NIST Standard Reference Database 4

NIST Thermophysical Properties of 

Hydrocarbon Mixtures Database 

(SUPERTRAPP)

Version 3.2 

Users' Guide 

Based on research sponsored by: 

The NIST Supercritical Fluid Property Consortium 

and Standard Reference Data 

M. L. Huber 

Physical and Chemical Properties Division 

Boulder, Colorado 

January 2007 

U.S. Department of Commerce

National Institute of Standards and Technology 

Standard Reference Data Program 

Gaithersburg, MD 20899 
The National Institute of Standards and Technology (NIST) uses its 

best efforts to deliver a high quality copy of the Database and to verify 

that the data contained therein have been selected on the basis of 

sound scientific judgment. However, NIST makes no warranties to 

that effect, and NIST shall not be liable for any damage that may result 

from errors or omissions in the Database. 

The mention of specific products, trademarks, or brand names in this guide is 

for the purpose of identification only. Such mention is not to be interpreted in 

any way as an endorsement or certification of such products by NIST. 

IBM-DOS, PC-DOS are registered trademarks of International Business 

 Machines, Inc. 

MS-DOS, Windows are registered trademarks of Microsoft Corporation. 

© 1990, 1998,1999, 2003, 2007 Copyright by the U.S. Secretary of Commerce on behalf 

of the United States of America. All rights reserved. No part of this database may be 

reproduced, stored in a retrieval system, or transmitted, in any form or by any means, 

electronic, mechanical, photocopying, recording, or otherwise, without the prior written 

permission of the distributor. 
ACKNOWLEDGMENTS

This work was sponsored in part by a consortium consisting of Air Products 

and Chemicals, Inc., BP America and Shell Development Co. Additional 

support was provided by NASA-Lewis Research Center and the NIST 

Standard Reference Data Program. We wish to recognize James F. Ely for this 

important contribution while at NIST, to the development of the original version 

of this database and its Users' Guide. 
CONTENTS

Chapter 1 INTRODUCTION ..................................................................3 

Chapter 2 GETTING STARTED............................................................4 

2.1 System requirements .................................................4 

2.2 Database files ............................................................4 

2.3 Installation..................................................................5 

Chapter 3 RUNNING SUPERTRAPP....................................................5 

Chapter 4 COMMAND OPTIONS..........................................................8 

TECHNICAL COMMANDS 

4.1 BUBP, Bubble point pressure calculation...................9 

4.2 DEWP, Dew point pressure calculation....................10 

4.3 BUBT, Bubble point temperature calculation ...........10 

4.4 DEWT, Dew point temperature calculation ..............10 

4.5 FEED, Change the composition...............................11 

4.6 FLTP, Isothermal flash (default)...............................11 

4.7 FLTD, Isochoric flash (T,D flash) .............................12 

4.8 FLTS, Isentropic flash (T,S Flash) ...........................12 

4.9 FLPH, Isenthalpic flash (P, H Flash)........................12 

4.10 FLPS, P,S flash........................................................12 

4.11 FLTH, T,H flash .......................................................12 

4.12 KIJ, Change the extended corresponding states 

(EXCST) interaction parameters ..............................12 

4.13 KIJV, Change the vapor-liquid equilibrium 

(VLE) interaction parameters ...................................13 

4.14 MASSIN, Toggle mass/mole input mode. ................13 

4.15 MODEL, Change equation of state model................13 

4.16 MODIFY, Change pure component 

property data............................................................14 

4.17 NORMAL, Toggle the composition mode.................16 

4.18 SATF, Pure component saturation properties ..........16 

4.19 SLATE, Change the components 

in the mixture ...........................................................16 

4.20 TABLE, Generate a table.........................................17 

4.21 UNITS, Change the current units .............................17 
CONTROL COMMANDS 

4.22 CLOSE, Close the output file ...................................18 

4.23 EDIT, Edit the feed composition...............................18 

4.24 OPEN, Open a new input or output file ....................18 

4.25 RESET, Restart SUPERTRAPP ..............................20 

4.26 STOP, Terminate the program.................................20 

SYSTEM COMMANDS 

4.27 DIR, Obtain the directory that is 

associated with a pathname.....................................20 

4.28 PRINT, Print file on printer .......................................21 

4.29 SYSTEM, Execute a system command ...................21 

4.30 TYPE, List a file on terminal.....................................21 

OTHER COMMANDS 

4.31 LIB, Create library file for use with 

SUPERTRAPP source code ....................................21 

Chapter 5 ADVANCED FEATURES....................................................21 

5.1 Entry of a new component .......................................21 

Chapter 6 REFERENCES ...................................................................24 

Appendix A NOMENCLATURE 

 I. List of Commands .............................................26 

 II. List of Abbreviations ..........................................27 

Appendix B SUPERTRAPP LIBRARY LIST...................................28 

Appendix C USE OF SOURCE CODE SUBROUTINES................34 

Appendix D CONTACTS................................................................36 
SUPERTRAPP 3

Chapter 1: INTRODUCTION

NIST SUPERTRAPP is a powerful, interactive computer database for the 

prediction of thermodynamic and transport properties of fluid mixtures. It may 

be used for pure fluids or for mixtures of up to 20 components. The 

components are selected from a database of 210 components, mostly 

hydrocarbons. It also can be used for petroleum fractions that are 

characterized by an average boiling point and an API gravity. NIST 

SUPERTRAPP performs phase equilibria calculations and gives the 

thermophysical properties of all phases and the feed. These results include 

both equilibrium properties (density, compressibility factor, enthalpy, entropy, 

Cp, Cp/Cv, sound speed, Joule-Thomson coefficient) and transport properties 

(viscosity and thermal conductivity). The database also has many help 

messages available, and although it is has an old-fashioned interface that runs 

on DOS, it is easy to use. 

NIST SUPERTRAPP features allow users to: 

─ perform bubble point pressure and temperature calculations; 

─ perform dew point pressure and temperature calculations; 

─ perform a variety of flashes: (T,P), (T,D), (T,S), (P,H), (T,H), 

and (P,S); 

─ obtain properties of pure components along the saturation 

 boundary; 

─ compute tables of properties; 

─ change units; 

─ learn (and remember) a new component not in the current database; 

─ enter data from the keyboard or from data files; and 

─ save results in a file. 

1.2 Uncertainties in Calculated Properties 

Our objective for SUPERTRAPP is to implement predictive models for 

nonpolar hydrocarbon systems that are thermodynamically consistent and valid 

over a wide range of state conditions, rather than to provide individual 

correlations for each property. The program does not contain experimental 

data; it contains only models. The user should be aware that the uncertainties 

in these models vary considerably depending on the fluid, property, and 

thermodynamic state. It is thus impossible to give a simple, global statement of 

uncertainties. Even for the most-studied fluids with equations of state based on 

accurate, wide-ranging data, uncertainties are complicated functions of the 

temperature and pressure. The interested user is referred to the original 

literature sources discussing the development of the model. (References to the 

literature are in Chapter 6.) 
 SUPERTRAPP 4

The user is further cautioned that, by the very nature of a calculational 

database, property data are often displayed with more digits than can be 

justified based on the accuracy of the property models or the uncertainties in 

the experimental data to which the models were fitted. 

Chapter 2: GETTING STARTED

2.1 System requirements

SUPERTRAPP runs in a DOS window under MS Windows 95, 98, 2000, NT, 

XP or ME. The package requires 430 kilobytes of available RAM and a hard 

disk drive with 1.5 megabytes of available space. 

A math coprocessor is required. A printer is required to run the PRINT 

command. 

2.2 Database files 

The database is supplied on CD-ROM, and contains the following files: 

1. STPHELP 

2. STPLIB2 

3. STRAPP.EXE 

4. LF90.EER 

5. EXMPL1.TXT 

6. EXMPL2.TXT 

7. README.TXT 

8. COPYRGHT.TXT 

9. DEFAULTS 

Also included are FORTRAN source code subroutines for computing 

properties, sample driver programs, sample output, and a User Manual 

(Supertrapp.pdf). 

1. STPV2A.FOR 

2. STPV2B.FOR 

3. SAMPLE1.FOR, SAMPLE1.OUT 

4. SAMPLE2.FOR, SAMPLE2.OUT 

5. SAMPLE3.FOR, SAMPLE3.OUT 

6. SAMPLE4.FOR, SAMPLE4.OUT 

7. SAMPLEP.FOR, SAMPLEP.OUT 
SUPERTRAPP 5

8. WRITLIB2.FOR 

9. PORTLIB 

10. LIBFILE 

11. README2.TXT 

12. Supertrapp.pdf 

If any files are missing, please contact the Standard Reference Data Program 

at (301) 975-2208. 

