NUREG/CR-3468

SAND84 -0383

R3

Printed December 1986

Hydrogen: Air: Steam Flammability Limits

and Combustion Characteristics in the

FITS Vessel

Billy W. Marshall, Jr.

Prepared by

Sandia National Laboratories j;

Albuquerque, New Mexico 87'185!;'fid

for the United States Department of En!

under Contract DE-A004-76DP007,89!

SF2900Q(8-81)
NOTICE

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United

States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any

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Superintendent of Documents

U.S. Government Printing Office

Post Office Box 37082

Washington, D.C. 20013-7982

and

National Technical Information Service

Springfield, VA 22161
NUREG/CR-3468

SAND84-0383

R3

HYDROGEN:AIR:STEAM FLAMMABILITY LIMITS AND

COMBUSTION CHARACTERISTICS IN THE FITS VESSEL

by

Billy W. Marshall, Jr.

December 1986

Sandia National Laboratories

Albuquerque, New Mexico 87185

*Operated by

Sandia Corporation

for the

U. S. Department of Energy

Prepared for

Division of Reactor System Safety

Accident Evaluation Branch

Office of Nuclear Regulatory Research

U. S. Nuclear Regulatory Commission

Washington, DC 20555

Under Memorandum of Understanding DOE 40-550-75

NRC FIN A1246

ABSTRACT

For the past few years, the United States Nuclear Regulatory Commission

has sponsored research at Sandia National Laboratories addressing the

combustion characteristics and flammability limits of combustible atmospheres

that might occur inside containment during a loss-of-coolant accident inside a

pressurized water reactor (PWR). Combustion of certain hydrogen:air:steam

atmospheres could, at least hypothetically, threaten the integrity of the

containment structure. To assist in the resolution of these issues, a series

of 239 hydrogen:air:steam combustion experiments was performed in a 5.6 m3

vessel.

Experimentally observed flammability limits of hydrogen:air:steam mixtures

in both turbulent and quiescent environments were measured and a correlation

developed that describes the three-component flammability limit. The newly

developed correlation can be used to estimate the flammability of a mixture at

these scales and larger scales to obtain approximate ignition conditions.

Transient combustion pressures of hydrogen:air mixtures were found to

increase with increasing hydrogen concentrations up to '-30%, at which point a

decrease was observed W~ith further increases in the hydrogen concentration.

More severe combustion environments occurred for tests initially at ambient

temperature ('-300 K) than for those initially at elevated temperatures

('-385 K) due to decreases in the bulk gas density with increases in the gas

temperature. The transient combustion-pressure data measured for the

hydrogen:air:steam tests indicate that the addition of steam reduces the

normalized peak combustion pressure (Pmax/Po) as compared to equivalent

hydrogen:air burns. Furthermore, turbulence was found to affect the extent of

combustion and other cqmbustion characteristics of the lean hydrogen b~urns

(i.e., •10% hydrogen by volume) where bouyancy governs flame propagation.

However, burns containing richer hydrogen concentrations were not appreciably

affect by turbulence.

The experimentally measured pressure decays were used to infer the

"global" total, radiative, and convective heat transfer characteristics during

the postcombustion cooling phase. Convection was found to dominate the timeintegrated heat transfer (i.e., energy deposition) of the leaner (<10%)

hydrogen:air burns, accounting for 50 to 70% of the postcombustion heat

transfer. In contrast, radiation was slightly more prevalent than convection

for the hydrogen:air burns near stoichiometry. When moderate quantities of

steamn were added to the environment, radiation became the dominant

postcombustion (or time-integrated) cooling mechanism due to the increase in

bulk gas emittance. If richer steam concentrations (i.e., >'-30% by volume)

were added to the environment, radiation and convection appear to be equally

important heat transfer mechanisms.

iii/iv

TABLE OF CONTENTS

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

1.,1 Background ........................................................ 1

1.2 Literature Review ................................................. 1

1.3 Combustion Experiments Conducted at FITS...........................6

2. EXPERIMENTAL APPARATUS ................................................. 7

2.1 The Fully Instrumented Test Site (FITS)............................7

2.2 Experimental Procedures........................................... 10

2.3 Experimental Measurements.........................................11

2.4 Data Acquisition and Analysis .................................... 11

2.4.1 Data Acquisition .......................................... 11

2,.4.2 Data Analysis Using SMOKE ................................. 13

3. INITIAL GAS CONCENTRATIONS ............................................. 15

4. EXPERIMENTAL RESULTS AND INTERPRETATIONS............................... 17

4.1 Hydrogen:Air:Steam Flammability Results........................... 17

4.1.1 Development of a Correlation for the

Hydrogen:Air:Steam Flammability Limits ..................... 22

4.2 Hydrogen:Air Combustion Results...................................26

4.2.1 Combustion Pressure Results................................26

4.2.2 Peak Gas Temperature Results............................... 29

4.2.3 Heat Transfer Results......................................34

4.3 Hydrogen:Air:Steam Combustion Results............................. 40

4.3.1 Combustion Pressure Results................................40

4.3.2 Peak Gas Temperature Results...............................43

4.3.3 Heat Transfer Results......................................43

4.4 Combustion Completeness...........................................52

5. CONCLUSIONS ........................................................ 54

6. REFERENCES ............................................................ 56

7. APPENDICES ............................................................ 59

1. Corrected Initial Gas Concentrations ............................. 59

2. Experimental Uncertainty Analysis ................................66

3. Combustion Pressure Data for the Hydrogen:Air Burns .............. 68

4. "Global" Heat Transfer Data for the Hydrogen:Air Burns

Processed with SMOKE ............................................. 72

5. Combustion Pressure Data for the Hydrogen:Air:Steam Burns ........ 75

6. "Global" Heat Transfer Data for the Hydrogen:Air:Steam Burns

Processed with SMOKE ............................................. 79

7. Representative Pressure Signatures for each of

the Combustion Tests ............................................. 82

V/vi

LIST OF FIGURES

1 Flammability Limits of Hydrogen:Air:Steam Mixtures ...................... 2

2 Flammability Limits for Hydrogen:Air:Steam Mixtures with Fans Off.......3

3 Flammability Limits for Hydrogen:Air:Steam Mixtures with Fans On ........ 4

4 Schematic Drawing of the 5.6-cubic-meter FITS Vessel .................... 8

5 Schematic Drawing of the FITS Facility with Important

Hardware Identified ........................................... 9

6 Flow Chart Showing the Data Acquisition System at the FITS Facility ... 12

7 Hydrogen:Air:Steam Flammability Data with Fans Off f..................... 18

8 Hydrogen:Air:Steam Flammability Data with Fans Operational ............. 20

9 Hydrogen:Air:Steam Flammability Limits for Steam and Nitrogen .......... 21

10 Exponential Check using the Inert Mixtures of Hydrogen,

Air, and Steam ........................................................ 22

11 Hydrogen:Air:Steam Flammability Data with Fans On

and Of f Shown with the Exponential Curve Fit ........................... 24

12 Comparison of the Flammability Curve Fit with those

Proposed by Zabetakis and Tamm et al .. ................................ 25

13 Normalized Peak Combustion Pressure for the Coldand Hot-wall Hydrogen:Air Burns ........................................27

14 Comparison of the Experimental Peak Pressures to the AIOC

Calculated Peak Pressure for the Cold- and Hot-wall

Hydrogen:Air Burns ..................................................... 28

15 Combustion Duration for the Cold- and Hot-wall Hydrogen:Air Burns ...... 30

16 Comparison of Two Nominally 9.5% Hydrogen Burns with

and without Fans Operational ...........................................31

17 Mean Pressure Derivative for the Cold- and Hot-wall

Hydrogen:Air Burns .....................................................*32

18 Normalized Peak "GClobal" Gas Temperature for the'

Cold- and Hot-wall Hydrogen:Air Burns ..................................33

19 "Global" Total Peak Heat Fluxes for the Cold- and

Hot-wall Hydrogen:Air Burns ............................................ 35

20 Ratio of the "Global" Peak Radiative to Total Peak

Heat Flux for the Hydrogen:Air Burns ...................................36

21 Cumulative Total "Global" Energy Deposition for the

llydrogen:Air Burns ..................................................... 38

22 Ratio of the Cumulative Radiative to Total Energy

Depositions for the Hydrogen:Air Burns .................................39

23 Normalized Peak Combustion Pressure for the Hydrogen:

Air:Steam Burns, with fans on and off, as a Function of

the Hydrogen Concentration in Hydrogen:Air only ........................ 41

24 Ratio of the Experimental Peak to AICC Calculated Peak

Pressure for the Hydrogen:Air:Steam Burns ..............................42

25 Normalized Peak Combustion Pressure for the Hydrogen:

Air:Steam Burns, with fans on and off, as a Function of

the Volumetric Hydrogen Concentration ..................................44

26 Combustion Duration for the Hydrogen:Air:Steam Burns

with and without Fans Operational ......................................45

vii
27 Normalized Peak "Global" Gas Temperature for the

Hydrogen:Air:Steam Burns with and without

Fans Operational ....................................................... 46

28 "Global" Peak Heat Flux for the Hydrogen:Air:Steam

Burns with and without the Fans Operational ............................ 47

29 "Global" Peak Heat Flux for the Hydrogen:Air:Steam

Burns Shown as a Function of the Hydrogen

Concentration in Hydrogen:Air only ..................................... 48

30 Ratio of the "Global" Peak Radiative to Total Peak Heat Flux for

the Hydrogen:Air:Steam Burns shown as a Function of the Hydrogen

Concentration in Hydrogen:Air only .....................................49

31 "fGlobal"f Cumulative Total Energy Deposition for the

Hydrogen:Air:Steam Burns with and without the Fans operational ......... 50

32 "Global" Cumulative Total Energy Deposition for the

Hydrogen:Air:Steam Burns shown as a Function of the

Hydrogen Concentration in Hydrogen:Air only ............................ 50

33 Ratio of the "fGlobal" Radiative to Total Energy Deposition

for the Hydrogen:Air:Steam Burns ....................................... 51

34 Combustion Completeness Data shown Plotted against the

Precombustion Volumetric Hydrogen Concentration ........................ 53

%viii
ACKNOWLED GMENTS

This work was supported by the U. S. Nuclear Regulatory Commission under

the direction of Dr. P. Worthington and Dr. J. Larkins. Special thanks to A.

C. Ratzel for his constructive criticisms and support during this work. The

suite of computer. programs developed by A. Ratzel and coworkers, referred to

as SMOKE, has been extensively used to analyze many of the combustion tests

described in this document. .The use of this analysis tool has greatly

enhanced the results and interpretations presented.

M. Turner, G. B. StClair and J. Balkenbush of the KTech Corporation

assisted in the experimental work at the FITS facility. M. Turner, in

particular, was instrumental in conducting these experiments and the

subsequent data reduction. W. Schmidt also assisted in the posttest data

processing. Without the professional attitude and expertise of these

personnel, this work would not have been so successful.

MA. Berman was also an important, integral part of this work. Without his

continued support, enthusiasm, encouragement, and understanding during this

work, it would not have been published in such an extensive format. To these

and others I unintentionally failed to mention, I appreciate their

constructive criticism, encouragement, and useful dialogue during this work.

ix/x

EXECIJTI\TE SUMMARY

For the past few years, the United States Nuclear Regulatory Commission

has sponsored research at Sandia National Laboratories addressing the

combustion characteristics and flammability limits of combustible atmospheres

that might occur inside containment during a loss-of-coolant accident inside a

pressurized water reactor (PWR). Combustion of certain hydrogen:air:steam

atmospheres could, at least hypothetically, threaten the integrity of the

containment structure. Furthermore,' the survivability of safety-related,

equipment and exposed cables is of concern due to the severe temperatures and

heat flux conditions during and following combustion. To assist in the

resolution of these issues, a series of 239 hydrogen:air:steam combustion

experiments was 'performed in the 5.6 m3 Fully Instrumented Test Site (FITS)

vessel located at Sandia National Laboratories in Albuquerque, New Mexico.

This test series incorporated air partial pressures of -~83 kPa (at the desired

temperature) with both turbulent (fans on) and quiescent (fans off)

preignition conditions.

This work provides an extensive data. base for hydrogen:air:steam

combustion characteristics and flammability limits at 'intermediate scale.

Experimentally observed flammability limits of hydrogen:air:steam mixtures in

both turbulent and quiescent environments were measured and a correlation

developed that describes the three-component flammability limit. The,

correlation can be used to estimate the flammability of a mixture at these

scales and at larger scales to obtain approximate ignition conditions.

'Transient combustion pressures were measured for all experiments. The

normalized peak pressure was found to increase with increasing hydrogen

concentrations up to -30%, at which point a decrease was observed with further

i.ncreases in hydrogen concentration. For ambient (-300 K) and elevated

temperature (-'385 K) tests, the volume fractions of hydrogen, air and sýteam

were computed at the prevailing temperature. At elevated temperatures, fewer

moles of hydrogen and oxygen (or air) would be available for combustion since

the densities of the gases are lower. Therefore, more severe combustion

environments would be expected to occur, and did occur, for the tests at

ambient temperatures. Steam was found to reduce the normalized peak

combustion pressure (Pmax/Po) compared to equivalent hydrogen:air burns.

Comparison of the experimentally measured peak pressure to the calculated

Adiabatic Isochoric Complete Combustion (AICC). pressure also indicates that

relatively complete combustion occurs (>95%) for hydrogen concentrations

greater than -'10%. The extent of combustion for those tests containing less

than about 10% hydrogen, by volume, appeared to be a strong function of the

preignition turbulence. For quiescent conditions, the combustion completeness

appeared to decrease as the two- and/or three-component flammability limit was

approached. The le'~el of preignition turbulence affected both the combustion

completeness and general combustion characteristics of the lean hydrogen burns

where buoyancy governs flame propagation in the absence of turbulence. As

expected, preignition turbulence did not appear to significantly affect the

extent of combustion or combustion characteristics of the richer hydrogen

burns (i.e., >15% hydrogen by volume).

xi
The experimentally measured pressure decays were used to infer the

"global" postcombustion heat transfer characteristics. The term "global"

implies a spatially averaged property which is inferred from the

experimentally-measured pressure decay. The actual "local" conditions may be

somewhat different for the lean hydrogen concentrations where relatively slow

and incomplete burning may occur, although these "global" estimates appear to

be representative of the actual phenomena when complete and rapid combustion

occurs. The partitioning of the "global" energy depo 'sition and peak heat

flux into radiation and convection was also estimated. Convection was found

to dominate the time-integrated heat transfer (i.e., energy deposition) of the

leaner (<10%) hydrogen:air burns, accounting for 50 to 70% of the postcombustion heat transfer. In contrast, radiation was slightly more prevalent

than convection for the hydrogen:air burns near stoichiometry. The peak heat

flux results showed that radiation was the dominant early-time heat transfer

mechanism for burns near stoichiometric conditions, as might be expected,

while convection governed the lean hydrogen burns (<10%).

When moderate quantities of steam (<20% by volume) were added to the

environment, radiation became the dominant postcombustion (or time-integrated)

heat transfer mechanism due to the increase in bulk gas emittance. However,

these steam concentrations did not appear to reduce the total postcombustion

heat transfer, indicating that relatively complete combustion had occurred.

For the very rich steam concentrations (i.e., above -~30% by volume), radiation

and convection were equally important cooling mechanisms. Also, for these

rich steam environments, the total energy deposition decreased slightly

compared to equivalent hydrogen:air burns; e.g., evaluating these results as a'

f unction of the hydrogen-to-air ratio, the total energy deposition decreased

slightly with increasingly rich steam concentrations. These results are

consistent with expected trends since steam acts as an inert heat sink

reducing the bulk gas temperature and, with the addition of very rich steam

concentrations, the combustion of hydrogen with available oxygen would be

inhibited. Finally, comparisons to the large-scale NTS results show that the

radiative fraction of the total energy deposition was approximately half that

observed during in the NTS tests. This is a scale phenomena and reflects the

differences in radiation length-scales between the two facilities.

These data are useful for benchmarking existing computer codes such as

I{ECTR and CONTAIN for hydrogen:air:steam combustion phenomena at these scales

(-5 in3). The "global" heat transfer data and experimentally measured pressure

histories are also important for future combustion modelling and experimental

analysis efforts.

xii
1. INTRODUCTION

1.1 Background

The U. S. Nuclear Regulatory Commission and the reactor safety community

have long been aware of the potential threat to containment due to the

combustion of hydrogen mixtures during a hypothetical Light Water Reactor

(LWR) accident. It has been postulated that combustion of hydrogen:air:steam

atmospheres could lead to a breach of the containment building, due to the

transient pressures and dynamic loading of the containment structure, and

ultimately release radioactive material into the environment.' Equally

important are the extreme temperatures and heat flux conditions associated

with combustion and postcombustion cooling. These harsh environments may

damage important safety-related equipment, hampering the normal safety

procedures used during and following an accident.

The accident at Three-Mile Island (TMI), Unit 2, is the most recent

example of a loss-of-coolant acci-dent (LOCA) in a LWR. As the fuel rods heated

up, the Zircaloy metal cla-dding reacted with available steam to produce

hydrogen, some of which remained in the primary system, was dissolved in the

remaining coolant, or was released by an operator through the pressurizer into

the containment building. During the accident, an estimated 280 to 370 kg of

hydrogen was generated, resulting in a nearly uniform hydrogen concentration

of 7.3 to 7.9% by volume [1] . At approximately 10 hours after the turbines

tripped, a hydrogen burn occurred, resulting in a transient peak pressure

inside containment which exceeded 190 kPa (28 psig) over a burn time of

'-12 s.

During hypothetical LOCAs, hydrogen, air, and steam 'will be evolved

producing a potentially flammable mixture of gases. The actual quantities and

concentrations of each of these gases will depend upon the accident scenario

considered. Other combustible gases may be present in the atmosphere but are

generally assumed to be unimportant when compared to the concentrations of

hydrogen [2, 3, 41. This work considers the deflagration of mixtures of

hydrogen, air and steam but does not address issues related to detonations,

flame acceleration, transition from deflagration to detonation, or diffusion

flames. Furthermore, since mixtures of hydrogen, air and steam are

considered, the "limits of flammability" (generally referring to the two-gas

flammability limit) will be broadened here to include the three-component

mixture which is inerted.

1.2 Literature Review

During a hypothetical degraded-core accident, the initial conditions

inside containment prior to ignition and combustion of the atmosphere will

include an elevated atmospheric pressure and temperature along with various

concentrations of hydrogen and steam. The flammability limits and combustion

characteristics of a hydrogen: air: steam environment have been considered by

numerous authors. A few of these studies are briefly reviewed below.

1
Figure 1 shows the work of Shapiro and Moffette [5] and Zabetakis [6]

which define the regions of flammability of hydrogen:air:steam mixtures.

Figures 2 and 3 show an accumulation of the flammability data by Berman and

Cummings [7] for hydrogen:air:steam mixtures which have been reported by

various research facilities throughout the world. (Details of the experiments

comprising the data base shown in Figures 2 and 3 can be found in References 6

and 8 through 14). Note that Figure 2 shows mixtures which were in a

quiescent (or fans-off) state at the time of ignition, while Figure 3 shows

mixtures that were in a turbulent (or fans-on) state.

