMM2 0 132 MLI Shield 25 Profile 2 Type E 15 / 310 Kelvin NoneTMM3 0 133 MLI Shield 25 Profile 3 Type E 15 / 310 Kelvin NoneTMM4 0 134 MLI Shield 25 Profile 4 Type E 15 / 310 Kelvin NoneTMM5 0 135 MLI Shield 25 Profile 5 Type E 15 / 310 Kelvin NoneTMM6 0 136 MLI Shield 25 Profile 6 Type E 15 / 310 Kelvin NoneTMM7 0 137 MLI Shield 25 Profile 7 Type E 15 / 310 Kelvin NoneTMN1 0 138 Manhole 0 deg Diode 15 / 310 Kelvin NoneTMN3 0 139 Manhole 90 deg Diode 15 / 310 Kelvin None

0 140

TMO1 0 141 MLI Shield 45 Profile 1 Type E 15 / 310 Kelvin NoneTMO2 0 142 MLI Shield 45 Profile 2 Type E 15 / 310 Kelvin NoneTMO3 0 143 MLI Shield 45 Profile 3 Type E 15 / 310 Kelvin NoneTMO4 0 144 MLI Shield 45 Profile 4 Type E 15 / 310 Kelvin NoneTMO5 0 145 MLI Shield 45 Profile 5 Type E 15 / 310 Kelvin NoneTMO6 0 146 MLI Shield 45 Profile 6 Type E 15 / 310 Kelvin NoneBAD CH 0 147

0 1480 149

TPL1 0 150 Pressurization line 3.8 cm from tank CY7 - SD1 D03906 15 / 310 Kelvin None

Table 12. MHTB ZBO test article measurements (Continued).
70

TEST ARTICLE MEASUREMENTS

MID LINK SIU CH J-BOX Measurement Description Xducer Serial No. Range UNITS CAL DUETPL2 0 151 Pressurization line 7.6 cm from tank CY7 - SD1 D03907 15 / 310 Kelvin NoneTPL3 0 152 Pressurization Line SOFI above TPL2 Type E 15 / 310 Kelvin NoneTPL4 0 153 Pressurization line SOFI above HG5 Type E 15 / 310 Kelvin None

0 1540 1550 1560 157

TSF1 0 158 #1 (90) 1.25” on foam pressurization DT-470-SD-11A 15 / 310 Kelvin None

0 159

TSF3 0 160 #3 (90) barrel midplane DT-470-SD-11A 15 / 310 Kelvin NoneTSF4 0 161 #4 (210) barrel midplane DT-470-SD-11A 15 / 310 Kelvin NoneTSF5 0 162 #5 (330) barrel midplane DT-470-SD-11A 15 / 310 Kelvin None

0 1630 164

TSL1 0 165 Leg # 1 1” below tank leg adapter Diode 15 / 310 Kelvin NoneTSL2 0 166 Leg # 1 3” below tank leg adapter Diode 15 / 310 Kelvin NoneTSL3 0 167 Leg # 3 1” below tank leg adapter Diode 15 / 310 Kelvin NoneTSL4 0 168 Leg # 3 3” below tank leg adapter Diode 15 / 310 Kelvin NoneTSL5 0 169 Leg #1 comp profile 20.8 cm from socket Type E 15 / 310 Kelvin NoneTSL6 0 170 Leg #1 comp profile 25.4 cm from socket Type E 15 / 310 Kelvin NoneTSL7 0 171 Leg #1 comp profile 30.48 cm from socket Type E 15 / 310 Kelvin NoneTSL8 0 172 Leg #1 comp profile 35.56 cm from socket Type E 15 / 310 Kelvin NoneTSL9 0 173 Leg #1 comp profile 40.64 cm from socket Type E 15 / 310 Kelvin NoneTSL10 0 174 Leg #1 comp profile 45.72 cm from socket Type E 15 / 310 Kelvin NoneTSL11 0 175 Thin SOFI by zero g vent penetration Type E 15 / 310 Kelvin NoneTSL12 0 176 Thick SOFI by lower trunoin Type E 15 / 310 Kelvin NoneTSL14 0 177 Leg #1 interior below SOFI Type E 15 / 310 Kelvin NoneTSL15 0 178 Leg #3 interior below SOFI Type E 15 / 310 Kelvin NoneTSL17 0 179 Leg #1 SOFI profile 10.2 cm from socket Type E 15 / 310 Kelvin NoneTSL18 0 180 Leg #1 SOFI profile 2.54 cm from socket Type E 15 / 310 Kelvin None