2.3 Installation

Put the CD-ROM in the CD-ROM drive (D, E, R— will vary depending on your 

particular computer). In Windows 3.1 or later or Windows NT, select File from 

the Program Manager’s Menu Bar followed by Run from the File menu. In 

Windows 95, click the Start button and select Run. In the Command line: box, 

type 

D:\SETUP (where “D” is the appropriate drive designation) 

and press ENTER. Follow the remainder of the Installation instructions. A NIST 

SUPERTRAPP 3.2 Program Group is created at the end of installation. 

NOTE: Because SUPERTRAPP allows changing the database file 

 (STPLIB2) permanently, keeping a backup copy of the original release 

 of STPLIB2 is strongly recommended. 

NOTE: In some Windows applications the MS-DOS window may remain 

 open after the program is terminated. To close the window, click the 

 Close button in the upper right corner of the window when the 

 statement “Program Terminated – Exiting NIST4” appears. 

Chapter 3: RUNNING SUPERTRAPP

After the installation process has been completed successfully, you can 

proceed. There are a few general comments about SUPERTRAPP to keep in 

mind. First of all, the program is case-insensitive so that either upper or lower 

case input is allowed. Also, there are many questions for which a YES or NO 

response is called for. The default answer is whichever appears first after the 

question-for example, (N,Y) indicates that NO is the default, while (Y,N) 

indicates that YES is the default. Pressing ENTER is equivalent to the default 

answer. Y or N is also acceptable. Typing a question mark (?) will generally 

cause a context-appropriate help message to appear. 

To start SUPERTRAPP, simply type from the DOS prompt or launch from 

Windows: STRAPP

After a few seconds the sign-on banner appears. To start program execution, 

press ENTER. 
 SUPERTRAPP 6

The database program proceeds by displaying a set of questions, which are 

answered by keyboard entry. The first is whether to use the defaults (for units, 

model, etc.). If the answer is No, the program asks whether the compositions 

are to be inputted as mole fractions. An ENTER, N, or No response means the 

compositions are inputted as moles, and the program computes the mole 

fractions. Should you choose to input in mole fraction mode, the program will 

check that the sum of the mole fractions is unity. The next question is whether 

to receive input from a previously prepared file. For more information about file 

input, see the command OPEN described in Chapter 4. 

The following questions concern output to a file. You may want to save the 

results in a file and/or see the results on the screen. To save results in a file, 

answer YES to this question. See command OPEN in Chapter 4 for more 

details. The next questions deal with units. SUPERTRAPP starts up with a 

default set of units (K, bar, liter, kJ, mol, m, s, μpoise, mW). To change any or 

all of these units, answer YES to this question. Details on changing units are 

covered in Chapter 4 under the UNITS command. 

The program asks for the number of components in the mixture. Enter the 

appropriate number of species from 1 to 20. A zero causes the program to 

stop. After the number of components is entered, the program asks for the 

names of the components. SUPERTRAPP has a built-in library of 210 

components, which are listed in Appendix B. To see the library list on screen, 

enter ? in response to a prompt for a component name. Be careful to type in 

the component name, or its synonym, exactly as it appears on the screen or in 

Appendix B, or the program does not recognize the name. (When this 

happens, you are given an opportunity to view the component name list and 

correct the spelling. For a petroleum fraction, enter any of the reserved names 

(petroleum #1, petroleum #2, petroleum #3 or their synonyms pet1, pet2 and 

pet3). You are then asked to enter an average boiling point and API gravity. 

The API gravity is given in degrees API, and is defined as °API=(141.5/sp60) - 

131.5, where sp60 is the specific gravity of the fluid with respect to water at 

60°F. If the component is still not in the database, you then have the option of 

adding it. If the program does not recognize the name of the component, it 

asks you a series of questions to allow you to enter the component as a new 

fluid. For details on this procedure, see Chapter 5.1. After the components 

have been input, you are asked to enter the composition (unless there is only 

one component). (Note: although water is present in the component list, 

calculations for pure water or for mixtures of more than 5 mole percent water 

are not permitted.) 

Finally, you reach at the main "command line," which is: 

Enter command or, if you wish to do a flash calculation, 

enter T(K) and P(bar) separated by a comma. 
SUPERTRAPP 7

At this point, you can either do a flash calculation by entering the temperature 

and pressure of interest, or enter any of the commands that SUPERTRAPP 

supports, including the option of changing any pure component property values 

stored in the library. For details on this step, see the command MODIFY in 

Chapter 4 (4.16). 
 SUPERTRAPP 8

Chapter 4: COMMAND OPTIONS

From the command line, any of the following commands can be entered: 

TECHNICAL COMMANDS

BUBP Bubble point pressure calculation 

BUBT Bubble point temperature calculation 

DEWT Dew point temperature calculation 

FEED Change the composition 

FLTP Isothermal flash (default command) 

FLTD T,D flash 

FLTS T,S (isentropic) flash 

FLPH P,H (isenthalpic) flash 

FLPS P,S flash 

FLTH T,H flash 

KIJ Change extended corresponding states (EXCST) interaction 

parameters 

KIJV Change the vapor-liquid equilibrium (VLE) interaction parameters 

MASSIN Toggle mass/mole input mode 

MODEL Change equation of state model 

MODIFY Change pure component property data 

NORMAL Toggle the composition mode 

SATF Pure component saturation properties 

SLATE Change the components in the mixture 

TABLE Generate a table 

UNITS Change the current units 

CONTROL COMMANDS

CLOSE Close the output file 

EDIT Edit the feed composition 

OPEN Open a new input or output file 

RESET Restart SUPERTRAPP 

STOP Terminate the program 

SYSTEM COMMANDS

DIR List the directory that is associated with a pathname 

PRINT Print file on printer 

SYSTEM Execute a DOS system command 

TYPE List a file on terminal 

OTHER COMMANDS

LIB Create portable library file 

For additional help, type the name of the command followed by a question 

mark, for example, UNITS?. Additional information on the available commands 
SUPERTRAPP 9

is given in the following sections. 

TECHNICAL COMMANDS

4.1 BUBP

A bubble point pressure calculation computes the vapor (bubble) composition 

and pressure using known values of the liquid composition (in equilibrium with 

the vapor) and the temperature. To perform the calculation, enter "BUBP" 

mode at the command line, and then enter the temperature at the point of 

interest. Enter a new command or an "X" to leave the BUBP mode. A sample 

BUBP screen is given below (Fig. 1). BUBP can be used for pure components 

or mixtures. Tables of bubble points can be generated using the TABLE 

command, (see section 4.20). 

 2-Phase Bubble Point results at T = 200.000 K and P = 0.116754 MPa 

-----Component------ ---Feed--- --Liquid-- --Vapor--- ---Phi---- --K-- 

 propane 0.500000 0.500000 0.927125E-01 0.870237E-01 .19E+00 

 ethane 0.500000 0.500000 0.907287 0.879587 .18E+01 

 Molar Basis 

 1.00000 1.00000 0.000000 Feed Fraction 

 37.0823 37.0823 31.3695 Molar Mass 

 0.451373E-02 0.451373E-02 0.965358 Comp. Factor, Z 

 0.576826 0.576826 0.228156E-02 D, kg/liter 

 -3159.78 -3159.78 -2917.66 H, kJ/kg 

 4.05164 4.05164 6.83080 S, kJ/kg.K 

 2.31336 2.31336 1.49442 Cp, kJ/kg.K 

 1.62313 1.26284 Cp/Cv 

 1308.11 249.601 Sound Speed, m/s 

 -0.441795 36.0524 JT, K/MPa 

 204.504 6.23615 Visc., uPa.s 

 153.487 11.9750 Th. Cond.,mW/m.K 

 (VLE=PRS,PROPS=EXCST) 

Figure 1. Sample bubble point pressure calculation. 

This sample BUBP result shows the type of information provided by the 

calculation. The mole fractions of the components in the phases are given, 

along with the "Kvalue", which is the ratio of the vapor phase composition of a 

component to the liquid phase composition of that component. The relative 

quantities of the phases present are also given in the line labeled “Feed 

Fraction.” For the example shown, because it is a bubble point calculation, only 

a minute bubble of vapor is present, and the vapor fraction is essentially zero. 