The discrepancies observed from this data base have been largely

attributed to differences in initial temperature, although subtle differences

in the vessel geometry (i.e. , surface area and volume) and initial pressure

will have an effect. These differences, especially in the "knee" region of

the curve at about 10% hydrogen, make, a clear definition of the lean

flammability limit difficult. Furthermore, the current body of data for

turbulent mixtures is somewhat incomplete and again difficult to draw

conclusions from for reactor safety analysis. These data for turbulent

environments are especially important in reactor safety analysis since fans

and possibly sprays may be operational at the time of ignition.

100 0

80 ........... 20

297 K. 1 ATM.

60 ..... .......... 4 0 -A

U' 420 K. 7.8 ATM.

40 60 20.TM

0 100

100 80 60 40 20 0

% HYDROGEN

Figure 1

Flammability Limits of Hydrogen:Air:Steam

Mixtures (taken from Reference 5)

2
701

60 

'

50 0

~ 40\Burn%' NO burn

30 13 Z?

20

103

0 10 20 30 40 so 60

STEAM (aol %)

F ITS WNRE TVA Fenwal LLNL WNRE SM

Burn 0 AV 0 0

No burn U 0

Marginal 0 0 A 0 Y

r..K 1

0 C) 38331101 353-368 333-473 Ta. 314(631 42211491

480-951 460-1001

Figure 2

Flammability Limits for Hydrogen:Air:Steam

Mixtures with Fans Of f (taken from Reference 7).

{FITS, Fully Instrumented Test Site (Sandia National

Laboratories); WNRE, Whiteshell Nuclear Research Establishment

(Canada); TVA, Tennessee Valley Authority; Fenwal, Fenwal, Inc.;

and LLNL, Lawrence Livermore National La~boratories.}

3
70

60

50

40 -Burn No buarn

0

2.0 001

20C 0w 0

10~

0 10 20 30 40 so 60

STEAM Ival %)

FITS WNRE TVA Fenwal LLNL

Buwn 0 A 0

No burn U A * Marginal 0 A 0

rT K (

0 C) 38311101 353-368 333-473 Towt

(80-951 160-1001

PO' ipa(altm) 101 (11 101101I 141.401.41 110-283

Figure 3

Flammability Limits for Hydrogen:Air:Steain

Mixtures with Fans on (taken from Reference 7).

{FITS, Fully Instrumented Test Site (Sandia National

Laboratories); WNRE, Whiteshell Nuclear Research Establishment

(Canada); TVA,. Tennessee Valley Authority; Fenwal, Fenwal, Inc.;

and LLNL, Lawrence Livermore National Laboratories.}

4
The most complete and comprehensive work related to the f lammability

limits of gases available in the literature has been prepared by Coward and

Jones of the Bureau of Mines [15]. This work reviews the limits of

flammability for numerous combustible gases with air or oxygen (i.e., the twocomponent flammability limit). The flammability limits were defined in this

work as:

"the borderline composition; a slight change in one direction

produces a flammable mixture, in the other direction a nonflammable mixture."

From the Coward and Jones study, the flammability limits of hydrogen:air

mixtures were observed to widen as the vessel diameter increased, rapidly at

first and more slowly afterward. In general, increases in the vessel diameter

above 5 cm rarely showed an increase of more than a few tenths of one percent

in the range of flammability. The limits were also shown to not be

appreciably affected by normal variations in atmospheric pressure although

they were narrowed slightly at elevated pressures. Increasing the bulk gas

temperature was also observed to widen both the upper and lower hydrogen:air

flammability limit. At standard conditions, the lower flammability limit for

hydrogen:air mixtures was reported to be 4.0% hydrogen (by volume) while the

upper limit was 75% hydrogen.

The characteristics of the hydrogen:air combustion process have been

studied by numerous authors [13, 16, 17, 18, 19, 20]. ane of the most recent

experimental studies was performed by Benedick and coworkers who studied the

combustion characteristics of hydrogen:air and hydrogen: air: carbon dioxide

mixtures in the Variable Geometry Experimental System (VGES) vessel located at

Sandia National Laboratorlies [16]. This 5-cublic-meter cylindrical vessel was

used to perform eleven test series in which over 100 combustion experiments

were conducted. During this study, it was observed that the combustion

process of hydrogen:air mixtures containing less than -~8% hydrogen (by volume)

was governed by the preignition turbulence. Higher peak pressures were

observed for the turbulent (fans on) tests compared to equivalent quiescent

(fans off) tests. This is probably due to the different horizontal and

downward propagation limits for quiescent mixtures of the hydrogen:air.

Another interesting observation was the fact that the normalized peak pressure

(1'max/Po) fell away from the Adiabatic Isochloric Complete Combustion (AICC)

[21] calculation as the volumetric hydrogen concentrations exceeded -10%.

This is contrary to expected trends since combustion of rich hydrogen

concentrations (>10%) occurs very rapidly compared to leaner (<10% hydrogen)

burns, consuming most of the hydrogen and decreasing the heat transfer from

the flame zone to the surroundings on the time-scale of combustion. Carbon

dioxide diluent in the combustible mixture was found to reduce the peak

pressures, pressure differential, burn velocity, and pressure rise time. It

was also determined that 54% carbon dioxide (by volume) would inert any

hydrogen: air mixture.

A study of hydrogen: air: steam combustion characteristics in a 2.3 mdiameter sphere (volume of 6.4 in3) was performed by Kumar, Tamm, and Harrison

of the Electric Power Research Institute (EPRI) [17] . This research

demonstrated that at low hydrogen concentrations (4 - 9%), turbulence and

gratings within the vessel significantly increased the rate and extent of

5
combustion. Steam was shown to decrease the extent of combustion and also the

normalized peak combustion pressures. As in Benedick's work [16], turbulence

did not appear to greatly enhance the combustion characteristics of

atmospheres containing hydrogen concentrations greater than -"10% although

turbulence did enhance the lean combustion experiments. Even when 40% steam

was present, complete combustion was observed for the richer concentrations of

hydrogen, although the normalized peak combustion pressure was less than those

measured for comparable hydrogen:air. tests.

Recently, Ratzel analyzed data collected during the EPRI/EG&G combustion

studies conducted in a ' 2048-cubic-meter spherical hydrogen dewar located at

the Nevada Test Site (NTS) [18]. Mixtures of hydrogen, air, and steam were

studied, with hydrogen concentrations ranging from 5 to 13% and steam

concentrations from 4 to 40%. Some of the experiments incorporated spray

systems, similar to those installed in LWRs, and fans which tended to enhance

the combustion rate and significantly change the postcombustion heat transfer

characteristics. The measured pressures during this series of tests indicate

that combustion of lean hydrogen -.concentrations is incomplete, with slow

burning and relatively small pressure increases. As the hydrogen

concentration increases, the peak combustion pressure increased while the

duration of combustion decreased as observed at smaller scales. The datareduction program SMOKE was used to infer "global" gas temperatures and

radiative, convective and total heat fluxes following combustion [22]. The

inferred gas temperatures compared reasonably well with measured gas

temperatures. Global estimates of the total peak heat fluxes were typically

less than local measurements for lean combustion and higher for mixtures above

10% hydrogen. Global estimates of the radiative heat transfer were found to

be 30 to 80% of the total heat transfer depending upon the hydrogen and steam

concentration. Furthermore, for hydrogen concentrations greater than -"8%,

radiation dominated the early postcombustion cooling phase, especially for

tests with large initial steam concentrations. Combustion completeness data

were also analyzed, indicating that relatively complete combustion occurs for

hydrogen concentrations above -"8%.

1.3 Combustion Experiments.Conducted at FITS

Combustion studies have also been conducted and reported in the 5.6 m3

FITS cylindrical test vessel located at Sandia National Laboratories in

Albuquerque, New Mexico. Currently, three studies have been reported in the

literature. In the earliest of these studies, the effects of steam and carbon

dioxide as a diluent were considered [13, 23] . Flammability limits of

hydrogen: air: steam mixtures were addressed, but the matrix of experiments was

incomplete and could not support any rigorous conclusions. Comparisons of

the experimental pressure ratios to the AICC calculations [21] revealed

experimental values which exceeded the AICC results as hydrogen concentrations

exceeded about 15%. This trend contradicted those observed in similar work by

Benedick et al., discussed briefly above [16]. These higher than expected

pressures were later attributed to instrumentation and- measurement problems.

In particular, the harsh thermal environment during and following combustion

affected the pressure transducer diaphragm and ultimately led to the

misleading data and interpretations [24].

6
A series of hydrogen: air: steam burns was also conducted to evaluate the

response of calorimeters and some reactor saf ety related equipment during

hydrogen combustion f or the Hydrogen Burn Survival Program [25] . Gas and

component temperatures f rom twenty-one experiments were reported and, as

expected, were found to increase with increasing hydrogen concentrations.

Although the experiments revealed interesting results about component response

during combustion at these scales, the results could not be used to infer

component survivability during combustion inside an LWR containment building.

This was due to the fact that the burn times and associated heat transfer were

substantially shorter in the FITS tank than would be expected during a burn

inside containment. These tests were intended, however, to benchmark code

simulations at small-to-intermediate scales.

Most recently, a series of hydrogen:air tests were performed to evaluate

the dynamic response of three pressure transducers during combustion [24].

This work showed that the, harsh environment of combustion affected the

response of a Precise Sensor model 111-1 gauge while not appreciably affecting

the response of the other two gauges (a Precise Sensor model 141-1 and a

Kulite model XT-190). Brunswick Felt Metal 1101 was also evaluated during

this study and found to serve as an excellent thermal barrier while not

affecting the response of the transducer to the transient pressure signature

(this observation was validated only for deflagrations and pressure rise times

greater than about 10 ins).

2. EXPERIMENTAL APPARATUS

2.1 The Fully Instrumented Test Site (FITS)

All of the combustion. experiments -discussed in this report were conducted

at the Fully Instrumented Test Site (FITS) located at Sandia National

Laboratories, Albuquerque, New Mexic-o. This vessel was originally designed

and built by an NRC-funded research program investigating Molten Fuel-Coolant

Interaction phenomena. It was modified ,for. use by the NRC-supported hydrogen

combustion behavior research program in 1981 [26].

The 5.5-cubic-meter cylindrical vessel is -~3.4 m tall with a diameter of

-15m as shown in Figure 4. The vessel was built to ASME codes and has a

des-ign working pressure of 2.38 Mpa with a wall thickness of 2.86 cm. There

is a 1.72 MIPa burst disk in place during all testing for safety reasons. The

upper head is removable and is attached to the vessel with 48 3.8 cm bolts.

There are twenty-five port penetrations of various sizes most of which can be

used for instrumentation access and gas feedthroughs. The port fittings and

flanges were designed to high-pressure boiler standards and have been tested

to 2.07 MIPa. The vessel was typically instrumented with pressure gauges at

the C- and E-port levels. Two of these ports (.C-2 and E-2) had recessed

flange inserts that positioned the front surface of a pressure transducer

approximately flush with the inner tank wall., In a few tests, port E-1 was

used which did not have a recessed insert, resulting in the front surface of

the pressure transducer being approximately 18 cm from the inner tank wall.

Additionally, hydrogen, steam, carbon dioxide, and nitrogen gas feedthroughs,

an igniter and gas sampling system were positioned at the F port level and a

7
4 C-LEVEL PORTS

- 1.52 m

4 E-LEVEL PORTS

.425 m SPARK AND GLOW IPLUG IGNITERS

6 F-LEVEL PORTS

.425 m

L LOWER FAN 2 G-LEVEL. PORTS

LOWER HEAD PORT

Figure 4

Schematic Drawing of the 5.6-cubic-meter FITS Vessel

8
liquid-ring pump at the G-level. A schematic of the facility, including the

data acquisition and control room, is shown in Figure 5. Additional

information on the FITS vessel and it's capabilities are available in

References 13, 19, 20, 23, and 24.

9940 CONTROL ROOM WITH

DATA ACQUISITION SYSTEM

FITS BUILDING BOILER ROOM

STEAM BOILER I

LIQUID-RING

VACUUM PUMP::

HYDROGEN SUPPLY

DATA AND CONTROL

CABLE TRAYS

Figure 5

Schematic Drawing of the FITS Facility with

Important Hardware Identified

9
2.2. Experimental Procedures

The hydrogen:air:steam combustion experiments were conducted in the

following manner:

1. The tank was preheated to the desired temperature by injecting

steam into the vessel and circulating steam around the heating

coils surrounding the exterior of the vessel.

2. The tank pressure was vented out the bottom and top vents to

atmospheric pressure.

3. The tank was sealed and a liquid-ring pump was used to

evacuate the vessel to a pressure of '-13 kPa. The tank was

then purged with atmospheric air from the top vent. This

procedure (step 2 and 3) was repeated at least twice before

each test.

4. The tank was sealed and allowed to come to an initial

equilibrium pressure and temperature and the conditions

recorded.

5. A prescribed quantity of hydrogen, determined using partial

pressure calculations, was introduced and allowed to

equilibrate with the air already in the vessel. Two pneumatic

14,200 LPM (500 CFM) fans were used to mix the hydrogen:air

mixture. The equilibrium pressure and temperature was

recorded for posttest calculations.

6. A prescribed quantity of steam (if desired) was added to the

hydrogen:air mixture and mixed with the pneumatic fans. The

equilibrium pressure and temperature was recorded for posttest

calculations.

7. If the hydrogen:air:steam Mixture was to be ignited in a

quiescent state, the fans were turned off for ten minutes

prior to ignition. If the mixture was to be ignited in a

turbulent state, the fans were left operational throughout the

experiment.

8. Once the desired initial conditions were achieved and

recorded, either the glow plug or spark plug ignition source

was energized remotely to initiate combustion.

9. The data /acquisition system recorded the various

instrumentation signals for -5 s prior to combustion and '-30 s

after ignition. The data were plotted and preliminary

comparisons to the AICO and to one-another were performed

before the next experiment was conducted.

Additional information about general procedures is available in References 13,

19, 20, 23, and 24.

10
2.3 Experimental Measurements

Two different pressure transducer models, the 141-1 gauge manufactured by

Precise Sensor Inc. and the XT-190 gauge manufactured by Kulite Inc., were

used to record the transient pressure signatures during these experiments. A

detailed experimental study of these two gauges was performed at Sandia which

indicate that these two pressure gauges record accurate pressure magnitudes

and rise times for deflagration combustion experiments [24]. The Kulite XT190, however, must be protected from the harsh thermal combustion environment

(as suggested by the manufacturer) since the silicon diaphragm, on which a

wheatstone bridge is bonded, is sensitive to elevated static and transient

temperatures. 'The Kulite gauge has a perforated screen over the silicon

diaphragm for protection, but is not designed for operation in transient

thermal environments unless additional protection is provided. Therefore, a

flame arrestor and thermal shield was used to protect these gauges. The

thermal protection device incorporated Brunswick 1101 felt metal held in front

of the gauge diaphragm with a steel insert. Based on the results obtained in

Reference 24, felt metal serves as an excellent thermal barrier for

deflagration type experiments since it does not change the transient pressure

signature, the peak pressure magnitude or the pressure rise time.

The Precise Sensor 141-1 was the second gauge-type used during this

experimental combustion study. This gauge is relatively insensitive to the

transient thermal environment of combustion, although felt metal protection

was incorporated in most experiments to ensure accurate results. The model

141-1 is a bonded strain-gauge -type transducer with the sensing element

positioned approximately 5 cm from the front surface of the gauge housing.

The sensing element consists of a stainless-steel diaphragm and straincylinder combination with a four-active-arm strain gauge permanently bonded to

the cylinder. The Precise Sensor gauges were internally cooled with nitrogen

gas through a baffle arrangement. A nominal inlet gauge pressure of 69 kPa

was provided to the cooling manifold (resulting in a volumetric flow rate of

approximately 1.42 LPM) in all experiments. The reader should refer to

Reference 24 for a complete description and evaluation of the two gauges and

thermal protection used in thes-e experiments.

2.4 Data Acquisition and Analysis

2.4.1 Data Acquisition

The data acquisition system at FITS, shown in a flow chart in Figure 6,

empl~oys Le~roy ten-bit (model 8210) and twelve-bit (model 8212) transient

Analog-to-Digital converters (ADCs) in a Kinetic System model 1500 Camac

crate, which is controlled by an LSI 11/23 microprocessor using an RT-11

operating system. Generally, the ten bit ADCs were used to record the voltage

output of the pressure transducers, since these modules recorded approximately

8200 points of data over the thirty second time interval. The period of data

acquisition for each ADC module was controlled with LeCroy 8501 programmable

3-speed clock generators, allowing sample rates of 20 Hz to 2 MHz.

11
Figure 6

Flow Chart Showing the Data Acquisition System at

the FITS Facility

12
Approximately 12 percent (one eighth) of the available module memory was

allocated to preignition data and the remainder was used to record the

postignition data. The ADO modules were triggered using a Transiac model 1020

amplifier/trigger source. This trigger was accomplished by monitoring

(through the transiac) the output voltage of a pressure transducer. When a

preset voltage level was detected, a TTL "trigger signal" was sent to the

clock generators and AD~s, designating time zero, and the combustion data were

recorded.

The voltage signals generated by a pressure transducer were amplified

using Dynamic series 7600 differential amplifiers that incorporated model

7860-A strain-gauge conditioners. These amplifiers have a variable gain

switch in addition to a multiturn variable gain control, which allows the

exact gains to be calibrated and set.

2.4.2 Data Analysis Using SMOKE

The experimentally measured combustion-pressure transient can be used to

infer "global" heat transfer characteristics of the postcombustion cooling

phase. The term "global" implies a spatially averaged property that is

inferred from a transient pressure-decay measurement. The actual "local"

conditions may be somewhat different than these "global" estimates, especially

near the flammability limits where relatively slow and incomplete combustion

can occur. However, for burns in which rapid and relatively complete

combustion occurs, the inferred "global" heat transfer results are considered

representative of the actual "local" phenomena.

The partitioning of the "global" total energy deposition and peak heat

flux rate into radiation and convection can be estimated from the

experimentally measured pressure decay. The total heat flux rate is obtained

using the expression

C V dF

; R i -A dt (2. 1)

and the radiative heat transfer from,

q ~e 9T 9 -a gT w(2.2)

where

q=the total heat flux rate (W/m )

q=the radiative heat flux rate (W/m )

R

Cv= the specific heat capacity at constant Y6lume(J/kg-K)

R = the ideal gas constant (kPa-m3 /kg-K)

V = the vessel volume = 5.6 m3

13
A = the surface area of the vessel = 19.5 m2

E g the total hemispherical gas emittance

a' = the Stefan-Boltzmann constant for radiation (W/m2-K4)

Tg= the bulk gas temperature (K)

a g = the total hemispherical absorptance of the gas

T w= the vessel wall temperature (K)

and

dP the first time derivative of the measured pressure decay.

dt

The beat transfer inside the vessel includes both convection and radiation.

In this report, the convective heat transfer is assumed to be the difference

between the total and radiative heat transfer. The energy depositions are

estimated by numerically integrating the respective heat flux rates expressed

in Equations (2.1) and (2.2), over time. A suite of computer codes, referred

to as SMOKE, was developed by A. Ratzel and coworkers at Sandia to analyze

experimentally measured combustion data [18, 22]. A summary of these computer

codes and their functions will be briefly reviewed here for convenience. For

additional information, the reader should consult these cited References.

