NBSIR 76-1002

Industrial Process Data for

Fluids: A Survey of Current

Research at the National

Bureau of Standards

Howard J. White, Jr., Editor

Office of Standard Reference Data

National Bureau of Standards

Washington, D. C. 20234

April 1976

Summary Report

U S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NBSIR 76-1002

INDUSTRIAL PROCESS DATA FOR

FLUIDS: A SURVEY OF CURRENT

RESEARCH AT THE NATIONAL

BUREAU OF STANDARDS

Howard J. White, Jr., Editor

Office of Standard Reference Data

National Bureau of Standards

Washington, D. C. 20234

April 1976

Summary Report

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

James A. Baker, III, Under Secretary

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

NATIONAL BUREAU OF STANDARDS. Ernest Ambler, Acting Director

TABLE OF CONTENTS

Page

ABSTRACT, KEY WORDS 1

INTRODUCTION . . 2,3

RESEARCH PROJECTS

1. Properties of Cryogenic Fluids 4,5,6

2. Hydrogen/Oxygen Properties 7

3. Fluid Transport Properties 8,9

4. Properties of Cryogenic Fluid Mixtures 10, 11

5. Development of Cryogenic PVT Algorithms for

Space Applications 12, 13

6. Thermophy sical Properties Data for Pure

Components of LNG Mixtures 14, 15, 16, 17

7. Densities of Liquefied Natural Gas Mixtures . . . 18, 19

8. LNG Density References System . 20, 21

9. Heating Value of Flowing LNG 22

10. LNG Fuels Safety 23, 24

11. Energy Conservation Potential in the LNG

Industry 25, 26

12. Survey of Current Literature on LNG and Methane . 27, 28

13. Cryogenic Data Center Information Services . . . 29, 30

14. Analysis, Evaluation, and Compilation of

Chemical Thermodynamic Data 31, 32

15. Thermodynamic Data on Organic Compounds 33, 34

16. Joint Industry-Government Project on the

Thermophy sical Properties of Ethylene 35 , 36

17. Excess Property Data for Binary Liquids ...... 37, 38

18. Thermal Conductivity of Selected Substances . . . 39, 40, 41
TABLE OF CONTENTS

Page

RESEARCH PROJECTS (continued)

19. Transport Properties of Fluids in the Critical

Region 42, 43

20. Thermodynamic Properties of Fluids 44, 45

21. Thermodynamic Properties of Fluids in the

Critical Region 46 , 47 , 48

22. PVT Relations in Gases 49
Industrial Process Data for Fluids: A Survey

of Current Research at the National Bureau of Standards

Howard J. White, Jr., Editor

ABSTRACT

This report summarizes current activities sponsored

by three groups within the National Bureau of Standards

that are involved with the production of industrial

process data for fluids. The three groups involved

are the Cryogenics Division, the Equation of State

Section of the Heat Division, and the Office of

Standard Reference Data; other organizations in NBS

and outside are also involved in various ways.

The report takes the form of a listing of projects

with some detailed information about each. Some of

the projects are designed to provide industrial process

data directly. Others systematically cover types of

data that are of continual utility in industrial process

calculations with the result that the data produced

will be used for industrial purposes as well as for

other purposes. A few of the projects attack problem

areas that must be resolved before proper industrial

process data in the area can be obtained. All of the

projects focus on quantitative numerical data obtained

for direct measurement, critical evaluation of data

from the literature or theoretical estimation or

calculation

.

This report has been prepared to show interested

readers the interrelationships within a set of projects

that might otherwise pass unnoticed because different

organization'al units within NBS are involved. Continued interaction between the program managers involved

leads to interactions between the projects so that the

listing is not a listing of independent unreacting

projects but rather a listing of interacting projects

following broad programmatic lines.

KEY WORDS

Industrial process data; project summaries;

quantitative numerical data.
INTRODUCTION

This report summarizes the current status of a set of projects

being carried out under the program management of the National

Bureau of Standards. Each of the projects included in the set

is concerned with the generation of data of a type widely used

in industry.

Taken collectively, the projects involve data compilation and

evaluation, experimental measurements and theoretical developments; they reach across organizational bounds within NBS and

include activities being carried on outside of NBS. They have

been collected here because together they indicate a programmatic

thrust which might not be evident from a consideration of the NBS

program as a whole or as listed along organizational lines. A

further justification for collecting them lies in the fact that

the programs of which these projects are parts are sufficiently

coordinated that there is substantial interaction between projects

and the collection is not simply a listing of independent entities.

The projects included are concerned with the thermodynamic and

thermophy s ical properties of fluids. The fluids under consideration are single substances that are gases or relatively volatile

liquids in the vicinity of room temperature or are mixtures of

these. The properties under consideration fall into three broad

types: the chemical thermodynamic properties, those properties

needed to characterize chemical equilibria; the PVT and related

physical thermodynamic properties, those properties needed to

characterize the equilibrium behavior of ch em ically stable systems

as a function of temperature, pressure, and composition; and the

transport properties, those properties needed to characterize

the flow of matter and energy in systems not in physical equilibrium. Data of these types are used in industrial calculations

such as are involved in process and equipment design, optimization of reactor conditions, product purification, process control,

pollution and hazard control, intermediate and product analysis

and custody transfer. The industries to which the data involved

can be expected to be of most interest are the chemical, petrochemical, petroleum, gas and gas transmission industries.

It should be stressed that the projects selected do not include

all NBS projects on fluids as defined above, all projects involving

thermodynamic or thermophy sical properties, nor all projects that

will produce data of interest to industry. They do represent a

substantial effort with a common technical base and a certain

commonality of purpose.

The relevance of the types of data concerned to industrial needs

has been stated. However, something more might be said about the

2
relevance of the individual projects. The application of some

projects is evident from inspection of their descriptions. The

direct importance of others is obvious from their industrial

sponsorship. But, there is a third group of projects whose

relevance is only revealed by broader considerations. The

numbers of substances, the ranges of concentrations, temperatures

and pressures for which data are now, or will soon be needed, are

innumerable. There is no possibility for a program of direct

measurement to fill all such needs. Methods are needed to

interpolate and extrapolate over ranges of temperature and

pressure, to relate the properties of mixtures to those of

their components, to use one set of properties of a substance

to estimate others and, ultimately, to estimate the properties

of a substance from those of chemically related substances.

Accompanying this need for such methods is a need for selected

data of high quality for use in verifying the methods developed

and to provide the framework on which the network of estimating

techniques must be based. It is to the building of this network of techniques and reference data that the third group of

projects is directed.

Industrial time pressures are such that, if data are not available,

they are estimated; if an accurate estimation technique is not

available, a crude one is used. The price for the gaps and

crudities in our current network of reference data and estimation

techniques is paid in occasional spectacular failures and in

thousands of inefficiencies, some obvious in retrospect, some

still hidden. The relationships between cause and effect are

usually subtle. Industrial organizations support projects in

those areas where lack of a particular type of data can be seen

to be handicapping their efforts. Some of these projects are

proprietary; others are supported on a joint or industry-wide

basis. Examples of the latter type exist in this report.

However, the development of a satisfactory network of estimation

techniques and reference data is a task too large in size and

too pervasive in effect to be supported industrially on a

specific project basis. Recognition of the importance of this

task and the need for government leadership is one of the reasons for the preparation of this report.

Responsibility for the preparation of this report and for a

number of the projects reported herein lies with four groups

in NBS--the Cryogenic Data Center of the Cryogenics Division,

the Properties of Cryogenic Fluids Section of the Cryogenics

Division, the Equation of State Section of the Heat Division,

and the Office of Standard Reference Data. Inquiries on

material included in this report may be directed to Mr. Neil

Olien, Cryogenic Data Center, National Bureau of Standards,

Boulder, Colorado 80302 (Telephone 303 499-1000, Ext. 3257);

or to Dr. Howard J. White, Jr., Office of Standard Reference

Data, National Bureau of Standards, Washington, D. C. 20234

(Telephone 301 921-2581) .

3
Title. PROPERTIES OF CRYOGENIC FLUIDS

Principal Investigators . G. C. Straty and D. E. Diller

NBS , Boulder, Colorado 80302

Cost Center Number . 2750141

Sponsor. NBS

Introduction . Accurate thermophysical properties data and predictive

calculation methods for cryogenic fluids are needed to support advanced

cryogenic technology projects. For example, liquefied natural gas is

expected to supply an increasing percentage of the United States'

energy requirements through 1990. Liquefaction plants, ships and

receiving terminals are being constructed to transport and store

natural gas in the liquid state (LNG) . Accurate thermophysical

properties data for LNG are needed to design low temperature processes

and equipment. Accurate data will benefit the energy industries and

the consumer by providing for safe and efficient operations and reduced

costs

.

Objectives or Goals . The objectives of this project are to provide

comprehensive accurate thermodynamic, electromagnetic and transport

properties data and calculation methods for technically important

compressed and liquefied gases (helium, hydrogen, oxygen, nitrogen,

methane, ethane, etc.) at low temperatures. Precise compressibility,

calorimetric and other physical property measurements will be performed

to fill gaps and reconcile inconsistencies. Definitive interpolation

functions, computer programs and tables will be prepared for engineering

calculations. The immediate goals of this work are to obtain accurate

sound velocity and thermal diffusivity data for compressed and

liquefied gases by using laser light scattering spectroscopy techniques.

Sound velocity data are useful for testing the consistency of

volumetric, calorimetric and thermodynamic properties data, and are

potentially useful for density gauging applications. Thermal diffusivity

data are required for performing thermodynamic and heat transfer

calculations

.

Background . When light is incident on a perfectly homogeneous fluid,

the reradiated (scattered) light field sums to zero in all but the

exact forward direction. For a "real" fluid, however, fluctuations,

arising through various mechanisms, destroy the perfect homogeneity

and results in the scattering of light in other directions as well.

For example, thermally activated density fluctuations (phonons)

,

propagating with the characteristic velocity of sound, give rise to

scattered light which is Doppler shifted in frequency from the incident

light frequency and whose spectrum contains information on the sound

velocity and attenuation. Local non-propagating temperature fluctuations

which decay diffusively, give rise to scattered light in a narrow

frequency band about the incident light frequency and whose spectrum
contains information on the lifetime of the fluctuations (thermal

diffusivity) . Since the frequency shifts are generally very small,

it was not until the advent of the lasers with their extremely

well defined frequency, that practical experiments using these phenomena

were possible.