The molecular weights of the phases and feed are also given. Equilibrium 

properties (compressibility factor (defined as Z=PV/RT), density (D), enthalpy 

(H), entropy (S), Cp, Cp/Cv, sound speed and Joule-Thomson coefficient), as 

well as transport properties (viscosity, thermal conductivity) are calculated. The 

final entry shows which model was used in the calculations. The phase 
 SUPERTRAPP 10

equilibria (VLE) are always calculated using the PRS option, while the 

properties can be found using either the PRS or EXCST models. For more 

information on the models used, see the MODEL command, (see section 

4.15). 

4.2 DEWP

A dew point pressure calculation finds the liquid (dew) composition and 

pressure using known values of the vapor composition (in equilibrium with the 

liquid) and the temperature. To perform the calculation, enter "DEWP" mode at 

the command line, and then enter the temperature. To leave DEWP, enter any 

other valid command. An "X" returns program control to the main command 

line. DEWP can be used for pure components or mixtures. Tables of dew 

points can be generated using the TABLE command. The output from a DEWP 

calculation is very similar to that for a BUBP calculation. The mole fractions of 

the components in the phases are given, along with the "Kvalue". The relative 

quantities of the phases present are also given in the line labeled “Feed 

Fraction.” For a dew point calculation, only a minute drop of liquid is present. 

4.3 BUBT

A bubble point temperature calculation computes the vapor (bubble) 

composition and temperature using known values of the liquid composition and 

the pressure. To perform the calculation, enter "BUBT" mode at the command 

line, and then enter the pressure at the point of interest. Enter a new command 

or an "X" to leave the BUBT mode. BUBT can be used for pure components or 

mixtures. Tables of bubble points can be generated using the TABLE 

command. The type of information provided by the BUBT calculation is the 

same as for BUBP. The difference is that for BUBP, the temperature is a 

known input, while for BUBT the pressure is a known input. 

4.4 DEWT

A dew point temperature calculation computes the dew (liquid) composition 

and temperature using known values of the vapor composition and the 

pressure. To perform the calculation, enter "DEWT" mode at the command 

line, and then enter the pressure at the point of interest. Enter a new command 

or an "X" to leave the DEWT mode. DEWT can be used for pure components 

or mixtures. Tables of dew points can be generated using the TABLE 

command. The type of information provided by the DEWT calculation is the 

same as for DEWP. The difference is that for DEWP, the temperature is a 

known input, while for DEWT the pressure is a known input. 
SUPERTRAPP 11

4.5 FEED 

The FEED command enables changing the concentrations of the components 

in the mixture. If you enter FEED, the program prompts for the new 

concentration of each component. 

4.6 FLTP 

An isothermal flash calculation finds the quantities and compositions of the 

vapor and liquid phases in equilibrium at a given pressure, temperature and 

overall composition. The isothermal flash is the default command at the 

command line in SUPERTRAPP. Simply enter the temperature and pressure 

(separated by a comma) at the point of interest. If another command has been 

performed, to return to a flash calculation, type the command "FLTP". A 

sample FLTP screen is shown below (Fig. 2). The program is designed to 

operate within the range 10-1000 K and 0-3000 bar. Points outside this range 

are ignored. 

 2-Phase Flash results at T = 265.000 K and P = 1.00000 MPa 

-----Component------ ---Feed--- --Liquid-- --Vapor--- ---Phi---- --K-- 

 propane 0.500000 0.554896 0.242160 0.190756 .44E+00 

 ethane 0.500000 0.445104 0.757840 0.677790 .17E+01 

 Molar Basis 

 1.00000 0.824466 0.175534 Feed Fraction 

 37.0823 37.8523 33.4657 Molar Mass 

 0.176969 0.345867E-01 0.845725 Comp. Factor, Z 

 0.951033E-01 0.496718 0.179596E-01 D, kg/liter 

 -2940.09 -2974.52 -2757.17 H, kJ/kg 

 4.96122 4.68395 6.43422 S, kJ/kg.K 

 2.59044 2.70354 1.98959 Cp, kJ/kg.K 

 1.71037 1.33695 Cp/Cv 

 849.828 247.259 Sound Speed, m/s 

 -0.119548 19.7208 JT, K/MPa 

 104.723 8.13051 Visc., uPa.s 

 114.109 19.3834 Th. Cond.,mW/m.K 

 (VLE=PRS,PROPS=EXCST) 

Figure 2. Sample results from an isothermal flash calculation. 

The mole fractions of the components in the phases present are given, along 

with the "Kvalue", which is the ratio of the vapor phase molar composition of a 

component over the liquid phase molar composition of that component. The 

relative quantities of the phases present are also given in the line labeled 

“Feed Fraction”. For the example shown, if there is one mole of feed, the flash 

calculation predicts 0.824466 moles of liquid and 0.175534 moles of vapor. In 

addition, the molecular weights of the phases and feed are given. The sample 

result shows a case where two phases result from the flash calculation. (It also 

is possible to obtain only one phase from a flash calculation). SUPERTRAPP 

labels the phases present and gives properties of the phases, calculated with 

the currently active model (EXCST or PRS), as noted on the output. (To 

change the model, see the command MODEL). The phase equilibrium is 

always done with the PRS model. Equilibrium properties as well as transport 

properties are displayed in the output. 
 SUPERTRAPP 12

4.7 FLTD 

A T,D flash calculation determines the quantities and compositions of the 

vapor and liquid phases in equilibrium at a given temperature, density and 

overall composition. At the command line, enter FLTD to obtain a T,D flash. 

Next, enter the temperature and density (separated by a comma) at the point 

of interest. Output from FLTD looks very similar to FLTP. 

4.8 FLTS 

A T,S flash calculation determines the quantities and compositions of the vapor 

and liquid phases in equilibrium at a given temperature, entropy and overall 

composition. At the command line, enter FLTS to obtain a T,S flash. Next, 

enter the temperature and entropy (separated by a comma) at the point of 

interest. Output from FLTS looks very similar to FLTP. 

4.9 FLPH 

A P,H flash calculation determines the quantities and compositions of the 

vapor and liquid phases in equilibrium at a given pressure, enthalpy and overall 

composition. At the command line, enter FLPH to obtain a P,H flash. Next, 

enter the pressure and enthalpy (separated by a comma) at the point of 

interest. Output from FLPH looks very similar to FLTP. 

4.10 FLPS 

A P, S flash calculation determines the quantities and compositions of the 

vapor and liquid phases in equilibrium at a given pressure, entropy and overall 

composition. At the command line, enter FLPS to obtain a P,S flash. Next, 

enter the pressure and entropy (separated by a comma) at the point of interest. 

Output from FLPS looks very similar to FLTP. 

4.11 FLTH 

A T,H flash calculation determines the quantities and compositions of the 

vapor and liquid phases in equilibrium at a given temperature, enthalpy and 

overall composition. At the command line, enter FLTH to obtain a T,H flash. 

Next, enter the temperature and enthalpy (separated by a comma) at the point 

of interest. Output from FLTH looks very similar to FLTP. 

4.12 KIJ

The KIJ command allows changing or viewing the interaction parameters for 

the binary pairs in the mixture when using the EXCST model. The parameters 
SUPERTRAPP 13

can be used to fine-tune the model to a particular point or set of data. In 

general, the model predictions are sensitive to these parameters, so care 

should be taken when adjusting them. When you enter KIJ, you are shown the 

current values of kij and lij for each of the possible binary combinations of the 

mixture components and prompted for new values. The kij parameter is used 

in computing the "f", or energy-related shape factor, while the lij parameter is 

used in computing the "h" or size-related shape factor for the mixture. If you do 

not use this command, a default set of values is assumed. To view kij and lij, 

but not change them, press ENTER after invoking KIJ. When you change these 

parameters, the changes are NOT stored permanently in the database, so it is 

necessary to re-enter the changes each time a new SLATE command is 

invoked, or upon start-up. 

4.13 KIJV

KIJV allows changing or viewing the PRS interaction parameters without 

changing the EXCST parameters. The phase equilibrium tends to be very 

sensitive to the KIJV interaction parameters, so care should be used when 

adjusting them. Upon invoking the KIJV command, you are shown the current 

value and prompted for a new value for the binary interaction parameter for 

each possible binary pair in the mixture. The program starts up with default 

values of Peng-Robinson binary interaction parameters, which are found using 

a generalized procedure based on the general type or family that a species 

belongs to. To view the kijv but not change them, press ENTER after invoking 

KIJV. When you change these parameters, the changes are NOT stored 

permanently in the database, so it is necessary to re-enter the changes each 

time a new SLATE command is invoked, or upon start-up. 