SMOKE is a series of computer codes developed at SNLA to analyze

combustion data taken at FITS, VGES, and the NTS hydrogen combustion dewar.

A two-step process was used to reduce the combustion data. In the first step,

the raw data was smoothed and curve fit such that continuous first derivatives

could be calculated from the experimentally-measured pressure signals. In the

second step, the desired modules of SMOKE were run on the "smoothed" data and

the results stored for review. Each of these processes will be briefly

reviewed here.

Preliminary Reduction using SMOOTH

The data collected at the FITS facility was prepa red for data processing

in SMOKE in two steps. The first step was to selectively cull and format the

data into 300 to 500 time-voltage pairs. These data pairs were then smoothed

using the computer code SMOOTH to provide continuous signals and first

derivatives needed for processing.

The computer code SMOOTH operates on the data using a smoothing filter

such as a Hanning filter or a rational function fit. The rational function

fitter was particularly useful for obtaining continuous first derivatives of

the postcombustion pressure data which was used to estimate the "global' total

and radiative heat transfer characteristics.

SMOKE.

Upon completion of the smoothing and filtering processes, the suite of

computer codes comprising SMOKE was used to analyze the data. The version of

SMOKE used to analyze these data consisted of two separate computer modules,

MERGE and PRESS, which are briefly discussed below.

MERGE

MERGE is the initialization code which gathers information about

the experiment, such as initial concentrations of the gases,

initial gas temperature and pressure, the type of instrumentation

14
and their respective locations, amplifier gains, any associated

calibration, and other pertinent information important to the

processing of the signals. MERGE then configures this information

into data files for further use by the remaining modules of SMOKE.

Adiabatic Isochloric Combustion (AIC) calculations were also

performed in the MERGE Module and stored for comparison 'with the

experimental data.

PRESS

The code PRESS is capable of processing up to three pressure

transducer signals. Basically, PRESS uses the information

obtained in MERGE to calculate the associated pressure in

engineering units and then estimates the "global" radiative and

total peak heat fluxes and cumulative energy deposition from the

pressure decay. Output from PRESS include the absolute peak

pressure and rise time, the absolute peak temperature 'which is

inferred from the peak pressure, ratio of the peak to initial

pressure, ratio of the peak to AIC peak pressure, and the "global"

total and radiative postcombustion heat transfer conditions.

"Hot-wall" (no condensation occurs) and "cold-wall" (condensation

is allowed to occur) analyses were also incorporated in PRESS.

Of the 239 burns conducted during this test series, 120 were processed

with SMOKE. For a burn to be processed with SMOKE,' it had to have a

relatively noise-free pressure gauge signal which recorded an overpressure due

to combustion of greater than -35 kPa (5 psig). Of the 120 burns processed,

82 were hydrogen:air burns and 38 were hydrogen:air:steam burns.

3. INITIAL GAS CONCENTRATIONS

The initial gas concentrations were calculated using partial pressure

approximations. Generally, for a mixture of hydrogen, air, and steam, the

compositions are calculated as;

%H2 =- x 100 = APdxl100 (3.1)

and

P3 -P2 APsteam

%Steam P xl100 xl100 (3.2)

where

%H2 = the volumetric percentage of hydrogen,

%Steam = the volumetric percentage of steam,

P1 = the beginning absolute pressure of air, kPa

P2= the absolute pressure after hydrogen is added, kPa

P3 = the absolute pressure after steam is added, kPa

APhyd = the pressurization due to the addition of hydrogen, kPa

APsteam = the pressurization due to the addition of steam, kPa.

15
These equations are accurate as long as the temperature within the fixed

volume remains constant and the behavior of the gases can be represented using

ideal gas laws.

Experimentally,'the temperature of the gases within the FITS vessel may

change in time for the "hot-walled" tests where heat transfer from the vessel

walls becomes important. To provide more accurate determinations of the

precombustion gas concentrations in the vessel, the change in pressure due to

these temperature fluctuations during the filling process 'Was accounted for.

Assuming ideal gas laws apply, the pressure in the chamber after the first

fill (state 2) can be expressed as,

P2 =C n2 T2 , C =R/V (3.3)

where the number of moles in the second state is given by

n2 =nhyd + nair (3.4)

The initial number of moles of air in the volume ('state 1) can be written as

nai= P (3.5) air CT1

Substituting Equation (3.4) and (3.5) into Equation (3.3) and rearranging,

gives the following expression for the number of moles of hydrogen:

nhd1 ~2 1l (3.6)

Similarly, the number of moles of hydrogen can be written in terms of the

partial pressure of hydrogen as

AP y

n hyd _CT 2 (3.7)

Substitution of Equation (3.7) into Equation (3.6), yields the following

expression:

APhy P2 - P1 jT2 (3.8)

hyd T2 T1 2

In a similar manner, the pressure in the vessel due to steam can be developed

as

16
A~'ta [ P3 - '2 ]T3 (3 .g.)

stam T3 T2 3

The corrected partial pressures for hydrogen and steam addition can now be

used to obtain accurate concentrations of the gases using Equations (3.1) and

(3.2), respectively. The pressure and temperature used in these calculations

were taken from the preignition experimental data after each fill process and

after A steady-state condition was achieved. The initial hydrogen and steam

concentrations for each experiment have been calculated using this technique

and the results are presented in Appendix 1. These corrected concentrations

are reported throughout this text. The corresponding uncertainty in these

calculations is addressed in Appendix 2. In general, the uncertainty of these

calculated initial volumetric percentages for hydrogen and steam was less than

+7.5% and +2.2%, respectively, of the calculated concentrations.

4. EXPERIMENTAL RESULTS AND INTERPRETATIONS

For convenience, the presentation of the results from the FITS testing has

been split into four major sections. In the first section, the flammability

limits of hydrogen:air:steam are discussed. The second and third sections

present the combustion pressure and heat transfer results for the hydrogen:air

and hydrogen:air:steam burns, respectively. In the final section, the

combustion completeness data is presented.

4.1 Hydrogen:Air:Steam Flammability Results

One of the goals of this work was to provide a more complete data base for

the flammability limits for hydrogen:air:steam mixtures, both in quiescent and

turbulent environments, at intermediate-scale. Experimentally, a mixture was

classified as a "no-burn" if no appreciable pressure rise was detected

(generally much less than 6 kPa), while a mixture was classified a "marginal

burn' if the measured overpressure was less than 10% of the AICO calculated

overpressure for the same initia conditions. (This definition is somewhat

arbitrary, but gives a consistent method of defining a "marginal burn.")

Those tests in which the combustion overpressure exceeded 10% of the AICO

calculated overpressure were classified "burns."

In Figure 7 the three-component flammability results are shown for

quiescent (fans off) mixtures of hydrogen, air and steam with air partial

pressures of one Albuquerque atmosphere (- 83 kPa) and an initial temperature

of approximately 110*C. The shaded symbols represent a mixture which did not

ignite, the unshaded symbols represent one which ignited and the crossed

symbols represent the marginal burns according to the definition above.

The experimental procedure used to define the flammability of a mixture

was as follows:

1. Attempt to ignite the mixture with a spark plug ignition

source. If no ignition (i.e., pressure rise) was detected,

two more spark ignitions were attempted.

17
z

uLj

0

0

00

80-

70-

60-

50-

40-

30]

20-

INITALCONDITIONS, IFANS OFFI

HOT TANK 0383 K)

~ PAN 180 

0

NO BURN

BURN

0

0 c

o 0 oz p 0 0 is I c~1 00

I

V T-?

0 10 20 30 ~40 50 60

% STEAM

LEGED:] 0BURN

S MRGIALBURN

NO BURN

Figure 7

Hydrogen:Air:Steam Flammability Data with Fans Of f

18
2. If no ignition was detected with the spark plug source, a glow

plug was energized for -1 min.

3. If still no ignition was detected, the fans were turned on and

a spark ignition attempted-one more time. If no ignition was

observed, one final ignition was attempted with the glow plug

energized for -'1 minute while the fans were operational.

Following this procedure, an inert mixture was defined for both turbulent and

quiescent conditions. In one case, ignition occurred in a turbulent

environment while no ignition occurred in the quiescent environment (i.e.,

steps 1 and 2). This result has been included as a "no-burn" in the quiescent

flammability data base while it was'classified as a "burn" or "marginal-burn,"

which ever the case, in the turbulent data base.

The results shown in Figure 7 also indicate that any combustible hydrogen:

air mixture is inerted in the FITS vessel with -v52% steam by volume. This is

relatively close to the 54% carbon dioxide inerting percentage found in the

VGES tank which is of comparable volume [16].

In Figure 8, the flammability results of hydrogen, air and steam mixtures

in a turbulent (fans on) environment are presented. Similar to the quiescent

mixtures shown in Figure 7, the air partial pressure was -83 k~a with an

initial precombustion temperature of -1100C. These results also indicate that

complete inerting occurs at around 52% steam.

The flammability limits are-a function of one or more of several initial

and boundary conditions. These conditions included, the initial temperature

and pressure, the presence of suspended liquid droplets, the preignition

turbulence and the strength and location of the ignition source. Comparing

Figures 7 and 8, the importance of preignition turbulence is apparent near the

flammability limit; very few marginal burns are observed for a turbulent

environment, while numerous burns are observed for the quiescent environment.

Buoyancy-driven flame propagation is the dominant process governing the

combustion of quiescent mixtures near the flammability limits. If a mixture

is capable of local ignition,. preignition turbulence results in more extensive

flame propagation and larger fractions of hydrogen being consumed. Preignition turbulence affects the combustion completeness and, therefore, the

chamber pressurization of the lean hydrogen concentrations near the

flammability limits. Thus, qualitatively different characteristics would be

expected for turbulent versus quiescent mixtures near their respective

flammability limits.

The scatter in the marginal and no-burn flammability data shown in Figure

7 and 8 are unavoidable at these scales. Marginal burns appear to be random

in nature and their appearance cannot be correlated to any one initial or

boundary condition, except possibly preignition turbulence. If a mixture is

capable of "marginal" flame propagation in a quiescent environment,

preignition turbulence allows the flame to propagate resulting in a "burn"

classification. Furthermore, the scatter in the data may also be a result of

small variation in one or all of the initial and boundary conditions mentioned

above. Generally, these deviations from desired conditions are small and

unavoidable at these scales.
80-

70-

60-~

509

1

INITIAL CONDITIONS:

FASOPERATIONAL

HOT TANK 0383 K)

0

0 0

z

wJ

0

0

od

0K

0 4 0

NO BURN

0%

0 0a 0 0

201

10j

0.0 00

BURN

0 0 0* JB

00 0

0

c

0

0

~00 00

0

0004~

0

.0

0 so

0 to

9*

0 10 20 30 40 50 60

% STEAM

LEGEND

0BURN

IDMARGINAL BURN

NO BURN

Figure 8

Hydrogen:Air:Steam Flammability Data with Fans Operational

20
*Finally, the flammability limits of hydrogen: air and a diluent may be

directly related to the heat capacity (and therefore the molecular structure)

of the diluent gas. Steam is a triatomic gas that may suppress the combustion

process more effectively than a diatomic gas such as nitrogen. In Figure 9,

the hydrogen:air:steam flammability correlation developed in the next section

is shown plotted against the flammability curve for nitrogen as reported by

Drell and Belles in 1975 [27]. Also, inerting limits similar to those shown

for steam were experimentally observed by Benedick et al., [16] for carbon

dioxide in a similar sized vessel. The nitrogen curve, shown in Figure 9,

indicates that larger concentrations of the diatomic gas are needed to inhibit

the combustion process. Furthermore, it appears likely that if a monatomic

gas such as helium were used as the diluent gas, the three-component

flammability limits would approach the lean oxygen and hydrogen flammability

limits. Hence, not only are the flammability limits affected by initial and

boundary conditions, they are also governed by the heat capacity of the

diluent gas.

80

70

60

Z 50 wL

0

0

09 40

30

20

10

0

0 10 20 30 40 50 60 70 80 90 100

% DILUENT GAS

Figure 9

Hydrogen:Air:Steam Flammability Limits for

Steam and Nitrogen

21
4.1.1 Development of a Correlation for the Hydrogen:Air:Steam Flammability

Limits

One of the contributions of this work, other than adding to the existing

data base, is the ability to curve fit these flammability results with an

exponential-type equation. This was achieved by using a piecewise exponential

curve fitting technique resulting in a single exponential equation which

describes the entire region of flammability. The technique is briefly

described below.

As is well known, if an exponential such as

Y(x) = A e-Bx (4.1)

is plotted on a linear-log scale, a straight line results and the constants A

and B can be defined using a standard linear regression curve-fitting

technique.. In Figure 10 the initial air concentration is plotted on a

linear-log grid against the hydrogen concentration for the inert mixtures.

From this plot, the influence of two distinct exponential are observed; one

over the range of 0 - 10% hydrogen and a second for hydrogen concentrations

greater than 15%.

A computer program was written which

routine to fit the data presented in

concentrations from the different "no-burn"

calculate a conservative expression for

limit.

incorporated a linear regression

Figure 10. Hydrogen and air

flammability tests were used to

the three-component flammability

100

-h

0

10

0 10 20

VOL/,

30 40Q 50 60

HYDROGEN

Figure 10

Exponential Check using the Inert Mixtures of

Hydrogen, Air, and Steam

22
The first least-squares curve fit incorporated data greater than 15%

hydrogen and resulted in the following expression:

ln(%Airl) = 3.62 - 0.007%H2 . (4.2)

The influence of this exponential term was subtracted from the data base and a

second f it calculated using the data between 0 and 10% hydrogen resulting in

the expression:

ln(%Air2) = 6.25 - 0.488%H2 (4.3)

Combining these two equations and accounting for the fact that the combustible

atmosphere consists of only hydrogen, air and steam, the steam content can be

expressed in terms of the hydrogen concentration as follows;

%Steam = 100-%H2--37.3 e-0 .007%112 - 518.0 eO0 4 88%H2 (4.4)

The approximate flammability of a mixture can be determined with this

correlation given a volumetric concentration of hydrogen. In Figures 11A and

11B, this correlation is plotted with the experimental data previously

reported in Figures 7 and 8, respectively. As shown, the correlation provides

a relatively good fit over the entire flammability region. Even at the knee

of the curve, the correlation compares reasonably. well with the scatter in the

data. Furthermore, this single correlation provides a. conservative

approximation of the flammability limits for both quiescent and turbulent

conditions since only the "no-burn" data was used.

Comparison of this correlation to the curves proposed by Zabetakis [6] and

Tamm, et al., [91 are shown in Figure 12. The correlation compares reasonably

well with the fans-on curve fit of Tamm for the lean hydrogen concentrations.

However, the correlation overpredicts the flammability limits with fans-off as

proposed by Tamm. or the curve introduce by Zabetakis. These differences may

be attributed to geometric differences such as the characteristics length

scales of the different vessels, the volume-to-surface area ratio of the

vessel, and the location and ignition energy of the igniters.

Zabetakis was the first to propose a curve for the entire region of

flammability, but his curve is significantly different than that developed in

this and other work. It predicts much narrower flammability' limits in the

knee region of the curve around 10% hydrogen. The curves proposed by

Zabetakis and Tamm were generated using engineering judgement to "hand-fit"

the data base. The technique described in this report defines a method of

curve fitting the data base with an expression usin Ig existing techniques.

This method does not require engineering judgment to fit the curve and,

therefore, should yield more credence to the resulting curves.

An expression of the type defined in Equation (4.4) could be easily

implemented into currently available reactor safety analysis tools such as

HECTR [28,29] and MAAP [30]. However, before an expression of this type is

used in such codes, an expression of the current world's data base should be

developed using this technique. Note that care must be taken in choosing the

23
80 III Iii I jil IIj II jilliji

z

wj

0

0

0ý

70L

60L

50-

30..

201

101

0-

INITALCONDITIONS, -

IFANS OFF HOT TANK 0-383 K)-

0

/ /-,XPONENTIAL 

CU RVE RT -

e ~NO BURN0 s

BURN

0

0

0 0 -P

IoBURR

IEMARGINAL BURN

2 10 20 30 .40 50 50

% STEAM

8'

7'

64

54 0

0

24

14

0

0

0

0

0 0 0 NO BURN I OBUR N

eMR0A BUR

NOURNR

0 00

0 00

0 00 030 04 50 6

% STEAM

Figure 11

Hydrogen:Air:Steam Flammability Data with Fans On

and Off Shown with the Exponential Curve Fit.

24
z

0

0

80

70

60

50

~40

30

20

10

0

0 10 20 30 40 60

% STEAM

Comparison-of

Proposed by

Figure 12

the Flammability Curve Fit

Zabetakis [6] and Tamm, et

with those

al., [9]

largest vessel geometries available from the existing data base to provide a

representative correlation for containment sized volumes. The expression

provided in this work will provide a much more accurate representation of the

flammability limits than currently exists in most of these combustion codes.

25
4.2 Hydrogen:Air Combustion Results

4.2.1 Combustion Pressure Results

The experimental combustion peak pressure data for each of the

hydrogen:air burns are included in Appendix 3 along 'with the Adiabatic

Isochloric Complete Combustion (AICC) theoretical maximum pressures for

reference. Also, representative pressure signatures are included in Appendix

7 for each combustion experiment. Graphical representation of these results

will be presented and discussed in this section.

Figure 13 shows the ratio of the peak-to-initial pressure as a function of

the initial hydrogen concentration for both the quiescent and turbulent burns

in cold-wall and hot-wall tests. As observed by other investigators [16,17],

preignition turbulence tends to promote more complete burning for lean ((10%)

hydrogen concentrations while preignition turbulence is relatively unimportant

for the richer burns. For lean quiescent burns, incomplete burning is most

likely a result of the downward and horizontal flame propagation limits; e.g.,

the flame kernel is able to propagate only upward due to buoyancy effects. In

contrast, turbulence induced by fans causes unburned gases to be "f 'ed" into

the flame zone, burning gases which otherwise might not be combusted. For

the richer burns (>10% hydrogen), the flame is able to propagate uniformly in

all directions independent of the preignition turbulence eliminating this

dependence.

The normalized peak pressure was also observed to increase to a maximum at

about 30% hydrogen by volume and then decreases with increasing hydrogen

concentration. For hydrogen concentrations greater than stoichiometry, the

mixture becomes oxygen lean and is unable to react with all the available

hydrogen. Thus, the extra hydrogen acts as a diluent, similar to nitrogen,

reducing the combustion peak pressures. Furthermore, preignition turbulence

was found to be unimportant for these rich hydrogen concentrations; i.e., the

data for quiescent burns are with the *scatter of the turbulent burn results.

The importance of the preignition gas temperature is also evident when the

results from these two figures are compared. At stoichiometry, a decrease of

-20% in the normalized peak combustion -pressure is observed for burns at

elevated preignition temperatures (-385 K, referred to as hot-wall) comparedto equivalent burns at ambient temperatures ('-300 K, referred to as coldwall). This is essentially due to the decreased quantity of hydrogen and

oxygen available for combustion. At elevated temperatures, fewer mole of

hydrogen and oxygen (or air) are available for combustion since the densities

of the gases are lowered as the temperature is increased. Therefore, more

severe combustion environments would be expected to occur, and did occur, for

the tests at ambient temperature.

