Accessing the databases#
In the preceding section, we stated that to initialize the Combustion Toolbox (load databases, default parameters, etc.), we have to run the following command:
self = App();
Now, let’s delve into how we can access the databases incorporated within the Combustion Toolbox (CT). There are two main types of databases: DB_master and DB. The former comprises all data from from McBride [2002], Burcat and Ruscic [2005], while the latter contains the same data in a more optimized format, ensuring faster data access.
Tip
Distinguishing between DB_master and DB is crucial because the latter, due to the utilization of griddedInterpolant objects, has a significantly larger size (~36 MB). A streamlined version of DB can be generated to conserve memory and reduce loading time (~1 second for 3603 species) when initializing CT. To achieve this, execute:
self.DB = generate_DB(self.DB_master, {'O2', 'N2'});
Subsequently, save the self.DB variable in the databases folder as DB.mat to be loaded in the remaining sessions.
Finding specific chemical species#
The thermodynamic data of the species, e.g., Cgr, can be accessed as follows:
self.DB.Cbgrb;
This command will yield information similar to the following:
FullName: 'C(gr)'
name: 'Cbgrb'
comments: 'Graphite. Ref-Elm. TRC(4/83) vc,uc,tc1000-1002. '
txFormula: 'C 1.00 0.00 0.00 0.00 0.00'
mm: 12.0107
hf: 0
ef: 0
phase: 1
T: [200 229.1457 258.2915 287.4372 316.5829 345.7286 … ] (1×200 double)
cPcurve: [1×1 griddedInterpolant]
h0curve: [1×1 griddedInterpolant]
s0curve: [1×1 griddedInterpolant]
g0curve: [1×1 griddedInterpolant]
ctTInt: 3
tRange: {[200 600] [600 2000] [2000 6000]}
tExponents: {[-2 -1 0 1 2 3 4 0] [-2 -1 0 1 2 3 4 0] [-2 -1 0 1 2 3 4 0]}
a: {[1×8 double] [1×8 double] [1×8 double]}
b: {[8.9439e+03 -72.9582] [1.3984e+04 -44.7718] [5.8481e+03 -23.5093]}
These details offer comprehensive insights into the thermodynamic properties of the specified species in the Combustion Toolbox database. We have the following fields:
FullName: full name of the species.name: short name of the species as defined in the database.comments: comments about the species.txFormula: chemical formula of the species.mm: molar mass [g/mol].hf: standard enthalpy of formation [J/mol].ef: standard internal energy of formation [J/mol].phase: phase of the species (0: gas, 1: liquid or solid).T: temperature vector [K].cPcurve: griddedInterpolant object containing the standard specific heat capacity at constant pressure [J/mol-K].h0curve: griddedInterpolant object containing the standard enthalpy [J/mol].s0curve: griddedInterpolant object containing the standard entropy [J/mol-K].g0curve: griddedInterpolant object containing the standard Gibbs free energy [J/mol].ctTInt: number of temperature intervals.tRange: temperature intervals.tExponents: temperature exponents for the standard specific heat capacity at constant pressure, standard enthalpy, and standard entropy, respectively.a: coefficients of the polynomial.b: coefficients of the polynomial.
Finding list of chemical species with given chemical elements#
To find the list of species that contain only some chemical elements, e.g., O and H, we can use the following command:
list_species = find_products(self, {'O', 'H'})
which will yield the following output:
list_species =
1×15 cell array
Columns 1 through 7
{'HO2'} {'H2O'} {'H2O2'} {'OH'} {'H2Obcrb'} {'H2ObLb'} {'H2O2bLb'}
Columns 8 through 15
{'O'} {'O2'} {'O3'} {'O2bLb'} {'O3bLb'} {'H'} {'H2'} {'H2bLb'}
Note
By default, the find_products.m function looks for species in the NASA database, includes condensed species, and excludes ionized species. To search for species in Burcat’s database and include ionized species, set flag_burcat and flag_ion options to true. Alternatively, we can modify the default value in the Species.m file. Chemical species from the Third Millennium database (Burcat) are indicated with the subscript _M.
list_species = find_products(self, {'O', 'H'}, 'flag_burcat', true)
which will yield the following output:
list_species =
1×25 cell array
Columns 1 through 7
{'HO2'} {'H2O'} {'H2O2'} {'OH'} {'H2Obcrb'} {'H2ObLb'} {'H2O2bLb'}
Columns 8 through 14
{'OH_M'} {'HO2_M'} {'HO3_M'} {'H2O2_M'} {'H2O3_M'} {'HOOOH_M'} {'O'}
Columns 15 through 21
{'O2'} {'O3'} {'O2bLb'} {'O3bLb'} {'O_M'} {'O2_M'} {'O3_M'}
Columns 22 through 25
{'O4_M'} {'H'} {'H2'} {'H2bLb'}
Note
Chemical species from the Third Millennium database (Burcat) are indicated with the subscript _M. By default, the find_products.m function looks for species in the NASA database, includes condensed species, and excludes ionized species. To search for species in Burcat’s database, we have enabled the flag_burcat option, setting it to true. Alternatively, we can modify the default value in the Species.m file.
list_species = find_products(self, {'O', 'H'}, 'flag_burcat', true, , 'flag_ion', true)
which will yield the following output:
list_species =
1×52 cell array
Columns 1 through 6
{'HO2minus'} {'H2Oplus'} {'H3Oplus'} {'OHplus'} {'OHminus'} {'HO2plus_M'}
Columns 7 through 11
{'HO2minus_M'} {'HO3plus_M'} {'HO3minus_M'} {'H2O2plus_M'} {'H2O3plus_M'}
Columns 12 through 17
{'H3O2plus_M'} {'Oplus'} {'Ominus'} {'O2plus'} {'O2minus'} {'O3plus_M'}
Columns 18 through 23
{'O3minus_M'} {'O4plus_M'} {'O4minus_M'} {'Hplus'} {'Hminus'} {'H2plus'}
Columns 24 through 29
{'H2minus'} {'H2minus_M'} {'H3plus_M'} {'eminus'} {'HO2'} {'H2O'}
Columns 30 through 36
{'H2O2'} {'OH'} {'H2Obcrb'} {'H2ObLb'} {'H2O2bLb'} {'OH_M'} {'HO2_M'}
Columns 37 through 43
{'HO3_M'} {'H2O2_M'} {'H2O3_M'} {'HOOOH_M'} {'O'} {'O2'} {'O3'}
Columns 44 through 51
{'O2bLb'} {'O3bLb'} {'O_M'} {'O2_M'} {'O3_M'} {'O4_M'} {'H'} {'H2'}
Column 52
{'H2bLb'}
Note
Chemical species from the Third Millennium database (Burcat) are indicated with the subscript _M. By default, the find_products.m function looks for species in the NASA database, includes condensed species, and excludes ionized species. To search for species in Burcat’s database and include ionized species, we have enabled the flag_burcat and flag_ion options, setting both to true. Alternatively, we can modify the default flag values in the Species.m file.
Tip
The same procedure can be used to identify all possible products after a chemical transformation given a set of chemical species (reactants), as described in Defining chemical system.