NBSIR 76-850

LIQUID HELIUM STORAGE AT HIGH DENSITY AND DISCHARGE

AT HIGH FLOW RATES

David E. Daney

Cryogenics Division

Institute for Basic Standards

National Bureau of Standards

Boulder, Colorado 80302

December 1976

Prepared for:

Air Force Weapons Laboratory

Kirtland Air Force Base

Albuquerque, New Mexico 87117

NBSIR 76-850

LIQUID HELIUM STORAGE AT HIGH DENSITY AND DISCHARGE

AT HIGH FLOW RATES

David E. Daney

Cryogenics Division

Institute for Basic Standards

National Bureau of Standards

Boulder , Colorado 80302

December 1976

Prepared for:

Air Force Weapons Laboratory

Kirtland Air Force Base

Albuquerque, New Mexico 87117

U.S. DEPARTMENT OF COMMERCE, Elliot L. Richardson, Secretary

Edward 0. Vetter, Under Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

CONTENTS

Page

1. INTRODUCTION 1

2. ANALYSIS 4 2.1. Fill Process 4 2.2. Pressurization - Discharge Process 5 2.3. Mixing 5

3. 'EXPERIMENTAL SYSTEM 6 3.1. Fill System 8 3.2. Test Dewar 14 3.3. Discharge System . 14 3.4. Instrumentation 17

4. RESULTS AND DISCUSSION 20

4.1. Fill Process 22 4.2. Discharge Process 23

5. SUMMARY AND CONCLUSIONS 33

6. ACKNOWLEDGEMENTS 36

7. NOMENCLATURE 36

8. REFERENCES 37 APPENDIX Discharge Data for Experiment 6 38

iii
ABSTRACT

Equipment to store supercritical helium at high density and to demonstrate pulsed discharge at high flow rates has been designed, fabricated and successfully tested. A

storage density of 0.193 x 10

3 kg/m3 (12.03 lb/ft 3

) at 8.3 MPa (81 atm) was achieved in a 135

liter (35 gal) dewar. Pulsed discharges of 2/ seconds and 4 seconds duration were demonstrated at a flow rate of 1.0 kg/s (2.2 lb/s), and flow fluctuations of less than ± 1 percent were achieved without feedback control. In general, the system operated in a very

stable and well behaved manner.

Key words: Cryogenic helium supply system; cryogenic storage; helium; helium supply system;

high density helium storage; liquid helium storage; supercritical heliumiv
1. INTRODUCTION

The Air Force Weapons Laboratory has developed a requirement for bulk storage and discharge of cryogenic helium at densities and flow rates significantly in excess of previous

3 3 3 applications. They require densities approaching 0.2 x 19 kg/m (12.5 lb/ft ) and pulsed

flow rates of several kg/s. By comparison, the Apollo Lunar Module Helium Storage System has 3,3 3 a fill density of 0.13 x 10 kg/m (8.1 lb/ft ) and a discharge rate of 0.04 kg/s

(0.09 lb/s)[l]. In order to demonstrate the practical feasibility of a system meeting these

requirements, the NBS Cryogenics Division was asked to design, build, and test a system to:

3 3 3 1. Store helium in a dewar at a density approaching 0.2 x 10 kg/m (12.5 lb/ft ) with a pressure less than 10.3 MPa (102 atm) , and

2. discharge helium in pulses of 2 seconds or more and at a flow rate of at least

1.0 kg/s (2.2 lb/s) at greater than 3.5 MPa (35 atm) pressure.

In addition to these specific objectives, more general goals were to demonstrate a relatively large field-type system, measure the operating parameters of this system, and

identify possible problems the system might have. Thus the task was to go from concept to practice, providing design information such as dewar fill time, agreement with equilibrium

thermodynamic calculations, temperature stratification, mixing of the pressurant entrance

jet, practical fluid supply temperatures, and blower requirements and performance. The

laying to rest of potential problems that fail to occur is also an important result of the

study

.

The principal constraint on the project was that the results were required within seven

months. Consequently, existing equipment was employed whenever possible, necessitating some design compromises. For example, the use of an Appolo oxygen dewar for the test vessel

restricted the maximum fill pressure to 8 MPa (81 atm) and resulted in some crowding in the

dewar neck.

The method of filling the test dewar is shown schematically in figure 1. The dewar is

first filled with boiling-point liquid helium, after which it is pressurized with cold helium

to the final fill pressure. Starting at ambient temperature, this helium is cooled to 80 K

(144° R) in the precooler and then to about 4.5 K (8.1° R) in the subcooler before it enters

the test dewar. The heat of compression of the helium in the dewar is removed by the test dewar cooler. Because of the relatively high compressibility of liquid helium, fill densities

60% greater than normal-boiling-point-liquid density can be obtained at 10 MPa (100 atm)

pressure by this method.

The discharge system, figure 2, achieves a constant mass flow rate by maintaining constant pressure and temperature at the discharge nozzle during flow. Self pressurization of

the dewar is accomplished by the blower-heat-exchanger loop in the upper portion of the

figure. Cold fluid is drawn from the bottom of the dewar, warmed to ambient temperature, and

returned to the top of the dewar. Temperature stratification results, and as fluid is drawn

from the dewar, a warm zone propagates towards the bottom.

Demonstrations of the completed system were highly successful and indicated that the

desired storage densities and discharge rates are indeed practical and require no technical

3
advances - only careful application of the existing state of the art. In the 135 liter (35

3 3 3 gal.) test dewar a density of 0.193 x 10 kg/m (12.03 lb/ft ) was achieved at 8.2 MPa (81 atm) 3,3 3 the maximum dewar operating pressure. Although lower than the 0.2 x 10 kg/m (12.5 lb/ft")

goal, extrapolation of the density-pressure fill curve gives the goal density at the 10 MPa

(102 atm) pressure limit. Discharge rates of 1 kg/s with a variability of less than + 1% were achieved without feedback control; and in general, the system operated in a very stable

and well-behaved manner. \

2. ANALYSIS

Several system processes merit careful analysis, viz., the fill process, the pressurization-discharge process, and mixing of the temperature stratified contents of the dewar.

Whereas analysis of the first two processes is necessary for the design of the fill and

discharge systems, the last process is important in considering field applications in which

sudden changes in dewar orientation might occur.

2.1 Fill Process

Consider the open system shown below.

The First Law of Thermodynamics for this system is

AE = Q - W + h.Am.

.

li (1)

Noting that the shaft work, W, is zero, and expanding the internal energy term gives

m u - m1 u 1 = Q + h.Am.,

2 2 11 li (2)

where subscripts 1 and 2 refer to the initial and final states, respectively. Now

Am_^ = - m^

,

so that eq. (2) becomes
m

l Q m

l u„ = — u. + + h. (1 - —) . (3) 2 m

2 1 m

2 i m' v

Using the definition of density

gives

m

2

p 2

and eq. (3) becomes

P l

P lP 0 Q

P l u = — Ul + — — + h. (1 - —) . (4) 2 p 2 1 p 2 P]

_ m0

i p 2

Absence of a simple equation of state requires that eq. (4) be solved by iteration since

P 2 appears on the right hand side and is unknown. The helium thermodynamic property programs

of McCarty [2] and Arp [3] were used in the numerical solution of eq. (4).

2.2 Pressurization - Discharge Process

During the discharge from the dewar we achieved constant discharge mass flow rate by

maintaining the dewar pressure constant. This condition requires that the volume flow rate

of the pressurant gas be equal to the volume flow rate of the fluid leaving the dewar. This

intuitively obvious statement is easily demonstrated by considering a control volume of fixed

dimensions moving along a column of temperature stratified fluid. The motion of the control

volume does not affect the pressure in the column (neglecting the hydrostatic effect) , and

the fixed dimensions require equal volumes entering and leaving. When we consider that a portion of the discharged stream is recirculated as pressurant, we obtain

o

P i /P 0 o

( _. m. = • m (5)

for the pressurant mass flow rate, where the subscript i refers to the warm pressurant, and

the subscript 0 refers to the cold discharge fluid.