4.14 MASSIN 

This command toggles between input on a mass or mole basis. 

4.15 MODEL

SUPERTRAPP calculates phase compositions with the Peng-Robinson 

equation of state (EOS) and offers a choice of the Peng-Robinson (PRS) or the 

NIST extended corresponding states model (EXCST) for the calculation of 

phase properties. The MODEL command allows changing the model used for 

bulk phase property calculation. Enter PRS for the Peng- Robinson EOS, or 

EXCST for the NIST extended corresponding states model. The default mode 

is to compute phase properties using the EXCST model, and vapor-liquid 

equilibria (VLE) with the Peng-Robinson model. The models used are identified 

in the output display. 
 SUPERTRAPP 14

4.16 MODIFY

This command allows changing pure component property data. It also can be 

used simply to view data for a given component. (Note: you have the option to 

change data values ─ permanently or just temporarily. We STRONGLY 

recommend that, before changing anything, you have a backup copy of the 

database file STPLIB2.) You are first shown the current values of pure 

component property values. Next, you are asked which component to modify, 

and which property to modify. The options for modification are: 

 Cp ideal gas heat capacity Sh shape factors (see 4.16.8) 

H0 enthalpy reference state Tb normal boiling point 

Hf heat of fusion Tc critical temperature 

LJ Lennard-Jones parameters Tt triple point temperature 

Mw molecular mass Vc critical volume 

Pc critical pressure w acentric factor 

S0 entropy reference state 

In addition, if you want to change units at this step, type “Units” or “Un.” You 

can alter more than one component by entering the name of each component. 

After finishing the modifications, press ENTER to exit the loop. You are asked if 

you want the modifications to be permanent. If the answer is YES, the 

modifications are written to the random access file that contains the database 

and essentially become permanent. If the answer is NO, the modifications are 

lost when you change the component slate. This allows performing calculations 

with your modifications until changing the component slate and then being able 

to return to the original settings. More detailed information on the MODIFY 

options is given in sections 4.16.1 - 4.16.9. 

4.16.1 Cp

SUPERTRAPP uses ideal gas heat capacities in the computation of enthalpy, 

entropy, thermal conductivity, Cp, Cp/Cv, w, and JT. There are built-in values 

that may be changed and overwritten by entering Cp data at this step. You will 

be asked to enter data (up to 20 points) as (T, ideal gas Cp) pairs. When 

entering values, bear in mind that it is best to input the ideal gas heat 

capacities over as wide a temperature range as possible. 

4.16.2 S0, H0

You can change the reference value for entropy or enthalpy. This is useful 

when trying to compare results with another program or tabular data. The usual 

value for reference state enthalpy is the heat of formation of the ideal gas at 

298.15 K. For entropy, the usual reference state value is the entropy of the 

ideal gas at 298.15 K and one atmosphere. However, a zero or any other value 
SUPERTRAPP 15

may be inputted since it is just a reference point value and has no effect on 

changes in enthalpy or entropy. The program interprets your entry as the value 

of the ideal gas at 298.15 K and one atmosphere. 

4.16.3 Tc, Pc, Vc

The critical properties of the component can be changed with these 

commands. 

4.16.4 Mw

The molecular mass can be changed using this option. 

4.16.5 Tb 

The normal boiling point (the temperature at which the species boils at a 

pressure of one atmosphere) can be changed with this command. 

4.16.6 Tt, Hf

These commands allow changing the triple point temperature or the heat of 

fusion of a component. This information is not essential to the operation of the 

program; it is used only in an ideal solid solubility calculation to check for the 

presence of solids. 

4.16.7 w

The Pitzer acentric factor may be changed with this option. This factor is 

defined in terms of the reduced vapor pressure of a pure species evaluated at 

a reduced temperature (Tr = T/Tc) of 0.7 and is given by 

w = -1.0 - log10(Pr

sat)Tr=0.7 

4.16.8 Sh

When SUPERTRAPP performs extended corresponding states calculations 

(the EXCST model), it uses quantities called shape factors. The current 

implementation uses vapor pressure and saturated liquid density information to 

generate the shape factors for equilibrium thermodynamic properties. It uses 

information on saturated liquid viscosities and thermal conductivities to develop 

a kind of mass shape factor used in transport calculations. To change these 

quantities, invoke the Sh option. You are asked if you have vapor pressure 

data, then saturated liquid density data, then saturated liquid viscosity and 

thermal conductivity data. You can enter data for any or all of these quantities 
 SUPERTRAPP 16

(with a maximum of 20 points). 

4.16.9 Lennard-Jones Parameters

During the estimation of low density transport properties, SUPERTRAPP can 

often improve the accuracy of the predictions by using Lennard-Jones potential 

parameters. Some components have built-in values for these parameters. 

Others have no values available and a default method is used in the 

computations. You can change the values of the Lennard-Jones collision 

diameter parameter (usually called "sigma") and the Lennard-Jones energy 

well depth parameter ("epsilon/k") by invoking the LJ option. 

4.17 NORMAL 

You have the option of always entering a feed composition whose mole 

fractions sum to unity or having the program normalize the input feed 

composition. NORMAL enables switching back and forth between the mole 

fraction input and the molar input modes. The prompt shows which mode is in 

use when entering a composition. 

4.18 SATF 

SATF allows the calculation of saturation thermodynamic properties for the 

pure components in the mixture. The saturated vapor and liquid densities, the 

saturation pressure, the heat of vaporization and the fugacity coefficient (f/P) 

are displayed (but not thermal conductivity or viscosity). (If this information is 

desired, run the DEWP, BUBP, DEWT, BUBT or TABLE options using a pure 

fluid to get saturation values). The model used for property calculation is also 

shown. To perform the calculation, enter "SATF" at the command line. 

Terminate SATF by pressing ENTER or entering "X". 

4.19 SLATE

The SLATE command enables changing the components in the mixture. You 

are asked for the number of components, and then the names of the 

components. If you enter a question mark (?) at the "name the component" 

prompt, the current component library can be listed. The component names 

and synonyms supplied in SUPERTRAPP are given in Appendix B. For a 

petroleum fraction, enter one of the reserved names for petroleum fractions 

(PETROLEUM #1, PETROLEUM #2 or PETROLEUM #3) or synonyms (PET1, 

PET2 or PET3). You are then asked to supply an average boiling point and 

API gravity. If the component name is not in the database, you may enter it as 

a new component. For details on the entry of a new component, see Chapter 

5. 
SUPERTRAPP 17

4.20 TABLE

The TABLE generates tables for selected combinations of independent and 

output variables. The choices of independent variables are: T, P, D, H, and S. 

Also available is a "SAT" option that provides results along the vapor-liquid 

saturation boundary and is valid for both pure fluids and mixtures. You are 

asked to input the minimum, maximum and increment values for the 

independent variables chosen for the table. Up to seven output variables can 

be selected. For a pure fluid, the choices are: T, P, D, Z, H, S, viscosity, 

thermal conductivity, sound speed, MW, Cp, Cv, and Joule-Thomson 

coefficient. For mixtures, there are additional choices available: equilibrium 

phase compositions, Kvalues (defined as yi

/xi where yi is the mole fraction of i 

in the vapor phase, and xi

 is the mole fraction of i in the liquid phase), and the 

feed fraction in each resulting phase. The feed fraction shows how the feed is 

"split" between the phases. 

4.21 UNITS

It is possible to select from various input/output unit combinations in 

SUPERTRAPP. This command brings up a menu-driven unit selection routine. 

The current units and the unit options are shown on the menu, as shown 

below. To change a specific unit, enter the new unit. For example, to change 

the pressure to megapascals enter "MPA". To select one of four "default" sets 

of units, enter a number between 1 and 4. To exit, enter an "X". For example, 

to enter several units on one line and exit, type, 

 MPA,CAL,X 

This selects pressures in MPa, energies in calories and exits the Units 

subroutines. To see the menu again, press ENTER. 
 SUPERTRAPP 18

CONTROL COMMANDS

4.22 CLOSE

The CLOSE command closes the current output file. Combinations of OPEN 

and CLOSE commands enable saving results in different files. (Only one 

output file may be open at a time.) 

4.23 EDIT

The EDIT option allows changing the feed composition of a single component 

selectively, leaving the others unchanged. This option is particularly useful for 

the case where you are entering mole fractions and have made a typing 

mistake that causes the overall composition not to sum to unity. To leave the 

edit loop, press ENTER or enter "X". A sample edit loop is shown below. Note 

that either the full component name or its synonym can be entered (See 

Appendix B for synonyms). 