The application of laser light scattering techniques to obtaining

thermophysical properties data was initiated to complement and check

other measurement methods and to solve measurement problems inherent

in more conventional methods. For example, laser light scattering

techniques permit measurements of sound velocities for fluids and

under conditions for which sound absorption is too large to perform

ultrasonic measurements; laser light scattering techniques permit

measurements of thermal diffusivities under conditions for which

convection interferes with measurements of thermal conduction. The

feasibility of light scattering experiments to obtain data on binary

diffusion coefficients has also recently been demonstrated.

7. Program and Results . An apparatus has been assembled for laser light

scattering spectroscopy on compressed and liquefied gases (76 - 300 K,

350 bars). The apparatus consists of a high pressure optical cell,

a cryostat for refrigeration with liquid nitrogen, an argon ion laser,

low-level light detection equipment, a pressure scanned Fabry-Perot

interferometer, and a commercial digital correlation function computer.

The light scattered from fluctuations in the fluid can be analyzed with

either digital autocorrelation techniques for the examination of the

very narrow lines associated with scattering from temperature

fluctuations (Rayleigh scattering) or with a pressure scanned Fabry

Perot interferometer for the measurement of the Doppler frequency

shifts associated with the scattering from propagating density (pressure)

fluctuations (Brillouin scattering)

.

Data on the hypersound velocities in pure methane have been obtained by

Brillouin scattering techniques at low densities (< 1A mol/£) where the

large sound absorption in methane prohibits more conventional ultrasonic

measurements. Data have been obtained along several isotherms from

210 K to 300 K at densities down to 1 mol/l. Agreement with previously

measured ultrasonic velocities in the regions of overlapping data is

good. The data have been combined with previously measured PVT data

to obtain the isentropic compressibility and ratio of the specific

heats. A manuscript reporting the results of these measurements has

been prepared and submitted to Cryogenics for publication.

We have completed equipment modifications to permit the determination

of the thermal diffusivity, X/pCp, of compressed and liquefied gases,

including the critical region. The most accurate method for doing

this is to use photon-counting and digital autocorrelation techniques

to measure the temporal behavior of the spontaneous temperature

fluctuations occurring in the fluid which is governed by the bulk fluid

thermal diffusivity. This is equivalent to measuring the very narrow

Rayleigh line width and requires a resolution of about one part in 1012.

5
Preliminary checks of the modified apparatus on a well-characterized

test fluid appear to have been satisfactory. Preparations for

thermal diffusivity measurements on liquefied methane are in progress.

6
1. Title , hydrogen/oxygen properties

Principal Investigator . L. A. Weber,

NBS , Boulder, Colorado 80302

2. Cost Center Number . 2750547

3. Sponsor . NASA (Lewis Research Center)

4. Introduction . Comprehensive accurate theimophysical properties data

for compressed and -liquefied hydrogen and oxygen at high pressures

(up to 100 MPa (15,000 psi)) are needed to support NASA's advanced

chemical propulsion system development program.

5. Obj ectives . The purpose of this project is to provide NASA with accurate

thermodynamic properties data for hydrogen and oxygen at high pressures

(5000-15,000 psi) and at temperatures encountered in developing and

testing space shuttle propulsion systems. The goal for our immediate

work is to perform high precision PVT measurements on gaseous and

liquid oxygen (55-300 K) at pressures up to 12,000 psi (827 bar) and

calculate accurate thermodynamic properties data (entropy, internal

energy, enthalpy).

6. Background . During the period 1958-1970 the NBS Cryogenics Division

provided comprehensive accurate thermophysical properties data for

compressed and liquefied hydrogen and oxygen at pressures to 35 MPa

(5000 psi) in support of NASA's propulsion system development program.

Advanced propulsion systems now being developed will use these fluids

at higher pressures. The thermophysical properties data base is now

being extended from 5000 psi to 15,000 psi to provide measurements

and calculation methods sufficient for all foreseeable engineering

calculations

.

7. Program and Results . Preparations for new equation of state (PVT)

measurements on compressed and liquefied oxygen at pressures to

82.7 MPa (12,000 psi) are in progress.

7

I
Title . FLUID TRANSPORT PROPERTIES

Principal Investigator . Howard J. M. Hanley

NBS , Boulder, Colorado 80302

Cost Center Number . 2750124

Sponsor - NBS-Office of Standard Reference Data

Introduction . Methods for predicting the transport properties of

fluid mixtures are unreliable and data are scarce. Prediction methods

are needed, however, to supply the necessary design data needed to

increase efficiency and reduce costs.

Objectives or Goals . The long range or continuing goal of the program

is to perform a systematic study of the theories and experimental

measurements relating to transport properties, specifically the

viscosity and thermal conductivity coefficients, of simple mixtures

over a wide range of experimental conditions. The. specific objectives

of the program include: 1) the systematic correlation of the transport properties of simple binary mixtures and the development of

prediction techniques, 2) development of a mixture theory for the

dilute gas region and the dense gas and liquid regions, 3) extension

of the theory and prediction techniques to multicomponent systems,

and 4) suggested guidelines for future areas of experimental work.

Background . A continuing program has successfully expanded the stateof-the-art of transport phenomena for pure fluids. Information for

pure fluids is required as a prerequisite for mixture studies. The

theory of transport phenomena has been developed and applied to

produce practical numerical tables of the viscosity, thermal conductivity and diffusion coefficients of simple fluids: Ar, Kr, Xe, N2,

02, F2, He, H2, CH4. Recent work has extended this approach to

ethane. It is felt that a successful mixture program will emerge from

combining the results for pure fluids with equation of state studies.

The equation of state work is being carried out by other investigators

in this laboratory.

Program and Results . Statistical mechanics has been applied to predict

and correlate the dilute and moderately dense thermophysical properties

of carbon dioxide^. Carbon dioxide was selected as a typical polyatomic

molecule. The self-diffusion coefficients of methane have been

correlated and tabulated2. Results for the dilute gas transport

properties of oxygen and nitrogen have been published^. The well-known

critical point anomaly in the thermal conductivity can now be predicted

to within experimental error^. An equation to calculate the dense gas

and liquid transport properties of several simple fluids has been

report ed5. Preliminary work on the transport properties of mixtures

has been very promising. Theoretical studies on transport theory

have been reported**.

8
References

1. J.F. Ely and H.J.M. Hanley, Mol. Phys. 30, 565 (1975).

2. K.R. Harris, H.J.M. Hanley, et al., "The Self-Diffusion of Simple

Fluids," Australian National Univ. Press., DRU-RR 2 (3 974).

3. H.J.M. Hanley and J.F. Ely, J. Chem. Phys. Ref. Data 2, 735 (1973).

4. H.J.M. Hanley, J.V. Sengers and J.F. Ely, Proc. 14th Int. Conf.

Thermal Conductivity (Pergamon Press, 1975).

5. H.J.M. Hanley, W.M. Haynes and R.D. McCarty> Cryogenics 15 , 413

(1975); J. Chem. Phys. Ref. Data 3, 979 (1974).

6. For example, H.J.M. Hanley and W.M. Haynes, J. Chem. Phys. 63 , 358 (1975); H.J.M. Hanley and R.O. Watts, Physica 79A, 353 (1975).

9
1. Title. PROPERTIES OF CRYOGENIC FLUID MIXTURES

Principal Investigators . M. J. Hiza, A. J. Kidnay (part-time)

R. C. Miller (part-time), and W. R. Parrish (part-time)

NBS , Boulder, Colorado 80302

2. Cost Center Numbers . 2750142; 2750145

3. Sponsor. NBS; NBS (OSRD)

4. Introduction . Accurate thermodynamic properties data and predictive

calculation methods for mixtures of cryogenic fluids are needed to

design and optimize low temperature processes and equipment. This

project provides new experimental measurements on equilibrium properties

and compilations of evaluated equilibrium properties data which are

suitable for direct technological use or for the evaluation of predictive

calculation methods.

5. Objectives or Goals . The overall objectives of this project are to

provide critically evaluated data, original and from other sources,

on the phase equilibria and thermodynamic properties of cryogenic

fluid mixtures. The program has been divided into the following

elements

a) Preparation of a comprehensive bibliography on experimental

measurements of equilibrium properties for mixtures of

selected molecular species of principal interest in cryogenic

technology.

b) Selection and/or development of methods for correlation,

evaluation and prediction of equilibrium properties data.

c) Retrieval and evaluation of experimental data for specific

mixture systems selected on the basis of theoretical and/or

technological importance.

d) Preparation of guidelines for future research based on the

deficiencies noted in (a) , (b) , and (c)

.

e) Performing experimental research to alleviate deficiencies

and provide a basis for improvement of prediction methods.

6. Background . A physical equilibria of mixtures research project was

established in the Cryogenics Division in 1959. The initial effort,

based on a bibliographic search and other considerations, was directed

toward the acquisition of new experimental data on the solid-vapor and

liquid-vapor equilibria and physical adsorption properties for a

limited number of binary and ternary mixtures of components with

widely separated critical temperatures. Most of the systems studied

included one of the light hydrocarbon species—methane, ethane, or

ethylene (ethene) — with one of the quantum gases—helium, hydrogen,

or neon. The data for these systems led to significant improvements

10
in the predictions of physical adsorption equilibrium and a correlation

for the prediction of deviations from the geometric mean rule for

combining characteristic energy parameters. In addition, significant

new information was obtained for interaction third virial coefficients

which was used in a correlation by one of our consultants, J.M. Prausnitz.

The approach taken in this work has been as fundamental as possible with

the intention of having an impact on a broad range of mixture problems.

Recent efforts have been directed toward problems associated with

systems containing components with overlapping liquid temperature

ranges, such as the nitrogen + methane system.