Comparisons of the experimental peak pressures to the AICC theoretical

maximums are shown in Figure 14. These plots indicate that as the hydrogen

concentration increases from -5% to -10%, the ratio of the experimental to

AICC peak pressure also increases. For hydrogen concentrations richer than

-10%, this ratio tends to level off between 0.9 and 1.0 and then begins a

slight decrease for hydrogen concentrations exceeding about 30%.

26
aa- N

a10

9

8

7

6

5

4

3

2

1

0

0 10 20 30 40 50 60 70 s0

Vol/, HYDROGEN

a

aNK

10

9

8

7

6

5

4

3

2

1

0

IO 7 :II

090

HTWALL BURNS

6b0-FANS ON

~SFAN FF

0 10 20 30

Vol/*

40 50

HYDROGEN

60 70 80

Figure 13

Normalized Peak Combustion Pressure for the Coldand Hot-wall Hydrogen:Air Burns

27
'IL

0.

I.

50

% HYDROGEN

1.:

I- A 0

AO

0

0

0 0 0 C

~.1

'-p

a.

0.

0.6 -

0.4-

0.2- HOT-WALL BURNS

AýFANS ON0 FANS OFF

4 . I I I I

0 0 10 2'0 3'0 4'0 5'0 60 70

% HYDROGEN

Figure 14

Comparison of the Experimental Peak Pressures to the

AICO Calculated Peak Pressure for the Coldand Hot-wall Hydrogen:Air Burns

28
The duration of combustion, as measured by the time from combustion

initiation to the time of peak pressure, is plotted in Figure 15 against the

initial hydrogen concentration and is shown in tabular form in Appendix 3.

Here, the hot- and cold-wall-tests are shown together for both quiescent and

turbulent burns. As expected, the duration of combustion is significantly

longer for the lean quiescent burns compared to similar turbulent burns. This

observation is more clearly shown in Figure 16 where the pressure signatures

of two nominally 9.5% hydrogen:air burns are shown. The most striking

difference is the, overall pressure signature recorded for these two

experiments. For the quiescent burn, the initial pressure rise from the

preignition pressure to the first "bump" in the signature is probably due to

flame propagation in essentially an upward direction. Once the flame reaches

the top of the vessel, it then propagates down the vessel walls, burning some

(or all) of the remaining gases. Downward and horizontal flame propagation

probably also occurred during the initial pressure rise but moved very slowly

compared to the upward moving flame kernel. Furthermore, any upward movement

of the bulk gases would retard the propagation of the flame in the downward

direction until the top of the vessel is reached.

Another measure of the combustion severity can be obtained by considering

the mean pressure derivative (calculated as the measured overpressure divided

by the pressure rise time) as a function of the initial concentration of

hydrogen, as shown in Figure 17. These results indicate that there is very

little difference between the turbulent and quiescent burns near

stoichiometry. However, more distinct differences are observed for those

hydrogen burns containing less than 10%; the mean pressure derivative is

greater for the turbulent burns than for the quiescent burns, indicating that

the chemical energy release rate is higher for turbulent burns than for

quiescent burns. Additionally, the mean pressure derivative for the burns at

ambient temperature are generally greater than for *the burns at elevated

temperature, indicating again that more energy is released and combustion is

generally more severe at the lower initial temperature. These trends are

consistent with those already presented and serve as an additional check point

for the observations and conclusions discussed previously.

4.2.2 Peak Gas Temperature Results

The "global" peak gas temperatures inferred from the pressure signals

using SMOKE have also been provided in Appendix 3 with the combustion pressure

results for reference. In Figures 18A and 18B, the normalized peak gas

temperatures are shown for the combustion experiments at ambient and elevated

initial temperatures, respectively. For these results, there appears to be

very little difference in the peak gas temperature between the turbulent and

quiescent burns, although some differences would be expected in the very lean

hydrogen burns. There is, however, a significant dependence of the results

upon the preignition temperature as might be expected from the previous

discussion. The burns initially at ambient temperature (cold-wall) generally

achieve higher peak gas temperatures than do comparable burns at elevated

temperature (hot-wall). These results again suggest that the heat fluxes and

energy depositions are more severe during cold-wall burns than during hot-wall

combustion due, as noted before, to the larger quantities of hydrogen

available for combustion in the cold-wall burns.

29
0

0

1=

0

0

0

z

0

I0

U

10:

17:

0.1

HOT-WALL BURNS

*AFANS ON-

* FANS OFF -

Ac

00

0 7

0 0

I

19.............................................

0 10 20 30 40Q 50 60 70

0 10 20 30 40 50 60 70

% HYDROGEN

Figure 15

Combustion Duration for the Cold- and Hot-wall

Hydrogen:Air Burns

30
3

-O UIESCENT CONDrITON4

LU

0 5 1015 20

TIME. SECONDS

Figure 16

Comparison of Two Nominally 9.5% Hydrogen Burns with

and without Fans Operational

31
(o 1000-

> 0

00

Cie

(n 1- 0 U.J COLD-WALL BURNS'=

0- A FANS ON

20 0 FANS OFF

0110 20 30 40 50

% HYDROGEN

U 1000 .. LU

00 0

100- 0

LJ

> 00

~ tA

LUJ

0 1

CAI

Wj HOT-WALL BURNS od 0.17 0 A FANS ON

o oFANS OFF

0 10 20 30 40 50 60 70 80

% HYDROGEN

Figure 17

Mean Pressure Derivative for the Cold- and

Hot-'wall Hydrogen:Air Burns

32
LLU

LU

I.-

LU

LU

0

z

10-

7-

6-

5-

4-

3-

2-

0-

000

COLD-WALL BURNS_

6 FANS ON

o - FANS OFF

0 10 20 30

% HYDROGEN

40 50

LUCie

:-

LU

Cie

LU

LU

Cie

0

LU

10

9

8

7

6

5

4

3

2

0

0 10 20 30 40 50

% HYDROGEN

60 70 80

Figure 18

Normalized Peak "Global" Gas Temperature for the

Cold- and Hot-wall Hydrogen:Air Burns

33
4.2.3 Heat Transfer Results

The "lglobal"I heat flux and energy depositions have been inferred from the

pressure signals using the suite of computer programs referred to as SMOKE and

are reported in tabular form in Appendix 4. In Figure 19, the "global" total

peak heat fluxes for the combustion experiments at elevated (hot-wall) and

ambient (cold-wall) preignition temperatures are shown. Comparing the lean

(-10%) and stoichiometric precombustion conditions, the total peak heat flux

increases by a factor of -10 for the hot-wall burns and by '-12 for the coldwall burns. Furthermore, stoichiometric cold-wall burns are -~20% more severe

than comparable hot-wall combustion tests. This is a further evidence that

combustion severity increases as the preignition temperature decreases.

Analyses show that the heat transfer processes during and after combustion

are dominated by convection and radiation. Results from SMOKE indicate, as

shown in Figure 20, that during and immediately following combustion, heat

transfer is governed by radiation for hydrogen concentrations greater than

-~20%, while convection becomes more important for burns with less than 10%

hydrogen. For the lean burns, the ratio of the radiative to the total peak

heat flux is generally less than 50% indicating that postcombustion beat

transfer is dominated by convection. This observation occurs at both elevated

and ambient preignition temperatures, implying that the mechanisms of heat

transfer at early times after combustion are unaffected by the initial gas

temperature, at least for the lean cases (<10%). Near stoichiometry,

radiation accounts for -90% of the early postcombustion heat transfer for the

cold-wall tests and -~75% for similar hot-wall burns. Radiation dominated heat

transfer would be expected for the rich hydrogen burns since radiation is

proportional to the fourth-power of the gas temperature and is more

significant at elevated gas temperatures than convection which is proportional

to the first-power of the gas temperature. Thus, although similar trends in

the heat transfer mechanisms are observed for lean burns at both ambient and

elevated preignition temperatures, some differences do exist between the two

at concentrations near stoichiometry.

Results from the large-scale NTS combustion tests [18] appear similar to

these reported here. Ratzel reported that the ratio of the peak radiative to

total heat flux varied from '0.34 at 6.0% hydrogen (test NTSP9P) to 0.56 at

9.9% hydrogen (test NTSP15). It should be noted that a dramatic increase in

this ratio was observed for concentrations near 8%. Specifically, for test

NTSPOO with 6.6% hydrogen, the ratio of the two peak heat fluxes was 0.31

while for test NTSP13 with 7.8% hydrogen, the ratio increased to 0.53.

Although the number of "'dry" burns in the NTS series was relatively small,

these four tests seem to fall within the general scatter of the results

obtained from the combustion experiments in the FITS vessel. However, due to

the increased vessel geometry and the characteristic radiation length-scale,

the integrated radiation heat transfer would be expected to be more

significant in the NTS combustion dewar than in the FITS vessel [31].

The time-integral of the heat flux, or cumulative energy deposition, has

also been estimated using SMOKE. The cumulative energy deposition is an

integral measure of the postcombustion heat transfer and indicates the total

34
1000

E

1:00

~10

0-

0 10 20 30 40 50 60 70 80

%o HYDROGEN

Figure 19

'Global" Total Peak Heat Fluxes for the Cold- and

Hot-wall Hydrogen:Air Burns

35
1

0~.9

~0.7

0.6

1.5O.5

<r-

~0.3

u.0.2

0

0 0.1

0 10 20 30 40 50 60 70 80

X HYDROGEN

Figure 20

Ratio of the "Global" Peak Radiative to Total Peak

Heat Flux for the Hydrogen:Air Burns

36
energy absorbed by the vessel surfaces over the data recording period ('-30 s).

The time-rate of energy deposition (i.e., heat flux profiles) may also be an

important parameter when considering the heat transfer phenomena associated

with combustion, but is not presented here. It is safe to say, however, that

the decay-of the heat flux with time is directly related to the pressure decay

since this decay represents the cooling processes within the vessel. However,

the "local" conditions may be somewhat different from the "global" conditions,

especially for lean hydrogen burns where relatively slow, incomplete and

localized burning can occur. I 'f relatively uniform combustion occurs, the

differences between the local and global postcombustion heat transfer should

diminish.

If the cumulative total energy deposition is plotted as a function of the

initial hydrogen concentration, as shown in Figure 21, the difference in

postcombustion heat transfer due to the initial precombustion gas temperature

is evident. An increase of '-30% in the total energy deposition is observed

for burns at ambient temperature compared to equivalent burns at elevated

temperature and at hydrogen concentrations near stoichiometry. The total

energy depositions for the hot-wall combustion experiments were observed to

increase from '-10 J/cm2 near the lean flammability limit ('-5% hydrogen) to '-80

J/cm2 near stoichiometric ('-30% hy dro en) while the cold-wall counterparts

increased from '-15 J/cm2 to '-95 J/cm§ over the same range. As observed

before, this is a result of more hydrogen and oxygen available for combustion

at lower preignition temperatures.

If the ratio of the radiative to total energy deposition is considered as

a function of the initial volumetric hydrogen concentration, as shown in

Figure 22, convectioxi is observed to be the dominant integral postcombustion

heat transfer mechanism for mixtures less than '-10% hydrogen. Thus, at this

scale, postcombustion. heat transfer for the lean hydrogen burns is governed

by convection during both early and late periods after combustion. Radiation

and convection were found to play approximately equal roles in the

postcombustion cooling process for burns greater than 15%. Furthermore, this

trend continues for the very rich hydrogen burns (>30%) indicating that the

excess hydrogen does not greatly influence -the postcombustion cooling heat

transfer mechanisms. These integral heat transfer results are true in spite

of the fact that radiation was observed to be the dominant mechanism of heat

transfer shortly after combustion for the rich burns (refer back to the peak

heat flux results). Convection is the dominant mechanism of heat transfer at

late times after combustion, for both rich and lean hydrogen concentrations,

since it is proportional to the gas temperature difference and radiation is

weakly proportional to'the fourth-power of the gas, temperature. Thus, as the

bulk gas temperature decreases, convection will ultimately become the dominate

mode of heat transfer.

If these experimental results are compared to the large-scale NTS data,

some differences become apparent. Ratzel reported that the ratio of the

cumulative radiative to total energy deposition varied from 0.33 at 6.0%

hydrogen (test NTSP9P) to 0.47 at 9.9% hydrogen (test NTSP15). If these NTSinf erred results are compared to the FITS results, radiation accounts for a

larger partition of the total heat transfer at large-scale than at

intermediate scales. As evident from Figure 22, the NTS data are

approximately twice that of the FITS data. Thus, although convection

mechanisms will eventually dominate the postcombustion heat transfer

37
0

0-

z

01.

100-

10.

0 10 20 30 40 50 60 70 80

% HYDROGEN

Figure 21

Cumulative Total "Global" Energy Deposition for

the Hydrogen:Air Burns

38
z

0

0

z

w

0

0

tiad

1

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

0 10 20 30 40 50

% HYDROGEN

60 70 80

Figure 22

Ratio of the Cumulative Radiative to Total Energy

Depositions for the Hydrogen:Air Burns

39
processes, the importance'of radiation during the postcombustion cooling phase

must increase relati've. to the vessel volume. These observations have also

been observed and "reported by Ratzel and Shepherd [31]. Briefly, the

*radiative heat transfer is directly related to the characteristic length scale

for radiation; in particular, the effective emittance of the gases in the

volume increases as the vessel size increases. Due to the large differences

in vessel volume and geometry, the emittance would be expected to increase by

a factor of '-2 resulting in an approximate equal increase in the radiative

heat transfer for the NTS combustion tests [31] and [32]. Therefore, the

differences between the FITS data and the large-scale NTS data are attributed

solely to the differences in scale.

4.3 Hydrogen:Air:Steam Combustion Results

4.3.1 Combustion Pressure Results

The experimentally measured peak pressures and ATOC calculated peak

pressures for each of the hydrogen:air:steam experiments are presented in

Appendix 5. Also, representative pressure signatures are presented in

Appendix 7 for each combustion experiment for future reference. These results

are presented graphically in this section and are discussed in detail.

The measured pressures during combustion of the hydrogen:air:steam

mixtures indicate that the normalized peak pressure (i.e., the ratio of the

peak-to-initial pressure) decreases with increasing steam, as shown in

Figure 23. (Note that in this figure and those to follow, comparisons of the

burns with and without steam are made relative to the hydrogen concentration

in hydrogen:air only. Comparison on a volumetric basis will be presented in a

later part of this section.) Turbulent lean burns are affected by the

addition of steam compared to the hydrogen:air counterpart, although not as

much as the quiescent burns; up to a 50% reduction is observed for the

quiescent burns. This again implies that preignition turbulence may be one of

the most important condition determining the combustion characteristics of

lean mixtures of hydrogen with and without steam. Furthermore, steam was

found to affect the combustion pressurization of the richer hydrogen

concentrations (>15%) for both turbulent and quiescent conditions; a reduction

in the normalized peak pressure of up to '-50% was observed depending upon the

steam concentration. Thus, as might be expected, steam acts as an inert heat

sink and reduces the bulk gas temperatures and chamber pressurization during

combustion of the available hydrogen with oxygen.

As the hydrogen concentration increases away from a particular

hydrogen:air:steam flammability limit, increasing fractions of hydrogen are

consumed during the combustion process. This general trend is shown in,

Figure 24 as the ratio of the measured peak to AICC calculated peak pressure.

Substantial decreases in this ratio are observed for the quiescent lean burns

indicating decreasing amounts of hydrogen are consumed during combustion as

the steam concentration increases. The turbulent burns, on the other hand,

appear to be less affected by the addition of moderate concentrations of

steam; again preignition turbulence is an important factor. The combustion of

near-stoichiometric concentrations also appear to be affected by moderate to

high concentrations of steam for both turbulent and quiescent environments.

40
10 1 1 1

9I TURBULENT + - *DRY' BURNS CONDITIONS

& a ,0-20% STEAM

WU o - 20-30% STEAM

v - 30-40% STEAM

7 o a0),40% STEAM

4. +A

0.. +

< to +

4 +

0U 0 A

N 10 2v0 30 400 5 0 0

Zi HYROE INHD ENAROL

0~~ ~ 10 )20~ STEAM060 70 s

3ý0-20% STEAM

CL 0 - 40% STEAM

o 4 + us A

0 0 Y 0

+ 00

09 2 A 00 0

0

0 1 . . -

0 10 -20 30 40 s0o 6 70 80

X HYDROGEN IN HYDROGEN:AIR ONLY

Figure 23

Normalized Peak Combustion Pressure for the Hydrogen:Air:Steam

Burns, 'with fans on and off, as a Function of the Hydrogen

Concentration in Hydrogen:Air only

41
111

0.9 6+

0.8 +

0.7 +7 0

~0.+ +

Lo 0.46_________

0.3 TUBUEN

0.3 + - "DRY' BURNS a - ),0-20% STEAM

0.2 0: 20-30% STEAM v 30-40% STEAM 0.1 -. )40% STEAM

0 .....

o 10 20 30 40 50 60 70 80

% HYDROGEN

0 .1 ++

0.9 ++ +

0.8 0 % 0 

.0.6 0

~0.0 0

p0.5 0

S0.4 It_______

0 QUIESCENT CONDITIONS 0.3 + -

A -0~-20% 

DRY'BURNS 

STEAM 

1

I

0.2 20:O-30% STEAM I

S30-40% STEAM *

0.1 o= )40% STEAM

0

o 10 20 30 40 50 60 70 80

% HYDROGEN

Figure 24

Ratio of the Experimental Peak to AICO Calculated

Peak Pressure for the Hydrogen:Air:Steam Burns

42
The results presented in Figures 23 and 24 show that if the hydrogen

concentration is considered on a hydrogen-in-air basis only, steam affects the

combustion of hydrogen with oxygen for both turbulent and quiescent

conditions. If, however, these data are considered as a function of the

volumetric hydrogen concentration as shown in Figure 25, relatively small

differences exist between the lean turbulent burns with and without steam.

The quiescent burns, on the other hand, are affected. Buoyancy is thought to

dominate the flame propagation of lean hydrogen burns in a quiescent

environment, while similar turbulent burns are less affected. For turbulent

preignition conditions, steam acts only as an inert gas, similar to nitrogen

in air,, and combustion properties are similar to those observed for similar

hydrogen:air burns with the same total volumetric hydrogen concentrations.

For example, a turbulent burn containing (by volume) -'8% hydrogen and 20%

steam would be similar to one containing no steam and -'8% hydrogen.

Therefore, on a volumetric basis, the combustion characteristics of lean

turbulent mixtures containing steam are not significantly affected by the

addition of moderate quantities of steam compared to similar hydrogen:air

burns. For the richer burns, however, buoyancy is not the dominant role of

flame propagation and steam acts as a diluent, equally reducing the combustion

pressures of quiescent and turbulent burns.

The duration of combustion was found to increase with increasing steam

content compared to equivalent hydrogen:air burns. As shown in Figure 26, the

quiescent burns are more influenced by the addition of steam than turbulent

burns. The duration of combustion increases for the -lean hydrogen:air

concentrations in both turbulent and quiescent burns. Quiescent burns

containing more than -10% hydrogen in air seem to be most affected by the

addition of steam, increasing the duration of combustion by as much as two

orders-of-magnitude. Similar turbulent burns do not appear to be as affected

unless rich steam concentrations (>40%) are present. Thus, the duration of

combustion for hydrogen:air:steam burns is related not only to the quantities

of steam available in the volume but also to the preignition turbulence.

