Warning
This documentation is for an old version of Cantera. You can find docs for newer versions here.
% Tutorial 1: Getting started
%
% Topics:
% - creating a gas mixture
% - setting the state
% - cleaning up
%
help tut1
% Start MATLAB, and at the prompt type:
gas1 = GRI30
% If you have successfully installed the Cantera toolbox, you should
%see something like this:
% temperature 300 K
% pressure 101325 Pa
% density 0.081889 kg/m^3
% mean mol. weight 2.01588 amu
%
% 1 kg 1 kmol
% ----------- ------------
% enthalpy 26470.1 5.336e+04 J
% internal energy -1.21088e+06 -2.441e+06 J
% entropy 64914 1.309e+05 J/K
% Gibbs function -1.94477e+07 -3.92e+07 J
% heat capacity c_p 14311.8 2.885e+04 J/K
% heat capacity c_v 10187.3 2.054e+04 J/K
%
% X Y Chem. Pot. / RT
% ------------- ------------ ------------
% H2 1 1 -15.7173
% [ +52 minor] 0 0
%
% What you have just done is to create an object ("gas1") that
% implements GRI-Mech 3.0, the 53-species, 325-reaction natural gas
% combustion mechanism developed by Gregory P. Smith, David M. Golden,
% Michael Frenklach, Nigel W. Moriarty, Boris Eiteneer, Mikhail
% Goldenberg, C. Thomas Bowman, Ronald K. Hanson, Soonho Song, William
% C. Gardiner, Jr., Vitali V. Lissianski, and Zhiwei Qin. (See
% http://www.me.berkeley.edu/gri_mech/ for more information about
% GRI-Mech 3.0.)
%
% The object created by GI30 has properties you would expect for a gas
% mixture - it has a temperature, a pressure, species mole and mass
% fractions, etc. As we'll soon see, it has many other properties too.
%
% The summary of the state of 'gas1' printed above shows that new
% objects created by function GRI30 start out with a temperature of
% 300 K, a pressure of 1 atm, and have a composition that consists of
% only one species, in this case hydrogen. There is nothing special
% about H2 - it just happens to be the first species listed in the
% input file defining GRI-Mech 3.0 that the 'GRI30' function reads. In
% general, the species listed first will initially have a mole
% fraction of 1.0, and all of the others will be zero.
% Setting the state
% -----------------
% The state of the object can be easily changed. For example,
setTemperature(gas1, 1200)
% sets the temperature to 1200 K. (Cantera always uses SI units.)
% Notice in the summary of properties that MATLAB prints after this
% command is executed that the temperature has been changed as
% requested, but the pressure has changed too. The density and
% composition have not.
%
% When setting properties individually, some convention needs to be
% adopted to specify which other properties are held constant. This is
% because thermodynamics requires that *two* properties (not one) in
% addition to composition information be specified to fix the
% intensive state of a substance (or mixture).
%
% Cantera adopts the following convention: only one of the set
% (temperature, density, mass fractions) is altered by setting any
% single property. In particular:
%
% a) Setting the temperature is done holding density and
% composition fixed. (The pressure changes.)
% b) Setting the pressure is done holding temperature and
% composition fixed. (The density changes.)
%
% c) Setting the composition is done holding temperature
% and density fixed. (The pressure changes).
%
% Setting multiple properties: the 'set' method
% ---------------------------------------------
% If you want to set multiple properties at once, use the 'set'
% method. (Note: a 'method' is just the term for a function that acts
% on an object. In MATLAB, methods take the object as the first
% argument.)
set(gas1, 'Temperature', 900.0, 'Pressure', 1.e5);
% This statement sets both temperature and pressure at the same
% time. Any number of property/value pairs can be specified in a
% call to 'set'. For example, the following sets the mole fractions
% too:
set(gas1, 'Temperature', 900.0, 'Pressure', 1.e5, 'MoleFractions', ...
'CH4:1,O2:2,N2:7.52');
% The 'set' method also accepts abbreviated property names:
set(gas1,'T',900.0,'P',1.e5,'X','CH4:1,O2:2,N2:7.52')
% Either version results in
%
% temperature 900 K
% pressure 100000 Pa
% density 0.369279 kg/m^3
% mean mol. weight 27.6332 amu
%
% 1 kg 1 kmol
% ----------- ------------
% enthalpy 455660 1.259e+07 J
% internal energy 184862 5.108e+06 J
% entropy 8529.31 2.357e+05 J/K
% Gibbs function -7.22072e+06 -1.995e+08 J
% heat capacity c_p 1304.4 3.604e+04 J/K
% heat capacity c_v 1003.52 2.773e+04 J/K
%
% X Y Chem. Pot. / RT
% ------------- ------------ ------------
% O2 0.190114 0.220149 -27.9596
% CH4 0.095057 0.0551863 -37.0813
% N2 0.714829 0.724665 -24.935
% [ +50 minor] 0 0
% Other properties may also be set using 'set', including some that
% can't be set individually. The following property pairs may be
% set: (Enthalpy, Pressure), (IntEnergy, Volume), (Entropy,
% Volume), (Entropy, Pressure). In each case, the values of the
% extensive properties must be entered *per unit mass*.
% Setting the enthalpy and pressure:
set(gas1, 'Enthalpy', 2*enthalpy_mass(gas1), 'Pressure', 2*oneatm);
% The composition above was specified using a string. The format is a
% comma-separated list of <species name>:<relative mole numbers>
% pairs. The mole numbers will be normalized to produce the mole
% fractions, and therefore they are 'relative' mole numbers. Mass
% fractions can be set in this way too by changing 'X' to 'Y' in the
% above statement.
% The composition can also be set using an array, which can be
% either a column vector or a row vector but must have the same
% size as the number of species. For example, to set all 53 mole
% fractions to the same value, do this:
x = ones(53,1); % a column vector of 53 ones
set(gas1, 'X', x)
% To set the mass fractions to equal values:
set(gas1, 'Y', x)
% This clears all Matlab objects created
clear all
% and this clears all Cantera objects created
cleanup
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% end of tutorial 1
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%