4.24 OPEN

This command allows you to open a new file. You are asked whether an input 

or output file is desired. 

i. output files

Output files may be created to save the results of calculations to a file for 

later use. It is also possible to see the results of the calculations 

simultaneously on the terminal. Output continues to go to the output file 

until a CLOSE or RESET command is issued. The output file can be 

reviewed during the session by using the TYPE or PRINT commands. 

 

ii. input files

Input files can be used instead of keyboard data entry. For an input file, 

the program reads taking data from that file until an end-of-file or $END is 

encountered. Two sample data files are shown below 

(Fig. 3), and are included on the distribution diskettes. 
SUPERTRAPP 19

 example file 1 (EXMPL1.TXT) example file 2 (EXMPL2.TXT) 

COMP 1 N-BUTANE COMP01 C2 

COMP 2 METHANE COMP02 C10 

COMP 3 ETHANE FEED 1 0.5000 

FEED 1 0.5000 FEED 2 0.5000 

FEED 2 0.2000 PRS 

FEED 3 0.2000 KIJV 1 2 0.95 

FLTP 300 1.0 FLTP 300 1.0 

$END FLTP 350 2.5 

EXCST 

KIJ 1 2 0.95 

LIJ 1 2 0.95 

FLTP 300 1.0 

FLTP 350 2.5 

$END 

Figure 3. Sample data input file. 

The first entries in a data file must be COMP statements, which identify 

the components in the mixture. The names must be selected from the 

database, and the name or a synonym (C4 for n-butane) can be used. 

They must be input in the format COMP##bbbbNAME where ## is a 

number from 1 to 20, bbbb represents four blank spaces, and then the 

name. A complete list of the components and their synonyms is given in 

Appendix B. Note that either upper or lower case can be used. After the 

COMP statements, the FEED statement is used to input each component 

in mole or mole fractions (depending on what is chosen when the 

program was started, or when a NORMAL command is invoked). Default 

mode is to input feed as moles. The next line can be any of the 

commands: BUBP, DEWP, BUBT, DEWT, FLTP, FLTD, FLPH, FLTS 

along with the appropriate input variables. You can also change the 

calculation model (PRS or EXCST), or specify interaction parameters 

using KIJV, KIJ and/or LIJ. 

In the first example file, FLTP asks for a flash calculation at T=300 K and 

P=1.0 bar. The current default units as specified in the DEFAULTS file 

are used. (After entering the data filename, you are asked whether to 

change the units). In the second example, the model is changed from the 

default model (which is EXCST) to the Peng-Robinson (PRS). The model 

used in the calculations is identified in the output and remains the same 

until another PRS or EXCST is encountered, as shown in the example. 

For more information on the models, see the MODEL command. The 

second example file shows changing the interaction parameter for the 

1-2 pair (c2-c10 in this example) from the default value to 0.95. If the 

mixture contains more than two components, specify the pair for which 
 SUPERTRAPP 20

you want to change the interaction parameter. For example, to change 

the butane-ethane VLE interaction parameter in the first example to 0.97, 

include the line: 

 KIJV 1 3 0.97 

 in the data file. The EXCST interaction parameters may also be changed 

by using KIJ and LIJ commands as shown in the second example. For 

further details, see instructions for the KIJ and KIJV commands. The last 

entry in a data file must be a $END statement. At the end of data file 

operations, the program resumes interactive mode. 

iii. filenames

 The name of an input or output file can be any legitimate MS/PC DOS 

filename including device (or drive):filename.extension. Pathnames are 

not currently supported. examples: 

 A:DATA.INP 

INPUTD.FIL 

STPDAT.DAT 

NOTE: If problems are encountered with this command, it may be necessary to 

increase the FILES= statement in your CONFIG.SYS file. 

4.25 RESET

RESET starts SUPERTRAPP over from the beginning. (Only the changes 

explicitly committed to the database remain after RESET.) 

4.26 STOP

This command terminates the program and returns to the system prompt. 

SYSTEM COMMANDS

4.27 DIR

DIR lists the contents of any directory or subdirectory. After entering the DIR 

command, you are prompted for the path. Pressing ENTER in response to the 

prompt produces the contents of the current directory. NOTE: If you encounter 

problems with this command, you may have to increase your FILES= 

statement in the CONFIG.SYS file. 
SUPERTRAPP 21

4.28 PRINT

PRINT lists a file on the printer [PRN] device. Any ASCII file may be printed. If 

the current output file is to be printed, it is closed and then reopened to flush 

the buffer. If a file other than the output file is requested, the current output file 

(if any) remains unchanged. 

4.29 SYSTEM

SYSTEM executes an MS/DOS command from within SUPERTRAPP. After 

entering "SYSTEM", you are prompted for the system command. The total 

command length must be shorter than 77 characters. For example, if you enter 

the phrase >CURRENT.DIR DIR C:\DOS, the directory of C:\DOS is placed in 

the file CURRENT.DIR, which can then be manipulated by SUPERTRAPP or 

by invoking an editor with the system command. 

4.30 TYPE

TYPE lists a file on the screen. Any ASCII file may be typed. If you request the 

current output file to be typed, it is closed and then reopened to flush the 

buffer. If you request that a file other than the output file be typed, the current 

output file (if any) remains unchanged. 

OTHER COMMANDS

4.31 LIB

The LIB command is used to create a sequential ASCII library file called 

PORTLIB. This file contains component constants and parameters for all fluids 

in the library. It is used to install SUPERTRAPP on non-IBM compatible 

machines. For more information, see Appendix C, "Use of the Source Code 

Subroutines". Also see the sample driver routines (SAMPLE1.FOR, etc.) and 

the file README2, located on the distribution CD. 

Chapter 5: ADVANCED FEATURES

5.1 Entry of a new component

SUPERTRAPP has an extensive database with 210 components. Advanced 

users, however, may wish to add new components to the database. (We stress 

however, that the program is designed primarily for nonpolar hydrocarbons, 

and we do not recommend the addition of highly polar or associating 

substances.) The absolute minimum information required for a new component 

is the critical temperature, pressure and volume, the molecular weight, and the 
 SUPERTRAPP 22

normal boiling point. The program accepts other information to improve the 

accuracy of the predictions. Useful information includes the Pitzer acentric 

factor, ideal gas heat capacities, saturated liquid densities, vapor pressures, 

saturated liquid viscosity and thermal conductivity, the heat of fusion and the 

triple point temperature. In addition, a reference value for enthalpy and entropy 

must be specified. 

To enter a new component, first enter the SLATE command. When prompted 

for the name of the component, enter the new component name. If the 

program cannot match the name with those in the database, a listing of the 

components currently in the database is shown. Next, the program asks if the 

entry is misspelled and gives a chance to correct it. It next asks if you want to 

enter component parameters for the component. If the answer is YES, you are 

first prompted for a synonym for the component and then asked to identify the 

family that best describes the new component. This information is used in a 

generalized method to determine the Peng-Robinson binary interaction 

parameters. 

If the fluid is not a petroleum fraction, the next series of questions prompts for 

the molecular weight, the critical pressure, the critical volume and the critical 

temperature. You must input a value for these quantities. At any time, to 

change the units, type "UNITS" to enter the units selection menu. After the unit 

change, you are returned to the previous place in the program. If you change 

your mind and want to exit the new component entry mode, type an "X". 

 

The next question asks if you have a value for the Pitzer acentric factor. If you 

do, answer "YES" and then enter the value. Pressing ENTER is interpreted as a 

NO. If you do not provide a value, the program calculates one based on 

available vapor pressure information and the definition of the acentric factor. 

The next question asks for the normal boiling point of the substance. This is 

essential information, and a value must be input. 

If the fluid is a petroleum fraction, the program will ask for an average boiling 

point and API gravity. It will then estimate the properties Tc, Pc, Vc, w, Mw. 

Two more questions follow asking for reference values for enthalpy and 

entropy. The usual value for the reference state enthalpy is the heat of 

formation of the ideal gas at 298.15 K. For entropy, the usual reference state 

value is the entropy of the ideal gas entropy or enthalpy at 298.15 K and one 

atmosphere pressure in Pa. However, a zero or any other value may be input, 

because it is just a reference point value and has no effect on changes in 

enthalpy or entropy. The program interprets your entry as the value of the ideal 

gas at 298.15 K and one atmosphere. 

The next two questions ask if the triple point temperature and heat of fusion 
SUPERTRAPP 23

are known. This information is not essential to the operation of the program; it 

is used only in an ideal solid solubility calculation to check for the presence of 

solids. 