4.3.2 Peak Gas Temperature Results

The "global" normalized peak gas temperatures were obtained from the

hydrogen:air:steam burns processed with SMOKE and are presented in Appendix 5

with the combustion pressure results for reference. These results are shown

in Figure 27. For the lean turbulent burns with steam, the normalized peak

gas temperatures are generally equal to or slightly less than equivalent

hydrogen:air burns. Quiescent lean burns are, however, significantly affected

by the addition of steam. In both cases, the very rich hydrogen burns are

more, dramatically affected by the addition of steam, lack of sufficient oxygen

for combustion, and diffusion rate of oxygen and hydrogen.

4.3.3 Heat Transfer Results

The "global" heat flux and energy deposition results have been calculated

using SMOKE for the hydrogen:air:steam burns. The numerical results are

presented in Appendix 8. The total peak heat flux results, shown in Figure

28, indicate that early-time combustion heat transfer is significantly reduced

43
I0 I I I I I

I ft ft* PL. ak* .. IaL.e I

9 HUEDULCRIIi.JIuIFI +Iw DRY*BURNSS

a8 -- 0 STEAM o -20-0%STEAM

v a30-0XSTEAM

7 o - 3,401 STEAM

+

A( +

+ CL 4 +3 +

+ 0 A

2 %.

0O

0 10 20 30 40 50 60 70 80

Vol/. HYDROGEN

7 I QUIESCENT CONDITIONS

* 0-20% STEAM

6 o a20-30X STEAM -30-40X STEAM

o+ -)40% STEAM j

x 4 +

a.0 0

2 +a 0

A 00

0 . . . ..

0 10 20 30 40 50 60 70 so

Vol/. HYDROGEN

Figure 25

Normalized Peak Combustion Pressure for the Hydrogen:Air:Steam

Burns, with fans on and off, as a Function of

the Volumetric Hydrogen Concentration

44
0

z

0

0

U

100

10

0.

0.01

TURBULENT CONDITIONS

* = 'DRY* BURNS

3 a - 3-0-20% STEAM

*0- 20-30% STEAM

7 w 30-40% STEAM

+ 00 0 0 o )40X STEAM

00

* ý- 13 00

+

+ 0

0 10 20 30 40 50 60 70 80

% HYDROGEN IN HYDROGEN:AIR ONLY

V

uJ

0

z

0

Fo

0

0

100

10

0.1

0.01

0 10 20 30 40 50 60 70 80

% HYDROGEN IN HYDROGEN:AIR ONLY

Figure 26

Combustion Duration for the Hydrogen:Air:Steam

Burns with and without Fans Operational

45
LU

U)

'U

Ix

LU

0

uJ

10

9

8

7

6

5

3

2

0

0 10 20 30 40 50 60 70 80

% HYDROGEN IN HYDROGEN:AIR ONLY

'U

aLU

'U

at

0

Z

10

9

8

7

6

5

3

2

0

0 10 20 30 40 50 60 70 80

% HYDROGEN IN HYDROGEN~AIR ONLY

Figure 27

Normalized Peak "Global' Gas Temperature for the

Hydrogen:Air:Steam Burns with and without Fans Operational

46
1000

-%100

-j

LL- 10

I0.1

I---. I

+ 4&

60

a+-"DY BURNS

a m20-0%STEAM

v -30-0%STEAM o -)-0%STEAM

0 10 20 30 40 50 60 70 80

% HYDROGEN

Figure

"Global" Peak Heat Flux for

Burns with and without

28

the Hydrogen:Air:Steam

the Fans Operational

47
by the addition of relatively large concentrations of steam. There are,

however, numerous lean hydrogen burns in which the addition of moderate

quantities of steam have increased the peak heat fluxes. As discussed

earlier, the severity of a hydtogen:air:steam burn is clearly related to the

hydrogen concentration relative to air (or more correctly the oxygen). If the

total peak heat flux is plotted against the hydrogen percentage in air, as

shown in Figure 29, a decrease in the peak heat flux due to the addition of

steam is observed for all cases. This is consistent with expected trends.

Steam provides a formidable heat sink, reducing the bulk gas temperature and

retarding the normal combustion of hydrogen with oxygen. The partitioning of

the early-time heat transfer (i.e., ratio of the radiative-to-total peak heat

flux) is shown in Figure 30 plotted against the hydrogen concentration in air

for the burns with and without steam. Here we observe that heat transfer

shortly after combustion of a lean hydrogen:air environment is dominated by

convection. With the addition of steam to the atmosphere, radiation begins to

play a larger role in the early-time postcombustion heat transfer process due

to the increased gas emittance and *absorptance. However, as the

hydrogen:air:steam flammability limits are approached by the addition of very

rich steam concentrations, convection again becomes the prevalent heat

transfer mechanism due to the reduced combustion severity and lower post100

Uj

Ua.-

0.1

0

+V 0

zb 0

++ 0 0

0 BURN

L- -V 0 STEAM -

STEA

04%STEAM

0 4)4%STEAM

0 10 20 30 40 50 60 70 80

% HYDROGEN IN HYDROGEN:AIR ONLY

Figure 29

"Global" Peak Heat Flux for the Hydrogen:Air:Steam

Burns Shown as a Function of the Hydrogen

Concentration in Hydrogen:Air only

48
0

0.9 0

0. 0 + +3

0.8 7 0+ 0

~0.6 + 0

~0.5 + 00

~ .5+ 00 0

S0.4 .+mDYBUN

+4

4r 0.3 a-)02%S]A

02 20-30% 30 STEEAM

0.2. v7 - 30-40% STEAM

0 10 20 30 40 50 60 70 80

%HYDROGEN IN HYDROGEN:AIR ONLY

Figure 30

Ratio of the "Global" Peak Radiative to Total Peak Heat

Flux for the Hydrogen:Air:Steam Burns shown as a Function

of the Hydrogen Concentration in Hydrogen:Air only

combustion gas temperatures. Therefore, for a particular hydrogen concentration relative to air, the partitioning of the early postcombustion heat

,transfer is governed by the extent of combustion and the quantity of steam in

the volume.

In Figure 31 the total energy deposition (i.e., the time-integrals of the

calculated heat fluxes) for the hydrogen:air:steam burns is shown plotted

against the volumetric hydrogen concentration. From this plot, the combustion

severity again appears to increase with increasing steam content, especially

for burns containing less than -25% hydrogen by volume. Furthermore, the

burns containing more than 40% steam by volume resulted in the greatest total

energy depositions. If the same data are plotted against the hydrogen

concentration in air, as shown in Figure 32, the influence of steam is less

obvious. For moderate quantities of steam, the integral heat transfer is not

appreciably changed since combustion is not significantly inhibited; i.e.,

approximately the same combustion energy is released for these burns as the

"dry" burns. However, the rich steam quantities begin to inhibit the normal

49
C4.

E 100

0

0

0-

LL 0

0~

z

-LJ

0 1

00 +

4V0

+0

+jt

+

+ + DYBURNS

* a20-0%STEAM

* n30-0%STEAM

0 A0%STEAM -

0 10 20 30 40 50 60 70 80

% HYDROGEN

"Global" Cumulative

Steam Burns

Figure 31

Total Energy Deposition for the Hydrogen:Air:

with and without the Fans Operational

100

0

U,

adW

z

0

40 00

0: 0 0

0P

,7 0 0 0

A 0

0 4-+ +

10 +

a * DY BURNS

* 02%STEAM

E3- 0-0%STEAM

7 -30-0%STEAM

0-)4%STEAM I

+

I. .1.... I I . . . . I . . . . I 1

0 10 20 30 40 50 60 70 80

% HYDROGEN IN HYDROGEN~AIR ONLY

Figure 32

"Global" Cumulative Total Energy Deposition for the Hydrogen:Air:

Steam Burns shown as a Function of the Hydrogen

Concentration in Hydrogen:Air only

50
combustion process and the total energy

deposition) is correspondingly less. k~

addition of more than -40% steam reduceE

to -'50 J/cm2.

released (or equally the total energy

an example, around stoichiometry the

the energy deposition from '-70 J/cm2

The partitioning of the heat transfer is significantly changed by the

addition of steam, as shown in Figure 33 where the ratio of the radiative to

total heat transfer quantities are shown against the volumetric hydrogen

concentration. The addition of steam greatly influences the radiative heat

transfer mechanisms during the postcombustion cooling processes. For burns

containing less than -10% hydrogen, the radiative heat transfer increases from

'-50% of the total transfer for burns without steam to as much as -70% for

those with steam. Thus, radiation heat transfer is the dominant gas cooling

mechanism following combustion of the lean burns with steam, although natural

convection would be expected to ultimately dominate the late-time heat

transfer process.

1

0.9

0.8

z 0.7

t0.6

0

W 0.5

a 0.4

0 0.3

0.2

0.1

0

A 0 0

OA 0

+ A~0 0 An

0 0 0 0+-

+ - *DRY* BURNS

A - >0-20% STEAM 7:

o - 20-30% STEAM

V -30-40% STEAM

0 ->40% STEAM

0 10 20 30 40 50 60 70 80

% HYDROGEN IN HYDROGEN:AIR ONLY

Figure 33

Ratio of the "Global" Radiative to Total Energy

Deposition for the Hydrogen:Air:Steam Burns

51
In general, we see from the FITS data that steam reduces the overall heat

transfer compared to equivalent hydrogen:air burns at these scales. Steam

does affect the partitioning of the heat transfer mechanisms compared to the

"dry" hydrogen:air burns; i.e., radiation becomes the dominant heat transfer

mechanism for the lean hydrogen burns with rich steam concentrations. The

important parameter which must be accounted for when considering the effect of

steam as a diluent is the quantity of hydrogen relative to the available air.

If the volumetric concentrations are considered alone when analyzing these

data, misleading conclusions about the effect of steam on the postcombustion

heat transfer processes and general combustion characteristics could result.

4.4 Combustion Completeness

Gas samples were taken in a few of the combustion experiments reported

here. These gas samples were taken before and after the burns and were

analyzed with a gas chromatograph. However, due to systematic problems with

the sampling procedure, gas samples were not taken in all of the experiments.

Furthermore, the data obtained and reported in this section is used only to

compute the fraction burned and not for quantitative interpretation of the

initial gas concentrations. The difficulty in obtaining accurate pre and

posttest "grab samples" has plagued numerous experimentalist in the field [16,

23]. Desirable alternatives include a dynamic system capable of on-line

analysis of the gas concentrations inside the FITS chamber. One possibility

would be a mass spectrometer, giving rapid and potentially accurate results

with relatively little maintenance or disturbance from condensables such as

steam.

The gas samples taken during this series are shown in Table 1. As with

other facilities, a 10 to 15% difference occurred between the partial pressure

calculations and the gas analysis which is attributed to systematic problems.

Therefore, the gas sample analysis was used only to compute the approximate

percent fraction burned during combustion according to:

(%H) - (%H )f[ (%N 2).i

,fraction burned = 2 % % 2)f (4.5)

where (%112)i = the preburn hydrogen concentration,

(%H12)f = the postburn hydrogen concentration,

(%N2)i = the preburn nitrogen concentration, and

(%N2)f = the-postburn nitrogen concentration.

These results are shown in Figure 34 and generally show that as the steam

fraction increases, the extent of the burn decreases. Furthermore, most of

the burns above -8% hydrogen by volume appear to be relatively complete,

although the data are sparse and should not be over emphasized.

52
Table 1

Pre and Posttest Gas Sample Analysis for 14 Combustion Tests.

Burn Test %H2 %N2 %H2 %2Fraction

Number ID Precombustion Postcombustion Burned

129 HECTRS 6.25 73.53 5.45 74.03 0.13

130 HECTR6 7.11 75.97 5.73 74.41 0.18

131 HECTR7 11.41 69.18 TRACE 85.89 1.00

132 HECTR8 13.18 67.91 N.D. 84.85 1.00

133 HECTR9 13.43 67.89 3.55 83.77 0.85

134 HECT10 16.58 65.53 N.D. 87.44 1.00

137 HECT13 5.40 75.09 0.68 80.01 0.88

138 HECT14 7.80 73.47 N.D. 81.96 1.00

139 HIECT15 10.04 70.43 N.D. 82.94 1.00

140 HECT16 7.01 74.24 3.95 76.71 0.46

142 HECT18 10.93 70.27 TRACE 82.73 1.00

143 HECT19 13.52 68.55 N.D. 86.10 1.00

144 HECT20 14.03 67.28 2.35 81.86 0.86

145 HECT21 17.06 65.191 N.D. 87.75 1.00

TRACE = Trace amounts were detected in the sample.

N.D. = None detected

* Results are based on H2 +(02+AR) + N2 =100%

" These gas analyses were performed by Sandia's Analytical

Chemistry Division and do not account for any water vapor

present in the sample (i.e., dry gas analysis).

110

% t100

~70

~60

0

V 50

0 40

S30

S20

0 10

0

'DRY* BRNS

I+20XSTEAMI

4 OZ STAM

0 2 4 6 a 10 12 14 16 18 20

PREIGNITION HYDROGEN CONCENTRATION IN HYDROOEN&AIR ONLY

Figure 34

Combustion Completeness Data shown Plotted against the

Precombustion Volumetric Hydrogen Concentration

53
5. CONCLUSIONS

This work has provided a complete data base for hydrogen:air:steam

combustion characteristics and flammability limits at intermediate scale.

Experimentally observed flammability limits for hydrogen:air:steam mixtures in

turbulent and quiescent environments were measured to within an average of

+7.5 and +2.2% of the calculated hydrogen and steam concentration,

respectively. An exponential peeling routine was used to define a correlation

for these data which describes the entire region of flammability and is given

by;

%Steam =100 - %H 2-~ 37. 3e-0 .

0 07%11 2 - 518.0-e-0 .488%H2 (5.1)

This correlation may be used in reactor safety analysis codes for determining

the flammability of a calculated mixture. It could also be used to estimate

the earliest time into an accident sequence that ignition of a hydrogen:air:

steam environment could occur assuming an ignition source were available.

Transient combustion pressures have been measured for most of these

experiments. The normalized combustion peak pressure (Pmax/Po) was found to

increase with increasing hydrogen concentrations of up to -30%, at which point

a decrease was observed for further increases in hydrogen concentration.

Steam was found to decrease the normalized peak pressures compared to the

hydrogen:air counterpart. Comparison of the experimentally measured peak

pressure to the AICO calculated peak indicates that relatively complete

combustion occurs (>95%) for hydrogen concentrations greater than -10%, while

lesser quantities of hydrogen are burned as the lean hydrogen:air flammability

limit is approached. Turbulence was found to increase the extent of

combustion and combustion characteristics of the lean burns, while not

appreciably affecting the combustion characteristics of rich burns. Ambient

preignition temperatures of '-300 K resulted in more severe combustion

environments than equivalent burns at elevated temperature (-385 K). This

result is directly related to the decrease in hydrogen and oxygen mass as the

bulk temperature increases for a given fixed volume (e.g., for a fixed volume

and air partial pressure, increases in the bulk gas temperature result in

lesser quantities of hydrogen being introduced into the vessel to achieve the

same partial pressure condition). Thus, as we observed, more severe burns for

combustion experiments at lower preignition temperatures would be expected.

The experimental pressure signatures were used to infer the "~global"~

total, convective and radiative postcombustion energy deposition (or thermal

loading) and peak heat fluxes. These results indicate that burns at lower

preignition temperatures tended to be more "severe than those at elevated

temperatures. Convection was found to play the dominant role in the leaner

(<15%) hydrogen:air burns, accounting for 70 to 90% of the postcombustion heat

transfer while radiation and convection played equal roles near stoichiometry.

Steam was found to increase the total energy deposition and peak heat fluxes

if considered as a function of the volumetric hydrogen concentration,

especially for hydrogen concentrations of 25% or less. If, however, the heat

transfer results are considered as a function of the hydrogen concentration in

54
air, the addition of steam tends to decrease the total energy deposition and

peak heat fluxes. Thus, the postcombustion heat transfer characteristics are

governed by the hydrogen concentration in air.

Radiation was found to dominate the postcombustion heat transfer processes

for lean hydrogen burns containing steam. Furthermore, comparisons to the

large-scale NTS results show that the radiative fraction of the total energy

deposition at this scale was approximately half that observed at large-scale.

This result is a scaling phenomena; the partitioning of the radiative heat

transfer is directly related to the characteristic length-scale for radiation.

In particular, the gas emittance would be expected to approximately double due

to the increased radiation length scale; e.g., an increase in the radiation

length scale will effectively increase the gas emittance. Based on

differences in vessel geometry and volume, the bulk gas emittance and

radiative partition in the NTS tests would be expected to increase by

approximately twice the values observed in the FITS vessel.

Generally, the combustion pressures, "global" gas temperatures, and

"global" heat transfer data provided in this report should be useful in

assessing the importance of hydrogen:air:steam flammability limits and

combustion characteristics for nuclear reactor safety analyses. The data

provide useful reference points for benchmarking existing and newly developed

computer codes for hydrogen:air:steam combustion characteristics and for

containment response modelling. These data should also provide useful

information for determining the response of safety-related equipment to

hydrogen burns.

55
6. References

1. R. G. Zalosh et al., Analysis of the Hydrogen Burn in the TMI-2

Containment, EPRI NP-3975, Factory Mutual Research Corporation,

Massachusetts, April 1985.

2. Core-Meltdown Experimental Review, NUREG/CR-0205, SAND 74-0382

(Revision), Sandia National Laboratories, Albuquerque, NM, March 1977.

3. M. P. Sherman et al., The Behavior of Hydrogen During Accidents in Light

Water Reactors, NUREG/CR-1561, SAND8O-1495, Sandia National Laboratories,

Albuquerque, NM, August 1980.

4. A. L. Camp et al., Light Water Reactor Hydrogen Manual, NUREC/CR-2726,

SAND82-1137, Sandia National Laboratories, Albuquerque, NM, August 1983.

5. A. M. Shapiro and T. R. Moffette, Hydrogen Flammability Data and

Applications to PWR LOCA, WARD-SC-545 Bettis Plant, 1957.

6. M. G. Zabetakis, Research on the Combustion and Explosion Hazards of

Hydrogen-Water Vapor-Air Mixtures, Bureau of Mines, Pittsburgh,

Pennsylvania, AECU-3327, September 1956.

7. M. Berman and J. C. Cummings, "Hydrogen Behavior in Light Water

Reactors," Nuclear Safety, Vol. 25, No. 1, January-February 1984.

8. M. Berman et al., Light Water Rector Safety Research Program Semiannual

Report, April-September 1982, NUREG/CR-3407, SAND83-1576, Sandia National

Laboratories, Albuquerque, NM, October 1983.

9. H. Tamm et al., "A Review of Recent Experiments at WNRE on Hydrogen

Combustion," Proceedings of the Second International Conference on the

Impact of Hydrogen. on Water Reactor Safety, M. Berman, J. Carey, J.

Larkins, and L. Thompson (technical program committee), NUREG/CP-0038,

EPRI RP 1932-35, SAND82-2456.

10. W. E. Lowry et al., Final Results of the Hydrogen Igniter Experimental

Program, NUREG/CR-2486, UCRL-53036, February 1982.

11. Tennessee Valley Authority, Sequoyah Nuclear Plant, Research Program on

Hydrogen Combustion and Control Quarterly Report #3, Appendix A.2, June

1981.