Table 12. MHTB ZBO test article measurements (Continued).
71

TEST ARTICLE MEASUREMENTS

MID LINK SIU CH J-BOX Measurement Description Xducer Serial No. Range UNITS CAL DUETSL19 0 181 Leg #1 SOFI profile -5.08 cm from socket Type E 15 / 310 Kelvin NoneTSS1 0 182 Temperature support structure Type E 15 / 310 Kelvin NoneTSS2 0 183 Temperature support structure Type E 15 / 310 Kelvin NoneTSS3 0 184 Temperature support structure Type E 15 / 310 Kelvin NoneTSS4 0 185 Temperature support structure Type E 15 / 310 Kelvin NoneTTB1 0 186 Inner MLI tank bottom Type E 15 / 310 Kelvin NoneTTB2 0 187 Outer MLI Ttank bottom Type E 15 / 310 Kelvin NoneTUP1 0 188 Ullage pressure line Type E 15 / 310 Kelvin NoneTUP2 0 189 Ullage pressure line Type E 15 / 310 Kelvin None

0 1900 191

TVL1 0 192 Vent line penetration 3” CY7 - SD1 D03908 15 / 310 Kelvin NoneTVL2 0 193 Vent line penetration 2” CY7 - SD1 D03910 15 / 310 Kelvin NoneTVL3 0 194 Vent line penetration top flange DT-470-BO-11A D02257 15 / 310 Kelvin NoneTVL4 0 195 Rake 1 99.2% fill DT-470-SD-11A 15 / 310 Kelvin NoneTVL5 0 196 Rake 1 99.2% fill DT-470-SD-11A 15 / 310 Kelvin NoneTVL6 0 197 Vent line penetration SOFI above TVL2 Type E 15 / 310 Kelvin NoneTVL7 0 198 Vent line penetration SOFI 15 cm from TVL6 Type E 15 / 310 Kelvin NoneTW1 0 199 T. wall barrel 255 98.9% ullage DT-470-SD-11A 15 / 310 Kelvin NoneTW2 0 200 T. wall barrel 255 83.7% ullage DT-470-SD-11A 15 / 310 Kelvin NoneTW3 0 201 T. wall barrel 255 63.6% ullage DT-470-SD-11A 15 / 310 Kelvin NoneTW4 0 202 T. wall barrel 255 43.5% ullage DT-470-SD-11A 15 / 310 Kelvin NoneTW5 0 203 T. wall barrel 255 23.3% ullage DT-470-SD-11A 15 / 310 Kelvin None

0 204

PL25 0 205 Liquid level 25% fill 118CPS 0/10 VOLTS Volts NonePL50 0 206 Liquid level 50% fill 118CPS 0/10 VOLTS Volts NonePL1 0 207 Sierra Lobo pt. Lvl. sensor 61.1% DT470SD-11A 15 / 310 Kelvin NonePL2 0 208 SIERRA LOBO PT. LVL.SENSOR TOP DT470SD-11A 15 / 310 Kelvin NONE

Table 12. MHTB ZBO test article measurements (Continued).
72

TEST ARTICLE MEASUREMENTS

MID LINK SIU CH J-BOX Measurement Description Xducer Serial No. Range UNITS CAL DUE

CRYOCOOLER (ZBO-Specific) INSTRUMENTATION

GD1 0 209 Gallium diode TP022SQNO04 10093 15 / 310 KelvinGD2 0 210 Gallium diode TP022SQNO04 10094 15 / 310 KelvinGD4 0 211 Gallium diode TG120P 10031 15 / 310 KelvinGD5 0 212 Gallium diode TG120P 10024 15 / 310 KelvinGD6 0 213 Gallium diode TG120P 10025 15 / 310 KelvinGD7 0 214 Gallium diode TG120P 10026 15 / 310 KelvinGD8 0 215 Gallium diode TG120P 10027 15 / 310 KelvinGD9 0 216 Gallium diode TG120P 10028 15 / 310 KelvinGD10 0 217 Gallium diode TG120P 10029 15 / 310 KelvinGD11 0 218 Gallium diode TG120P 10032 15 / 310 Kelvin