2.3 Mixing

In some field applications sudden changes in dewar orientation might occur, and it is

important to know what changes in dewar pressure could result from the consequent mixing of

the temperature-stratified contents. If a sudden pressure rise were to occur, rupture of the

dewar might result. A large pressure decline could temporarily reduce the discharge capacity

of the system.

5
Let us consider a system initially divided into n subsystems, each one of

internally in a state of stable equilibrium, and which is in thermal isolation

neighbors and the surroundings. Pressure equilibrium is assumed.

which is

from its

Let mixing or thermal equilibrium of the total system occur. During this process there is no external work, heat transfer with the surroundings, or mass flow; so the first law of thermodynamics becomes

AU = 0.

The mean specific internal energy is given by

Eu .m.

1 1 E.u.p.X. 1111

E.p .X. ill (6)

where X. is a volume fraction.

i The mean density of the fluid in the dewar is given by

(7)

Equations (6) and (7) define the initial and, for this process, the final state of the

fluid in the dewar. The final pressure is then obtained by iteration for the state p, u.

3. EXPERIMENTAL SYSTEM

The experimental system, figure 3, is comprised of three subsystems: the fill system,

the test dewar, and the discharge system.

In the fill system, a single fill line serves the dewar. Liquid transfer occurs with

valve V-23 open, and supercritical fluid transfer with V-23 closed. The test dewar is initially filled with liquid helium, via V-23, the vent valve V-34 is closed (along with V-23),

and the dewar is then pressurized and filled with supercritical helium (T - 4.5 K) from the

subcooler. Continuous transfer from the helium supply dewar to the subcooler occurs during

this fill operation. High pressure (16 MPa, 160 atm) helium gas, supplied from a 1100 std. nf (40,000 scf) tube trailer, passes through a molecular sieve purifier and then to a domeloaded pressure regulating valve which controls the pressure and flow rate. Passing to the

precooler, the helium is then cooled to near 80 K (144°R) by helium and nitrogen boil-off gas

in the three-pass counter flow heat exchange of the precooler. Cooling to 80 K (144° R)
7
occurs in the coil immersed in liquid nitrogen (LN^) , and trace impurities are removed in the

charcoal purifier. Further cooling to near 5 K (9°R) by the helium boil-off gas then occurs

in the two-pass counter flow heat exchanger, which is vacuum and multilayer insulated. After

passing through a vacuum- insulated transfer line to the subcooler, the final temperature of

4.5 K is achieved in the liquid helium cooled coil. Finally, the stream passes through a second transfer line (vacuum insulated and vapor shielded) to the test dewar

.

The test dewar cooler is supplied with liquid helium drawn from the subcooler and

throttled through valve V-24. The cooler boil-off stream is split as it emerges from the

dewar with one stream cooling shields on the transfer line and subcooler. The other stream

cools an antipercolation line in the Apollo dewar, which was originally thought to be a shield line.

The discharge system is composed of the main heat exchanger, the blower heat exchanger

and the blower. Pulsed, constant flow rate discharges of 1 kg/s are achieved by simultaneously starting the blower and opening valves V-31 and V-32 (V-33 is open except during

filling). The blower and its associated heat exchanger provide the high flow rate of pressurant gas required to maintain constant pressure in the test dewar during the discharge.

Regulation of the discharge rate is achieved by the fixed diameter discharge nozzle. By

supplying this nozzle with gas of a relatively constant temperature and pressure, the desired

fixed flow rate is achieved. Discharge flow measurement is achieved by simply measuring the

temperature and pressure at the inlet to this sonic nozzle.

General views of the apparatus are given in figures 4 and 5, and figure 6 shows details

near the test dewar. Operation of the test dewar at high pressures required installation of

the equipment behind a protective concrete wall and operation by remote control when pressurized. The main control panel, located in an adjacent trailer, is shown in figure 7.

3.1 Fill System

The heat exchanger type fill system was chosen because it appeared to pose the fewest

problems for development of a working system in the short time allowed. A system employing a high pressure reciprocating liquid helium pump would offer superior helium supply logistics

because only a liquid helium supply would be required, but this system would require development of a pump.

Figure 8 gives a view of the fill system with the precooler dewar, subcooler vacuum can, and subcooler radiation shield removed. Both counter-flow heat exchangers are located in the

subcooler for convenience. The high temperature heat exchanger sits in the nitrogen vapor

space uninsulated, whereas the low temperature heat exchanger has multilayer insulation in a vacuum jacket.

Both heat exchangers are fabricated from ribbon packed heat exchanger tubing with an

2 2 active surface area (all channels) of 0.13 m /m (4.2 ft /ft) and a hydraulic diameter of

-3

2.4 x 10 m (0.008 ft). Two parallel 1.0 meter lengths of tubing form the high temperature

heat exchanger, and a single 1.0 meter length forms the low temperature heat exchanger. At the design flow rate of 11 g/s, the calculated number of transfer units (NTU) of the low

temperature heat exchanger is 11. In practice, flow rates were limited to 5 g/s by the rate
9
10
Figure 6. Test dewar and discharge piping.

11
Figure 7. Main control panel.

12
13
of transfer from the liquid helium supply dewar to the subcooler pot, giving an estimated NTU

of 24.In the precooler, the liquid nitrogen-cooled coil consists of 3 meters (10 ft) of 9.5 mm

(3/8- inch) O.D. copper tubing. The subcooler coil is 10 meters (33 ft) of 9.5 mm (3/8-inch)

O.D. copper tubing, giving an estimated temperature difference between the bath and exit

fluid of 0.1 K (0.2 R) . y Gas-cooled radiation shields around the subcooler pot and fill line assure a low heat

leak to the cold helium as it flows to the test dewar.

3. 2 Test Dewar

The schedule did not allow time for fabrication of a dewar designed specifically for

these tests. Instead, we modified an existing Apollo oxygen dewar by cutting off the bonnet

and removing the neck plug and the dewar contents. Figure 9 shows the modified dewar, and

Table 1 lists the characteristics of the dewar. The design pressure for this dewar is 7.2

MPa (1040 psi) , but the operating pressure was extended for these tests to 8.3 MPa (1205 psi)

by placing the equipment behind a protective barrier and operating it remotely.

Relatively large discharge (23.9 mm I.D.) and vent (16.6 mm I.D.) lines are required in

order to achieve a low pressure drop in the blower circuit; otherwise, the blower head re- quirements would become excessive. The pressurant gas enters the dewar through the

31.8 mm (1-1/2 inch) I.D. x 44.5 mm (1-3/4 inch) O.D. annular space between the discharge and

the dewar neck. No significant disturbance of the thermal stratification by the pressurant

entrance jet was observed with this arrangement.

The cooler, which is wrapped around the discharge tube, is formed from 6.35 mm (1/4

inch) O.D. x 4 m (13 ft) long copper tubing. In these tests its cooling capacity was limited

by the cooler flow rate rather than heat transfer capacity. The cooling rate based on the

cooler flow rate is 10 watts, compared to a capacity of 88 watts calculated for a 0.5 K

(0.9°R) AT.

3.3 Discharge System

The discharge heat exchanger represented the greatest problem in the design of the

system because it must transfer 1.5 x 10 watts in order to warm the 1 kg/s discharge flow to ambient temperature. Ambient temperature discharge was not a specific requirement of the

tests, but this seemed the best way to overcome the problems of flow control and flow measurement, since cold discharge would be accompanied by problems of large temperature transients

and non- ideal gas properties.

The pulsed nature of the discharges, with the opportunity for recovery in between,

suggested that a hybrid thermal-regenerator-heat-exchanger might satisfy the requirements.

During the discharge, heat is withdrawn from the heat exchanger wall at a rate limited

primarily by the thermal diffusivity of the wall. Between discharges, the wall temperature

recovers through heat exchange with water circulated through the jacket of the heat exchanger.