After these questions, you are then asked if you have ideal gas heat 

capacities. If so, the program asks how many there are. Up to twenty points 

may be input. The program has a built-in fitting routine, which fits the data to a 

function. To change the units before entering, type "UNITS". Otherwise, enter 

the ideal gas heat capacity data as (T, Cp) pairs. The program prints what you 

have entered and gives you a chance to edit the data before the fit is 

performed. The ideal gas heat capacities are used in the computation of 

thermal properties such as enthalpy and entropy as well as thermal 

conductivity. If you have no values, default values are assumed. If you have 

values, bear in mind that it is best to input the ideal gas heat capacities over as 

wide a temperature range as possible. For example, if you are interested in 

computations at 600 K, be sure to input ideal gas heat capacities valid up to 

600 K; otherwise the results for enthalpy, entropy and thermal conductivity may 

be in error. 

The last four quantities requested, vapor pressures, saturated liquid densities, 

saturated liquid viscosities and thermal conductivities, are used in the 

computation of "shape factors". The vapor pressure and saturated liquid 

density are used in calculating shape factors for the equilibrium thermodynamic 

properties. The transport data are used in calculating a mass shape factor 

used in transport predictions. SUPERTRAPP takes the user-supplied data and 

fits them to various correlations. You can input up to twenty points for each 

property. After the data are input, there is an option for editing data before the 

fitting procedure begins. It is best to supply data over as wide a temperature 

range as possible. The units can be changed before data entry begins by 

typing "UNITS". The program does not keep each datum in the database, only 

the results of the fitting process so that if, in the future, more or better data 

become available, this step must be repeated using the MODIFY command 

with the option Sh for SHape factors. If no data are available, a generalized 

procedure is used by default. 

Note: It is easy to add a component, and to change parameters for a 

component, but once saved permanently in the database, it is not possible to 

remove a component. 
 SUPERTRAPP 24

Chapter 6: REFERENCES

This manual is meant to be a users’ guide, and not a detailed description of the 

various methods used in the program. The following publications are useful 

references on the various technical procedures used in the NIST 

SUPERTRAPP program. 

1. Transport Property Prediction

Ely, J.F., An Enskog Correction for Size and Mass Difference Effects in Mixture 

Viscosity Prediction, J. Research NBS, 86, No. 6, 597-603 (1981). 

Ely, J.F. and Hanley, H.J.M., Prediction of Transport Properties. 1. Viscosity of 

Fluids and Mixtures, I&EC Fund., 20, No. 4, 323-332 (1981). 

Ely, J.F. and Hanley, H.J.M., Prediction of Transport Properties. 2. Thermal 

Conductivity of Pure Fluids and Mixtures, I&EC Fund., 22, No. 1, 90-97 (1983). 

Baltatu, M.E., Chong, R.A., Huber, M.L. and Laesecke. A. Transport Properties 

of Petroleum Fractions. Int. J. Thermophys., 20, No. 1, 85-95 (1999). 

2. Corresponding States Method

Cullick, A.S, and Ely, J.F., Densities of Vinyl Chloride from 5 to 65°C and 

Saturation Pressure, J. Chem. Eng. Data 27, 276-281 (1982). 

Fisher, G. D. and Leland, T. W. The corresponding states principle using 

shape factors, I&EC Fund., 9, 537-544 (1970). 

Huber, M.L. and Hanley, H.J.M., The corresponding-states principle: dense 

fluids, Ch 12 in Transport Properties of Fluids, Ed. J. Millat, J.H. Dymond and 

C.A. Nieto de Castro, Cambridge University Press, (1996). 

Leach, J. W., Chappelear, P. S. and Leland, T. W., Use of molecular shape 

factors in vapor-liquid equilibrium calculations with the corresponding states 

principle, AIChE J., 14, 568-576 (1968). 

Leland, T. W., Chappelear, P. S. and Gamson, B. W., Prediction of 

vapor-liquid equilibria from the corresponding states principle, AIChE J., 8, 

482-489 (1962). 

Leland, T. W. and Chappelear, P. S., The corresponding states principle, A 

review of current theory and practice, I&EC Fund., 60, 15-43 (1968). 
SUPERTRAPP 25

3. Binary Interaction Parameters

Nishiumi, H. and Arai, T., Generalization of the Binary Interaction Parameter of 

the Peng-Robinson Equation of State by Component Family, Fluid Phase 

Equilibria, 42, 43-62 (1988). 

Valderrama, J.O. and Molina, E., Interaction Parameter for Hydrogen 

Containing Mixtures in the Peng-Robinson Equation of State, Fluid Phase 

Equilibria, 31, 209-219 (1986). 

4. Peng-Robinson Equation of State

Peng, D.Y. and Robinson, D.B., A New Two-Constant Equation of State, I&EC 

Fund., 15, 59-64 (1976). 
 SUPERTRAPP 26

Appendix A

NOMENCLATURE

 I. List of Commands

BUBP Bubble point pressure calculation 

BUBT Bubble point temperature calculation 

CLOSE Close the output file 

DEWP Dew point pressure calculation 

DEWT Dew point temperature calculation 

DIR Obtain the directory that is associated with a pathname 

EDIT Edit the feed composition 

FEED Change the composition 

FLTP Isothermal flash (default command) 

FLTD T,D flash 

FLTS T,S (isentropic) flash 

FLPH P,H (isenthalpic) flash 

FLPS P,S flash 

FLTH T,H flash 

KIJ Change EXCST interaction parameters 

KIJV Change the VLE interaction parameters 

LIB Create portable library file 

MASSIN Toggle mass/mole input mode 

MODEL Change equation of state model 

MODIFY Change pure component data 

NORMAL Toggle the composition mode 

OPEN Open a new input or output file 

PRINT Print file on printer 

RESET Restart SUPERTRAPP 

SATF Compute pure component saturation properties 

SLATE Change the components in the mixture 

STOP Terminate the program 

SYSTEM Execute a system command 

TABLE Generate a table 

TYPE List a file on terminal 

UNITS Change the current units 
SUPERTRAPP 27

II. List of Abbreviations and Terms

°API defined by °API =141.5/sp60 -131.5 

 Comp. Factor compressibility factor, PV/RT 

Cp specific heat capacity at constant pressure 

Cp/Cv ratio of heat capacity at constant pressure to heat 

capacity at constant volume 

D density 

Dc critical density 

Dsat,L saturated liquid density 

Dsat,V saturated vapor density 

EXCST NIST extended corresponding states model 

f/P fugacity coefficient divided by pressure 

H enthalpy 

H0 enthalpy reference state 

Hf heat of fusion 

Hvap heat of vaporization 

JT Joule-Thomson coefficient 

Kvalue ratio of vapor phase composition of a component 

to the liquid phase composition of that component 

LJ Lennard-Jones potential function 

Mw molecular mass 

P pressure 

Pc critical pressure 

Phi fugacity coefficient of component divided by partial 

 pressure 

PRS Peng-Robinson equation of state model 

Psat saturation pressure 

S entropy 

S0 entropy reference state 

Sh shape factors 

 Sp60 specific gravity=density of material at 60°F/density of 

 liquid water at 60°F 

T temperature 

Tb normal boiling point temperature 

Therm. Cond. thermal conductivity 

Tc critical temperature 

Tt triple point temperature 

μP micropoise (displayed on screen as uP) 