7. Program and Results . The recent progress of this program is summarized

as follows

a) The comprehensive bibliography of fluid mixtures data entitled

"Equilibrium Properties of Fluid Mixtures: A Bibliography of

Cryogenic Data" has been published.

b) Work is continuing on the compilation of liquid-vapor equilibrium

data and derivation of the excess Gibbs functions and Henry's

constants for binary systems containing methane with the light

hydrocarbons, argon and nitrogen. A paper, "On the Consistency

of Liquid-Vapor Equilibria Data for Binary Mixtures of Methane

with the Light Paraffin Hydrocarbons," which covers a portion of

this work, was presented at the 1975 Cryogenic Engineering

Conference.

c) A paper entitled "Liquid-Vapor Phase Equilibria in the System

N2 + CH4 from 130.00 K to 180.00 K," has been published, Cryogenics

15 , 531 (1975). This paper includes an evaluation of available

data for this system, as discussed in (b) , as well as the new

measurements.

d) New liquid-vapor equilibrium composition measurements at selected

conditions for the methane + ethane system have been obtained and

are being analyzed.

11

/
. _ . DEVELOPMENT OF CRYOGENIC PVT ALGORITHMS FOR SPACE

1. lxt±e. APPLICATIONS

Principal Investigators . R. D. McCarty and H. M. Roder

NBS, Boulder, Colorado 80302

2. Cost Center Number. 2750423

3. Sponsor . National Aeronautics and Space Administration, Johnson

Space Center, Houston, Texas, Mission Planning and Analysis

Division/FM-7

.

4. Introduction . Cryogenic hydrogen and oxygen systems were used as the

sources for the fuel cells during the Gemini, Apollo and Skylab

programs. During these programs the stored cryogens became one of

the main limiting consumables involving mission length. The critical

nature of the cryogenic systems required very accurate premission

analysis. Onboard monitoring of the cryogens was relatively

inaccurate (5-10 percent) and required periodic updates from the

ground. One of the major improvements in Space Shuttle operations

will be the capability of monitoring consumables onboard accurately

so as t:o reduce support requirements. Also, because of the expected

frequency of flights a more efficient premission computational

technique will be required.

5. Objectives or Goals . The objectives of this study are:

a. Develop a detailed equation of state for hydrogen based on the

recently completed measurement program.

b. Develop density explicit equations over a limited pressuretemperature range for hydrogen, oxygen, nitrogen and ammonia.

These equations will be used for both onboard computers (as a back-up quantity gaging system) and ground computer remote

terminal operation.

c * Provide other thermodynamic and transport properties fox

ammonia in addition to the equation of state. The most

important of these are^ the heat of vaporization and

saturation temperature versus pressure.

d. Develop slush properties of oxygen and hydrogen. The area of

work has application in space programs beyond Shuttle and in

industry as well.

It should be pointed out that the culmination of these objectives

will not only be in the analytical results, but also in the development of computer programs available for general use to NASA and

industry. The basic intent of a study of this type is to provide

data in such a form that they not only satisfy the NASA, requirement,

but will be adequate for a wide range of other users in government

and industry.

12
6. Background . The Cryogenic Data Center provided the data and equation?;

used for the cryogenic consumables during the Apo.Uo and Skylab

programs. The staff of the Center have developed an internationally

recognized expertise in the statistical treatment of data and in the

development and optimization of empirical equations of state for

fluid properties. In addition the NBS-Cryogenics Division has

produced the bulk of the available source data on the properties of

hydrogen and oxygen by means of NASA-funded experimental programs.

The most recent work involved measurement to extend the PVT properties

of hydrogen from 35 to 100 MPa. The data are being used in the space

shuttle main engine development. A corollary program was started to

revise an existing equation of state for hydrogen to include these

data. This effort was stopped short of the intended goal due to lack

of funds. It is the intent of this project not only to complete that

work, but to extend the techniques into an onboard computational

capability.

7. Program and Results . An existing 32-term modified Benedict-Webb-Rubin

(MBWR) equation of state for parahydrogen has been modified to fit the

new, high pressure data to within the precision of the data. An

equation of state has been provided as well as tables of properties

for ammonia. The bulk of the effort has been expended on attempts

to develop a functional form for an accurate, density explicit equation

of state. Thus far, only one form has been found which even approaches

the accuracy. This form, in essence, relates the actual density at a

given pressure and temperature to a corresponding density on the

saturated liquid and vapor lines. Final testing and optimization of

the equation have not as yet been accomplished on parahydrogen.

13
, THERMOPHYSICAL PROPERTIES DATA FOR PURE COMPONENTS

" ±±S±&' OF LNG MIXTURES

Principal Investigators . R. D. Goodwin, G. C. Straty, L. A. Weber,

H. M. Roder, and R. Tsumura, NBS , Boulder, Colorado 80302.

2. Cost Center Numbers. 2750574 (2750364)

3. Sponsor . American Gas Association, Inc., Project BR50-10.

4. Introduction . Accurate phase equilibrium, equation of state (PVT)

,

and thermodynamic properties data are needed to design and optimize

gas separation and liquefaction processes and equipment. Accurate

data for the pure components of LNG mixtures will permit developing

comprehensive accurate predictive calculation methods which take

into account the dependence of the thermophysical properties of

mixtures on the composition, temperature, and density.

This project will provide comprehensive accurate thermophysical

properties data and predictive calculation methods for compressed

and liquefied hydrocarbon gases to support the development of LNG

technology at NBS and throughout the fuel gas industry.

5. Objectives or Goals . The objectives of our work are the determination

of comprehensive accurate thermophysical properties data and

predictive calculation methods for the major pure components (methane,

ethane, propane, butanes, and nitrogen) of liquefied natural gas

mixtures at temperatures between 90 K and 300 K and at pressures up

to 350 bar (5000 psi) . Our goal is to provide a range and quality

of data that will be recognized as definitive or standard for all

foreseeable low temperature engineering calculations.

6. Background Liquefied natural gas is expected to supply an increasing

percentage of the United States' future energy requirements. It is

likely that massive quantities of liquefied natural gas will be

imported during the years 1976 - 1990. Ships and importation terminals

are being built for transporting, storing, and vaporizing liquefied

natural gas for distribution. Accurate physical and thermodynamic

properties data for compressed and liquefied natural gas mixtures are

needed to support these projects. For example, accurate compressibility

and thermodynamic properties data are needed to design and optimize

liquefaction and transport processes; accurate data for the heating

value, which for liquefied natural gas mixtures depends on the total

volume, the density, and the composition, are needed to provide a basis for equitable custody transfer.

Accurate thermodynamic properties data for liquefied gas mixtures must

be based on precise compressibility and calorimetric measurements;

compressibility data give the dependence of thermodynamic properties

14
on pressure and density (at fixed temperatures); calorimetric data

give the dependence of thermodynamic properties on temperature

(at fixed pressures and densities). It is impossible, however, to

perform enough compressibility and calorimetric measurements directly

on multicomponent mixtures to permit accurate interpolation of the

data to arbitrary compositions, temperatures and pressures. Instead,

thermodynamic properties data for multicomponent mixtures usually

must be predicted (extrapolated) from a limited number of measurements

on the pure components and their binary mixtures.

This project was initiated to provide the natural gas industry with

comprehensive accurate data for pure compressed and liquefied

methane, the most abundant component in LNG mixtures. We have

published National Bureau of Standards Technical Note 653,

\ "Thermophysical Properties of Methane, From 90 to 500 K at Pressures

\to 700 Bar," by Robert D. Goodwin (April 1974). This report contains

the most comprehensive and accurate tables available for the thermophysical properties of pure gaseous and liquid methane, and provides

an accurate basis for calculating thermophysical properties data for

LNG mixtures.

7 . Program and Results .

7.lj Melting Pressures, Vapor Pressures and Equation of State (PVT)

Data—G. C. Straty and R. Tsumura .

Comprehensive accurate measurements of the melting pressures, vapor

pressures and equation of state (PVT) for compressed and liquefied

ethane, 90 - 320 K, 5000 psi, have been completed. Two reports have

been submitted for publication:

a) G. C. Straty and R. Tsumura, "Solid Ethane and the Melting Line,"

J. Chem. Phys. (in press, 1976).

b) G. C. Straty and R. Tsumura, "PVT and Vapor Pressure Measurements

on Ethane," J. Res. Nat. Bur. Stand, (in press, 1976).

7.2 Ethane, Dielectric Constant Data—L. A. Weber .

Previous dielectric constant data for ethane have been limited to the

saturated liquid near the triple point and to the saturated liquid and

vapor in the region of the critical point. New experimental work has

been completed on the measurement of the dielectric constants of ethane

as a function of temperature and density over a wide range of densities

in the saturated and compressed fluid. The present data include the

saturated liquid in the temperature range 95 - 300 K and seven isotherms

at temperatures between 120 and 323 K and at pressures up to 390 bars.

The capacitance measurements were made with a commercial three-terminal

a-c bridge having a resolution of one part in 10^. The capacitor is made

15
up of a pa-tr of concentric cylinders and has a stability of one part

in 10-". Dielectric constant measurements are being combined with

accurate density data to form the Clausius-Mossotti (CM) function,

1/p (e-l)/(e+2) which for ethane, like other non-polar fluids, is

nearly independent of the temperature and density. This work has been

very valuable for examining the consistency of the available density

data for ethane, including the new equation of state (PVT) data

discussed above and the new magnetic densimeter measurements discussed

under "Densities of LNG Mixtures" below. Data analysis and report

preparation are nearly complete.

7.3 Ethane, Specific Heat Data—H. M. Roder .

Specific heat data (Gy) are required to define accurately the

derivatives of the equation of state (PVT) , which in turn are used to

calculate other thermodynamic functions such as enthalpy. Measured

values of Gy are particularly valuable for cross-checking thermodynamic

calculations for the compressed liquid states. We are preparing for

a series of Cv

and Cg^-j measurements on ethane similar to those

completed on methane under this program [1], Measurements of the heat

capacity of the empty calorimeter will be extended from 300 to 330 K

to permit Gy measurements of compressed gaseous ethane at temperatures

above critical. Since the critical temperature of ethane (305.3 K) is

well above room temperature, fluid of relatively high density will

reside in the filling capillary part of the system, and will have to

be accounted for accurately.

During this reporting period the heat capacity apparatus has been checked

out electrically, and for vacuum, and some heat capacity measurements

have been made on the empty calorimeter. Accuracy and consistency

checks on methane have been completed. Specific heat, Cg^-p and Gy,

measurements on compressed and liquefied ethane are in progress.

[1] B. A. Younglove, J. Research. NBS 78A, 401 (1974).

7.4 Ethane, Sound Velocity Data—R. Tsumura .

New ultrasonic measurements of the velocity of sound in compressed

and liquefied ethane (90 - 320 K, 35 MPa (5000 psi)) are in progress.