14
Figure 9. Test dewar assembly.

15
Table 1. Apollo oxygen tank characteristics [4].

Material Inconel 718

Ultimate strength, MPa (psi) 1240 (180,000)

Yield strength, MPa (psi) 1000 (145,000)

Youngs' modulus, MPa (psi) 21 x 10

4 (30 x

Safety factors (Apollo use)

Ultimate 1.5

Yield 1.33

Safety factors (these tests)

Ultimate 1.29

Yield 1.15

Pressure-vessel diameter, mm (in) 636.5 (25.06)

Pressure-vessel thickness, mm (in) 1.50 (.059)

Outer-shell diameter, mm (in) 0.51 (0.020)

Operating pressure

(these tests), MPA (psi) 8.31 (1205)

Proof pressure, MPa (psi) 9.36 (1357)

Burst pressure, MPa (psi) 10.55 (1530)

Tank volume (measured) m

3 (ft

3

) 0.1349 (4.76)

Tank weight before modification, kg (lb) 41 (91)

16
Figure 10 is a view of a short version of the partially assembled heat exchanger, before

assembly of the water jacket and header cap. The heat exchanger used in the tests consisted

of 19 tubes 12.7 mm (0.50 inches) I.D. x 25.4 mm (1.00 inches) O.D. x 3.7 m (12 ft) long of

type 6061 aluminum welded into a header, and surrounded by a water jacket. The weight of the

tubes is 72 kg (158 lbs) giving an ambient temperature heat capacity of 6.5 (10)^ j/K.

Typical decay rates of the exit temperature were 20 K/s. The construction of the blower heat

exchanger is similar to that of the main heat exchanger, except it is smaller because it

handles only 5 percent of the flow. It uses 3 aluminum tubes 12.7 mm (0.50 inches) I.D. x 25.4 mm O.D. x 1.8 m (6 ft) long.

The blower, which was subcontracted, was designed for the following conditions:

Gas Helium

Inlet pressure 5.2 MPa (750 psi)

Inlet temperature 294 K (70°F)

Mass flow rate 0.05 kg/s (0.11 lb/s)

Volume flow rate 6.2 Us (13.2 CFM)

Pressure rise 69 kPa (10 psi)

Housing design pressure 8.6 MPa (1250 psi)

It is a partial admission blower with a 180 mm (4.25 inch) diameter impeller (5 straight

vanes) attached directly to the motor shaft. The motor and impeller are enclosed in a single

high-pressure housing, eliminating the need for a high-pressure rotating shaft seal, and part

of the inlet flow cools the motor windings. Use of a universal motor in combination with a variable voltage dc power supply allows control of the blower over a wide range of operating

conditions.* Typical test operating conditions were:

Inlet pressure 4.1 MPa (610 psi)

Developed pressure 38 kPa (5.6 psi)

Mass flow rate 0.048 kg/s (0.106 lb/s)

Volume flow rate 7.55 l/s (16 CFM)

Speed 19,800 rpm

Input power 1.56 kW

The blower was operated at much lower speed if it was desired to build pressure in the dewar

between discharges, because the normal operating speed gave the rather high pressure rise

rate of 0.2 MPa/s (30 psi/s)

.

The discharge system piping is uninsulated and uses type 304 stainless steel pipe of the

following sizes:

dewar to main heat exchanger - 1-1/4 inch nominal (schedule 10)

main heat exchanger to discharge nozzle - 1-1/2 inch nominal (schedule 10)

blower circuit - 1 inch nominal (schedule 10)

.

3.4 Instrumentation

Data acquisition and reduction were accomplished with a minicomputer system using the

following instrumentation:

*The brush life is probably short in the dry helium atmosphere.

17
18
Figure 11. View of disassembled blower.

19
Temperature at bottom of test dewar (T ) - germanium resistance thermometer,

Estimated total error + 0.02 K (0.04°R).

Temperature at nine dewar locations - gold (0.07 at. percent iron)

vs. chromel (type KP) differential thermocouples referenced to

T . Estimated total error + 0.05 K (0.09°R) or + 1 percent of

measured AT. Temperature at dewar inlet - germanium resistance thermometer

(shorted out. and did not function)

Dewar pressure - variable reluctance pressure transducer. Estimated

total error + 0.1 MPa (1 atm)

Discharge nozzle temperature - copper-constantan thermocouple

referenced to ice bath. Estimated total error + 1 K (1.8 °R)

.

Discharge nozzle pressure - variable reluctance pressure transducer.

Estimated total error + 0.1 MPa (1 atm).

Blower developed pressure - variable reluctance pressure transducer.

Estimated total error + 2 percent.

Blower venturi AP - variable reluctance pressure transducer. Estimated

total error + 2 percent.

Blower venturi temperature - copper-constantan thermocouple referenced

to ice bath. Estimated total error + 1 K (1.8°R).

Blower speed - magnetic shaft pick up. Estimated total error + 3 percent.

The total error in the discharge and blower flows is estimated to be about +3 percent. In addition to the pressure transducer, a bourdon tube pressure gauge with an accuracy of + 50 kPa (0.5 atm) was used to measure the test dewar pressure.

Liquid level in the test dewar and subcooler were indicated with superconducting liquid

level sensors since knowledge of these levels is necessary for operation of the apparatus.

The primary method of density determination was by measurement of the dewar pressure and

temperature. The average bulk density was calculated using equation (7) and using volume

weighting factors based on horizontal segments. In the first experiment (before the discharge piping was attached), mass determination was also attempted with a load cell, but the

suspension system was inadequate for the thermal and pressure stresses of the fill piping. A

mass balance of the gas supplied from the tube trailer gave agreement to within 1/2 percent

of the density calculated from the pressure and the volume average temperature — well within

the accuracy of the calculation.

4. RESULTS AND DISCUSSION

Six tests, which are summarized in table 2, were made with the system. Except for fill

system oscillation problems, which were eliminated, the system operated in a well behaved

manner, and no other problems were encountered.

After attachment of the discharge system to the test dewar between tests 1 and 2 (with

V-31 adjacent to the discharge nozzle and V-32 and V-33 absent), pressure oscillations with a frequency near 1/2 Hz occurred when liquid fill was attempted. The severity of these oscillations

20
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21
was such that no liquid could be accumulated in the dewar because of the concomitant heat

input

.

Pressure oscillations within helium systems are relatively common, but they are generally

the thermal-acoustic (thistle tube) variety which occur in gauge lines, etc., and which have

frequencies measured in ten's of hertz [5,6]. In contrast, these oscillations are believed

to result from the addition to the vent and discharge lines of a large volume (about 30

liters), which acted as a soft pneumatic spring. With this configuration, a negative vent

pressure perturbation moves cold fluid to a warmer region where heating and expansion occur, resulting in a pressure rise and motion of warm fluid towards the cold region.

One solution to the problem consists of increasing the spring constant of the attached

volume (decreasing its volume). Thus, the first corrective action taken was to eliminate the

heat exchanger volumes from the discharge side of the dewar by moving discharge valve V-31 to the position shown in figure 3, and to add V-32 to the system. These changes greatly reduced

the oscillation problem, permitting filling during test number 3, but mild oscillations still

occurred. Complete elimination of the oscillations was accomplished with the installation of

V-33, which isolates the blower and blower heat exchanger from the vent line.

4.1 Fill Process

Densities attained during the tests are shown in figure 12. Extrapolation of the results

3 3 3 for experiment number 6 indicates that the goal of 0.20 x 10 kg/m (12.5 lbs/ft ) is closely

approached at the upper pressure limit of 10.3 MPa (102 atm) . Restriction of the test dewar

3 3 3 working pressure, however, limited the maximum density to 0.193 x 10 kg/m (12.04 lb/ft ) at

a pressure of 8.2 MPa (81 atm). The densities were determined from the measured temperature

profile and pressure and have an estimated total uncertainty of + 1 percent — about half of

which is due to the uncertainty in the thermodynamic properties.