0 2190 220

SD102 0 221 Silicon diode DT-470 D30429 15 / 310 Kelvin NoneSD103 0 222 Silicon diode DT-470 D30430 15 / 310 Kelvin NoneSD104 0 223 Silicon diode DT-470 D30431 15 / 310 Kelvin NoneSD105 0 224 Silicon diode DT-470 D30432 15 / 310 Kelvin NoneSD106 0 225 Silicon diode DT-470 D30433 15 / 310 Kelvin NoneSD107 0 226 Silicon diode DT-470 D30434 15 / 310 Kelvin NoneSD108 0 227 Silicon diode DT-470 D30435 15 / 310 Kelvin NoneHTC25 0 228 Motor heater temp. top TYPE E 15 / 310 Kelvin NoneHTC26 0 229 Motor heater temp. bottom TYPE E 15 / 310 Kelvin None

0 230

TPT2 0 231 Temp. press. Transducer TVS - backup TYPE E 15 / 310 Kelvin NoneTPA1 0 232 Tvs pump inlet temp. TYPE E 15 / 310 Kelvin NoneTPA2 0 233 Tvs outlet temp. TYPE E 15 / 310 Kelvin NoneTCP1 0 234 Manway pumpout line temp. TYPE E 15 / 310 Kelvin NoneTCP2 0 235 Manway pumpout line temp. TYPE E 15 / 310 Kelvin None

0 236

FM1 0 237 Flowmeter FT24AESWLAAS 2402088 15/150 GPM None

Table 12. MHTB ZBO test article measurements (Continued).
73

TEST ARTICLE MEASUREMENTS

MID LINK SIU CH J-BOX Measurement Description Xducer Serial No. Range UNITS CAL DUECHT1 0 238 Copper hsg surface temp. top DT470SD-11A 15 / 310 Kelvin NoneCHT2 0 239 Copper hsg surface temp. bot DT470SD-11A 15 / 310 Kelvin NoneHT1 0 240 Cryo cooler hsg wall temp. top TYPE E 15 / 310 Kelvin NoneHT2 0 241 Cryo cooler hsg wall temp. bot TYPE E 15 / 310 Kelvin NoneDP1 0 242 Ullage differential pressure MKS 698 95256248A 0 / 133.332 PAD 4/20/03P1 0 243 Ullage pressure MKS 390 59135-4B 0 / 133.332 KPAA 2/26/03P2 0 244 Ullage pressure TABER 254 781298 0 / 350 KPAG 2/16/03P3 0 245 Reference pressure vessel MKS 690 92150128A 0/ 133.332 KPAA 3/24/03P4 0 246 Ullage pressure MKS 390 19551-3B 0 /34.473 MPAA 4/5/03

NOTES:6/11/01 - Deleted: P501, P502, PJ1, PJ2, PUP2, PV2, T601, T602, T603, T604, T605, TCP1, TCP2, TJT1, TJT2, TSA1, TSA2, TVA1, TVA2.6/11/01 - Corrected typo HSA74, HSA1116/12/01 - Deleted: TSF2, TSF6, TSF7, TW6 Damaged unable to repair at this time. added HSA17. Moved HSA8, TL19, TM4, TMI2, TMO7 due to bad SIU CH.6/14/01 - Moved calculated measurements to SIU-1, DPP1, PSA1, PPA1, PSB1, and associated inputs TPT1, TD23, PP1, PS1. Deleted PS10, PS20, PS30, T1, 

 T2, PTC28, PTC27. Added V1, V2, V3, V4, E1, E2, I1, I2, I5, I6, I7.

7/2/01 - Deleted HS72, HS73, HS112, HSB12, (OPEN T/C beads), TMN4, (unable to locate), GD12, SD101, (grounded silicon diode to facility). 

 Added DP1, P1, P2, P3, P4. Deleted PVA2, not used no transducer found.

7/6/01 - Added TCP1, TCP2.