Preliminary measurements on saturated liquid ethane (90 - 305 K) have

been completed. Preparations for measurements of the dependence of

the sound velocity on the pressure and density are underway.

* Guest Worker, supported by a fellowship from Consejo Nacional De

Ciencia Y Tecnologia (CONACYT) , Mexico City, Mexico.

16
7.5 Ethane, Thermodynamic Properties Data—R. D. Goodwin .

Preparations for a substantially improved iteration of our provisional

thermodynamic properties data for ethane, reported in NBSIR 74-398,

"Provisional Values for the Thermodynamic Functions of Ethane," by

R. D. Goodwin, are in progress. This second, and final^ iteration will

include all available new physical property measurements for ethane,

obtained both as a part of this program and elsewhere, during the last

two years. Comparisons between calculated and directly measured

specific heats and sound velocity data mentioned previously in this

report will also be included. Substantial improvements in the equation

of state for ethane have been obtained.

17
1- Title . DENSITIES OF LIQUEFIED NATURAL GAS MIXTURES

Principal Investigators . W. M. Haynes, M. J. Hiza, W. M. Parrish

and R. D. McCarty , NBS, Boulder, Colorado 80302.

2. Cost Center Numbers . 2751574, 2752574

3. Sponsor . LNG Density Project Steering Committee, American Gas

Association, Inc., Project BR50-11.

4. Introduction . Accurate density measurements and calculation methods

for liquefied natural gas mixtures are needed to provide a basis for

custody transfer agreements and for mass, density, and heating value

gauging throughout the fuel gas industry.

The basis for the custody transfer of natural gas is its heating value.

It is difficult to determine and agree on the heating value of extremely

large volumes of natural gas in the liquid state. For example, methods

for calculating the heating value of a liquefied natural gas mixture

require knowing its density, which in turn depends on its composition,

temperature, and pressure. As the compositions of LNG mixtures vary

considerably, depending 6n the sources of the gas and the processing

conditions, accurate methods are needed for calculating liquid

densities at arbitrary compositions, temperatures and pressures. The

accuracy is important because of the extremely large volumes of liquid

involved.

5. Objectives or Goals . The objectives of this work are to perform

accurate (0.1%) and precise (0.02%) measurements of the densities of

saturated liquid methane, ethane, propane, butanes, nitrogen and their

mixtures mainly in the temperature range 105 - 140 K, and to test and

optimize methods for calculating the densities of LNG mixtures at

arbitrary compositions and temperatures.

6. Background . This project is being carried out at NBS because of the

realization that equitable custody transfer agreements could be reached

more readily if the density measurements and the evaluation and

development of calculation methods were performed by independent

professionals of established reputation.

Prior to this reporting period an apparatus incorporating a magnetic

suspension technique has been developed for absolute density measurements on liquids and liquid mixtures, particularly at saturation, for

temperatures between 90 and 300 K. The repeatability and estimated

precision of measurement are better than 0.02% while the accuracy is

better than 0.1%.

7. Program and Results . Saturated liquid density measurements have been

completed for the pure components of liquefied natural gas in the

following temperature ranges: (a) methane (105 - 160 K) ; (b) ethane

18
(100 - 270 K); (c) propane (100 - 280 K) ; (d) normal butane (135 -

(e) isobutane (115 - 300 K) ; and (f) nitrogen (95 - 120 K)

.

300 K)

;

Comprehensive accurate density measurements on selected binary mixtures

of LNG components are in progress. Accurate density measurements on

multicomponent (<_ 6) mixtures of LNG components have been initiated.

The evaluation and optimization of predictive calculation methods for

the densities of LNG mixtures are in progress.

19
1. Title . LNG DENSITY REFERENCES SYSTEM

Principal Investigator . Ben Younglove

Boulder, Colorado 80302.

2. Cost Center Number . 2751361

3* Sponsor . American Gas Association, Inc.

Project BR-50-10.

4. Introduction . The emphasis of the LNG effort of NBS is in providing

technical support to industry in meeting the energy needs of our

economy with natural gas.

The density reference system will evaluate the ability of commercially

available instruments to measure densities of LNG. Density is an

essential measurement in performing total energy content determinations of natural gas reservoirs. This effort is oriented towards

metrology and the output is correlated with cost center 2751574 which

provides basic reference data on pure liquids and mixtures which will

serve as density standards.

5. Objectives . This research will provide a system for evaluating the

density measurement capability of commercially available meters. We

will evolve a density reference system capable of generating accurate

densities for this evaluation. From the commercial meters we will

attempt to select one capable of performance as a transfer standard in

order to provide traceability of accuracy to field density measurement

systems.

6. Background . The density reference system was initiated in 1973 with a proposal to the AGA for research on LNG technology. Since that time

the reference system has been selected, designed, constructed, and is

now in operation, evaluating density metering systems.

7. Program and Results . The density reference system has shown consistent

good agreement in density measurements to the densities of Haynes (ref.

cost center 2751574) for liquid methane. That is, essentially all of

the measurements are within 0.15% of Haynes.

Data on the performance of density measurement by the vibrating cylinde

vibrating plate, and capacitance meter in liquid methane have been

taken.

The suppliers of the above densitometers have kept in close touch with

the progress in evaluation of their meters. There has been some malfunctioning in these devices and some modifications made

The capacitance meter was altered by its design engineer to

include a temperature sensor (platinum thermometer) and a new set of

electronics for readout. This device now features readouts of density,

temperature, and capacitance. The designer's intent is that the

temperature sensor will allow a more accurate measurement of density

over variations in hydrocarbon composition.

20
We have had input from the NBS statistical group as to statistical

approaches for testing, they have also been of significant help in

advising on detailed operation of the weighing head.

Colin McClune of Thornton Research Center (Shell Research Ltd.) has

visited us and has given us the benefit of his knowledge on the qualitative behavior of two of the above devices. He intends to make

further evaluations with his density system. It is our intention to

keep in touch with his progress.

21
1. Title . HEATING VALUE OF FLOWING LNG

Principal Investigators . J. A. Brennan and J. M. Arvidson

NBS, Boulder, Colorado 80302.

2. Cost Center Number . 2756579

3. Sponsor . pipeline Research Committee (American Gas

Association) PR-50-48.

4. Introduction . This project will draw on information and facilities

generated by other sectors of the NBS LNG effort. Thus, the calibration

of a densitometer used will be traceable to the NBS density reference

system being constructed by Younglove under cost center 2751361.

Mixture density data produced under 2751574 by Haynes and Hiza will also

provide a necessary input to the proper interpretation of results.

5. Objectives . The objective of this program is to measure the heating

value of LNG flowing in a pipeline by the integration of individual

measurements of flow, density and heating value. Flow measurement

requires determination of flowmeter performance in line sizes larger

than presently available calibration facilities. Therefore, a

secondary objective is to establish appropriate flowmeter scaling laws.

6. Background . The LNG .flow facility at NBS will be ut ilized to evaluate

the response of the individual elements in the heating value measurement. Different cbmpositions of LNG will be prepared to provide a

range of densities sufficient to determine any dependencies. A limited

amount of sampling work is included to determine the relative importance

of this parameter to the overall measurement.

Flowmeter scaling is being done utilizing the cryogenic and the water

flow facilities at NBS and private LNG peak shaving facilities. This

portion of the program is behind schedule because of scheduling

problems at the private LNG facilities.

7. Results . LNG Tests on the four-inch flowmeter that had been scheduled

at an industrial LNG plant for early 1975 were not completed because

there was no LNG send out. It now appears that a brief test might be

possible during late November or early December 1975. Therefore, this

critically important phase of the program has been delayed approximately

one year from the original plan. In order to keep the delay in the

flowmetering phase of the program as short as possible it was decided

to go ahead with the necessary plans for the next larger size flowmeter

(eight inch) and try to test both sizes during the next send-out season.

22
1. Title. LNG FUELS SAFETY

Principal Investigators . Neil A. Olien and A. F. Schmidt

NBS, Boulder, Colorado 80302.

2. Cost Center Number . 2750427

3. Sponsor National Aeronautics and Space Administration, Cleveland,

Ohio, Aerospace Safety Research and Data Institute.

Order No. C-39327-C.

4. Introduction . The NASA-Aerospace Safety Research and Data Institute

(ASRDI) was established to provide a focal point for information and

research in aerospace safety. One of the areas of concern for ASRDI is

Cryogenic Fluid Safety. In fact, this was the first area of effort for

ASRDI. The thrust of the program is two-fold: first, to provide an

automated information bank for retrieving references, and second, to

publish series of state-of-the-art reviews. The information system is

now operational and contains over 7000 references in cryogenic fluid

safety. In addition, ASRDI has published approximately twenty reviews.

Until this time, ASRDI has focused its attention and efforts on the two

primary cryogenic propellants, hydrogen and oxygen. The oxygen work was

started at NBS-Boulder in 1970 and the hydrogen work in 1972. With the

coming possibility of methane or LNG fueled aircraft and the close

affinity of LNG safety and cryogenic safety s ASRDI felt that it was

timely to begin work in that area.

5. Objectives or Goals . The following objectives are to be achieved:

a) Review and modify an existing Cryogenic Fluids Safety Grid and

thesaurus to include and adequately cover LNG safety.

b) Make a thorough search of over eleven information sources for

LNG information. This will include published and unpublished

material

.

c) Catalog, index, abstract and put into machine readable form all

available documents located in b) above. The indexing will be

done by technical personnel with demonstrated competence in

cryogenic safety and related fields.

6. Background . This program was started at NBS-Boulder by ASRDI in 1970.

Since then considerable skill and experience has been gained in

locating, processing and, most important, detailed subject indexing

of safety-related information. In addition, NBS-Boulder has been

providing detailed coverage of the LNG field for the American Gas

Association since early 1970. The present program, then, provides an

opportunity for industry, government and the public to capitalize

on the accumulated past efforts of two seemingly unrelated programs.

23
Program awA Results . Under this and another ASRDI-funded program we

have started a major review of the indexing and retrieval terminology

which will be used in the Cryogenic fuels safety information system.