12. D. Renfro et al., "Development and Testing of Hydrogen Ignition Devices,"

Proceedings of the Second International Conference on the Impact of

Hydrogen on Water Reactor Safety, M. Berman, J. Carey, J. Larkins, and L.

Thompson (technical program committee), NUREG/CP-0038, EPRI RP 1932-35,

SAND82-2456.

56
13. S. F. Roller et al., "Medium-Scale Tests of H2:Air:Steam Systems,"

Proceedings of the Second International Conference, on the Impact of

Hydrogen on Water Reactor Safety, M. Berman, J. Carey, J. Larkins, and L.

Thompson (technical program committee), NUREG/CP-0038, EPRI RP 1932-35,

SAND82-2456.

14. D. D. S. Liu et al., Canadian Combustion Studies Related to Nuclear

Reactor Safety Assessment, Available as Atomic Energy of Canada Report

AECL-6994, October 1980.

15. H. F. Coward and G. W. Jones, Limits of Flammability of Gases and Vapors,

Bulletin 503, U. S. Bureau of Mines, Washington D. C., 1952.

16. W. B. Benedick et al., Combustion of

Cylindrical Tank, NUREG/CR-3273,

Laboratories, Albuquerque, NM, May 1984.

Hydrogen:Air Mixtures in the VGES

SAND83-1022, Sandia National

17. R. K. Kumar et al., Intermediate-Scale Combustion Studies of HydrogenAir-Steam Mixtures, EPRI NP-2955, Electric Power Research Institute, June

1984.

18. A. C. Ratzel, Data Analyses for Ne

Combustion Tests, NUREG/CR-4138,

Laboratories, Albuquerque, NM, May 1985.

vada Test Site (NTS)

SAND85-0135, Sandia

Premixed

National

19. B. W. Marshall, Jr., Flammability Limits and Combustion Characteristics

of Hydrogen:Air:Steam at Intermediate Scale, Proceedings of the ANS/ENS

Topical Meeting on the Operability of Nuclear Power Systems in Normal and

Adverse Environments, Albuquerque, NM, September" 29 - October 3, 1986.

20. B. W. Marshall, Jr., Hydrogen:Air:Steam Flammability Limits and

Combustion Results at Intermediate Scale, Presented at the 1986 Spring

Technical Meeting of The Combustion Institute, Banff, Alberta, Canada,

April 28 - 30, 1986.

21. S. Gordon and B. J. McBride, Computer Program for Calculation of Complex

Chemical Equilibrium Compositions, Rocket Performance, Indicent and

Reflected Shocks, and Chapman-Jouguet Detonations, NASA SP-273,

Washington DC: Scientific and Technical Info Of c, NASA, 1971.

22. A. C. Ratzel, S. N. Kempka, J.

Reduction Package for Analysis

SAND83-2657, Sandia National

1985.

23. S. F. Roller, Pressure Measure:

Hydrogen-Air Combustion Test S,

3721 (1 of 2), SAND83-2621

Albuquerque, NM, March 1985.

24. B. W. Marshall, Jr. and A.

Hydrogen Combustion Environmi

Transducers, NUREG/CR-3721 (!

National Laboratories, Albuque:

E. Shepherd, and A. W. Reed, SMOKE: A Data

of Combustion Experiments," NUREG/CR-4136,

Laboratories, Albuquerque, NM, September

rients in a Hydrogen Combustion Environment:

,ries 1 and 2 in the FITS Tank, NUREG/CR-

(1 of 2), Sandia National Laboratories,

Ratzel III, Pressure Measurements in a

mnt: An Evaluation of Three Pressure

!of 2), SAND83-2621 (2 of 2), Sandia

-que, NM, May 1984.

57
25. E. H. Richards and J. J. Aragon, Hydrogen-Burn Survival Experiments at

Fully Instrumented Test Site (FITS), NUREG/CR-3521, SAND83-1715, Sandia

National Laboratories, Albuquerque, NM, August 1984.'

26. M. Berman, ed., Light Water Reactor Safety Research Program Semiannual

Report, April-September 1981, NUREG/CR-2481, SAND82-0006, Sandia National

Laboratories, Albuquerque, NM, October 1982.

27. 1. L. Drell and F. E. Belles, Survey of Hydrogen Combustion Properties,

National Advisory Committee for Aeronautics, Report 1383, 1958, Update

1975.

28. C. C. Wong, HECTR Development and As sessment, SAND85-1792C, Proceedings

of the 13th-l Water Reactor Safety Research Information Meeting,

Gaithersburg, MD, October 1985.

29. A. L. Camp, M. J. Wester, and S. E. Dingman, HECTR Version 1.0 User's

Manual, NUREG/CR-3913, SAND84-1522, Sandia National Laboratories,

Albuquerque, NM, February 1985.

30. R. E. Henry, et al., Technical Report 16.2-3 MAAP Modular Accident

Analysis Program User's Manual-Vol. I, Industry Degraded Core Rulemaking

Program, August 1983.

31. A. C. Ratzel and J. E. Shepherd, "Heat Transfer Resulting from Premixed

Combustion," Heat Transfer and Fire and Combustion Systems, HTD-Vol.. 45,

Published by ASME, SAND84-2262C, August 1985, pp 191-202.

32. S. N. Kempka, A. C. Ratzel, A. W. Reed, and J. E. Shepherd,

Postcombustion Convection in an Intermediate-Scale Vessel, Proceedings of

the joint ANS/ASME conference on design, construction, and operation of

Nuclear Power Plants, Portland, Oregan, SAND83-2180C, August 1984.

58
APPENDIX 1

Corrected Initial Data

This appendix presents the corrected initial precombustion gas

concentrations of hydrogen and steam as well as the initial temperature and

pressure for each of the 239 burns performed in this test series. For

convenience, the burn have been numbered to provide a method of correlating

the initial data to the combustion pressure and "global" heat transfer results

presented in subsequent appendices and throughout this report. The type of

ignition for each test was classified according to the following:

S = Spark plug ignition;

G = Glow plug ignition;

M = Marginal ignition (i.e., AP/APaicc •0.1);

N = No detectable ignition.

The preignition gas turbulence is either given a fans-on designation ('0') or

a fans-off designation ('F') depending upon the condition of the fans at the

time of ignition.

59
BURN TEST ID % 112 %H20 P0 To IGN. FAN

(atm) (K)

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

1106S30

S301106

S301105

S30H05

S301105

30S05H1

30S05H1

30S06H1

30S0711

1107S40

071140S

06HS540

05HS40

1105S40

1105S40

1107S50

1106S50

S501106

S501105

O0ilSOS

OSESOS

50SH05

1108550

S501108

HlOS50

1113S50

Hl10S55

1110S60

Hl10S60

101H60S

11110

S55H108

H120S45

H120S50

S50H120

S501120

H120S48

S481120

H130S43

1130S43

H130S40

1130S38

101H20S

H130S35

40S30H1

S451130

7.67

6.61

5.74

6.26

6.51

6.87

7.52

9.04

8.84

10.25

8.13

6.89

7.37

7.17

7.49

9.00

8.26

8.51

8.31

6.17

8.47

6.03

9.32

9.44

11.66

15.41

11.41

9.92

7.65

8.97

9.97

8.81

19.94

22.75

22.33

21.28

21.57

20.88

30.92

31.28

30.53

30.60

8.96

30.41

31.02

30.97

26.16

29.46

30.07

26.51

24.88

30.78

27.98

29.33

29.43

34.10

38.07

38.08

38.03

37.51

36.84

47.86

45. 11

42.71

45.38

45. 11

41.70

46.44

45.54

45.71

43.91

38.06

44.45

49.75

50.61

50.33

0.00

45.48

37.11

41.30

44.20

46.01

43.47

45.29

41.07

41.17

39.39

36.77

22.96

33.67

38.04

43.30

1.18

1.23

1.21

1.18

1 .15

1.25

1.21

1.26

1.25

1.40

1 .47

1 .42

1.41

1.40

1.37

1.76

1.63

1.61

1.67

1.64

1.67

1.67

1.76

1.80

1.82

1.70

1.80

1.94

1.87

1.91

0.89

1.75

1.95

2.17

2.43

2.38

2.25

2.27

2.76

2.75

2.52

2.35

1.13

2.18

2.48

2.98

368.85

370.75

379.35

363.85

355.45

373.45

367.25

379.65

379.25

366.45

379.65

379.85

380.35

374.05

374.45

392.55

378.45

369.35

381.05

379.15

364.85

382.75

383.15

382.35

379.25

376.45

375.95

381.05

378.45

359.45

379.65

379.85

384.55

382.55

381.95

378.85

383.45

385.95

386.25

376.05

386.35

382.05

375.35

384.35

385.75

60
BURN TEST ID % 112 %H20 P0 To IGN. FAN

(atm) (K)

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

43SH130

30HS40

H140S30

H140S35

10HS15

40H33S

30SH140

33SH140

06HS30

30SH106

07HS40

S4007H1

50SH107

H150S25

S30H140

S3040H1

30H1S35

S4520H1

H4030S

50SH20

S 501115

151140S

30S15H1

50H1S10

H150S20

5011S20

i5SS1511

SI 01115

H12015S

l0S13H1

H5HF

1111F

1161F

11F511

11F511

8HFW

811WF

60H110S

H160S5

115025S

FW8H

H16010S

10111

H160Sl5

30.91

30.62

39.89

37.37

8.44

41.87

41.20

41.25

5.72

5.54

6.77

6.64

6.81

50.39

21.23

40.44

29.80

20.26

40.29

20.26

14.92

14.29

15.27

49.29

50.46

50.36

14.40

14.40

18.94

11.89

3.44

5.03

5.54

5.00

5.60

6.96

7.77

60.67

58.77

50.56

8.43

57.23

9.41

57.18

41.27

39.18

30.83

37.31

18.13

30.99

28.33

31.53

30.45

30.38

39.28

40.42

48.91

25-03

47.97

29.52

35.30

44.40

29.66

48.12

49.32

40.52

29.18

10.83

19.30

19.47

17.14

13.56

17.22

14.18

0.00

0.00

0.00

0.00

0.00

0.00

0.00

9.07

6.80

24.30

0.00

7.85

0.00

16.86

2.75

2.54

2.60

3.01

1.08

2.80

2.47

2.77

1.24

1.24

1.46

1.48

1.79

3.12

2.52

2.59

2.26

2.21

2.58

2.50

2.17

1.71

1.42

1.99

2.59

2.62

1 .17

1.11

1.25

1.07

0.84

0.83

0.83

0.83

0.83

0.84

0.85

2.64

2.27

3.08

0.88

2.41

0.92

3.10

388.55

375.85

395.65

391.75

395.75

386.55

381.05

385.25

384.95

385.55

377.45

385.75

383.55

387.35

382.85

381.65

387 .05

388.65

382.65

379.95

389.75

387 .15

391.35

391.25

384.65

392.45

391.15S

403 .0S

397.55

392.75

384.75

406.15

393.75

394.45

389.35

311.55

352.25

393.25

396.35

393.55

311 .05

382.55

392 .0S

377.85

N

G

G

N

S

N

M

N

M

G

M

S

S

N

G

G

G

G

C

G

G

S

C

G

G

C

S

S

S

S

N

N

S

N

N

S

S

G

G

N

S

C

S

N

61
BURN TEST ID % H2 %H20 P0 To IGN. FAN

(atm) (K)

91

92

93

94

95

96

97

98

99

100

101

102,

103

104

105

106

107

108

109

110

ill

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

S5010H

H1010S

GC06

GC08

INIT1

INIT2

INIT3

INIT4

INIT5

INIT6

INIT7

INIT8

INITO

FLANKi

FLAMM2

FLAWM

FLAMM4

FLAMM5

FLAMM6

FLAMM7

FLAMM8

FLAIAM9

FLAM10

FLAY11

FLAM12

FLAM13

FLAM14

FLAM15

FLAM16

FLAM17

FLAN18

FLAM19

FLAM20

FLAM21

HECTRl

HECTR2

HECTR3

HECTR4

HECTR5

HECTR6

IIECTR7

HECTR8

HECTR9

HECT10

HECT11

HIECT12

10.95

8.70

5.86

7.24

9.30

9.43

11 .55

10.02

14.49

20.17

6.41

9,83

11.19

10.91

11.41

11.15

11.14

11 .20

13.80

13.72

12.48

12.66

13.23

15.50

16.54

17.12

17.64

17.67

17.04

8.23

8.37

9.03

9.09

8.83

6.28

4.94

6.38

10.80

4.86

6.36

8.88

11 .47

9.73

10.68

6.24

6.74

42.85

15.68

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

46.68

53.56

50.85

52.97

54.85

54.67

52.31

51.12

52.23

49.22

48.01

44.87

48.75

45.48

52.35

48.01

48.63

48.88

49.12

54.53

51.72

0.00

0.00

0.00

0.00

20.44

21.04

21.65

21.37

38.77

41.23

0.00

0.00

1.81

1.12

0.86

0.87

0.90

0.94

0.98

0.90

0.95

1.02

0.86

0.90

0.92

2.06

2.40

2.22

2.28

2.43

2.64

2.44

2.26

2.36

2.24

2.30

2.13

2.44

2.26

2.84

2.34

1.94

1.97

1.98

2.38

2.11

0.87

0.84

0.85

0.95

1.11

1.12

1.16

1.21

1.57

1.69

0.88

0.88

385.55

392.65

292.65

293.85

296.25

296.85

296.25

293.85

296.25

298.55

302.75

296.25

298.05

393.85

382.05

392.65

384.35

384.95

393.85

384.35

398.55

392.65

384.95

395.05

387.35

396.25

386.75

404.45

380.85

396.25

400.35

390.85

392.65

390.25

374.35

373.15

373.15

380.85

384.35

382.55

384.35

368.95

387.95

390.85

383.15

393.85

62
BURN TEST ID % H2 %H20 P0 To ION. FAN

(atm) (K)

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

HECT13

HIECT14

HECT15

HECT16

HECT17

BIECT18

BECT19

HECT20

HECT21

H20HD

ýARTi

ART2

ART3

ART4

ARTS

ART6

PRES1

PRES2

PRES3

PRES4

PRESS

PRES6

PRES7

PRES8

PRESO

PRES10

PRES11

PRES12

PRES13

PRES14

PRES15

PRES16

PRES 17

PRES18

PRES19

PRES20

PRES21

PRES22

PRH10QA

PRH 10B

PRH20A

PRH20B

PRH25A

PRH25B

PRH30A

PRH30B

6.03

7.83

10.19

6.63

8.53

8.87

9.70

9.09

10.01

16.85

5.62

12.91

14.74

15.76

8.02

15.56

9.90

18.95

29.53

9.29

19.31

9.36

20.52

31.32

10.26

11 .05

19.45

9.67

10.36

9.25

9.62

22.65

Ii1.47

9.53

10.12

9.13

19.69

11.43

9.34

9.36

20.09

18.98

24.32

24.16

29.23

0.00

0.00

0.00

18.81

17.97

16.62

19.39

36.34

37.43

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.87

0.88

0.91

1.08

1.10

1.09

1.14

1.46

1.53

0.98

0.84

0.95

0.96

0.96

0.87

0.95

0.91

1.01

1.14

0.89

1.02

0.91

1.03

1 .17

0.92

0.91

1.01

0.89

0.91

0.90

0.91

1.06

0.94

0.94

0.93

0.92

1.05

0.94

0.87

0.86

0.96

0.94

1.01

1.05

1.13

1.16

383.75

393.85

392.65

387.35

384.35

389.65

388.55

385.55

383.75

384.35

376.65

377.25

387.35

377.85

295.65

295.05

296.85

298.05

300.95

306.25

306.85

296.85

297.45

300.35

305.65

305.65

305.65

298.05

295.0OS

296.85

298.55

296.25

370.75

374.35

379 .0S

355.35

359.55

398.55

293.25

296.85

297.45

300.35

303.35

295.05

299 .15

303.35

63
BURN TEST ID % H2 %H2 0 P0 T IGN. FAN

(atm) (K)

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

'214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

PRH10C

PRH20C

PRH10D

PRH30C

PRH35A

PRH10H

PRH20S

PRSH20

PRH50A

PRH60A

PRH30D

PRH40A

PRH40S

PRSH40

PR40HS

PRH70A

H1OHD

LASTI

LAST2

LAST3

LAST4

LASTS

LAST6

LAST7

LAST8

LAST9

LAST10

LAST11

LAST12

LAST 13

LAST14

LAST15

LAST16

RANGE 1

RANGE2

RANGE3

RANGE4

RANGES

RANGE6

RANGE7

RANGE8

RANGE9

RANG10

RANG 11

RANG 12

RANG13

10.98

19.18

11. .24'

31.33

34.74

10.55

19.03

19.06

51.53

59.93

30.08

39.99

37.53

38.86

38.52

68.37

7.09

10.21

10.68

26.18

27.58

26.34

25.86

26.43

28.65

25.99

26.82

25.83

26.34

26.69

25.43

26.35

9.78

18.51

10.28

8.94

18.93

9.97

11.14

18.53

27.97

10.06

20.76

30. 16

10.80

0.00

0.00

0.00

0.00

0.00

0.00

22.27

15.71

0.00

0.00

0.00

0.00

23.78

21.76

17.41

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.96

1.10

0.94

1.22

1 .32

0.92

1 .39

1.21

1.64

2.02

1.17

1.37

2.04

2.05

1 .82

2.58

0.87

0.93

0.92

1.12

1.12

1.12

1.12

1.12

1.12

1.15

1.14

1.14

1.12

1.13

1.14

1.12

1.14

0.90

1.01

0.91

0.89

1.00

0.90

0.91

1.02

1.14

0.91

1.03

1.18

0.93

308.65

307.45

301.55

301.55

306.85

370.15

382.55

384.95

377.25

378.45

358.95

355.95

382.55

393.25

389.65

392.05

390.85

306.8S

305.65

293.85

306.25

296.25

302.15

305.65

310.45

313.95

298.55

303.95

308.65

310.45

315.15

318.15S

318.75

293.15

292.65

296.25

296.25

296.85

293.25

296.25

300.95

300.95

304.55

303.95

306.8S

296.25

S

S

S

S

S

S

S.

S

S

S

S

S

S

S

S

S

S

G

G

S

S

S

S

S

G

G

G

S

G

S

G

G

G

S

S

S

S

S

S

S

S

S

S

S

S

S

64
BURN TEST ID % H2 %H20 P0 To ION. FAN

(atm) (K)

229 RANG14 20.41 0.00 1.04 296.25 S a

230 RANG15 30.42 0.00 1.18 300.35 S a

231 RANG16 12.65 0.00 0.95 305.65 S 0

232 RANG17 20.16 0.00 1.04 308.05 S 0

233 RANG18 9.31 0.00 0.91 297.45 S 0

234 RANG19 19.79 0.00 1.04 298.55 S 0

235 RANG20 30.17 0.00 1.19 302.75 S 0

236 RANG21 9.99 0.00 0.92 308.65 S a

237 RANG22 20.11 0.00 1..04 309.25 S 0

238 RANG23 30.02 0.00 1.19 294.45 S 0

239 RANG24 9.98 0.00 0.92 302.15 S 0

65
APPENDIX 2

Experimental Uncertainty Analysis

As discussed in Section 3 of this report,. the volumetric gas compositions

were calculated using partial pressure calculations. The error or uncertainty

associated with these calculations .can be estimated using a Kline-McClintock

uncertainty analysis [2.1]. In this analysis, the uncertainty associated with

a calculated results r can be estimated as

ar w r I8n r x ) 0.5 a'x1 x.1 I +[ 2 Wx2 I+ +[L (A2-1)

where xj, x2, ... ,I and Xn are the independent variables and wxl, wx2, ... , and

wxn are the uncertainties associated with each experimental measurement.

