The NASA thermo data file format was documented in:
Sanford Gordon and Bonnie J. McBride, "Computer Program for Calculation of
Complex Chemical Equilibrium Compositions and Applications: I. Analysis",
NASA Reference Publication 1311, October 1994.
Bonnie J. McBride and Sanford Gordon, "Computer Program for Calculation of
Complex Chemical Equilibrium Compositions and Applications: II. Users Manual
and Program Description", NASA Reference Publication 1311, June 1996.
The equations below for nondimensional specific heat, enthalpy, and
entropy, are given in Sanford and Bonnie (1994). Eqs. 4.6-4.8 are the
"old" NASA format, and Eqs. 4.9-4.11 are the "new" NASA format as discussed
in this file.
Eq. 4.6: Cp0/R = a1 + a2*T + a3*T^2 + a4*T^3 + a5*T^4
Eq. 4.7: H0/RT = a1 + a2/2*T + a3/3*T^2 + a4/4*T^3 + a5/5*T^4 + a6/T
Eq. 4.8: S0/R = a1*ln(T) + a2*T + a3/2*T^2 + a4/3*T^3 + a5/4*T^4 + a7
Eq. 4.9: Cp0/R = a1*T^-2 + a2*T^-1 + a3 + a4*T + a5*T^2 + a6*T^3 + a7*T^4
Eq. 4.10: H0/RT = -a1*T^-2 + a2*T^-1*ln(T) + a3 + a4*T/2 + a5*T^2/3 +
a6*T^3/4 + a7*T^4/5 + b1/T
Eq. 4.11: S0/R = -a1*T^-2/2 - a2*T^-1 + a3*ln(T) + a4*T + a5*T^2/2 +
a6*T^3/6 + a7*T^4/4 + b2
The following information is quoted directly from McBride and Gordon (1996):
"Appendix A: Format for Thermodynamic Data
The library of thermodynamic data contains data for both reaction products
and reactants. All reaction products and some reactants are in the
nine-constant functional form discussed in section 4.2 of Gordon and
McBride (1994). The format for these data is given here. Thermodynamic
data are provided with the program on a separate file, thermo.inp.
Sections 2.8 and 5.24 discuss the processing of the thermo.inp data and
the storing of the processed data in thermo.lib for subsequent use in the
CEA program. Names of species contained in thermo.inp are listed in
Appendix B.
The general format is given in table A1. This format is applicable for
all gaseous species and for those condensed species whose data extend over
a temperature range. For those condensed species with data given at only
one temperature, the format is somewhat different. On record 2, instead
of the last number being a heat of formation, it is an assigned enthalpy.
(Note that if the temperature is 298.15 K, the heat of formation and the
assigned enthalpy are equivalent.) The first number in record 2 (number
of temperature intervals) is always zero. On record 3, only one number is
given, the temperature of the assigned enthalpy on record 2. Two examples are
given. Example A1, for chlorine gas, illustrates the general format.
Example A2, for liquid acetylene, illustrates the format for a condensed
species with data given at only one temperature. The general equations
for dimensionless heat capacity, enthalpy, and entropy (eqs. (4.6) to (4.8)
from Gordon and McBride, 1994) are repeated for convenience.
Record Constants Format Column
1 Species name or formula A24 1 to 24
Comments (data source) A56 25-80
2 Number of T intervals I2 2
Optional identification code A6 4-9
Chemical formulas, symbols, and numbers 5(A2,F6.2) 11-50
Zero for gas and nonzero for condensed phases I1 52
Molecular weight F13.5 53-65
Heat of formation at 298.15 K, J/mol F13.5 66-80
3 Temperature range 2F10.3 2-21
Number of coefficients for Cp0/R I1 23
T exponents in empirical equation for Cp0/R 8F5.1 24-63
{H0(298.15)-H0(0)}, J/mol F15.3 66-80
4 First five coefficients for Cp0/R 5D16.8 1-80
5 Last two coefficients for Cp0/R 3D16.8 1-48
Integration constants b1 and b2 2D16.8 49-80
... Repeat 3, 4, and 5 for each interval
Example A.1:
CL2 Chlorine gas. TPIS 1989, v1, pt2, p88.
2 tpis89 CL 2.00 0.00 0.00 0.00 0.00 0 70.90540 0.000
200.000 1000.000 7 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 0.0 9181.110
3.46281724D+04 -5.54712949D+02 6.20759103D+00 -2.98963673D-03 3.17303416D-06
-1.79363467D-09 4.26005863D-13 0.00000000D+00 1.53407075D+03 -9.43835303D+00
1000.000 6000.000 7 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 0.0 9181.110
6.09256675D+06 -1.94962688D+04 2.85453491D+01 -1.44996828D-02 4.46388943D-06
-6.35852403D-10 3.32735931D-14 0.00000000D+00 1.21211722D+05 -1.69077832D+02
Empirical equations for example A.1:
Heat capacity: Cp0/R = a1*T^-2 + a2*T^-1 + a3 + a4*T + a5*T^2 + a6*T^3 + a7*T^4
Enthalpy: H0(T)/(RT) = -a1*T^-2 + a2*T^-1*ln(T) + a3 + a4*T/2 + a5*T^2/3 +
a6*T^3/4 + a7*T^4/5 + b1/T
Entropy: S0(T)/R = -a1*T^-2/2 - a2*T^-1 + a3*ln(T) + a4*T + a5*T^2/2 +
at*T^3/3 + a7*T^4/4 + b2
Example A.2:
C2H2(L),acetyle Acetylene. JANAF Prop.Ser.E,1/67. TRC a-3000,10/86.
0 1 3/95 C 2.00H 2.00 0.00 0.00 0.00 1 26.03788 207599.000
192.35"
Notes:
1. Besides a very different file layout, the most significant change between
the older (1971) NASA thermo data and the 1996 data is the generalization
to any number of temperature intervals.
2. The preceding discussion only mentions the format of individual species
data blocks. In addition, the thermo input file included with the NASA
CEA program contains:
a. Comments at the top of the file marked by exclamation (!) points in the
first column
b. Two lines at the beginning of the species data:
i. One line containing only "thermo"
ii. One line with 4 temperatures and a date
c. A line containing only "END PRODUCTS" separating product species from
reactants, and a line at the end of the file containing only
"END REACTANTS".
3. There are some differences between the format actually used by CEA and
the format described in McBride and Gordon (1996), and some undocumented
features:
a. In the CEA code, the actual read and format statements differ from the
documentation by:
i. The species name on the first line of a block is 15 characters long,
not 24. The rest of the line is comments.
ii. The heat of formation at the end of line 2 is read with f15.3, not f13.5
iii. The temperature range at the beginning of line 3 is read as 2F11.3,
not 2F10.3.
iv. Line 5 is formatted as 2D16.8,16x,2D16.8 rather than
3D16.8,2D16.8. The 16x acknowledges that the third field is
not actually used. The first two fields are the 6th and 7th
polynomial coefficients, and the last two fields are the 8th and
9th (integration constants).
b. Although the number of polynomial coefficients is included in the data,
this number is almost always 7 (plus 2 integration constants). In the
current NASA database, there are only 3 species that use less than
7 coefficients (P4O10(cr), P4O10(cr), and P4O10(L)). Apparently if
less than 7 are used, they are the lowest numbered (a1, a2, a3, ...).
4. In the preceding excerpt from McBride and Gordon (1996), reference is
made to eqs. (4.6) to (4.8). These should be eqs. (4.9) to (4.11).
[Corrected by DL and JES April 29, 2005]