Fill experiments 1, 4, and 5 were run with an initial liquid-fill temperature of 4.1 K

(7.4°R), an estimated helium supply temperature of 4.5 K (8.1°R), and a net cooling rate of

5 watts (17 BTu/hr) (equivalent to 7.5 J/kg-atm for a 30 minute fill at 67 atm). The inlet

line thermometer was shorted out, but the measured subcooler pot pressure indicates a temperature of about 4.4 K (7.9°R) for the subcooler liquid. Allowance for a 0.1 K (0.2°R) AT between the liquid bath and the exit fluid results in the 4.5 K (8.1°R) supply temperature

given above. The net cooling rate of 5 watts (17 BTu/hr) is based on measured cooler flow

rate of 0.5 g/s (0.011 lb/s) (giving a cooling rate of 10 watts assuming use of the latent

heat only) and a heat leak of 5 watts (determined from the boil-off rate) . The estimated

uncertainty in the cooling rate is about 3 watts (10 BTu/hr)

.

Experiment 6 was run with a reduced fill temperature, 4.3 K (7.7 °R) and increased

cooling, 12.5 J/kg-atm. The resulting one percent increase in density, at the same pressure,

is apparent in figure 12. These conditions were achieved by filling at a reduced rate and

precooling the dewar a day before the experiments. The reduced fill rate resulted in a lower subcooler pressure and temperature, and it increased the cooling time per unit mass. Precooling the dewar reduced the heat leak to the steady state value rather than the higher

initial values exhibited by dewars with warm insulation.

22
The analytical curve in figure 12 was obtained using the method described in section

2.1. The excellent agreement with the experimental data is partly fortuitous because of the

estimated 5 percent uncertainty in the specific heat of helium in the region of concern. The

agreement does indicate, however, that the actual fill process can be modeled rather well by

a thermodynamic analysis that assumes continuous mixing (thermal equilibrium) of the tank

contents

.

The calculated effect of the amount of dewar cooling is illustrated in figure 13.

Higher liquid-fill and supply temperatures are satisfactory for high density storage, given

sufficient dewar cooling.

Figure 14 shows the dewar temperature profile during the fill process. The temperatures

are measured along a vertical line displaced 49 mm (1.9 inches) from the vertical axis.

Because previous studies [7,8] have demonstrated the virtual absence of horizontal temperature gradients (except in a thin wall boundary layer) during natural convection within vessels,

a single vertical temperature profile is sufficient to characterize the dewar contents.

Approximately 400 liters (100 gal) of liquid helium were required for cooldown of the

fill system and test dewar, fill of the dewar to final density, and supply of the cooler.

This compares to an equivalent of 200 liters (50 gal) of helium stored in the 135 liter (35

gal) test dewar. Fill times varied somewhat, but times as short as the following were observed

dewar cool down 6 minutes

(dewar precooled to near 100 K)

Liquid fill 20 minutes

Supercritical fill 22 minutes

total 48 minutes

4.2 Discharge Process

Figures 15 through 18 are typical traces of the discharge nozzle pressure and flow rate. Mass flow variations of less than + 1 percent were attained with fixed nozzle size and blower

supply voltage, i.e., without feedback control. A slow decay of the nozzle pressure com- pensates for the 20 K/s (36°F/s) decay in the nozzle temperature. A 0.1 second pressure rise

time and the large flow decay tail are characteristics of this particular heat exchangervalve arrangement and should not be considered unalterable. Placement of the discharge valve

next to the discharge nozzle could reduce transient times to near valve response times.

Valves in the positions of V-31, V-32 and V-33 would still be required to prevent fill

oscillations

.

The blower performance, figure 19, exhibits some modulation. Part of this may be instrument noise, but the congruence of part of the wave forms suggests that some of the modulation

may be real. The small pressure dips in figures 15 and 17 suggest that pressure waves may be

present in the system which effect the blower behavior and pressure and flow instrumentation.

The vertical temperature distribution in the dewar is shown in figure 20 as a function

of the fraction of the initial mass which is left in the dewar. Although there is no liquid

level, the region of steep temperature gradient (40 to 80 K) is somewhat analogous to one. When warm fluid reaches the discharge line inlet, the dewar may be considered empty since the

23
\

u/qi AiiSN3Q xina

CO OJ

CTJ OO

00

LO CO

d o d d

c c c c

oj as 03 03 E £

111 1 E

i_ i—i 03 03 Q. a. a. a. Ex X

LU

X

LU

X

LU • 3

E

03 CD

k_ • 3 OS

2 >-

co — =

5 ^ °

OO

E

CD

CO

CO

CM

CM

CM CM

to CM

to

oi -o

SaiD.X

0ix_ui/6>| AIISN3G >HR8

24
£

oix £

ui/B)| 'AHSN3Q »ina
TEMPERATURE. K

Figure 14. Dewar temperature profile during filling.

26
>

(/) ooO)O

u

Z3ooO

2

+-> cn

•r—s_

Z3 T3

0)

S-

=3to

oo

CD

s-CL

0)N

N

O

£Z • 00

cu 0) cn cn

S- s-

<T3 nD .cu o

to 00

-

1

"r- Q T3

<D
s/6>l '31VH 39UVH0SIQ

28
une ganssiad
s/ B 1 31Va 39UVH3SIQ

30

32
blower can no longer maintain the dewar pressure during discharge. The downward progression

of the warm zone, which should not be confused with thermal diffusion, is simply the result

of withdrawal of cold fluid from the bottom and its replacement by warm fluid at the top.

Heat transfer with the discharge tube and mixing in the ullage reduce the temperature of the

pressurant from ambient (285 K) to the values indicated in figure 20. The temperature of the fluid entering the discharge tube, figure 21, varies with the

amount of fluid discharged. Although the density of the discharge fluid decreased by over 30

percent during the course of the discharges, the blower flow required to maintain constant

mass discharge was invarient until the discharge temperature exceeded 16 K. This apparent

contradiction with the requirement established in section 2.2 is reconciled by noting that

the temperature at the top of the dewar gradually increased as the dewar was emptied. Thus

the system is self-compensating.

When the dewar is considered empty (unable to supply flow at specified conditions) is a somewhat arbitrary judgement, of course, which depends on the tolerances specified for discharge flow, discharge pressure, and blower flow. For fixed blower supply voltage, an

3 3 3 initial fill density of 0.193 x 10 kg/m (12.03 lb/ft ), and a minimum acceptable discharge

flow of 0.9 kg/s (2.0 lb/s), the dewar was empty with 11.8 percent of the initial mass re3 3 3 maining. If conditions of 0.2 x 10 kg/m (12.5 lb/ft ) initial density and 0.75 kg/s (1.65

lb/s) minimum flow are accepted, then only 8.6 percent of the initial mass remains. In- creasing the blower flow could increase the remaining usable mass even further.

The problem of the pressure change that accompanies mixing of the dewar contents is

studied by applying the analysis of section 2.3, using experimentally determined dewar tem- perature profiles. The results of these calculations, table 3, are for complete mixing, so in practice the pressure decay would always be less. Because the pressure falls upon mixing,

there is no danger of dewar rupture due to sudden accidental mixing. The calculated pressure

decays are modest enough that there would be little problem in maintaining pressure with the

blower during the mixing process.

The original discharge process data for experiment 6 are given in the Appendix.

5. SUMMARY AND CONCLUSIONS

Equipment to store supercritical helium at high density and to demonstrate pulsed discharge at high flow rates has been designed, fabricated, and successfully demonstrated.

3 3 3 A storage density of 0.193 x 10 kg/m (12.03 lb/ft ) at 8.3 MPa (81 atm) was achieved

in a 135 liter (35 gal) dewar with an initial liquid fill temperature of 4.1 K (7.4°R) an estimated helium supply temperature of 4.3 K (7.8°R), and cooling of 12.5 J/kg*atm. The

dewar used in these tests was limited to a maximum working pressure of 8.3 MPa (82 atm) but

extrapolation of the experimental pressure-density curve indicates that the target density of

0.20 x 10

3 kg/m3 (12.50 lb/ft 3

) could have been achieved at 10.3 MPa (102 atm).