Using this technique, the uncertainty associated with the partial pressure

calculations defined by Equations (3.1), (3.2), (3.8), and (3.9) can be

estimated. If this technique is applied to the equation defining the hydrogen

partial pressure (Equation (3.8)), the uncertainty associated with this

calculation is given by;

Phyd ( I 13 ] 2

o[w2 + (P2

T2

2 2 0.

w T2 ) (A2-2)

In a like manner, the uncertainty associated with the steam partial pressure

calculation (Equation (3.9)) is

w stm 1 1 +

T3 T 2

T 2 I0 r 2

wP + ( P2 2 w2 ] }0.5 (A2-3)

If the hydrogen and steam concentrations are calculated using Equations (3.1)

and (3.2), respectively, then the uncertainty associated with these calculated

results can be expressed as

w %hyd={ [P stm

2

I +

wpair

P stm

12+ Phyd- air

P stm

j0.52 

V stml (A2-4)

and

w sm= f[ P stm

12 I P stm ) * Psm] . (A2-5)

Therefore, the uncertainty associated with these calculations can be estimated

if the uncertainty of each measurement is known.

66
For this analysis, the uncertainty of the experimental measurements are

assumed to be +10C for the temperature measurements and +0.0073 kPa (0.5 psia)

of the static pressure measurement.' On the average, the uncertainty of the

calculated initial volumetric percentages for hydrogen and steam were within

+7.5 % and +2.2 %, respectively, of the calculated concentration.

The experimental error of the dynamic pressure measurements can be

estimated by considering each component in the data acquisition system at the

facility. Generally, the pressure gauges used during this experimental series

were found to be accurate to within + -"5% over the entire range of the gauge

response. The dynamic amplifiers are reported as being accurate to within

0.1% of the gain setting which has been checked and calibrated during the

course of testing. The ADCs are accurate to within +9.8 mV (equivalent to

one-bit of resolution) of the actual voltage which was generally small

compared to the actual voltage reading and should introduce relatively small

errors (i.e., < 1%). Thus, the integral error associated with the transient

combustion pressure measurements were estimated to be within -"10%.

The uncertainty associated with the heat transfer calculations as inferred

from the pressure signals has not been addressed in this work, but the reader

should refer to Reference 2.2 for information pertaining to these codes.

References

2.1. J. P. Holman, Experimental Methods for Engineers, Third Edition,

McGraw-Hill Book Company, 1978.

2.2. A. C. Ratzel, S. N. Kempka, J. E. Shepherd, and A. W. Reed, SMOKE: A

Data Reduction Package for Analysis of Combustion Exper iments,"

NUREG/CR-4136, SAND83-2657, Sandia National Laboratories, Albuquerque,

NM~, September 1985.

67
APPENDIX 3

Combustion Pressure Data for the

Hydrogen: Air Burns

This appendix presents combustion pressure data for each of the hydrogen:

air burns conducted. Included are the normalized peak pressures, the ratio of

the measured peak to AICO calculated peak pressure, the combustion duration

(measured as the time from ignition to the peak pressure), the mean pressure

derivative, and the "global" bulk gas temperature as inferred from the

computer programs referred to as SMOKE. Note that if the experimental data

were not available due to hardware failures or experim *ental difficulties, the

columns are appropriately marked with "NA" (Not Available). If the test was

not processed using the suite of computer programs referred to as SMOKE, the

gas temperature column is appropriately label with "NP." Also, the burn

number is given and Appendix 1 should be referenced for the initial conditions

of the burns reported.

68
Q max Pmax AP (atm) Tmax

Burn %H2 in air %H20 -At

PO Paicc (S) At(s) T

31

79

82

83

87

89

93

94

95

96

97

98

99

100

101

102

103

125

126

127

128

135

136

137

138

139

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

9.97

5.54

6.96

7.77

8.43

9.41

5.86

7.24

9.30

9.43

11.55

10.02

14.49

20. 17

6.41

9.83

11.19

6.28

4.94

6.38

10.80

6.24

6.74

6.03

7.83

10.19

16.85

5.62

12.91

14.74

15.76

8.02

15.56

9.90

18.95

29.53

9.29

19.31

9.36

20.52

31.32

10.26

11 .05

19.45

9.67

9.97

5.54

6.96

7.77

8.43

9.41

5.86

7.24

9.30

9.43

11.55

10.02

14.49

20. 17

6.41

9.83

11 .19

6.28

4.94

6.38

10.80

6.24

6.74

6.03

7.83

10.19

16.85

5.62

12.91

14.74

15.76

8.02

15.56

9.90

18.95

29.53

9.29

19.31

9.36

20.52

31.32

10.26

11 .05

19.45

9.67

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

2.95

1 .62

2.32

2.68

2.59

2.72

1.66

2.28

1.68

3.21

3.69

4.28

5.35

6.61

2.09

4.05

4.38

1.51

1.49

2.30

2.83

2.03

1.93

2.10

2.73

2.91

4.93

2.30

3.20

3.99

4.13

3.12

5.14

3.76

6.15

7.71

3.60

6.15

3.62

6.19

7.80

3.63

3.45

5.96

3.81

0.81

0.67

0.71

0.84

0.80

0.83

0.54

0.65

0.41

0.78

0.78

0.99

0.98

0.99

0.66

0.96

0.95

0.56

0.63

0.84

0.77

0.77

0.72

0.81

0.93

0.84

1.00

0.91

0.78

0.91

0.89

0.84

0.89

0.88

0.95

0.97

0.90

0.97

0. 88

0.91

0.97

0.85

0.77

0.93

0.91

1.22

2.45

2.79

0.89

0.90

0.52

4.70

7.84

1 .32

0.88

NA

0.40

0.20

0.13

9.30

0.36

0.33

2.40

4.84

1.08

0.55

0.74

0.80

0.73

0.51

0.47

NA

4.77

0.69

0.20

0.14

0.78

0.22

0.51

0.07

0.03

0.46

0.07

0.56

0.08

0.03

0.46

1.03

0.09

0.43

1 .43

0.21

0.40

1.61

1.90

3.08

0.12

0.14

0.46

2.35

NA

7.44

21.06

44.00

1.01

7.60

9.51

0.18

0.09

1 .09

2.93

1.20

1.03

1.30

2.96

3.71

NA

0.23

3.03

14.16

21.46

2.36

17.62

4.93

80.00

263.8

4.99

73.77

4.28

66.96

283.9

5.27

2.17

55.67

5.88

3.1l1I

1.67

2.41

2.80

3.08

2.86

1.72

2.58

1.76

3.37

NP

4.51

5.78

7.36

2.17

4.27

4.64

1.55

1.53

2.38

3.00

2.10

2.00

2.17

2.84

3.08

NP

2.37

3.43

4.32

4.50

3.26

5.58

3.96

6.81

8.89

3.78

6.82

3.81

6.90

9.00

3.83

3.66

6.62

4.01

69
%H2 Pmax Pmax AP (atm) Tmax

Burn %H12 in air %H120 -At

PO Paicc (S) At(s) T

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

191

192

193

194

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

10.36

9g.25

9.62

22.65

11.47

9.53

10.12

9.13

19.69

11.43

9.43

9.36

20.09

18.98

24.32

24. 16

29.23

29.47

10.98

19.18

11.24

31.33

34.74

10.55

51.53

59.93

30.08

39.99

68.37

11.46

10.21

10.68

26.18

27.58

26.34

27.28

25.86

26.43

28.65

25.99

26.82

25.83

26.34

26.69

25.43

10.36

9.25

9.62

22.65

11.47

9.53

10.12

9.13

19.69

11.43

9.34

9.36

20.09

18.98

24.32

24. 16

29.23

29.47

10.98

19.18

11.24

31.33

34.74

10.55

51.53

59.93

30.08

39.99

68.37

11.46

10.21

10.68

26.18

27.58

26.34

27.28

25.86

26.43

28.65

25.99

26.82

25.83

26.34

26.69

25.43

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

0.00

3.67

3.69

3.53

6.65

3.16

2.81

2.79

3.11

4.85

2.74

3.88

3.95

6.54

6.07

7.26

7.33

7.66

7.63

3.48

6.06

3.81

7.63

7.76

3.20

5.42,

4.64

6.66

6.37

3.72

2.89

2.98

2.50

7.78

7.31

7.90

7.56

7.43

7.33

7.16

7.70

7.53

7.34

7.29

7.31

7.29

0.83

0.91

0.85

0.92

0.81

0.82

0.79

0.89

0.87

0.75

0.94

0.96

0.98

0.95

0.99

0.98

0.96

0.96

0.79

0.96

0.84

0.95

0.99

0.86

0.96

0.92

0.99

0.96

0.88

0.78

0.71

0.57

0.99

0.95

1.01

0.98

0.99

0.98

0.93

1.00

0.98

0.99

0.98

0.99

1.01

0.53

0.53

0.62

0.05

0.46

1.16

1.27

0.93

0.09

1.10

0.47

0.43

0.06

0.09

0.03

0.03

0.02

0.03

0.46

0.07

0.41

0.03

0.02

0.38

0.04

0.08

0.03

0.03

0.24

NA

4.01

7.00

NA

0.03

0.03

0.03

0.03

0.03

0.03

0.03

0.03

0.03

0.04

0.03

0.03

4.55

4.53

3.70

125.8

4.47

1 .46

1.31

2.08

47.03

1 .49

5.20

5.90

83.13

53.60

185.9

229.0

327.4

307.6

5.14

76.30

6.44

310.8

447.8

13.08

176.7

88.00

207.4

238.2

29.09

NA

0.46

0.20

NA

207.9

309.1

262.4

218.2

253.2

283.4

305.5

256.7,

236.7

203.1

239.9

234.7

3.88

3.88

3.71

7.49

3.37

2.96

2.95

3.26

5.39

2.91

4.01

4.15

7.28

6.72

8.23

8.30

8.83

8.80

3.69

6.72

4.05

8.81

8.94

3.38

6.04

5.08

7.68

7.26

3.99

NA

3.15

2.65

NA

8.33

8.80

8.65

8.33

8.30

8.19

8.54

8.44

8.26

8.29

8.09

8.01

70
%H max Pmax, AP (atm) Tmax

Burn %H2 in air %H20 -At

PO Paicc (S) At(s) T

215 25.35 25.35 0.00 7.22 1.00 0.03 236.3 8.00

216 9.78 9.78 0.00 2.83 0.66 4.10 0.40 2.97

217 18.51 18.51 0.00 5.60 0.87 0.14 33.34 6.18

218 10.28 10.28 0.00 2.96 0.68 3.78 0.47 3.13

219 8.94 8.94 0.00 3.52 0.89 1.23 1.83 3.69

220 18.93 18.93 0.00 6.04 0.94 0.13 38.99 6.68

221 9.97 9.97 0.00 3.68 0.85 0.91 2.65 3.88

222 11.14 11.14 0.00 3.90 0.84 0.35 7.49 4.14

223 18.53 18.53 0.00 5.56 0.87 0.06 79.65 6.01

224 27.97 27.97 0.00 6.22 0.80 0.12 49.18 NP

225 10.06 10.06 0.00 3.62 0.86 0.40 6.00 3.82

226 20.76 20.76 0.00 5.90 0.88 0.05 107.4 NP

227 30.16 30.16 0.00 7.40 0.94 0.03 260.7 8.55

228 10.80 10.80 0.00 3.71 0.82 0.34 7.42 3.93

229 20.41 20.41 0.00 6.02 0.89 0.09 54.77 6.71

230 30.42 30.42 0.00 7.63 0.95 0.03 270.9 8.82

231 12.65 12.65 0.00 3.43 0.70 0.40 5.77 3.67

232 20.16 20.16 0.00 5.71 0.88 0.11 43.74 6.36

233 9.31 9.31 0.00 3.48 0.85 0.44 5.21 3.65

234 19.79 19.79 0.00 5.79 0.88 0.12 43.30 6.43

235 30.17 30.17 0.00 7.48 0.94 0.03 233.5 8.63

236 9.99 9.99 0.00 3.50 0.85 0.40 5.72 3.70

237 20.11 20.11 0.00 5.63 0.88 0.10 48.20 6.27

238 30.02 30.02 0.00 7.80 0.95 0.07 124.5 9.02

239 9.98 9.98 0.00 3.58 0.85 0.47 5.10 3.78

71
APPENDIX 4

Global Heat Transfer Data for the

Hydrogen:Air Burns Processed with SMOKE

This appendix presents the "global" heat transfer data for the hydrogen:

air burns processed with the suite of computer program referred to as SMOKE.

Included are data for the total and radiative peak heat flux and cumulative

energy depositions. Note that the maximum energy deposition calculated using

adiabatic isochoric combustion conditions are presented for each burn

processed for comparison. Also shown are comparisons (i.e., ratios) of the

radiative and total energy depositions and peak heat fluxes, indicating the

partitioning of the postcombustion heat transfer. The burn number for each

test is given and Appendix 1 should be referenced for the initial conditions

of the burns reported.

72
Burn %H2 Q(AIC) Q(TOT) Q(RAD) Q(A) q(TOT) q(RAD) qRD

J/CM2 - Q(T0T) W/cm2

-L- q(TOT)

31

125

127

'128

135

136

137

138

139

153

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

191

9.97

6.28

6.38

10.80

6.24

6.74

6.03

7.83

10.19

9.90

29.53

9.29

19.31

9.36

20.52

31-32

10.26

11 .05

19-45

9.67

10.36

9.25

9.62

22.65

11.47

9.53

10.12

9.13

19.69

11 .43

9.34

9.36

20.09

18.98

24.16

29.23

29.47

10.98

19.18

11 .24

31.33

34.74

10.55

51.53

25.61

15.12

15.96

26.00

14.27

15.52

13.96

18.00

24.43

31.12

100.8

27.76

64.58

29.54

71.40

105.4

32.07

34.02

64.98

29.84

32.74

28.88

30.05

80.20

30.22

24.54

25.62

24.29

57.78

27.80

28.24

27.95

65.19

60.13

78.75

84.02

96.57

101.7

35.23

69.41

35.92

109.5

116.0

27.37

92.30

14.01

3.05

9.72

13.13

7.36

6.90

8.10

13.30

15.50

24. 11

87.48

21.65

54.90

22.56

57.16

90.96

22.65

19.95

51.20

23.79

23.36

23.02

21.82

63.27

17.11

13.55

11.81

13.02

35.88

12.00

23.77

23.99

56.74

50.75

70.60

75.36

90.19

87.96

22.49

58.04

25.50

92.80

98.96

17.76

66.45

6.54

1.69

3.16

8.49

2.11

2.13

2.44

5.17

7.13

5.84

41.63

5.63

30.61

6.01

32.61

39.74

6.49

6.30

32.20

6.18

6.88

5.74

6.08

36.89

7.45

6.00

5.58

5.15

21.84

6.48

6.43

6.89

33.51

26.80

43.10

43.24

38.69

39.03

6.79

32.60

7.72

47.54

40.34

7.85

36.89

0.47

0.55

0.33

0.65

0.29

0.31

0.30

0.39

0.46

0.24

0.48

0.26

0.56

0.27

0.57

0.44

0.29

0.32

0.63

0.26

0.30

0.25

0.28

0.58

0.44

0.44

0.47

0.40

0.61

0.54

0.27

0.29

0.59

0.53

0.61

0.57

0.43

0.44

0.30

0.56

0.30

0.51

0.41

0.44

0.56

5.62

0.20

3.39

3.09

1.47

1.47

1.66

4.24

5.41

9.27

101.7

6.66

39.88

5.92

36.57

109.6

6.89

10.45

38.06

7.51

5.99

7.91

5.20

58.90

5.82

6.67

6.79

8.95

38.17

6.99

6.54

7.00

41.12

34.94

70.72

78.76

123.5

106.4

6.35

39.46

7.74

87.13

118.6

6.65

60.38

2.96

0.12

0.84

2.91

0.51

0.48

0.59

2.35

3.57

3.59

75.90

3.26

34.90

3.07

33.76

76.97

3.60

3.03

31.45

3.80

3.46

3.38

2.88

43.61

4.19

2.44

2.76

2.96

25.59

3.36

3.65

4.09

39.15

30.37

65.93

65.01

77.57

76.18

3.46

34.18

4.45

77.46

79.31

4.49

48.87

0.53

0.60

0.25

0.94

0.35

0.33

0.36

0.55

0.66

0.39

0.75

0.49

0.88

0.52

0.92

0.70

0.52

0.29

0.83

0.51

0.58

0.43

0.55

0.74

0.72

0.37

0.41

0.33

0.67

0.48

0.56

0.58

0.95

0.87

0.93

0.83

0.63

0.72

0.55

0.87

0.58

0.89

0.67

0.68

0.81

73
Q(RAD) q(RAD)

Burn %H2 Q(AIC) Q(TOT) Q(RAD) - q (TOT) qfRAD)

J/cm2 Q(TOT) - W/cm - q(TOT)

192

193

194

198

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

221

222

223

225

227

228

229

230

231

232

233

234

235

236

237

238

59.93

30.08

39.99

68.37

27.58

26.34

27.28

25.86

26.43

28.65

25.99

26.82

25.83

26.34

26.69

25.43

26.35

9.78

18.51

10.28

8.94

9.97

11.14

18.53

10.06

30.16

10.80

20.41

30.42

12.65

20.16

9.31

19.79

30.17

9.99

20. 11

30.02

94.73

86.60

98.05

91.18

94.28

94.72

95.03

90.69

90.40

96.19

94.90

95.06

89.52

90.99

91.27

85.78

89.51

31.02

64.38

32.67

27.60

31.55

36.10

63.58

31.10

103.5

34.92

71.67

106.3

40.52

68.49

29.20

69.46

105.8

30.66

67.92

108.9

63.69

65.93

69.02

58.79

80. 64

85.88

82.57

80.29

78.63

77.93

85.42

83.24

78.39

79.26

78.84

76.09

76.76

14.69

48.13

8.30

19.55

21.55

25.70

45.19

22.64

83.70

24.29

53.83

87.86

22.50

49.93

21.46

51.84

87.47

21.33

50.37

90.73

32.16

39.74

40.85

24.29

44.01

43.67

44.67

44.96

44.43

49.25

44.86

45.36

45.13

44.73

42.99

41.98

43.34

3.93

30.92

1.23

6.30

5.90

7.53

26.89

5.72

44.72

6.28

27.34

48. 11

6.47

28.36

4.89

27.76

47.60

5.63

28.59

49.30

0.51

0.60

0.59

0.41

0.55

0.51

0.54

0.56

0.57

0.63

0.53

0.55

0.58

0.56

0.54

0.55

0.57

0.27

0.64

0.15

0.32

0.27

0.29

0.60

0.25

0.53

0.26

0.51

0.55

0.29

0.57

0.23

0.54

0.54

0.26

0.57

0.54

35.30

99.81

92.71

21.74

100.5

102.9

99.82

97.23

96.38

90.38

103.4

98.79

94.82

95.57

98.72

96.01

96.79

2.43

26.12

2.98

5.84

11 .18

7.54

27.47

6.94

69.28

6.62

27.19

72.18

5.76

24.77

5.41

25.22

85.19

6.37

26.94

88.22

27.99

73.29

74.07

13.62

74.15

74.32

74.28

73.06

73.21

74.29

74.17

74.31

72.77

73.18

73.54

72.14

73.14

1.04

24.05

0.25

2.57

3.04

4.45

21.34

3.46

68.86

3.51

26.99

71.92

3.32

24.77

2.55

25.15

76.27

3.20

26.94

76.86

0.79

0.73

0.80

0.63

0.74

0.72

0.74

0.75

0.76

0.82

0.72

0.75

0.77

0.77

0.75

0.75

0.76

0.43

0.92

0.08

0.44

0.27

0.59

0.78

0.50

0'. 99

0.53

0.99

1.00

0.58

1.00

0.47

1.00

0.90

0.50

1.00

0.87

74
APPENDIX 5

Combustion Pressure Data for the

Hydrogen: Air:Steam Burns

This appendix presents the combustion pressure information for each of the

hydrogen:air:steam burns which were conducted in this test series. Included

are the normalized peak pressures, the ratio of the measured peak to AIOC

calculated peak pressure, the combustion duration (measured as the time from

ignition to the peak pressure), the mean pressure derivative, and the 'global"

bulk gas temperature as inferred from the suite of computer programs referred

to as SMOKE. Note that if the experimental data were not available due to

hardware failures or experimental difficulties, the columns are appropriately

marked with "NA" (Not Available). If the test was not processed using the

suite of computer programs referred to as SMOKE, the gas temperature column is

appropriately label with "NP." As in the previous appendices, the burn number

is given and .Appendix 1 should be referenced for the initial conditions of the

burns reported.