Table 12. MHTB ZBO test article measurements (Continued).
74

APPENDIX F—FLUID SYSTEM FOR THE MULTIPURPOSE HYDROGEN TEST BED 

TANKING ZERO-BOILOFF DEMONSTRATION

Figure 29 is a schematic of the MHTB test article system and figure 30 is the cryo-refrigerator 

He system schematic.
75

Figure 29. Schematic for MHTB ZBO demonstration.
76

Figure 30. Schematic for cryo-refrigerator He system.
77

APPENDIX G—MULTIPURPOSE HYDROGEN TEST BED TEST REQUEST SHEET

G.1 Zero-Boiloff Cryogenic Storage/Optical Mass Gauging Sensor Testing

Test Name: Multipurpose Hydrogen Test Bed Heat Removal System (HRS) 

and Optical Mass Gauging Sensor (OMGS) Test 

Test Project ID: P2111 Test Requester: Leon Hastings/Chad Bryant

Test Date: 7/21/01 Test Conductor: Ed Johnson

Test Objectives:

• Demonstrate the flexibility, repeatability, and baseline the accuracy of the OMGS.

• Demonstrate the capability of the Sierra Lobo Cryotracker liquid level sensor.

• Measure steady-state boiloff to assess baseline insulation performance. These tests will also serve 

to set up the initial fluid conditions for HRS operations.

• Demonstrate and quantify the performance of ‘zero-gravity’ tank pressure control concepts 

in the 18 m3 (640 ft3) MHTB tank under normal gravity but in a simulated space thermal environment. This concept includes a radial flow HRS (equipped with a spray bar, HX, cryocooler, pump, 

and LH2 heater).

Test Fluid: LH2

Approximate Test Duration: 600 hr (25 days)

Data System Unit (DSU) Sampling Rate: High: One sample per second (used during system 

changes)

Low: One sample per 60 s (used during system monitoring)

(Note: Sampling rates can be adjusted by test engineer’s discretion.)

Sampling Start/End Time: 1/2 hr before chill/fill through test completion

Vacuum Chamber/Pump Operation: Orbit simulation—hard vacuum condition 10–6 torr range 

or better (evacuate chamber 24 hr before tanking)

Vacuum Chamber Purge: Dry GN2 (dewpoint –54 °C) initiate 3 days before test
78

Vacuum Chamber Coldwalls: LN2 at ≈80 K

Tank Pressure Control: Set up ice bath and constant pressure volume (set ref. vessel @ ≈17 psia)/

ice bath 2 days before testing to obtain steady-state environment. Check ice 

bath at 1- to 2-hr intervals. Fill or pack as needed to prevent temperature 

drift. Document all operations in the test log.

Other Vacuum Systems: Pump down HRS enclosure and test article manhole annulus before testing. 

Document all operations in the test log.

RGA Operation: Periodic as needed (write DSU times and file number on plots)

Camera Operation: Not required

Test Article Internal Purge: Holding: Dry (dewpoint –54 °C) missile grade air or GN2

Pretest: Dry GH2 or GHe 

Post-test: Dry GHe (when tank is below 100 K)

Dry GN2 (when tank is above 100 K)

Dry missile-grade air (MGA) (when tank is at ambient temperature)

Test Article Fill Level: ≈90+% First test condition (LH2)

≈25% Second test condition (LH2)

≈50% Third test condition (LH2)

Test Article Shroud Purge: May be required as needed

Test Article Shroud: Heating: Start/Stop: Continuous throughout test

Settings: 159–169 K

Cooling: As required to maintain temperature of 164 K

Test Article Ullage Pressure Control: Setting: 117.2 kPa (17 psia) or near

(used for boiloff testing only) Tolerance: Orbit ± 0.007 kPa (0.001 psi)

Duration: Steady-state boiloff interval

Chamber Pressurization: Minimum temperature of facility/test article: 85 K

Purge gas type: Dry GN2 or MGA (dewpoint –54 °C)

Pressurization rate: 30-min repressurization

Maximum time test article left at vacuum after test: 48 hr

Specific Test Hardware Parameters: Real-time adjustments of some of the parameters listed below 

may be required based on actual measured MHTB heat leak. 

Document all operations in the test log.