Pulsed discharges of 2 s and 4 s duration, with 2 s pauses between discharges, were demonstrated at a flow rate of 1.0 kg/s (2.2 lb/s), and flow fluctuations of less than + 1 percent were achieved without feedback control.

55
FRACTION EXPELLED

Figure 21. Dewar discharge temperature.

34
to

cm CD, CO o LO CNJ LOLO i

i

CSJ oo CsJ LO CM o oo • • CM o LO 1

I

r-. 1^ CO LO to o CO CM

a> LO «*

S- i—

to

CO

CD CO

£- to o O o QCD t£3 to

S- CM

rC '

s

cd "ac C\J o LO to

CD • o Lf) • CD Xf O LO E • • E E • E E • E E 4— o LO +-> +-> r

+-> -l-> o +-> +-> o rD CO ro ro LO ro ro

+-> "=3" CM CO co

O

O • • CD o LO LO CO O O CM

O 4— ro LQ LO LO LO CO 4

CD o LO to CO

CM

ro ro ro ro ro ro 0) Ci_ Q_ O- o_ Q_ a.

+-> s: S! ST SI sz

ro CO ro

O CO CTi CO "vl- LO

C\J to 1 to CO 1 LO co o <_> i

o LO LO to LO ai =3- rO

co CM r-~ • 1— to o LO

co • o LO II II to II II co II II CO i

J3

ro r— CD CD CDC

CD CD CD

sX SX S_

X 3

+J CD 'e +-> CD E +-> CD E

(13 S- ro s- ro i.

S_ s- s- S- S- Z3 SQ a> to 0) CD to CD CD to CD Q. to 4-> CL to +-> Q_ to +J X E CD tf- E CD ti- E CD ti- CD S- rO CD S- ro CD S- ro +J Q- Cl +-> Q.

CD CD CD o S- S_ S- r0 r0 ro ro ro rO

+-> to to CO

+-> +-> to +-> +-> to +-> +-> CO to CD CD CD o s_ c C S- c S- a- D. Q_

35
The pressurant flow (blower flow) required to maintain dewar pressure during discharge

was found to be 0.050 of the discharge flow rate for most of the range of discharge conditions,

A reasonable estimate of the unusable fraction of the initial fill mass is taken to be about

10 percent.

In general, the system operated in a very stable and well behaved manner.

6 . ACKNOWLEDGEMENTS

The author gratefully acknowledges the efforts of C. F. Sindt who contributed in several

areas, particularly with the mini computer data acquisition system; and the efforts of L. M. Anderson whose exceptional craftsmanship and productivity were essential to the success of

the project.

7 . NOMENCLATURE

E total energy of a system

h specific internal enthalpy m mass

NTU number of heat exchanger transfer units [9] P pressure

Q heat transferred

T absolute temperature

U total internal energy

u specific internal energy

V volume

W work

x volume fraction of a horizontal dewar segment

Greek

p density

36
8. REFERENCES

1. R. Haslett, G. R. Pinter, and P. Sanicola, Cryogenic helium pressurization system for

the descent stage of the lunar excursion module (LEM) , Bull.IIR Annexe 1966-5 (Meeting

of Comm. 1, Boulder, CO, June 15-17, 1966) 415-422 (1966).

2. R. D. McCarty, Thermophysical properties of helium-4, Nat. Bur. Stand. (U.S.) Tech. Note

631 (1972) .

3. V. Arp, New forms of state equations for helium, Cryogenics 1_4, 593 (1974).

4. M. L. Davis, R. K. Allgeier, Jr., T. G. Rogers, and G. Rysavy, The development of cryogenic storage systems for space flight, NASA SP 247 (1970).

5. J. R. Clement and J. Gaffney, Thermal Oscillations in Low Temperature Apparatus, Advances

in Cryogenic Engineering, K. D. Timmerhaus (ed.), 302-306, Plenum Press, New York (1960).

6. J. D. Bannister, Spontaneous pressure oscillations in tubes connecting liquid helium

reservoirs to 300 K environments, Bull. IIR Annexe 1966-5 (Meeting of Comm. 1, Boulder,

CO, June 15-17, 1966) 127-135 (1966).

7. L. B. Evans, R. C. Reid, and E. M. Drake, Transient natural convection in a vertical

cylinder, AIChE J. 14, 251-259 (1968).

8. D. E. Daney, Turbulent natural convection of liquid deuterium, hydrogen and nitrogen

within enclosed vessels, Int. J. Heat Mass Transfer, 1_9, 431-441 (1976).

9. W. M. Rohsenow and H. Y. Choi, Heat, mass and momentum transfer, 341, Prentice-Hall,

Englewood Cliffs, NJ (1961).

37
APPENDIX

Discharge Data for Experiment 6.

The position of the dewar thermometers is as follows:

Thermometer Dimension! ess distance from

hnttom UU U IUIII nf\J I fhp l/IIC Hpwar UCWOl I

\ f\X/n^ / u }

0. 05

1 0.10

2 0.20

3 0.30

5 0.50

7 0.70

8 0.80

9 0.90

The computer printed times start at the beginning of each discharge cycle.

atm = 1.01325 (10)

5 Pa.

38
ffl = 5.44336

1 = 5.42035

2 = 5.9*531

3 = 6.09582

5 = 5T. 25588

7 = ^.21*8^

R = 5.17046

9 = 5.31096

Discharge No. 1

Time: 0 min.

DEWAR PPESS = 72.3058 ATM

TIMS DEt'-AP. PP. N!0Z PR. !JOZ rrJt KIN SBC ATM ATM KG/8BC

0 :. .009 72. 2539 1.33667 2.9 3

. 438 4. 7049E

<3 : .193 o 4 . L z 1

1

5 r . 8 2 3 7 2^3 .

u? Q 0 1. 39845

w : . 3 / o

C 1 1 O O "3 b1 . 1 b J J 55c c .79"7 n n51 1 1 C 315 i. 34472

b : .559 CO C 1 /I c 52 . 5z45 2 5 5. i o c 195 i. 2^931

9 : . 73/1 55 . 1231 49 . 945? 252

.

53 3 i. 21473

@ : .906 5 2.5 S3 3 5 47 . °-97 249 . 74 3 i

.

17153

^ i no DiC .OOJ9 "7 Z <4 / . i

.

12-7

0 : 1.254 43.9173 4 4 . 5517 2^4. 525 i

.

l»3w2

0 : 1.438 47.4932 43 . 1^85 2 42

.

173 i. ^743

B : 1 . uzz AC 1 C T £ 4c » lozo /I Ci A A 1 41 .944/ o y 5. J i. Q4o 71

0 : 1.806 44.9776 40.75^2 237

.

P. o i. 02477

0 : 1.99 4 3.855 39.6979 235 . POQ i. 003*2

BLOW DP RPM BLOtf FLO'v BLOK TEMP

ATM KG/SEC f?

-6 .46118E-3 274. 755

7.02976E-2 8389.97 9 273. 325

.139984 10634.2 @ 272. 069

.171145 12257 7.034P4E-3 267. 515

.20259 12441.1 0 2*3. 055

.207303 12332.4 2.53537E-2 26 0. P37

.193032 12210.9 2.4931E-2 26 8. 537

.191024 12694.3 2.69559E-2 273. 576

.192H72 13413.4 2.75171E-2 274. 713

.17?761 133 50.

3

2.67609E-2 275. 147

.176404 12774.9 2.3Q917E-2 275. 5 .175-723 13^97.

1

2.44309E-2 275. 647

TIME 0 : 2.18 7 DEWAR TEMP.

0 4. 93691

1 5

.

14945

2 5! 37213

3 5. 3599

5 5. 35762

7 5. 4 263

8 5. 65072

9 64 .9302

BEWAS PRESS = 42.9553 ATM

39
TIMF 0 : .002

0 5.32311

1 5.68217

2 5.66142

3 5 . 6 4 0 ? 2

5 5.78941

7 6.37113

8 R. 22243

9 75.2672

DEVvAR PRESS = 50.674 ATM

TIME DEWAR PR. NOZ PR.