This review will result in a thesaurus to be published by NASA. The

review is complete and we are now in the process of editing and

preparing the thesaurus in its final form. Publication has been delayed

awaiting a decision as to publishing the thesaurus separately or

combined with one in fire safety and one in the mechanics of structural

failure. Most of the terminology unique to LNG safety is now

incorporated into this thesaurus. Approximately 500 papers, reports,

etc. have been carefully indexed, abstracted, cataloged and transmitted

to ASRDI.

2 4
1. Title . ENERGY CONSERVATION POTENTIAL IN THE LN6 INDUSTRY

Principal Investigators . D. B. Mann and T. M. Flynn

NBS, Boulder, Colorado 80302.

2. Cost Center Number . 2750103

3. Sponsor . ^BS Office of Energy Conservation

4. Introduction . By the end of 1975, there will be 166 LNG projects around

the world in operation, under construction, planned, or proposed.

Peak shaving accounts for the largest number of LNG facilities with 106

being completed within the U.S. This number includes 55 actual peak

shaving plants (which include liquefaction, storage, and gasification

equipment) and 51 satellite facilities (which consist of storage and

gasification equipment, but no liquefier) . These 106 plants comprise

a total storage capacity of approximately 65 billion cubic feet (equivalent gas volume) and a total liquefaction capacity of approximately

295 million cubic feet per day.

The impact of energy shortages world wide has underscored the need to

utilize this resource (LNG) as efficiently as possible. Therefore,

this program has been undertaken to provide the measurements and data

base necessary for energy conservation in the Liquefied Natural Gas (LNG)

industry. It will identify sources and degree of thermodynamic losses

incurred during liquefaction, shipping, storage, and regasification of

LNG and assure an adequate cryogenic measurement methodology and data

base to facilitate the most effective use of Liquefied Natural Gas.

5. Objectives . The objective of the project is to provide the technical

basis for the planned management of the cryogenic aspects of liquefied

natural gas to enable its more effective utilization and prevent its

exploitation or neglect. It will include, for instance, thermodynamic

analyses of representative LNG systems to define the thermodynamically

"ideal" base for comparison to actual practice. It will identify and

test instruments and measurement techniques in support of energy conservation, and analyze and test the feasibility of energy recovery

through utilization of the cold in LNG.

6. Background . New project.

7. Program and Results . During this fiscal year, we completed the first

four months of an intended three year study whose ultimate purpose is

to provide the measurements and data base necessary for energy conservation in the Liquefied Natural Gas (LNG) industry. Progress made

during these first four months include: „

1) An historical perspective of the LNG industry to identify trends,

2) The selection of peak shaving as the first subject for study,

including a description of the process and essential components;

3) A thermodynamic analysis of the peak shaving process;

4) An identification of the most pressing measurement and

instrumentation needs.

25
Specific objectives during this first period were to provide:

1) A documentation and definition of the LNG industry.

2) An LNG peak shaving process description.

3) A description of the variations among LNG peak shaving process

components

.

A) Thermodynamic analysis — reversible process.

5) Thermodynamic analysis — limitations.

6) Thermodynamic analysis — applications to existing facilities.

7) An analysis of energy conservation through the potential of

refrigeration recovery, or cold utilization.

8) An identification of tentative measurement instrument needs.

9) A base for measurement development for conservation requirements.

Among our first conclusions are the following:

1) LNG peak shaving is an established and growing U.S. industry.

2) Much technical information is already available for conservation

analysis

.

3) The peak shaving process is subject to analysis using classical

thermodynamics

.

4) It is possible to establish a thermodynamically reversible

process as an ideal, to measure real processes against.

5) Some irreversibilities are dictated by external requirements of

the process (e.g., vaporization for rapid send out).

6) Liquefaction is the largest single irreversibility, followed by

storage losses.

7) Process efficiencies could be further enhanced if it were possible

to build an integrated plant where cold utilization were a

coordinated objective.

8) Tentative measurement requirements identified are: thermometer,

densitometer, flowmeter, liquid level and mixture fraction, all

in gas or cryogenic liquid phases.

9) Some thermodynamic, electrodynamic , transport, and phase

equilibrium properties data are inadequate as of the reporting

period. Existing experimental and analytical programs on property

data will eliminate this inadequacy within the scope of the three

year study.

26
1. Title. SURVEY OF CURRENT LITERATURE ON LNG AND METHANE

Principal Investigator . Neil A. Olien

NBS, Boulder, Colorado 80302.

2. Cost Center Number . 2750362

3. Sponsor American Gas Association Project BR-50-10.

4. Introduction . It is important that all NBS personnel working in LNG,

as well as the AGA and others, keep up with what is going on throughout

the world in the LNG field. This project is designed to provide the

Current Awareness and other information services to allow workers to

keep abreast of new research and other developments.

5. Objectives or Goals . We will publish and distribute each April, July,

October and January a listing of all significant papers, reports and

patents relating to methane and LNG properties and technology. The

references will be listed under convenient subject headings. The

Quarterly will be distributed to all interested AGA member companies

and be made available to the general public on a subscription basis.

In addition, LNG related information will be entered into the Cryogenic

Data Center's Information System for quick retrieval. A continuing

awareness of the current publication scene will be maintained for any

new periodicals to be reviewed cover-to-cover. Finally we will update

and make available comprehensive bibliographies on the properties and

technology of LNG. There are three bibliographies involved: methane

properties, methane mixtures properties, and processes and equipment

involving methane and LNG. These three will be updated each October.

6. Background . In 1969 we made a thorough review of the world*

s

publications to determine which periodicals and abstracting services

should be scanned cover-to-cover to adequately encompass the LNG field,

The result is that we now scan over 300 primary publications and nearly

30 secondary publications. Of these approximately one-third are

directly related to LNG. In addition, within the past year we have

increased our coverage of the energy field to include hydrogen as a

future fuel. Much of this information is also pertinent to LNG and

as such is listed in our LNG-related publications. Our Current

Awareness Service has been published weekly since 1964 (beginning in

1975 the publication became biweekly) and the Liquefied Natural Gas

Survey has been published quarterly since 1970.

7. Program and Results . Four issues of the LNG Quarterly are prepared

each year and distributed. There are now 120 subscriptions going to

AGA Member Companies and 168 to other subscribers.

27
The three comprehensive bibliographies mentioned in section 5 have

been reviewed and shorter, more selective bibliographies have

resulted. These were prepared in January 1975.

B-1262 THE THERMOPHYSICAL PROPERTIES OF METHANE AND DEUTERO-METHANE

IN THE SOLID, LIQUID AND GASEOUS PHASES - A SELECTED

BIBLIOGRAPHY. Indexed by property, phase and author,

68 pages (Feb 1975). ($8.00).

B-1263 THE THERMOPHYSICAL PROPERTIES OF METHANE MIXTURES - A

SELECTED BIBLIOGRAPHY. Indexed by property, system and

author, 118 pages (Feb 1975). ($10.00).

B-1264 PROCESSES AND EQUIPMENT INVOLVING LIQUEFIED NATURAL GAS AND

METHANE - A SELECTED BIBLIOGRAPHY. Indexed by subject and

author, 76 pages (Feb 1975). ($8.00).

These are being updated now and will be available in January 1976.

Over the past five years we have distributed over 400 copies of these

and the comprehensive bibliographies. A bibliography on LNG Patents

was supplied to AGA in May, 1975. A supplement to this was completed

in July.

28
1. Title . CRYOGENIC DATA CENTER INFORMATION SERVICES

Principle Investigator . Neil A. Olien

NBS, Boulder, Colorado 80302.

2. Cost Center Numbers . 2750121, 2750126

3. Sponsor _ NBS-Institute for Basic Standards and NBS-Office

of Standard Reference Data.

4. Introduction . The need for information services in science and

technology has spawned several kinds of activities. One of these is

the Information Analysis Center (IAC). The Cryogenic Data Center is

one of over one-hundred IAC's. A typical IAC, whether it is mission

or discipline oriented, is concerned with obtaining all information

and data in a given area and then performing data evaluation of a

particular subset of that data. In the case of the Cryogenic Data

Center the field is physics and engineering below 150 K with data

analysis performed on the low temperature properties of fluids. In

most cases, the data evaluation is done critically and the resulting

data compilation is recognized as Standard Reference Data.

5. Objectives or Goals . We will publish and distribute a Biweekly

Current Awareness Service listing references to new published papers

in the fields of low temperature physics and chemistry and cryogenic

engineering. Literature on the properties of the Industrially

Important Gases will be identified and listed regardless of temperature

range. In addition associated areas in the energy field will be

covered. All important information will be thoroughly indexed and

cataloged and entered into an automated information storage and

retrieval system. Searches of this system will be made on demand.

Fluid properties papers will be indexed in greatest depth so as to

efficiently identify source data for evaluation projects throughout

the world. Literature searches utilizing the automated system will

be made on demand in answer to specific requests from NBS, other

government agencies, universities and the general public. Three

quarterly subscription services will be printed and distributed. These

all "Superconducting Devices and Materials," "Liquefied Natural Gas"

and "Hydrogen-Future Fuel." Charges will be made for Data Center

services on a cost reimbursable basis.

6. Background . The Cryogenic Data Center was established in 1958 to

serve as a central source of information on the properties of materials

at cryogenic temperatures and to evaluate data on the properties of

the cryogenic fluids. In 1963 the Center became a charter member of

the National Standard Reference Data System with the establishment of

the Office of Standard Reference Data within NBS. In addition contact

has been established with fluid properties evaluation groups throughout the world and with other, similar information centers. The staff

of the Center have pioneered in the application of advanced

statistical techniques in the development and optimization of

empirical equations of state and in the prediction of transport

29
properties by means of potential functions based on thermodynamic

data. In the area of documentation, the Center has adapted stateof-the-art techniques in the development of its computerized

information system. Highly skilled and experienced professionals

are used in all subject indexing functions.

7. Program and Results . The Current Awareness Service has been

published since 1964 and currently goes to over 400 subscribers.

Subscriptions and marketing are handled by the National Technical

Information Service. New marketing techniques have been and are being

explored and implemented to increase the sales of the products handled

by NTIS. The Superconducting Devices and Materials Quarterly has

been published since 1968 and is prepared in cooperation with the

Naval Research Laboratory, the NBS-Cryoelectronics Section, the Office

of Naval Research and Superconducting Technology, Incorporated. There

are currently 240 subscribers. The Liquefied Natural Gas Quarterly

has been published since 1970 in cooperation with the American Gas

Association and has 288 subscribers. The Hydrogen-Future Fuel

Quarterly was started in August 1973 and is now sent to 192 individuals

and firms. The automated information system contains over 100,000

carefully indexed papers in such areas as properties of fluids,

properties of solids, processes and equipment, patents, instrumentation

and metrology, etc. Over 150 major bibliographies are prepared each

year and other requests are distributed approximately as follows:

Visitors and telephone requests for information and data - 135 per

year; letter requests for information, data and technical advice - 480

per year; requests for reprints, reports and other publications - 770

requests each year for over 3200 documents.