V volume 

Vc critical volume 

Visc. viscosity 

VLE vapor-liquid equilibrium 

w Pitzer's acentric factor 

Z compressibility factor, PV/RT 
 SUPERTRAPP 28

Appendix B 

 SUPERTRAPP LIBRARY LIST

NAME SYNONYM FORMULA 

METHANE C1 CH4 

ETHANE C2 C2H6 

PROPANE C3 C3H8 

ISOBUTANE IC4 C4H10 

N-BUTANE C4 C4H10 

NEOPENTANE 22DMC3 C5H12 

ISOPENTANE IC5 C5H12 

N-PENTANE C5 C5H12 

2,2-DIMETHYLBUTANE 22DMB C6H14 

2,3-DIMETHYLBUTANE 23DMB C6H14 

3-METHYLPENTANE 3MP C6H14 

2-METHYLPENTANE IC6 C6H14 

N-HEXANE C6 C6H14 

2,2,3-TRIMETHYLBUTANE 223TMB C7H16 

3,3-DIMETHYLPENTANE 33DMP C7H16 

2,4-DIMETHYLPENTANE 24DMP C7H16 

2,3-DIMETHYLPENTANE 23DMP C7H16 

2,2-DIMETHYLPENTANE 22DMP C7H16 

3-ETHYLPENTANE 3EP C7H16 

3-METHYLHEXANE 3MHEX C7H16 

2-METHYLHEXANE 2MH C7H16 

N-HEPTANE C7 C7H16 

2,2,3,3-TETRAMETHYLBUTANE 2233TMB C8H18 

2,3,4-TRIMETHYLPENTANE 234TMP C8H18 

2,3,3-TRIMETHYLPENTANE 233TMP C8H18 

2,2,4-TRIMETHYLPENTANE 224TMP C8H18 

2,2,3-TRIMETHYLPENTANE 223TMP C8H18 

3-METHYL-3-ETHYLPENTANE 3M3EP C8H18 

2-METHYL-3-ETHYLPENTANE 2M3EP C8H18 

3,4-DIMETHYLHEXANE 34DMH C8H18 

3,3-DIMETHYLHEXANE 33DMH C8H18 

2,5-DIMETHYLHEXANE 25DMH C8H18 

2,4-DIMETHYLHEXANE 24DMH C8H18 

2,3-DIMETHYLHEXANE 23DMH C8H18 

2,2-DIMETHYLHEXANE 22DMH C8H18 

3-ETHYLHEXANE 3EH C8H18 
SUPERTRAPP 29

NAME SYNONYM FORMULA 

4-METHYLHEPTANE 4MC7 C8H18 

3-METHYLHEPTANE 3MC7 C8H18 

2-METHYLHEPTANE 2MC7 C8H18 

N-OCTANE C8 C8H18 

2,3,3,4-TETRAMETHYLPENTANE 2334TMP C9H20 

2,2,4,4-TETRAMETHYLPENTANE 2244TMP C9H20 

2,2,3,4-TETRAMETHYLPENTANE 2234TMP C9H20 

2,2,3,3-TETRAMETHYLPENTANE 2233TMP C9H20 

2,2,5-TRIMETHYLHEXANE 225TMH C9H20 

2,2-DIMETHYLHEPTANE 22DMC7 C9H20 

2-METHYLOCTANE 2MC8 C9H20 

N-NONANE C9 C9H20 

2,2,5,5-TETRAMETHYLHEXANE 2255TMH C10H22 

2,2,3,3-TETRAMETHYLHEXANE 2233TMH C10H22 

3,3,5-TRIMETHYLHEPTANE 335TMC7 C10H22 

N-DECANE C10 C10H22 

N-UNDECANE C11 C11H24 

N-DODECANE C12 C12H26 

N-TRIDECANE C13 C13H28 

N-TETRADECANE C14 C14H30 

N-PENTADECANE C15 C15H32 

N-HEXADECANE C16 C16H34 

N-HEPTADECANE C17 C17H36 

N-OCTADECANE C18 C18H38 

N-NONADECANE C19 C19H40 

N-EICOSANE C20 C20H42 

N-HENEICOSANE C21 C21H44 

N-DOCOSANE C22 C22H46 

N-TRICOSANE C23 C23H48 

N-TETRACOSANE C24 C24H50 

N-TRIACONTANE C30 C30H62 

N-HEXATRIACONTANE C36 C36H74 

N-DOTETRACONTANE C42 C42H86 

N-OCTATETRACONTANE C48 C48H98 

ETHYLENE ETHENE C2H4 

PROPYLENE PROPENE C3H6 

2-METHYLPROPENE IC3- C4H8 

CIS-2-BUTENE C-2C4- C4H8 

TRANS-2-BUTENE T-2C4- C4H8 

1-BUTENE C4- C4H8 

2-METHYL-2-BUTENE 2M2C4- C5H10 

2-METHYL-1-BUTENE 2M1C4- C5H10 
 SUPERTRAPP 30

NAME SYNONYM FORMULA 

3-METHYL-1-BUTENE 3M1C4- C5H10 

CIS-2-PENTENE C2C5- C5H10 

TRANS-2-PENTENE T2C5- C5H10 

1-PENTENE C5- C5H10 

1-HEXENE C6- C6H12 

1-HEPTENE C7- C7H14 

1-OCTENE C8- C8H16 

1-NONENE C9- C9H18 

1-DECENE C10- C10H20 

PROPADIENE 12C3= C3H4 

1,3-BUTADIENE 13C4= C4H6 

1,2-BUTADIENE 12C4= C4H6 

CYCLOPROPANE CC3 C3H6 

CYCLOPENTANE CC5 C5H10 

METHYLCYCLOPENTANE MCC5 C6H12 

ETHYLCYCLOPENTANE ECC5 C7H14 

CYCLOHEXANE CC6 C6H12 

METHYLCYCLOHEXANE MCC6 C7H14 

ETHYLCYCLOHEXANE ECC6 C8H16 

BENZENE BNZ C6H6 

TOLUENE TOL C7H8 

ETHYLBENZENE EB C8H10 

ORTHO-XYLENE OXYL C8H10 

META-XYLENE MXYL C8H10 

PARA-XYLENE PXYL C8H10 

PROPYLBENZENE C3BNZ C9H12 

ISOPROPYLBENZENE CUMENE C9H12 

BUTYLBENZENE C4BNZ C10H14 

ISOBUTYLBENZENE IC4BNZ C10H14 

T-BUTYLBENZENE TBBNZ C10H14 

NAPHTHALENE NAPH C10H8 

1-METHYLNAPHTHALENE 1MNAPH C11H10 

2-METHYLNAPHTHALENE 2MNAPH C11H10 

BIPHENYL BIPHEN C12H10 

HYDROGEN H2 H2 

NITROGEN N2 N2 

OXYGEN O2 O2 

WATER H2O H2O 

CARBON MONOXIDE CO CO 

CARBON DIOXIDE CO2 CO2 

SULPHUR DIOXIDE SO2 SO2 

HYDROGEN SULFIDE H2S H2S 
SUPERTRAPP 31

NAME SYNONYM FORMULA 

1,1-DIMETHYLCYCLOPENTANE 11DIMECYP C7H14 

TRANS-1,3-DIMETHYLCYCLOPENTANE TRANS13DIM C7H14 

TRANS-1,2-DIMETHYLCYCLOPENTANE TRANS12DIM C7H14 

1-TRANS,3-DIMETHYLCYCLOHEXANE 1TR3DMCH C8H16 

TRANS-1,2-CIS-4-

TRIMETHYLCYCLOPENTANE 

TR12C4TMCP C8H16 

TRANS-1,2-CIS,3-

TRIMETHYLCYCLOPENTANE 

TR12C3TMCP C8H16 

1-CIS,2-TRANS,4-

TRIMETHYLCYCLOPENTANE 

1C2T4TMCP C8H16 

1-TRANS,4- DIMETHYLCYCLOHEXANE 1TR4DMCH C8H16 

1,1-DIMETHYLCYCLOHEXANE 11DMCH C8H16 

1-CIS,3-DIMETHYLCYCLOHEXANE 1C3DMCH C8H16 

1-METHYL,TRANS-3-

ETHYLCYCLOPENTANE 

1MTR3ECP C8H16 

1-METHYL,TRANS-2-

ETHYLCYCLOPENTANE 

1MTR2ECP C8H16 

1-METHYL,CIS,3-ETHYLCYCLOPENTANE 1MC3ECP C8H16 

1-METHYL-1-ETHYLCYCLOPENTANE 1M1ECP C8H16 

1-CIS-2,CIS-3-

TRIMETHYLCYCLOPENTANE 

1C2C3TMCP C8H16 

ISOPROPYLCYCLOPENTANE IPCP C8H16 

CIS-1,2-DIMETHYLCYCLOHEXANE C12DMCH C8H16 

N-PROPYLCYCLOPENTANE PRCYPN C8H16 

1,1,3-TRIMETHYLCYCLOPENTANE 113TMCP C8H16 

P-ETHYLTOLUENE PARA ETOL C9H12 

1,3,5-TRIMETHYLBENZENE MESITYLENE C9H12 

O-ETHYLTOLUENE ORTHOETOL C9H12 

1,2,4-TRIMETHYLBENZENE 124TMBNZ C9H12 

1,1,4-TRIMETHYLCYCLOHEXANE 114TMCH C9H18 

1-CIS,3-CIS-5-TRIMETHYLCYCLOHEXANE 1C3C5TMCH C9H18 

1-CIS,2-TRANS,4-

TRIMETHYLCYCLOHEXANE 

1C2T4TMCH C9H18 

1,1,2-TRIMETHYLCYCLOHEXANE 112TMCH C9H18 

1-CIS,2-CIS,4-TRIMETHYLCYCLOHEXANE 1C2C4TMCH C9H18 

ISOBUTYLCYCLOPENTANE IBCP C9H18 

2,3,5-TRIMETHYLHEXANE 235TMH C9H20 

4-METHYLOCTANE 4MO C9H20 

2,4-DIMETHYLHEPTANE 24DMC7 C9H20 

2,5-DIMETHYLHEPTANE 25DMC7 C9H20 

3,5-DIMETHYLHEPTANE 35DMC7 C9H20 

3,3-DIMETHYLHEPTANE 33DMC7 C9H20 
 SUPERTRAPP 32

NAME SYNONYM FORMULA 

2,3-DIMETHYLHEPTANE 23DMC7 C9H20 

3,4-DIMETHYLHEPTANE 34DMC7 C9H20 

1-METHYL-3-ISOPROPYLBENZENE 1M3IPBNZ C10H14 

1-METHYL-2-ISOPROPYLBENZENE 1M2IPBNZ C10H14 

1-METHYL-3-PROPYLBENZENE 1M3PBNZ C10H14 