MIN SEC ATM ATM

0 .008 50.7884 1.1244

0 . 199 4 6.2 458 42.8737

0 . 3P2 45.6741 41 .0441

0 . 555 4 5.1023 40 . 21 Q3

0 . 726 44.7801 40.1529

0 .898 44.4 371 39.9349

0 1.0 69 44.1356 39.641

0 1.241 44.094 39.5033

0 1.413 4 3 . « 8 5

1

3«.423

0 1. 585 43.6471 39.1101

0 1.757 43.6159 39.058

0 1 .929 43 . 41R4 38.049

0 2.101 43.1221 3R.7641

(3 : 2.273 4 3.1793 38 . 5935

0 : 2.447 4 2.8311 3«.6172

0 : 2.621 42.7687 3R.347

0 • 2.793 42.7011 3° . 3754

0 2.965 4 2. 50 36 38.2711

0 - 3.137 42.3945 38.1147

0 3.3 09 42.3841 3^.1526

0 : 3.4*3 42.1865 37.°63

0 : 3.555 42 . 243« 37.8161

0 : 3.829 42.1762 37.P967

Discharge No. 2

Time: 7 min.

NOZ T. NOZ EL

K KG/SEC

293 .359 .0427402

261 .4 84 1.0274

2.5 3 .374 _ q qgfl 03

253 .09 .980826

240 .87 .98563

247 .079 .985802

244 .467 .98390 4 241 .936 .9R5791

239 . 448. .°88803

236 .733 .085722

234 .231 .990684

231 .606 .90355R

229 .149 .994224

2 26 .674 .995325

224 .121 1.0015

8

221 . 526 1.^00 52

21 Q . 383 1.00613

217 .18 1.00853

215 . 147 1.00922

212 .834 1.01568

211 .02 1.01507

20 9 . 2«4 1.01541

207 .454 1 . 02201

40
etiO* dp RLO1* ATM KO/SEC K

-] . 12939E-2 1<356.5^ g 27S .379

-7.7k,513E-2 13351.°- 0 27- .fl83

.299345 16° M .

1

3.9805E-2 277 .Q3*

.361711 17493.5 4.7367QF-2 27° .737

.35891? 17781.2 4.°-554°E-2 27 9 .357

.3659*1 1 3 4 9 £ . 3 4.83561E-2 279 .5 52

.3^4057 194 3°.

5

5.0S575R-2 279 .7t-P .36729? 19835.7 4.93595E-2 279 .745

.3742°! 18701.9 18501-482 279 .717

.3659*1 194-73 4 . =»2335"-? 270 .677

.354535 18713.4 5.P4177E-2 27° .62

.357522 18552.3 4 .Q67*7E-2 27 Q .595

.27^2°1 l869#. A 4 .979-5^-2 270 .513

.3295*7 19 2

'

i 7 4 . °3139F-2 27° . 4 51

.3 2" 23 1

c- 1 1 « . 2 A.95778E-2 27° . 3 Q 2

. 372 :?9^ l

c' ^55 .9 » 8 4 P 1 - . 27 9 .3^1

.3-j1-1IJ- * n ri t /! 1 r- *"» - ra9.7^ j

• - / "TO i 7

• O ") /l / t; .357522 19817 5 . 12 c 2*r-? 21° .2.22 .353315 19655.9 4 .P7239F-2 27 9 .141

.339753 1P449.7 4 „?5l97E-2 27 9 .359918 1

? 299 .

1

;04«j748 27° .0R4

.32571 1°^3.2 4.89428E-2 27° .9^3

.3"59G1 1997°.

1

5.13417F-2 27° . p

0 : 4.014

DEWAR IF"

5 . 2 s! 8 1

4

5. "116

5>. 52P36

5.43*7?

5.94854

55.3014

91.9945

11^.^74

D F - B R PTES? 42.1139

'IMP 3^2

41
5 . q S 4 ^ P

1 - 6 . r

v 2 w 4 6 2 6 . 215 53

-> = 6.54722 Discharge No. 3

c. -

. j — 1 1 IMc . JJ III 1 II .

7 = 5-7.47 r 4 Two discharges in

R 104.3

q = 1 4 2 . 8

0

Ifi = 3.7 ,22* (?f-2R

j\p pRSSS = 53.210 4 VP"

J Ml 05***1$ PP. VQ5! ^07 t. MO 7 PTr.. I sec ATM afM KG /SEC

. fi 3 7 53.3351 1.] 9 q° / H n ° n .042 58 3 .193 49.426

6

45. "352 2 5 3 . 3

Q. q 1.07434

0 . 37 q 4 p, . f. i 5 g 4 3. 471 2 5 4 . 3 ° 3 1.05651

t'; . 5 4

c> 4 7.9299 4 2. ° 1 1 6 2 51 . 103 1.04933

|PI .72 42* 5 7 d 247.833 1.04798

% 4 7.5555 42, 3 0 2 244 . 64

5

1.0 5041

: 1 . '3 ^"7.3155 42. 286 2 4 1 . R 9 3 l.«538-2

k' • 1.235 4 6.9734 ^2. 4 9 238*931 1. '15439

3 : 1.4 0

7

4 6 . 9 9 4

2

41 .

p., \a 2 5 236. 4 6

1

] . «5389

0 : J .57^ 4 6.7344 41 . 755.1 233 . 696 1 . 0 5

p Q 3

id . 1.751 4 5.4121 41. 5 37 -> -)

Jj Q 0 1 _ 0

c, o <r> Q

'/,

> 1.^23 46 . 38 % 9 41 . 252-5 2 2 ° . 2 9 9 1 .

' ;r> Q 7 5

BLOW '"'V Rpv RLO1 *-1 F LO;--J FLO* TEM!

AT'" KG/SFC K -.012801 -1.06772 0 27°. 156

8^9795Fr2 13-73ii.l . £ 2-8 7-9-7 ??5 . •'4 7 .347746 16699.4 .033925 277.706

.331263 18184 4.7«3&6E-2 27°. 203

.389643 184 8 3 . 3 5.119 7 9F-2 279.749

.389643 18609.9 5.2308F.-2 2.80.. 043

.3 0£>643 ] 83 5^.7 .0534692 280.003

.388246 18506.3 5.31263F-2 ?7<>. 0 36

.3^ 52 2*. 1°5"5. 3 5.15787S-2 279.824

.388246 17396.3 6 . .'-5^ 66F-2 279.741

.388245 38092 5.209Q1F-2 279.661

7o -i 18425.7 5.12811F.-2 279

TIME 0 : 2.108

D F s \ A p. T F

,v

i 9 . 0 = 5.75022

1 = 5

. n Q ] 4 4 2 = 5.51 no 7

3 = *i . 6 ,6 2 2 6

5 = 8 . 0 3 3 2 2

7 110 . 2-3

123. r

' 4 6
TIME DERAB PR. NOZ PR. NOZ T m NOZ EL.