Radial Flow HRS Inputs: • Psat = calculated from TD23

• Pmax = 124.106 kPa (18 psia)
79

• Pmin = 110.316 kPa (16 psia)

• PSA1 = 117.211 kPa (17 psia)

• Pump flow rate = 37.854 L/min (10 gal/min)

• Initial fluid saturation pressure = ≈110.32 kPa (≈16 psia)

• Use active control logic to operate LH2 heater

Additional General Instructions:

• Document file names and time stamps for all events in figure 31.

Activity

Chill/fill to 90+%

LH2 stratification

Baseline LH2 boiloff

Ullage pressure trend

LH2 HRS testing

Drain to 25%

LH2 HRS testing

Fill to 50%

Off-normal testing

Test Days

1 2 4 6 8 10 12 14 18 20 22 24 26

Figure 31. Test matrix timeline.

• Spray bar: After tanking is completed, the pump/motors shall be calibrated to determine the operational frequency for a flow rate of 37.854 L/min (10 gal/min). This value shall be noted in the test 

logbook and used for system operation.

• Steady-state criteria for boiloff: Real-time judgment is necessary to determine the onset of steadystate conditions; hence, discussion between the test requester and test engineer is critical to overall 

test success. (This approach has been used during past testing of this type quite successfully.) Basic 

parameters will include the following:

– MLI shield temperature change of 0.15 K/hr, averaged over a 6-hr timespan.

– Boiloff flow has stabilized to a change of <0.5 % per hour, averaged over a 6-hr timespan.

– Vacuum chamber and MLI interstitial pressure stable in the 10–6 torr range.

– Minimum 6 hr test data should be recorded past the onset of steady-state conditions 

(if time permits).

• General HRS operation: Real-time judgment is necessary to determine when sufficient component cycles have occurred; hence, discussion between the test requester and test engineer 

is critical to overall test success. (This approach has been used during past testing of this type quite 

successfully.) Basic parameters will include the following:
80

– Combined pump and cryocooler operation and multiple LH2 heater cycles.

– Potential for real-time changes in PSA1, Pmin, Pmax, and pump flow rate.

• Facility power outage/DSU and RS off-line: During any condition requiring that the DSU/RS or 

other systems be off-line (i.e., tape changes, power outages), tank pressure control must be maintained to prevent subcooling of the LH2. All facility systems related to the tank pressure control 

system and the tank vent must use an uninterruptible power supply. Subcooling of the tanked LH2

will have a disastrous effect on the overall test timeline.
81

REFERENCES

1. Hastings, L.J.; Plachta, D.W.; Salerno, L.; and Kittel, P.: “An Overview of NASA Efforts 

on Zero Boiloff Storage of Cryogenic Propellants,” Cryogenics, Vol. 41, pp. 833–839, 2002.

2. Plachta, D.W.: “Hybrid Thermal Control Testing of a Cryogenic Propellant Tank,” NASA/

TM—1999–209389, Glenn Research Center, Cleveland, OH, August 1999; in Advances 

in Cryogenic Engineering, Kluwer Academic/Plenum Press, New York, Vol. 45, pp. 465–472, 2000.

3. Hastings, L.J.; and Martin, J.J.: “Large-Scale Liquid Hydrogen Testing of a Variable Density 

Multilayer Insulation With a Foam Substrate,” NASA/TM—2001–211089, Marshall Space Flight 

Center, AL, June 2001.

4. Walker, G.: Cryocoolers, Part 1: Fundamentals, Plenum Press, New York, pp. 237–263, 1983.

5. Gifford, W.E.: “The Gifford-McMahon Cycle,” in Advances in Cryogenic Engineering, 

M. Timmerhaus (ed.), Plenum Press, New York, Vol. 11, pp. 152–159, 1966.

6. Flachbart, R.H.; Hastings, L.J.; and Martin, J.J.: “Testing of a Spray Bar Zero Gravity 

Cryogenic Vent System for Upper Stages,” AIAA Paper No. AIAA–99–2175, presented 

at the 35th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Los Angeles, 

CA, June 20–24, 1999.