1-METHYL-4-PROPYLBENZENE 1M4PBNZ C10H14 

1,2-DIETHYLBENZENE 12DEBNZ C10H14 

1,4-DIETHYLBENZENE 14DEBNZ C10H14 

1-METHYL-2-PROPYLBENZENE 1M2PBNZ C10H14 

1,4-DIMETHYL-2-ETHYLBENZENE 14DM2EBNZ C10H14 

1,2-DIMETHYL-4-ETHYLBENZENE 12DM4EBNZ C10H14 

SEC-BUTYLBENZENE SBBNZ C10H14 

1,3-DIMETHYL-2-ETHYLBENZENE 13DM2EBNZ C10H14 

1,2-DIMETHYL-3-ETHYLBENZENE 12DM3EBNZ C10H14 

1,2,4,5-TETRAMETHYLBENZENE 1245TMBNZ C10H14 

ISOBUTYLCYCLOHEXANE IBCHEX C10H20 

N-BUTYLCYCLOHEXANE NBCHEX C10H20 

2,2-DIMETHYLOCTANE 22DMO C10H22 

3,6-DIMETHYLOCTANE 36DMO C10H22 

3,3-DIMETHYLOCTANE 33DMO C10H22 

2,3-DIMETHYLOCTANE 23DMO C10H22 

2-METHYLNONANE 2MN C10H22 

3-METHYLNONANE 3MN C10H22 

2-METHYLBUTYLBENZENE 2MBBNZ C11H16 

1-TERT-BUTYL-2-METHYLBENZENE 1TB2MBNZ C11H16 

N-PENTYLBENZENE NPBNZ C11H16 

1-TERT-BUTYL-3,5-DIMETHYLBENZENE 1TB35DMBNZ C12H18 

1,3,5-TRIETHYLBENZENE 135TEBNZ C12H18 

1,2,4-TRIETHYLBENZENE 124TEBNZ C12H18 

N-HEXYLBENZENE NHBNZ C12H18 

1-METHYL,TRANS-2-(4-

METHYLPENTYL)CYCLOPENTANE 

1MTR24MPCP C12H24 

3-METHYLOCTANE 3MO C9H20 

ARGON AR Ar 

M-ETHYLTOLUENE METHTOL C9H12 

CIS-1,3-DIMETHYLCYCLOPENTANE C13DMCP C7H14 

CYCLOPENTADIENE CYCLOPD C5H6 

CIS-DECALIN C-DECL C10H18 

TRANS-DECALIN T-DECL C10H18 

ACETYLENE ETHYNE C2H2 

SILANE SIH4 H4Si 

CIS-1,4-DIMETHYLCYCLOHEXANE CIS14DMH C8H16 
SUPERTRAPP 33

NAME SYNONYM FORMULA 

CARBONYL SULFIDE CS COS 

SULFURHEXAFLUORIDE SF6 SF6 

2,6-DIMETHYLNAPHTHALENE 26MNAPH C12H12 

BICYCLOHEXYL BICC6 C12H22 

PENTAMETHYLBENZENE 5CBNZ C11H16 

HEXAMETHYLBENZENE 6CBNZ C12H18 

CYCLOOCTANE CC8 C8H16 

1,2,3,4-TETRAHYDRONAPHTHALENE TETRALIN C10H12 

2,2,4,4,6,8,8-HEPTAMETHYLNONANE ISOCETANE C16H34 

EXOTETRAHYDRODICYCLOPENTADIENE JP10 C10H16 

METHYL OLEATE #112-62-9 

 

C19H36O2 

** Water is included so that you may calculate properties of a hydrocarbon mixture with water as an 

impurity of no more than 5 mole percent. The program is not designed to do pure water calculations, 

nor is it intended to do aqueous solutions.
SUPERTRAPP 34

Appendix C

USE OF SOURCE CODE SUBROUTINES

The NIST Thermophysical Properties of Hydrocarbon Mixtures Database 

(SUPERTRAPP) is an interactive database for the prediction of the 

thermodynamic properties of hydrocarbon mixtures. For users who want to link 

the properties subroutines with their own codes, we also provide the source 

code for the properties routines along with some sample drivers. 

FORTRAN SOURCE CODE 

All source code is written in ANSI Standard FORTRAN 77. The following files 

are included: 

STPV2A.FOR Supertrapp source code subroutines 

STPV2B.FOR Supertrapp source code subroutines 

SAMPLE1.FOR Driver to illustrate sample (T,P), (T,S) and (P,H) flashes. 

SAMPLE2.FOR Driver to illustrate sample density and transport 

 properties calculation. 

SAMPLE3.FOR Driver to illustrate pure component saturation properties. 

SAMPLE4.FOR Driver to illustrate changing the interaction parameters. 

SAMPLEP.FOR Driver to illustrate calculations with a user-defined 

 petroleum fraction, not present in the database. 

WRITLIB2.FOR Reads PORTLIB to create LIBFILE database 

PORTLIB ASCII file to generate LIBFILE, given on distribution 

 diskette, or can be generated by using the “LIB” 

 command described in Section 4.31. 

LIBFILE Direct access FORTRAN file containing pure component 

 parameters. Must be present for source code routines 

 to work. This file must be created by the User’s 

 FORTRAN compiler by running WRITLIB2. 

README2.TXT Provides a description of Supertrapp source 

 code subroutines and their argument lists. 

We also include the output files obtained from running the sample drivers, 

SAMPLE1.OUT, SAMPLE2.OUT, SAMPLE3.OUT, SAMPLE4.OUT and 

SAMPLEP.OUT. 
SUPERTRAPP 35

MODIFICATION OF THE COMPONENT LIBRARY 

FOR USERS OF THE SOURCE CODE

This section is intended for users who wish to add a new component or change 

existing component parameters. The PC version of the database is required to 

modify the component library. 

The parameters for an existing component in the database can be modified or 

a new component added using the full PC version of NIST SUPERTRAPP and 

the MODIFY command, discussed in 4.16. After the desired changes have 

been made, invoke the "LIB" command. This creates a file called "PORTLIB" 

containing all the necessary constants and parameters for the fluids in the 

database. 

On your computer, load the "PORTLIB" file. Then compile and run the 

"WRITLIB2.FOR" program, which reads "PORTLIB" and creates "LIBFILE", the 

input library for running the SUPERTRAPP source code on your own platform. 

The library file STPLIB2 works only with the SUPERTRAPP executable code 

on the distribution disk. You must create LIBFILE with your own compiler, 

using the WRITLIB2.FOR code in order to be able to use the source code. 
SUPERTRAPP 36

Appendix D 

 CONTACTS

If you have comments or questions about the database, the Standard 

Reference Data Program would like to hear from you. Also, if you should have 

any problems with the CD or installation, please let us know by contacting: 

Joan Sauerwein 

National Institute of Standards and Technology 

Standard Reference Data 

100 Bureau Drive, stop 2320 

Gaithersburg, Maryland 20899-2320 

Internet: www.nist.gov/srd 

Phone: (301) 975-2008 

FAX: (301) 926-0416 

The technical contact for the database is: 

 Marcia Huber 

 Physical and Chemical Properties Division 

 National Institute of Standards and Technology 

 Boulder, CO 80305 

 (303) 497-5252 

marcia.huber@nist.gov