Data evaluation work has concentrated on the thermodynamic and transport properties of primarily the elemental gases. Compilations

representing Standard Reference Data have been published for hydrogen,

helium, nitrogen, oxygen, fluorine, neon, and argon. In addition, a

number of specialized data sets have been prepared for such things as

the solid properties of the isotopes of hydrogen and custody transfer

data for four industrial fluids. The techniques developed and

experience gained with pure fluids is now being extended to the

development of predictive calculational methods for fluid mixtures.

The goal is to develop mixtures equations of state which will be based

on pure fluid and binary mixture data only. The mixtures work is in

a very preliminary stage.

30
I L. Title. ANALYSIS, EVALUATION, AND COMPILATION OF CHEMICAL

THERMODYNAMIC DATA

Principal Investigator . D. D. Wagman

Chemical Thermodynamics Data Center

Physical Chemistry Division

National Bureau of Standards

Washington, D. C. 20234

>. Cost Center Number . 3160115

3. Sponsor . Office of Standard Reference Data, NBS

1 . Introduction . The Chemical Thermodynamics Data Center is

concerned with the systematic development of a set of selfconsistent values for the standard enthalpies, Gibbs energies

and entropies of formation at 298 C of nearly all inorganic

substances for which data are available and for organic

compounds having at most 2 carbons in a chain. The data

considered include all phases and many aqueous solutions

especially those of electrolytic systems. It is clear that

a large number of fluids is included even when the electrolytic

solutions are excluded from consideration.

i. Objectives or Goals . The objective of this project is the

development of a self-consistent set of standard enthalpies,

entropies and Gibbs energies of formation at 298 C for as

many substances as possible including their aqueous solutions.

5. Background . The standard enthalpies, Gibbs energies and

entropies are the primary thermochemical properties needed

to calculate the equilibrium constants for chemical reactions

which determine the maximum yields which may be obtained.

These properties are also useful for determining the heat

that must be supplied to carry on a reaction or alternatively

the heat generated in the reaction (heat which usually

must be removed to maintain control of the temperature of

the reactor) . The standard properties at 298°C form the

basic matrix of properties used. These must be corrected

for changes in termperature away from 298 C and for solvent

effects and nonideality of mixing for maximum accuracy;

however, they are always needed and often give revealing

information even without detailed correction.

7. Program and Results . The center is covering the substances

for which data are available in a systematic fashion. The

elements of the periodic table are considered according to

an ordering developed for the purpose. At each stage, the

element is considered along with any compounds it might

make with elements occurring earlier in the ordering system.

31
Most of the periodic table has been covered at this time,

the exceptions being the alkali metals and the actinide

elements. These are being worked on concurrently and

should be finished within 18 months. When these two sets

of substances are completed, there will be a complete

set of self -consistent data for substances for which

measurements are available covering the entire periodic

table .

This center also contributes the inorganic section and the

editing for the Bulletin of Thermodynamics and Thermochemistry which is a bibliographic collection indexed by substance

and property which is issued yearly.

32
Title. THERMODYNAMIC DATA ON ORGANIC COMPOUNDS

Principal Investigator . Bruno J. Zwolinski

Texas ASM University

FE Box H

College Station, Texas 77843

Cost Center Number . 1510200

Sponsor . Office of Standard Reference Data, NBS

Introduction . This data center has a long history of

compilation and evaluation of data on organic compounds

starting with the beginning of API Project 44, some 30

years ago. The API interest was focussed on hydrocarbons

and related substances found in petroleum, and work on these

substances under API sponsorship continues to the present.

The center has had support from the OSRD over the last

10 years to cover other types of organic substances.

Objectives or Goals . The objective of this project is the

provision of critically evaluated reference data on selected

thermodynamic and thermophy sical properties for selected

scientifically and industrially important organic chemicals.

i. Background . The properties covered by the center in its

various projects for the OSRD include ideal-gas thermal

functions, properties of the real gas, enthalpies and

entropies of formation, vapor pressures and transition

temperatures, densities and refractive indices. The substances chosen for study have scientific and/or industrial

importance. The properties covered are those properties

needed to determine the equilibrium behavior of the substances in question under the conditions met with in chemical

processing plants.

Program and Results . Recent results have included a definitive

work on the properties of the aliphatic alcohols, which was

published as a Supplement of the Journal of Physical and

Chemical Reference Data, and a series of papers on the

ideal-gas properties of the halogenated hydrocarbons.

At the present time, the center has undertaken to produce a

self -consistent set of thermochemical properties for a set

of oxygen-containing compounds having one to four carbon

atoms. The set includes representatives of major homologous

series such as alcohols, acids, ketones, ethers. There are

perhaps 15 compounds for which extensive data exist. Not

only will the results provide evaluated data on the initial

compound or two of important homologous series, but the

data will be consistent with the thermodynamic changes

observed when these compounds are changed one into the other

by chemical processes such as oxidation and reduction.

33
Since the compounds for which data exist are of industrial

importance, the data resulting from the project will be

important in their own right for industrial purposes and

will serve as the basis for estimation techniques, such as

are used to estimate the properties of higher homologs

through the addition of methylene groups.

In addition, the center contributes to the Bulletin of

Thermodynamics and Thermochemistry which is a bibliographic

collection indexed by substance and property which is issued

yearly

.

34
Title . JOINT INDUS TRY -GOVERNMENT PROJECT ON THE

THE RMOPHYS I CAL PROPERTIES OF ETHYLENE

i

Principal Investigators .

D. R. Douslin, ERDA Energy Research Center, Bar t le s vi 1 le

,

Oklahoma

M. Klein, Equation of State Section, Heat Division,

NBS, Gaithersburg , Maryland

R. D. McCarty, Cryogenic Data Center, NBS , Boulder, Colorado

J. Powers, University of Michigan, Ann Arbor, Michigan

H. J. White, Jr., Program Manager, Office of Standard

Reference Data, NBS, Gaithersburg, Maryland

Cost Center Numbers . 1510404, 1510430, 27501.28, 3104575

:. Sponsors . Office of Standard Reference Data, NBS

Industrial Sponsors Group

Celanese Chemical Company

Cities Service Oil Company

Continental Oil Company

Gulf Research and Development Company

Mobil Chemical Company

Monsanto Polymers & Petrochemicals Company

Phillips Petroleum Company

Union Carbide Corporation

L Introduction . Ethylene is one of the most extensively used

chemicals in the world, current US usage running in the vicinity

of 25 billion pounds per year. In addition to being handled

on a large scale at plant sites, ethylene is transported

in large quantities by pipeline and cryogenic tank ship.

The PVT and related thermodynamic properties are used for

process and equipment design, process and plant control,

instrumental analysis and custody transfer. However, at

the present time there is no authoritative wide-ranging

formulation of these properties of sufficient accuracy and

precision to serve all of these purposes. Furthermore, it

is not possible to obtain one without additional experimental

measurements to fill gaps and resolve contradictions in the

existing data. This project was initiated to obtain such a

formulation

.

>. Objectives or Goals . The objective of this project is to

prepare an authoritative, comprehensive and self -consistent

set of PVT and thermodynamic properties of ethylene to within

the accuracy and precision allowed by the state of the art

(0.1% in density).

35
6. Background . Requirements were established and the technical

program needed to meet them were specified in a series of

meetings with industrial representatives. Broadly based

industrial support and cooperation were needed to insure

products appropriate to industrial practices and widespread

acceptance of the results. It was also necessary that those

doing the work be expert in carrying out the experimental

measurements and data evaluation required. Finally, it was

necessary that the project be so organized that it would be

free from possible bias from special interests. A joint

project involving industrial and governmental support

under the program management of the Office of Standard

Reference Data seemed to meet these various requirements

and was established in 1974.

7. Program and Results . The project is scheduled over a

five-year period, and is into its second year. Measurements

have been completed which define the critical point and the

behavior in the critical region very accurately. The next

phases of the work will deal with the properties of the vapor

and liquid at temperatures between the critical and the triple

point. Data evaluation is being carried out concurrently

with the experimental program.

36
L. Title. EXCESS PROPERTY DATA FOR BINARY LIQUIDS

Principal Investigator . Buford D. Smith

Thermodynamics Research Laboratory

Washington University

St. Louis, Missouri 63130

1. Cost Center Number . 1510297

I. Sponsor . Office of Standard Reference Data, NBS

and industrial sponsors

\. Introduction . The Thermodynamics Research Laboratory carries

out a program of compilation and evaluation of data from

the literature, experimental measurement, and the development

of computer programs for correlation and computation of data

needed by industry. The fields covered are the excess volume,

heat of mixing and vapor-liquid equilibrium of binary nonelectrolyte systems. There are several sources of support;

however, the program on compilation and evaluation of data

from the literature, which is of primary interest here,

receives support from the Office of Standard Reference Data

and industry.

>. Objectives or Goals . The objectives of this project are the

compilation and evaluation of a comprehensive set of data

from the literature on the volume change on mixing, the

heat of mixing and the vapor-liquid equilibria for binary

systems in which both components are below their critical

temperatures and neither is an electrolyte.

>. Background . The chemical industry is continually concerned

with the properties of mixtures and the separation of these

mixtures into separate components (for example, product and

by-products) . The properties compiled and evaluated by

this center are those required for calculations needed in

the design of distillation columns, for example. The

compilation of a comprehensive set of evaluated data for

binary systems will not only be useful in process and

design calculations but will provide basic reference data

for the needed development of more successful equations

for interpolating, extrapolating and estimating the properties of solutions.

7. Program and Results . The center has developed a set of

criteria for screening data found in the literature according

to three criteria: the degree to which the data on vaporliquid equilibrim are consistent with the Gibbs-Duhem relationship, the extent to which data for binary systems extrapolate

to the evaluated data for the individual components and the

scatter of the data. These criteria do not represent a

37
complete evaluation of the data; however, all good data must

pass this screening and such a screening should be useful

for many purposes, particularly in cases where the data

available are limited.