7. Nguyen, H.: “Zero-G Thermodynamic Venting System (TVS) Performance Prediction 

Program,” Rockwell International Corp., Downey, CA, Contract NAS8–39202, Final Report, 

May 24, 1994.
82

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Large-Scale Demonstration of Liquid Hydrogen Storage

With Zero Boiloff for In-Space Applications

L.J. Hastings,* C.B. Bryant, R.H. Flachbart, K.A. Holt, E. Johnson, 

A. Hedayat, B. Hipp, and D.W. Plachta**

George C. Marshall Space Flight Center

Marshall Space Flight Center, AL 35812

National Aeronautics and Space Administration

Washington, DC 20546–0001

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Subject Category 20

Availability: NASA CASI (443–757–5802)

Prepared by the Propulsion Systems Department, Engineering Directorate

*Alpha Technology, Inc., Huntsville, AL, **Glenn Research Center, Cleveland, OH

M–1302

Technical Publication

NASA/TP—2010–216453

orbital cryogenic fluid management, orbital cryogenic storage, zero-gravity cryogenic pressure control,

zero-boiloff cryogenic storage

01–12–2010

UU 92

NASA

U U U

Cryocooler and passive insulation technology advances have substantially improved prospects for zeroboiloff cryogenic storage. Therefore, a cooperative effort by NASA’s Ames Research Center, Glenn 

Research Center, and Marshall Space Flight Center (MSFC) was implemented to develop zero-boiloff 

concepts for in-space cryogenic storage. Described herein is one program element—a large-scale, zeroboiloff demonstration using the MSFC multipurpose hydrogen test bed (MHTB). A commercial cryocooler was interfaced with an existing MHTB spray bar mixer and insulation system in a manner that 

enabled a balance between incoming and extracted thermal energy.

STI Help Desk at email: help@sti.nasa.gov

STI Help Desk at: 443–757–5802
The NASA STI Program...in Profile

Since its founding, NASA has been dedicated to the 

advancement of aeronautics and space science. The 

NASA Scientific and Technical Information (STI) 

Program Office plays a key part in helping NASA 

maintain this important role.

The NASA STI Program Office is operated by 

Langley Research Center, the lead center for 

NASA’s scientific and technical information. The 

NASA STI Program Office provides access to 

the NASA STI Database, the largest collection of 

aeronautical and space science STI in the world. 

The Program Office is also NASA’s institutional 

mechanism for disseminating the results of its 

research and development activities. These results 

are published by NASA in the NASA STI Report 

Series, which includes the following report types:

• TECHNICAL PUBLICATION. Reports of 

completed research or a major significant 

phase of research that present the results of 

NASA programs and include extensive data 

or theoretical analysis. Includes compilations 

of significant scientific and technical data 

and information deemed to be of continuing 

reference value. NASA’s counterpart of peerreviewed formal professional papers but has less 

stringent limitations on manuscript length and 

extent of graphic presentations.

• TECHNICAL MEMORANDUM. Scientific 

and technical findings that are preliminary or of 

specialized interest, e.g., quick release reports, 

working papers, and bibliographies that contain 

minimal annotation. Does not contain extensive 

analysis.

• CONTRACTOR REPORT. Scientific and 

technical findings by NASA-sponsored 

contractors and grantees.

• CONFERENCE PUBLICATION. Collected 

papers from scientific and technical conferences, 

symposia, seminars, or other meetings sponsored 

or cosponsored by NASA.

• SPECIAL PUBLICATION. Scientific, technical, 

or historical information from NASA programs, 

projects, and mission, often concerned with 

subjects having substantial public interest.

• TECHNICAL TRANSLATION. 

English-language translations of foreign 

scientific and technical material pertinent to 

NASA’s mission.

Specialized services that complement the STI 

Program Office’s diverse offerings include creating 

custom thesauri, building customized databases, 

organizing and publishing research results...even 

providing videos.

For more information about the NASA STI Program 

Office, see the following:

• Access the NASA STI program home page at 

<http://www.sti.nasa.gov>

• E-mail your question via the Internet to 

<help@sti.nasa.gov>

• Fax your question to the NASA STI Help Desk 

at 443–757–5803

• Phone the NASA STI Help Desk at 

443 –757–5802

• Write to:

NASA STI Help Desk

NASA Center for AeroSpace Information

7115 Standard Drive

Hanover, MD 21076–1320
National Aeronautics and

Space Administration

IS20

George C. Marshall Space Flight Center

Marshall Space Flight Center, Alabama

35812