M I M SEC ATM ATM K KG/SEC

0 : 4.019 50.4^73 1.1007 248 . 741 4 . 5843°E

0 : 4.193 47.0566 25.2692 264. 072 .610249

0 : 4.373 45.5182 40.4184 223. 308 1.04925

0 : 4.55 7 44 . 9049 39.9323 217. 404 1.05215

0 : 4.72 9 44.5618 3 9.9823 213. 72 1.06118

0 : 4.901 44 . 2504 39.6315 210. 977 1 .05*87

0 : 5.073 44.3539 39.3566 208. 58 1.0577

0 : 5.245 44.2188 3«.2286 206 . 538 1.05953

0 : 5.417 ^3.9277 38.9Q&4 204 . 46 1 .05*72

0 : 5. 589 44.0109 38.7783 202. 407 1 .05824

0 : 5.761 43.9173 38.7025 200. 6 1.06096

0 : 5.933 43.5847 38 . 5271 198. 354 1.05085

BLOW DP PPM BLOW FLOW BLOW TEMP

ATM KG/SEC V

1 . 42003E-2 4315.83 0 280 . 1.33093 13269.7 4 .54925E- 2 269. 4 .2 Q 5942 15744.1 2.95339E- 2 27 4 . P34

. 371487 17240.3 4.13965E- 2 278. 0 47

.370891 17R96.3 5.08907E- 2 278 . 906

.357522 * 3529.3 4.93848E- 2 279. 16

.37847 1R471 .7 5.18936E- 2 279. 032

.384057 18575.3 .0522382 278 . 858

.372834 1«333.6 5 . 09584E- 2 278 . 637

.374281 18853.1 5.11827E- 2 278. 452

.372^«4 19035.7 5.15336E- 2 278. 348

.377074 18161 5.33397E- 2 278. 154

6. 118

0 6 .06584

1 6 .19<U3

2 6.82733

3 7.14755

5 "30.3794"

7 141. «38

g 136 .P34

a 14 0.88

CEVvAR PRESS = 4 3.73«2 ATM

43
DEWAR TEMP.

» j i

j.2 = 3 . 0 ? 7 P, 3 = r!<?2136 Discharge No. 4

5 = 37.0511 Time: 60 min.

7 = 113.824 Three discharges in succession;

p, = 1 3 7 . .0 6 the discharge valve failed to

0 = 153.162 open for the third discharge.

DE'WAP PRESS = 51.5784 VI

TIME DEWAR PP. T NOZ PL.

MIM SEC ATM ATM KG/SEC

0

• . 007 51 . 4Q52 .7449 289 . 463 3. 4 5 4 1 8 S

0 .193 49.7 925 4 3.2713 2^6 .231 1

.

0 2941

Qi . 37 /! p . n Q 5 ]. 4 2.7126 2 55 . 2«7 1

.

p. ^ 5 0 5 0 . 543 47,569

9

4 2.1430 252 .4 57 1. 02813

0 .715 4 7. 52^4 41.9352 249 . 4 6 3 1

.

0 2 9 2 5

0 . R36 4 7 . 1 7 0 9 41.812 246 .447 1

.

0 3 2-65

0 • 1.057 4 6.7551 41. 537 2 4 3 . 5 1 . 0

0

1 3

0 : ] . 229 4 6.7967 41.3569 2 /i p| . 7P p i. 03346

0 • 1.401 4 6.5265 41.2526 23° . 246 1

.

9 3 6 3 P

9 : 1.573 46.225 41.0535 235 .64 9 1

.

0 3 7 3 7

0 • 1.745 46.2146 4 0.8165 232 .377 ]

.

^3717

0 1.917 46.0 379 4 0 .6933 2 3 0 .731 1. 3^99

RLO1 J DP P.P'i BLOW FLO'* BLOW T E :'1 P ATM KG/SEC [< -3.45595E-3 736 . 523 27« .976

.189322 13737.1 1 . 6R049E- 2 277 .236

.325793 1 6 0 5 6.4 3.60837E- 2 279 .014

.3714R7 17205.8 4 . 47 Q 7P-2 27^ .3 27

. 3910 39 17 712.2 4 . 94394E- 2 27° . 7 52. .393543 17723.7 5.08 413E- 2 279 .965

.399419 19162.3 5. 10 008 E- 2 27^ .37^

.3? 4 -5 7 17815.7 5.10 564F- 2 273 .864

. 4 0 9195 1810 3.5 5.14975^- 2 273 .7^4

. 392436 19116.2 .0508 ('! 0 2 273 .714

.395626 19415.5 5. 17533F- 2 270 .626

. 4n 22 12 18863.1 5.1 2.58 1E- 2 27 3 .40]

44
TIME 0 : 2. 102

f 1 "7 /l ') 1 (\ C

/ . a A. 1 '- A 3

] = 7 .71662

2 = R . 52.^24

3 = q _ 35559

5 67. 77 s

7 125.782

•a 1A""'.?71

Q 151. All

DEWAP PRESS = 45.7675 ATM

I «E ; 37. PP. "*02 T. NOZ PL.

IM SEC ATr " ATM WG/SEC

0 : 4.02 48 .6954 -1 .45522 24P . 167 -] . ^°2! or

0 4.194 46.34^7 I s . 23?2 277 . 226 .43477°

0 4.37 44.8217 39.607« 226 .167 1.022.1

V 4 . ^54 44.3643 30 . 3 P Q s 219. Q 4 1.030O<7

0 4 .726 44.1356 3 Q . 0 ? 5 8 216.^12 l.R2«-36

0 4 . 899 4 4.1356 38 .877° 213.952 1.03189

0 • 5.07

; 43.803 38 .7925 211.446 1 .03575

5.242 43.5847 38.5413 2 0 q . 2 9 0 1 . 03444

5.414 43.6159 33.3*7 207* 1.03503

!/> : 5.585 43 . 36*4 38.332 s 204 .925 1 . '1 3 9 8 0

: 5.7 58 43.0-805 3

q . 0341 202.955 ] .03694

0 : 5.93 43. 1 273 37.2824 201.3 1 ! 3 7 ] 3

I LOW DP RPM "LO- ?f..0« TP -» ATM K 1.67043E-2 6 732. 69 n 2*n .515

1 . 55438 1248 7 .1 6.527A4F- 2 26 5 .4?2

.3*6591 2.73°74F- 2 275 . 2*7

.385453 17677 4.32589?- 2 27» . 2^2

.388246 1«322 .1 4 . o^°61E- fiZ 278 0 a c .392436 17597 . 1 . pi 4 fi r> 9 5 2 27° . 1 4 4 .37^867 1^425 . 7 4 .P71«7 r - 2 27° .059

.389643 19381 5.10 814E- 2 27 s . 0 4 3 .392436 18241 .6 5 . 14Q95F- 2 27 8 .634

.372884 19580 .2 4 !oj2^5f- 2 27P

.391039 18 509 .9 4 . 90625F- 2 27 s .364

.392435 17999 . Q 4

.

Q 7 297F- ? 27 s- .222

I7F.WAP TEMP.

f?' = 9.3 3^33

1 = n. 57051

2 - 9.51496

3 = 23.2768

5 = ?4,5953

7 = 142.649

8 = 152.221

c = 15 5.264

45
DE WAR PRESS = 42.9415 AT

M

I ME DEWAR PR. NO 7, PP. NO 7. T NQZ EL.

IN SEC ATM ATM k KG/SEC

0 8 . 0 1.9 45.0608 -.80 58 37 227 . 027 -1 . 47369E- 4

0 8.193 4 5.3522 2.04678 223 . Iff 3 7 . 25008E- 2

%

' 8.367 4 5 . p 7 1

6

1.490.27 220 . 9 9 6 5 . 86066E- 2

0 8.541 4 6.3809 1 . 0 571 5 223 . 134 4 . 72.939E- 2

»:? 8.715 47 .1813 1.0^27 225 . 774 4 . 55779E- 2

0 8.889 4 7.7011 ] . « 0 7 2 3 227 . 3 9 4 . S59E-2

0 9.063 49 . 59 51 .95405

4

2 28 . 0 ]_£ 4 .41878E- 2

0 9.237 4 9 . 0 316 1.04085 228 . 434 4. 63260R- 2

0 : 9.411 4 9.9776 . 929317 228 . 9 9 7 .0434722

: 9.585 5 0.6117 1.0413 229 . 353 4 . 52503R- 2

0 : 9.7 59 51.4329 .94264P 229. 737 4 . 37357E- 2

f'i

: 9.933 52.2220 1.009° 2 3^ . 041 4 . 69935E- 2

LOW • DP RDM BLOW FLOW P LOW TEMP

ATM KG/SEC

2 .63657E-2 4822.22 7 . 3 4 2 9 7 E - 3 270

.