The center plans over a period of time to cover all classes

of binary systems for which data are available. Specific

classes to be covered in the immediate future are:

1. C_ plus heavier hydrocarbons (up to C ) 3 8

2. C. plus heavier hydrocarbons (up to C ) 4 o

3. Alcohols (C^ through C^) plus hydrocarbons

(C, through C Q )

38

i
Title. THERMAL CONDUCTIVITY OF SELECTED SUBSTANCES

Principal Investigators . Y. S. Touloukian

C. Y. Ho

Thermophys ical Properties Research

Center

Purdue University

Lafayette, Indiana 47907

Cost Center Number . 1510262

Sponsor . Office of Standard Reference Data, NBS

Introduction . This center is a major data center with support

from a number of sources. It compiles data on specific heat,

thermal conductivity, viscosity, thermal expansion and thermal

radiative properties. Other centers allied with it in the

Center for Information and Numerical Data Analysis and

Synthesis compile data on other properties, in particular

electrical conductivity which is of importance for the

project considered here. In addition to compilation of

data on a variety of properties for a wide range of substances,

the center carries out data evaluation with the support of

the Office of Standard Reference Data for selected properties

and substances.

Objectives and Goals . The objectives of this project are

to provide critically evaluated data on selected properties

of selected substances. The evaluation has been focussed

primarily on data for the thermal conductivity of metals and

alloys to date.

Background . The properties covered by this center are those

needed to understand and predict the transfer of heat from

one place to another in a physical system. As such, they

are needed in the design of processes and equipment whenever

transfer of heat is anticipated, whether it is the input of

heat to initiate or maintain a given process or the removal

of unwanted waste heat.

Program and Results. The primary initial task of this center

was the compilation and evaluation of the data for the thermal

conductivity of the elements. This work culminated in a

definitive text which was published as a Supplement to the

Journal of Physical and Chemical Reference Data.

More recently, the work has been concerned with the thermal

conductivity of a set of binary alloys. This work has required development of methods for interpolating among temperature ranges and between concentration ranges. A necessary

adjunct has been compilation and evaluation of data on electrical conductivity and thermoelectric power for the same

alloys and their individual components.

39
One further project of importance is the compilation and

evaluation of data on the viscosities, thermal conductivities,

and heat capacities of 73 fluids selected for their industrial

importance. The fluids and the extent to which there are data

on their properties are shown on the accompanying sheet.

40
STATUS OF TPRC TABLES ON PROPERTIES OF FLUIDS

VISCOSITY THERMAL CONDUCTIVITY

LIQUID VAPOR GAS SOLED LIQUID VAPOR GAS

SPECIFIC HKAT AT

CONSTANT PlU.SSUtF

SOLID LIQUID VAPOR CAS

oz £

7. Acetone • X X X X X Acetylene X X X 729 Air X X X X X X X X X 717 Ammonia X X X X X X X X X 740 Argon X X X X X X X X X X Benzene X X X X X Boron Trifluoride X • X X X Bromine X X X X X X 600a i30- Butane X X X X X X X X X 600 n- Butane X X X X X X X X X 744 Carbon Dioxide X X X X X X X X X Carbon Monoxide X X X X \

10 Carbon Tetrachloride X X X X X

14 Carbon Tetrafluoride X X X X X X X Chlorine X X X X X X 20 Chloroform X X X X X n-Decane X X X X Deuterium * X X X X X X 170 Ethane X X X X X X X X X Ethyl Alcohol (Ethanol) X X X X X 610 Ethyl Ether X X X X X 1150 Ethylene X X X X X X X X X Ethylene Glycol X X Fluorine X X X X X X Glycerol X X 704 Helium 4 X X X X X X X n-Heptane X X X x

» X n-Hcxane X X X X X 702 Hydrogen, normal X X X X X X X X X X 702 Hydrogen, para X X X X X X Hydrogen Chloride X X X X Hydrogen Iodide ' X X X X Hydrogen Sulfide X

1 X X X Iodine X X X X X Krypton X X X X X X X 50 Methane X X X X X X X X X Methyl Alcohol X X X X X 40 Methyl Chloride X X X X X X X X X 720 Neon X X X X X X X X X \

Nitric Oxide X X X X 72 H Nitrogen X X X X X X X X X X Nitrogen Peroxide X X X X X 744a Nitrous Oxide X X X X n-Nonane X X X X

n -Octane X X X X X 732 Oxygen X X X X X X X X X n- Penianc X X X X \

2>j0 Propane X X X X X X X X X 270 Propylene X X X X X X X X X Radon X X X

11 Rl 1 (Trichlorofluorotnethar..-!) X X X X X X X V X

12 R12 (Dichlorodifluoromethane) X X X X X X X X X

l:i Rl'l (Chlorotrifluorornethane) X X X X X X X X

13 1U R l:i HI ( Broinotrifluoromethane) X X X X X X X X X

.21 R2 1 (Dkhlorofluoromethanc) X X X X X X X X X 22 R22 (Chlorodifluoromctliane) X X X X X X X X X 2A R2:t (Tnfluoromcthanc) X X X X X X X X \

il;) RlLl (Trichlorotrifluoroethane) X X X X X X X X 114 Rl 14 (Diehlorotetrafluorocthane) X X X X X X X X 115 R115 (Chloropentafluoroethane) X X X X X X X X

1421; Rl 12b (Chlorodifluorocthane) X X X X 152a Rl 52a (Difluoroetliane) X X X X X 210 R216 ( 1, MDichlorol, 1, 2, 2,3.3. - hex ifluoropropane) X X X X

:ilh R:i 1 *i (Oi laf luorocyclobutane) X X X X X X X X

jyii R.'.OO (Hi:!, Rl!»2a a/.cotrope) X X X X X K \

lifC! R'.fiO:: (Rl::, III lr.a/.cotrope) X X X X X X X \ \

11. .iu (It Il2ta/eolri>po) X X X \ \

riii i Itl.iM (l( Ill 1'. a/.rotropu) X X X \ X K 1 iMllllll' DtoXllIc X X X X \

IVIli.-IK' X X \ \ \

l'l III .III \

Water X X X X X X X \ \ X< no

n

X X X X X X \ 41
i

1. Title . TRANSPORT PROPERTIES OF FLUIDS IN THE CRITICAL REGION

Principal Investigator . J. V. Sengers

University of Maryland

College Park, Maryland 20742

2. Cost Center Number . 1510286

3. Sponsor . Office of Standard Reference Data, NBS ; NASA

4. Introduction . The region in the vicinity of the critical point

is of particular importance for both the equilibrium and

transport properties of fluids. Many properties change

rapidly and substantially in magnitude as the critical point

is approached. These changes are of technological importance

for processes that approach or include the critical region.

Furthermore, properties in the critical region and the

critical constants themselves are used as base points and

constants for data reduction for a variety of extrapolation

and estimation procedures. As a result, methods for evaluating data in the critical region and for obtaining reliable

se 1

f -cons is tent sets of data are of considerable importance.

The importance of the evaluation procedures is increased

by the difficulties met in making the experimental measurements .

5. Objectives or Goals . The objectives of this project are the

development of methods for obtaining self-consistent, reliable

sets of data for thermodynamic and transport properties in

the vicinity of the critical point and formulations for the

data in this region that are soundly based theoretically,

make economical use of adjustable parameters and join smoothly

with the classical formulations for these properties known

to hold well away from the critical region.

6. Background . The critical region has been of unusual importance

for many years. The rapid and substantial changes of many

properties and the successful use of critical constants or

properties for a variety of data-reduction processes have

assured the practical importance of the region. At the

same time, lack of understanding of the properties in this

region and their apparent failure to follow classical theory

have assured theoretical interest. Recent theoretical developments have given broader insight and have offered methods for

analyzing data points in the critical region and comparing

and correlating the results of different types of measurements,

that are simple in form and economical in their use of adjustable

parameters. These so-called "scaling law" methods thus offer

the opportunity to develop self -consistent data sets for the

critical region and formulations that describe the region accurately and with sparing use of constants.

42
Program and Results . Results already obtained include a

method of separating the thermal conductivity in the

vicinity of the critical point into a "normal" portion that

reflects the behavior to be expected as a result of behavior

well away from the critical region and an "excess" portion

reflecting the change in behavior resulting from the proximity

of the critical point. A method for describing the asymptotic

behavior of the excess portion in the vicinity of the critical

point has been developed as has a relationship between the

thermal conductivity and the compressibility near the critical

point so that mutually consistent data for the two properties

can be obtained.

The program to be accomplished includes compilation and critical

evaluation of thermal conductivity data for those fluids

for which experimental data in the vicinity of the critical

point are available, development of interpolation methods in

the critical region and development of methods of joining , the asymptotic behavior near the critical point with the

normal behavior well away from the critical point.

43
1. Title. THERMODYNAMIC PROPERTIES OF FLUIDS

Principal Investigators .! J.M.H. Levelt Sengers, L. Haar

Equation of State Section, Heat Division

National Bureau of Standards

Washington, D. C. 20234

2. Cost Center Numbers . 2210143, 2210147, 2214443

3. Sponsors . NBS , U.S. Navy, Office of Standard Reference Data-NBS

4. Introduction . The thermodynamic properties of fluids have been

a long-term interest of the Heat Division of NBS. This interest results from the needs for such data for the handling

and use of industrially important fluids and for the use of

various fluids as working fluids in engines, heat exchangers,

refrigerators, and the like. Overall needs for data on

fluids encompass not only single fluids but mult icomponent

fluids and chemically interacting fluids as well. Similarly,

the conditions of interest include some that are difficult

or perhaps impossible to achieve and control in a research

laboratory. Therefore, the activities of the Heat Division

have covered a wide range of conditions and types of fluids.

5. Objectives and Goals . The objective of this project is the

production of tables of thermodynamic properties of single

and multicomponent fluids under a variety of equilibrium

conditions including those difficult or impossible to reach

under laboratory conditions.