75
Results for burns with 0 to 20%_steam by volume

%H12 Pmax Pmax AP (atm) Tmax

Burn %H2 in air %H2 0 At

I'0 Paicc (S) At(s) T

51 8.44 10.30 18.13 2.02 0.68 6.21 0.18 2.12

70 49.29 55.28 10.83 4.04 0.86 0.34 17.99 4.41

71 50.46 62.54 19.30 3.27 0.83 1.33 4.44 3.50

72 50.36 62.53 19.47 2.97 0.76 2.00 2.59 3.18

73 14.40 17.37 17.14 3.61 0.87 0.51 5.98 3.90

74 14.40 16.66 13.56 3.69 0.91 0.36 8.39 3.98

75 18.94 22.88 17.22 4.58 0.96 0.10 43.82 5.06

76 11.89 13.85 14.18 3.25 0.88 0.76 3.18 3.46

84 60.67 66.72 9.07 3.06 0.76 1.12 4.87 3.27

85 58.77 63.05 6.80 3.68 0.85 0.36 16.86 3.97

88 60.67 6.0 9.07 3.82 0.85 0.42 16.19 4.14

92 8.70 10.32 15.68 2.40 0.79 2.30 0.68 2.51

140 6.63 8.17 18.81 1.60 0.61 1.02 0.64 1.66

141 8.53 10.40 17.97 2.55 0.84 0.80 2.15 2.67

142 8.87 10.64 16.62 2.54 0.82 0.79 2.15 2.65

143 9.70 12.03 19.39 2.84 0.87 0.63 3.33 2.99

190 19.06 22.61 15.71 4.65 0.94 0.12 48.91 5.14

197 38.52 46.64 17.41 NA NA NA NA NP

Results for burns with 20-30% steam by volume

%H2 Pmax Pmax AP(atm) Tinax

Burn %H12 in air %H20 At

PO Paicc (S) At(s) To

1 7.67 10.39 26.16 1.18 0.40 5.65 0.04 1.23

2 6.61 9.36 29.46 1.14 0.43 3.98 0.12 1.18

5 6.51 8.66 24.88 1.28 0.47 3.52 0.09 1.32

8 9.04 12.79 29.33 1.13 0.36 5.43 0.03 1.19

9 8.84 12.52 29.43 1.28 0.42 3.56 0.10 1.34

43 8.96 11.63 22.96 2.28 0.73 4.59 0.31 2.39

53 41.20 57.48 28.33 3.26 0.83 1.34 4.15 3.49

62 40.44 57.38 29.52 2.90 0.75 1.26 3.87 3.09

65 40.29 57.29 29.66 2.97 0.77 1.81 2.81 3.18

69 15.27 21.56 29.18 3.74 0.90 0.47 8.28 4.06

129 4.86 6.11 20.44 1.06 0.47 16.83 0.004 1.08

130 6.36 8.05 21.04 1.18 0.46 5.54 0.04 1.22

131 8.88 11.34 21.65 2.50 0.83 0.65 2.67 2.72

132 11.47 14.59 21.37 2.90 0.78 0.53 4.05 3.09

189 19.03 24.48 22.27 4.75 0.97 0.13 41.07 5.26

195 37.53 49.24 23.78 NA NA NA NA NP

196 38.86 49.66 21.76 NA NA NA NA NP

76
Results for burn with 30-40% steam by volume

%H max Pmax AP (atm) Tmax

Burn %H2 in air %H20 At

10 10.25 15.55 34.10 1.35 0.39 4.06 0.12 1.43

11 8.13 13.12 38.07 1.21 0.42 6.62 0.05 1.27

12 6.89 11.12 38.08 1.10 0.42 3.92 0.04 1.14

26 15.41 24.88 38.06 3.37 0.79 0.95 4.24 3.65

33 19.94 31.71 37.11 3.29 0.71 0.84 5.31 3.63

44 30.41 45.86 33.67 NA NA NA NA NP

45 31.02 50.07 38.04 3.00 0.79 2.15 2.31 3.21

48 30.62 50.34 39.18' 2.92 0.77 2.78 1.76 3.13

49 39.89 57.66 30.83 2.66 0.72 2.91 1.49 2.84

55 5.72 8.22 30.45 1.13 0.47 8.54 0.02 1.17

56 5.54 T~.95 30.38 1.15 0.49 6.83 0.03 1.18

57 6.77 11.15 39.28 1.18 0.45 7.05 0.04 1.22

63 29.80 46.07 35.30 3.52 0.86 0.62 5.70 3.80

133 9.73 15.89 38.77 2.17 0.69 0.90 1.94 2.29

144 9.09 14.28 36.34 2.23 0.73 0.98 1.84 2.34

145 10.01 16.00 37.43 2.83 0.87 0.89 4.05 2.99

77
Results for burns with greater than 40% steam by volume

Results for burns with greater than 40% steam by volume

%H12 Pmax Pmax AP (atm) Tmax

Burn %H2 in air %H20 At

PO Paicc (S) At(s) T

16

17

18

19

21

23

24

25

27

29

30

37

38

58

59

61

64

66

67

68

104

106

107

ill

113

114

115

117

119

120

121

122

134

9.00

8.26

8.51

8.31

8.47

9.32

9.44

11.66

11.41

7.65

8.97

21.57

20.88

6.64

6.81

21.23

20.26

20.26

14.92

14.29

10.91

11.15

11.14

12.48

13.23

15.50

16. 54

17.64

17.04

8.23

8.37

9.03

10.68

17.26

15.04

14.86

15.21

14.53

17.11

.17.38

20.78

20.54

15.49

18.07

38.16

38.17

11.14

13.33

40.80

36.44

39.06

29.44

24.03

20.46

22.68

23.70

25.53

26.05

29.82

30.00

32.36

32.77

16.03

16.37

17.74

18.17

47.86

45. 11

42.71

45.38

41.70

45.44

45.71

43.91

44.45

50.61

50.33

43.47

45.29

40.42

48 .91

47.97

44.40

48.12

49.32

40.52

46.68

50.85

52.97

51 .12

49.22

48.01

44.87

45.48

48.01

48.63

48.88

49.12

41.23

1.23

1 .12

1.16

1.09

1.33

1.40

1.40

NA

2.58

1.25

1.15

3.47

2.84

1.21

1.21

2.90

3.26

2.79

2.79

3.55

2.23

2.08

1.10

1.90

2.58

2.11

3.25

2.83

3.06

1.22

1.18

1.22

2.80

0.42

0.39

0.39

0.38

0.44

0.46

0.45

NA

0.73

0.45

0.38

0.85

0.72

0.48

0.47

0.78

0.81

0.73

0.71

0.90

0.68

0.63

0.33

0.54

0.69

0.53

0.77

0.69

0.76

0.44

0.42

0.41

0.85

3.92

10.50

6.91

9.40

4.00

14.84

11.93

NA

1.97

4.70

3.74

1.24

1.97

4.06

4.45

2.74

1 .05

4.02

2.65

0.60

5.88

7.25

19.05

9.29

5.16

7.40

1.74

2.84

2.93

3.40

3.21

3.57

0.75

0.10

0.02

0.04

0.02

0.14

0.05

0.06

NA

1.45

0.10

0.07

4.46

2.13

0.08

0.08

1.75

4.76

1.12

1.47

7.31

0.43

0.33

0.01

0.22

0.69

0.35

2.77

1.46

1.65

0.13

0.11

0.12

3.94

1.29

1.17

1.21

1.14

1 .39

1.47

1.47

NP

2.74

1.30

1.20

3.75

3.07

1.25

1.25

3.11

3.53

3.00

3.03

3.83

2.36

2.21

1.17

2.03

2.77

2.29

3.55

3.07

3.31

1.28

1.24

1 .28

2.97

78
APPENDIX 6

Global Heat Transfer Data for the

Hydrogen:Air:Steam Burns Processed with SMOKE

This appendix presents the "global" heat transfer data for the hydrogen:

air:steam burns processed with the suite of computer program referred to as

SMOKE. Included are data for the total and radiative peak heat flux and

cumulative energy depositions. Note that the maximum energy deposition

calculated using adiabatic isochoric combustion conditions are presented for

each burn processed for comparison. Also shown are comparisons (i.e., ratios)

of. the radiative and total energy depositions and peak heat fluxes,,indicating

the partitioning .of the postcombustion heat transfer. Furthermore, as in the

previous appendices, the burn number for each test is given and Appendix 1

should be referenced for the initial conditions of the burns reported.

79
Results for burns with 0 to 20% steam by volume

%H12 Q(RAD) q(RAD)

Burn %H12 in air %H120 Q(AIC) Q(TOT) Q(RAD) - q(TOT) q(RAD)

J/cm2 Q(TOT) -W/cml 2 q(TOT)

73 14.40 17.37 17.14 46.14 27.21 23.22 0.85 11.13 11.13 1.00

74 14.40 16.60 13.56 42.11 26.87 22.40- 0.83 12.39 12.39 1.00

75 18.94 22.88 17.22 62.88 42.82 38.17 0.89 28.19 28.19 1.00

76 11.89 13.85 14.18 34.73 20.89 16.30 0.78 7.53 7.53 1.00

84 60.67 66.72 9.07 90.38 45.31 28.54 0.63 10.84 7.64 0.70

85 58.77 63.05 6.80 87.86 51.68 35.94 0.70 19.42 15.49 0.80

88 57.23 62.10 7.85 98.17 53.78 36.71 0.68 21.32 16.30 0.77

92 8.70 10.32 15.68 26.35 11.92 7.55 0.63 4.17 2.28 0.55

140 6.63 8.17 18.81 19.50 5.40 2.73 0.51 0.91 0.38 0.42

141 8.53 10.40 17.97 26.08 15.29 8.14 0.53 4.09 2.76 0.68

142 8.87 10.64 16.62 26.74, 15.18 8.01 0.53 4.29 2.77 0.65

143 9.70 12.03 19.39 30.70 18.92 10.21 0.54 6.34 4.66 0.74

190 19.06 22.61 15.71 63.39 44.64 30.62 0.69 31.42 31.42 1.00

Results for burns with 20-30% steam by volume

%H12 Q(RAD) q(RAD)

Burn %H12 in air %H120 Q(AIC) Q(TOT) Q(RAD) - q(TOT) qý(RAD)

J/cm2 - Q(TOT) -W/cm4- q(TOT)

43 8.96 11.63 22.96 28.45 11.49 8.13 0.71 2.62 1.81 0.69

69 15.27 21.56 29.18 60.87 35.54 30.92 0.87 13.77 13.77 1.00

132 11.47 14.59 21.37 37.93 19.63 9.85 0.50 7.100 4.48 0.64

189 19.03 24.48 22.27 74.02 54.29 35.77 0.66 -36.03 36.03 1.00

80
Results for burns with 30-40% steam by volume

%2Q(RAD) q(RAD)

Burn %H2 in air %H20 Q(AIC) Q(TOT) Q(RAD) - q(TOT) qfRAD)

J/cm2 - Q(TOT) -W/cm6- q(TaT)

45 31.02 50.07 38.04 93.43 48.20 26.80 0.56 12.83 7.48 0.58

133 9.73 15.89 38.77 41.39 16.31 9.78 0.60 2.56 1.98 0.77

144 9.09 14.28 36.34 38.11 12.91 6.79 0.53 2.35 1.73 0.74

145 10.01 16.00 37.43 44.06 22.22 11.27 0. 51 '7.89 4.22 0.54

Results for burns with greater than 40% steam by volume

%H12 Q(RAD) q(RAD)

Burn %H2 in air %H20 Q(AIC) Q(TOT) Q(RAD) - q(TOT) q(RAD)

J/CM2 - Q(TOT) -W/cm6- q(TOT)

27 11.41 20.54 44.45 61.02 30.47 13.55 0.45 7.87 3.61 0.46

38 20.88 38.17 45.29 95.29 51.48 30.65 0.60 15.65 9.58 0.61

61 21.23 40.80 47.97 95.94 51.79 25.36 0.49 13.11 6.66 0.50

64 20.26 36.44 44.40 94.99 58.17 39.30 0.68 19.73 14.47 0.73

66 20.26 39.06 48.12 98.37 50.11 22.91 0.46 13.06 5.65 0.43

68 14.29 24.03 40.52 70.51 42.59 33.88 0.80 15.16 14.20 0.94

104 10.91 20.46 46.68 63.77 21.02 14.64 0.70 .2.83 2.37 0.84

106 11.15 22.68 50.85 71.44 20.92 11.85 0.57 3.98 1.89 0.48

111 12.48 25.53 51.12 80.16 15.25 11.62 0.76 1.46 1.30 0.89

113 13.23 26.05 49,22 86.64 38.65 18.08 0.47 10.25 4.42 0.43

114 15.50 29.82 48.01 101.2 21.07 14.62 0.69 2.52 2.06 0.82

115 16.54 30.00 44.87 101.1 43.72 26.70 0.61 20.16 10.01 0.50

117 17.64 32.36 45.48 102.3 44.22 22.66 0.51 12.57 6.58 0.52

119 17.04 32.77 48.01 102.2 51.98 23.94 0.46 14.88 7.01 0.47

121 8.37 16.37 48.88 45.91 9.43 2.26 0.24 3.47 0.19 0.06

134 10.68 18.17 41.23 49.80 28.65 17.22 0.60 7.88 5.63 0.71

81
APPENDIX 7

Representative Pressure Signatures for

each of the Combustion Tests

In this appendix, representative pressure signatures from two types of

gauges (the Precise Sensor model 141-1 and the Kulite model XT-190) are shown

for comparison and reference. For all of the tests in which combustion

occurred and the data is available for posttest processing, the pressure

transients are shown for the two gauge types whenever possible. The two gauge

types are ýdistinguished using a solid line to represent the pressure transient

recorded by a Precise Sensor Model 141-1 and a dashed line to represent that

recorded by a Kulite Model XT-190. Both gauge types were not available in all

tests,' but comparisons of the two are presented whenever possible. Also note

that in some cases, a small offset in time between the two curves is apparent.

This is simply due to the fact that the entire data set is plotted on these

curves (i.e., time on these plots is relative) and in many cases the data for

the two gauges were recorded on two different digitizing modules. Therefore,

the number of pretrigger data points were generally different resulting in the

small time shift. However, comparison of the two pressure transients from the

time of ignition (i.e., the first deviation from the baseline) generally

reveals identical combustion-pressure signatures and magnitudes.

82
1.515 1.5

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w~ x 1.3

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1.-1.2- 1l!T

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TIME, SEC. TIME, SEC.

1.5- 1.5-

BURN 5

1.4 I

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S~ 1.3-

1.2

1.1.2

0 510 15 202530 35 0 5 10 15202530 35

TIME, SEC. TIME, SEC.

83
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TIME, SEC. TIME, SEC.

2

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126
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12 B-i

30.22BIBLIOGRAPHIC DATA SHEET NUREG/CR-3 468

SEE INSTRUCTIONS ON T..E REVERSE SAND84-0383

2 TITLE AND SUBTITLE 2* LEAVE BLANK

Hydrogen:Air:Steaxn Flammability Limits and

Combustion Characteristics in the FITS Vessel 4 DATE REPORT COMPLETED

MONT. I IEAR

5 AUT..OQIS1 August 1986

6 DATE REPORT ISSUED

Billy W. Marshall, Jr. MONT. YA

____ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ December 1986

? IERPORMINGORDýANIZATON NAME AND MAILING ADDRESS II..c,.OpZ,,COod. 8 PROJECTITASK'WORK UNIT NUMBER

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Division of Reactor System Safety Technical

Accident Evaluation Branch

office of Nuclear Regulatory Research PERIOD COVERED 11MCI .M).

U.S. Nuclear Regulatory Research

Washington, DC 20555 12 SUPPLEMENTARY NOTES

S1 3 ABSTRACT 1200 o 'sO ro.1- 1.

Experimentally observed flammability limits of hydrogen: air: steam mixtures in

both turbulent and quiescent environments were measured and a correlation developed

that describes the three-component flammability limit. The combustion pressure data

measured for the hydrogen: air: steam tests indicate that the addition of steam reduces

the normalized peak combustion pressure (Pmax/Po) as compared to equivalent

hydrogen:air burns. Turbulence was found to affect the extent of combustion and

other combustion characteristics of the lean hydrogen burns (i.e., •10% hydrogen by

volume) where bouyancy governs flame propagation.

The experimentally measured pressure decays were used to infer the "global" heat

transfer characteristics during the postcombustion cooling phase. Convection was

found to dominate the time-integrated heat transfer of the leaner (<10%) hydrogen:air

burns, accounting for 50 to 70% of the postcombustion heat transfer. Radiation was

slightly more prevalent than convection for the hydrogen:air burns near

stoichiometry. When moderate quantities of steam were added to the environment,

radiation became the dominant postcombustion cooling mechanism due to the increase in

bulk gas emittance. If richer steam concentrations were added to the environment',

radiation and convection appear to be equally important heat transfer mechanisms.

14 DOCUMENT AftALWSIS -. BENWONOSDESCA-VTORS IS AVAILABILITY

ST ATE MEN T

Flammability, Flammability Limits, Deflagration, Combustion,

Hydrogen Combustion, Reactor Safety

b IDENTIPIERSOPNENDEDfOTERMS

GPO/NTIS

IS SECURITY CLAS.SIPICATION

jlnc asifijer

,Unclassifiec

I I NUMBER OP PAGES

lB PRICE

*U.S. GOVERNMENT PRINTING OFFICE: 1987-773-049/41029