354

.190763 13993.3 4 . 21549E- 2 27Q. 343

.257351 16^23.2 5.34 8 28E- 2 279 . 3«7

.245011 18 0 4 5.9 5 .8Q278F- 2 27 0

. 341

.259064 182 30.1 5 . 88067E- ? 27 0 . 133

.303186 184 25.7 6 . 10488E- 2 27 9. 762

.312526 18 586.8 6.08 4 5 35- 2 27 8 . 482

.308118 1 8 0 2 2.0 6 . 21S91E- 2 278,. 274

.2Q4851 18517 . 9 6.43304E- 2 277. 964

.295549 17654.6 6.2] 939F- 2 277 . 772

.298386 18139 6.89799E- 2 277. 449

.271065 17907.8 .0 672002 277 . 099

DEWAP TEMP.

10 .12

0 8.96445

1 9.20841

2 10 . 59 5

3 27 . 2269

5 129 .312

7 168.17 2 8 168 . 233

9 169.354

DE'-jAR PRESS = 52.9362 ATM

46
T T M F 0 : • h 0 3 DEWAR TEMP.

M °> . 6 2 3 3 3 1 = 9.84851 - i*l

2 = 9.64126 -.01

3 9 . 6 0 1 P 5 + . 0^

5 9 .61516

7 9.62966

8 9:61244 A . ft 4

q 9.57343

DEWAR PRESS = 4Q .73 FT 5 ATM

T T M F 0 0 2 DEWAR TEMP.

0KJ 1 a 9 M R Q

1 10 . 7276

2 12.9895

3 28. 2.58

5 107. 513

142.544

16 0.9

172.3 07

Thermocouple zero check.

Discharge No. 5

Time: 78 min.

Two successive discharges.

DEWAP PRESS = 52.0773 »TM

I ME DEW&R PR. MO 7 PR. NO Z T. MOZ FL.

IN SEC ATM ATM V KC/SEC

0 .008 52.0773 .323739 234 . 762 3.67157F-2

0

' . 197 49 . 5098 43.0633 263. 199 1.02949

0 .384 49 .751 42.973 2 51.365 ] . 0 5^ 3

Q 0 . 565 48.2104 42.390 2 249. 266 l ! 04272

0

- .737 47 . 54°1 42.1248 245.037 1 . 0 4 3 0

1

0 • .909 47.3392 41.8025 242. 258 1 . 0 A \ 2 1 0 : 1.031 47.27"° 41.6224 239.685 1.04236

0 : 1.253 46 . 7967 ^1.3759 237 . 147 1.04183

0 1.425 46.5161 41.0725 2 3 4.581 1.03993

0 • 1.597 46.4121 40 . P639 232.168 1 . 0 4

ri 1

6

0 1.769 45.9755 40.6554 2 2 9. 0 ni 1.94027

0 1.941 4 5.6429 4 0.2667 227.439 1 .03^°6

47
LOvv

ATM

DP PPM

-2.918 61E-4

.19 2 0 9 4 .379 3 67

.42.8747

.43154

.418971

.43154

.432935

.416178

.424557

.42316

.42735

1133.2^

13292.8

16541.

8

18992

18218.6

19012.

7

18885

,

19312,

18 575

18 4 0 2,

1910 4, 18 5 4 0.8

BLOW FLOW

KG/SEC

PLOW TEMP

K

1 . 22167E-2

3.02248E-2

4 . 3094E-2

4 . 73561E-2

5.02243E-2

. 0 4 8 3

a 0 2 .0494472

4.92975E-2

5.01816E-2

5.12676E-2

5. 10527E—

2

277

276

275

278

27P

2 7 » 278

278

27«

27«

27«

277

8 3 16

288

112

631

773

697

465

348

203

036

918

TIME 2.126

EE WAR TEMP,

0

1

-23

12.4748

15.7593

31 .2478-

67.6929

= 126.811

140.838

148.615

154.89

DEWAR PRESS = 4 5.559 7 ATM

TIME DEWAB PR, NOZ PR. NOZ T MO 7, FL.

IN SEC ATM ATM f( KG/SEC

0 • 4.02 4 4.7073 .0 58 3332 242.21 2.09798E- 2

0 4 .194 45.0504 1 . 59 5 59 2 91.852 5.33423E- 2

0 4 .376 41.8436 36.545° 225 .537 .943971

0 4 . 55 4 0.8664 3 5.6167 221.02

6

. °31794

0 4.732 40.0295 3 4.9389 218.686 .919331

0 4.914 39 . 4 0 59 34.374P 216. 152 . 0 1 0 1 0 9

0 5.086 38.6471 3 3 . 0

3 9 2 215.063

0 5.258 37.8623 3 2 . 990

7

214.566 .877522

0 5.4 4 36 . P22P 31.91 215.145 .848313

0 5.622 35. 5754 30.6728 215.821 .914049

0 5.80 4 34.22^3 29.393 216.318 .7*0911

0 5.986 32. 77 c>2 27.9805 216.604 .743985

48
B LO * DP PPM FLOW 3 LOW t f; m

A X M KG /9. P C

3 . 1 0 0 2 7 E - 2 44 30 . 92 6 . 0 9 7 3 7 E— 3 27 9 .17^

. 197659 14 615.3 5 . 965^lE-2 271 0 5

1

29 "7 ri . z J 1 u j g g q q p 4

r- 9 ^ ^ . 6 6

^ 7 qp ^ 7 17 884.8 2 3 5 1 9 3 F - 2 27 2 .4 5^

• j " 10070 1

"3 /! S 1 5 5 F - 9 27el''6 2 3 7

. J

T Q" O }Z Ku 9 ± y !7> 1 7 * J. Z / 0 Q 7 /] 4 9 "1 1 M £ P — 9 O A A

• " .39685 19967.9 4\1937E-2 27 6 .57*

.384357 20,037 3 . 58065E-2 27 5 .76Q

.395229 19B54.3 3.16646E-2 274 .8«2

.384057 1951°.

1

2.72297E-2 27^ .218

.39^022 20474 . 3 ,«2 592:')2 273 .^77

TIME

DE'/'A R TEMP.

, R PSESS

6. 181

97.7286

1 1 fi 9.456

2 119. B 9 2

3 132.1171

5 16 3.^1*

7 1 7 5 . 6 S 4 P 19,^.612

9 17 Q .7":7

31. 3^5 5 AT

Reference thermometer outside calibration range; these temperatures

meaningless.

49
j NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIR 76-850

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

LIQUID HELIUM STORAGE AT HIGH DENSITY AND DISCHARGE AT HIGH

FLOW RATES

5. Publication Date December 1976

6. Performing Organization Code

275.. 05

7. AUTHOFUS)

David E. Daney

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 2750559

11. Contract/Grant No. 7T-008

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Department of the Air Force

Air Force Weapons Laboratory

Kirtland Air Force Base, New Mexico 87117

13. Type of Report & Period

Covered

rFinal 1 1 la i

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less [actual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.)

Equipment to store supercritical helium at high density and to demonstrate pulsed

discharge at high flow rates has been designed, fabricated and successfully tested.

A storage density of 0.193 x 103 kg/m 3 (12.03 lb/ft3

) at 8.3 MPa (81 atm) was achieved

in a 135 liter (35 gal) dewar. Pulsed discharges of 2 seconds and 4 seconds duration

were demonstrated at a flow rate of 1.0 kg/s (2.2 lb/s), and flow fluctuations of less

than + 1 percent were achieved without feedback control. In general, the system

operated in a very stable and well behaved manner.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Cryogenic helium supply system, cryogenic storage; helium; helium supply system; high

density helium storage; liquid helium storage; supercritical helium.

18. AVAILABILITY XX Unlimited 19. SECURITY CLASS

(THIS REPORT)

21. NO. OF PAGES

For Official Distribution. Do Not Release to NTIS

UNCL ASSIFIED 53

|

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Washington. D.C. 20402. SD Cat. No. C13

Office 20. SECURITY CLASS

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22. Price

j^- 1 Order From National Technical Information Service

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UNCLASSIFIED $4.50

USCOMM.DC 29042-P74