6. Background . To reach the objectives of this project, it is

necessary to examine all of the aspects of thermodynamic

tables in detail. It is essential to study the foundations

of theoretical descriptions, to determine the utility and

meaningf ulness of methods used for obtaining the parameters

associated with such descriptions, to develop and improve

theoretical models and to study the techniques used in the

statistical analysis of data needed to obtain information

from experiment. This comprehensive approach to the development of thermodynamic tables allows a clearer understanding

of the reliability of such tables, leads to the avoidance

of such pitfalls as the "over f itt ing " of individual sets of

data and permits the use of such statistical mechanical

constructs as intermole cular potentials in the development

of tables of numerical data.

7. Program and Results . A correlation for the properties of

ammonia has been completed and is being prepared for publication. This correlation extends considerably the range

of the previous correlation for ammonia which is nearly

50 years old.

44
I Computations of the composition and thermodynamic properties

of air to 15,000 K for densities to 1000 times normal sea

level density have been completed. At the highest temperatures, due to the dissociation and recombination of species,

air consists of more than 30 reacting species. The problem

is then one of calculating compositions and properties of

a reacting gaseous mixture to very high densities - a general

problem of some practical importance in explosives. Since

the temperatures involved are well outside the range of

experiment, the computational results cannot be checked

directly. The results are nevertheless very illuminating.

Of particular interest is the behavior of the different

species concentrations relative to each other as functions

of pressure. Details are included in a report to be submitted for publication.

The feasibility and utility of representing the equation of

state of fluid mixtures in field variables (PTy) have been

studied. Also simple but fundamentally based equations of

state have been developed and examined for applicability in

extensions of fluid property descriptions to high pressures.

Ideal gas thermodynamic properties for water to 0.01%

accuracy will be completed. An equation of state for

dense gases with permanent dipoles is being applied to

water at temperatures above 1.25 T c and densities to 3

times the critical density. Results to date indicate the

theory is consistent with the available data. A study of

the thermodynamic data for fluid water over the entire

range of T and P will be undertaken.

The extension of a generalized molecular theory of dense

fluids to the treatment of mixtures will be given major

emphasis

.

45
1. Title . THERMODYNAMIC PROPERTIES OF FLUIDS IN THE CRITICAL

REGION

Principal Investigator . J.M.H. Levelt Sengers

Equation of State Section, Heat Division

National Bureau of Standards

Washington, D. C. 20234

2. Cost Center Numbers . 2210140, 2210141, 2214441, 2210149

3. Sponsors . NBS , NASA, Office of Standard Reference Data-NBS

4. Introduction . The region of the PVT surface in the vicinity

of the critical point is important to theoreticians because

the underlying causes of the observed behavior are not understood and of practical importance because of the unusual

behavior that occurs in this region and the extensive use

of the critical constants in the reduction of data. For

these reasons the interests of the Equation of State Section

in this region are many and varied and include experimental

and theoretical work, data evaluation, and work on critical

behavior in one component and multi-component systems.

5. Objectives and Goals . The objective of these projects is to

carry out those measurements necessary to obtain an understanding and description of the behavior of fluid systems in

the vicinity of phase transitions including one-component

fluids and fluid mixtures.

6. Background . An understanding of the behavior of fluids near

their critical points is of considerable importance in

describing their properties over the entire space of thermodynamic states. The critical point is used as a point of

symmetry for the reduction of thermodynamic data in corresponding states approaches. Such methods are of considerable

utility in engineering calculations and, especially, in

engineering predictions of properties of materials for which

no measured data exist. Critical behavior is exhibited in

such diverse systems as pure fluids, liquid mixtures,

f erromagne ts , f erroelectr ics , order-disorder transitions

in alloys, glasses, etc. Because these appear to be describable by the same formalism, an understanding obtained

of one will be transferable to the description of another.

Thus, the objective of this work is to obtain a quantitative

understanding and description of fluids and of fluid mixtures

near their critical points.

7. Program and Results . The anomalous thermodynamic behavior of

fluids near their critical points can be described in terms

of scaling laws. Two critical region equations of state that

46
satisfy the scaling laws have been studied. These are the

NBS equation and the Linear Model parametric equation. Each

of the equations was fitted to^expe jimental equation of state

data for six fluids, namely He , He , Xe , C0

2

, o and H 2 0. The

two equations represented the experimental data in the range

| T-T | /T < 0.03 and | p — p I /P c

< 0.25 equally well. The

optimum critical exponents appear to vary little from

substance to substance in agreement with expectations based

on universality of critical behavior. The principle of

universality was used to predict critical region parameters

for nine additional fluids, including several for which only

limited experimental information was available. These fluids

were Ar, Kr , N_, H. , CH . , C„H., SF. , NH and D_0. A single

2. 2. 4 2 4 b 5 2

"universal" equation was thus developed for the critical region

of all fifteen fluids considered.

A practical representation of the properties of liquid-vapor

equilibrium state has been obtained for the critical region

of CC>2 - ethane. The work is being extended to other systems

such as SFg - propane and propane -n-octane as well as to one

phase states near the critical line.

In the experimental work on one -component fluids, two complementary experimental techniques are used - one a Burnett

method modified to meet the special demands of critical

region studies, and the other a laser inter ferome trie approach.

The laser inter ferome try experiment gives highly detailed

and accurate results for the chemical potential versus density

relation in the near vicinity of the critical point, a most

natural relation on theoretical grounds.

The work on liquid mixtures thus far consists of measurements

of liquid densities to a precision of 1 ppm using a magnetic

densimeter. These density measurements allow investigation

of the critical exponents a and 6 and, to some extent, the

effect of gravity on their determination.

Studies are being made on the roles of nucleation, diffusion

and gravitational sedimentation upon the process of phase

separation in pure fluids and fluid mixtures. Other studies

are being conducted to define exploratory measurements of

critical point anomalies and phase separation phenomena in

the vicinity of critical points of pure fluids and fluid

mixtures in the low gravity environment of the proposed space

laboratory. Studies have also been made to discover and eliminate or compensate for systematic errors in the laser interferometry experiment.

4 7
Pressure-vs-temperature measurements for ethylene have been

made along four isochores above T

c

, one within 1% of the

critical density. On the other three isochores, measurements were made both in the one-phase region and along the

metastable extension of each isochore in the two-phase

region. We have analyzed our vapor pressure and critical

isochore data with the help of the thermodynamic scaling

laws and have derived values of the critical exponents

a (0.10) and y (1.19). We have been able to measure metastable

pressures that lie far enough within the two-phase region to

exceed the limit calculated for carbon dioxide, according

to existing theories of homogeneous nucleation.

Plans for the immediate future call for completion of work

on ethylene and completion of measurements on the thermal

expansion and co-existence curve of mixtures of isobutyric

acid and water which have been started recently, and measurements on hexane-per f luorohexane mixtures.

48
Title . PVT RELATIONS IN GASES

Principal Investigator . M. Waxman

Equation of State Section, Heat Division

National Bureau of Standards

Washington, D. C. 20234

Cost Center Number . 2210142

Sponsor . NBS

Introduction . If a fluid is to be used as a working fluid, as

in a power generating plant, or is a principal component in

a chemical process, a thorough knowledge of the PVT properties

of the fluid is necessary for the design of equipment and

processes of optimum efficiency. Such properties may also

be needed for custody-transfer calculations. Specific examples

of needs of these types involving ethylene and liquefied natural

gas are detailed elsewhere in this report.

Meeting such needs requires the development of equipment and

methods to make the necessary measurements, and to advance the

state of the art to keep pace with the increasing needs of the

industrial community. The experiments being carried out at

the present time involve the use of ethylene and hence serve

to provide support to the ethylene project, which is described

elsewhere, as well as to lead to further development of the

techniques involved.

Objectives or Goals . The objectives of this project are the

measurement of the PVT properties of industrially important

fluids with the precision allowed by the state of the art and

the maintenance and enhancement of the capability to make such

measurements as a long-term objective of the Heat Division.

Background . The PVT method used to determine the compressibility

factors and virial coefficients is a simplified method introduced by Burnett in 1936. In this method neither the quantity

of gas (n) nor the volume (v) is measured; instead, accurate

isothermal pressure measurements are made before and after

stepwise expansions between two volumes. This method leads

to a decrease in the overall measurement error and can, in

principle, lead to more accurate results than can be obtained

from a method requiring the measurement of n and v. The

results derived from this method are sensitive to the details

of the non-linear data reduction procedures used to analyze

the experimental data for which reason we have spent considerable time on problems of non-linear statistics.

Program and Results . Immediate objectives are: (a) to obtain

isothermal Burnett PVT measurements on gaseous ethylene for

the temperature range 0°C to 150°C and for pressures to 35 bar;

(b) to calculate the compressibility factors and second virial

coefficients for ethylene from Burnett measurements and to

evaluate these results.

49
Abstract (continued)

This report has been prepared to show interested readers

the interrelationships within a set of projects that might

otherwise pass unnoticed because different organizational

units within NBS are involved. Continued interaction

between the program managers involved leads to interactions

between the projects so that the listing is not a listing of

independent unreacting projects but rather a listing of

interacting projects following broad programmatic lines.

USCOMM-NBS-DC
NBS.l 14A (rev. 7-73)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIR 76-1002

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Industrial Process Data for Fluids: A Survey of

Current Research at the National Bureau of Standards

5. Publication Date

Apr i 1 19 76

6. Performing Organization (ode

7. AUTHOR(S)

Howard J. White, Jr., Editor

8. Performing Organ. Report No. NBSIR 76-1002

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No.

11. Contract /Grant No.

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

Same as No. 9

13. Type of Report Si Period

Covered

Summary Report

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary ol most significant information. If document includes a significant

bibliography or literature survey, mention it here.)

This report summarizes current activities sponsored by three groups

within the National Bureau of Standards that are involved with the

production of industrial process data for fluids . The three groups

involved are the Cryogenics Division, the Equation of State Section

of the Heat Division, and the Office of Standard Reference Data; other

organizations in NBS and outside are also involved in various ways.

The report takes the form of a listing of projects with some detailed

information about each. Some of the projects are designed to provide industrial process data directly. Others systematically

cover types of data that are of continual utility in industrial

process calculations with the result that the data produced will

be used for industrial purposes as well as for other purposes. A

few of the projects attack problem areas that must be resolved

before proper industrial process data in the area can be obtained.

All of the projects focus on quantitative numerical data obtained

for direct measurement, critical evaluation of data from the literature or theoretical estimation or calculation.

( continued)

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

Industrial process data; project summaries; quantitative numerical

data

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