Sensitivity Analysis for chemical kinetic simulation (H2 combustion with lubricant oil) with the Cantera toolbox

Dear Matlab community!

As part of my Bachelor Thesis work I have to model the combustion of H2 under internal combustion engine conditions (pressure, temperature) in a 0 dimensional reactor using the chemical kinetics simulation toolbox Cantera, version 3.0.0. The current script is attached.

The goal is to analyze the impact of lubricant oils (represented by a single surrogate molecule) on the combustion process.

Hence it is neccesary to conduct a sensitivity analysis like in this example (for python. however i have to use matlab with the cantera toolbox instead): https://cantera.org/stable/examples/python/onedim/flamespeed_sensitivity.htmlOr in my zero dimenstional case, https://cantera.org/stable/python/zerodim.html#cantera.ReactorNet.sensitivities.

However the Matlab toolbox doesnt contain this function.

What could i do to still perform this analysis? Is there any way to manually program such a function or is there an available downloadable version for this that I can add to my toolbox?

Thanks in advance

Long Yu

[Long Runjia Yu]

%This is the code which conducts a series of simulations of the Hydrogen
%oxidization reaction.
%gas=Solution('gri30.yaml')
gas=Solution('HyLube_mechanism.yaml');
%gas=Solution('HyLube_mechanismDesor.yaml');
T=[800:5:1000];

P=200;
verzug=[];


for i=1:length(T)
set(gas,'T',T(i),'P',P*1e5,'X','H2:2,O2:1,N2:3.7');   %Zu jedem der 41 Temperaturschritten werden drei mal Gasgemische generiert mit je 60 100 oder 200 bar Druck                                                     
r = IdealGasReactor(gas);                %r ist ein Reaktionsraum mit Idealgasgesetzen --> Warum ist das nötig? Enthält gri30 nicht selbst Reaktionsmechanismen?
network = ReactorNet({r});               %network ist ein Netzwerk was mehrere Reaktoren vernetzt und beinhaltet. Ist das bei nur einem Reaktor nötig?
t = 0.0;  %Zeit und Zeitschritte werden generiert, die laufzeit cputime wird in t0 gespeichert

counter=1;
temperatur=[];
maximalwert=0;
zeitpunkt=0;
zusammensetzung=0;

    while t<1.0e-5*10000
        t=step(network);
        temperatur(counter)=temperature(r);
        zeit(counter)=time(network);
        zusammensetzung(counter,1:3)=moleFraction(gas,{'OH','H','H2'});
        if maximalwert<zusammensetzung(counter,2)
            maximalwert=zusammensetzung(counter,2);
            zeitpunkt=t;
        end
        counter=counter+1;
    end
    
zeitpunkt
verzug(i)=zeitpunkt;
end


clf;
subplot(2,2,1);
plot(temperatur);
grid on
xlabel('Time (s)');
ylabel('Temperature (K)');
subplot(2,2,2)
plot(zusammensetzung(:,1));

grid on
xlabel('Time (s)');
ylabel('OH Mole Fraction (K)');
subplot(2,2,3)
plot(zusammensetzung(:,2));
grid on
xlabel('Time (s)');
ylabel('H Mole Fraction (K)');
subplot(2,2,4)
plot(zusammensetzung(:,3));
grid on
xlabel('Time (s)');
ylabel('H2 Mole Fraction (K)');


%for %Temperatur: 430-450 Celsius
 %   for %Druck: um die 100 bar 
        %500 Celsius und 100 bar
        %Kompressionszündung
        %Ansaugzündung: Neu: Druck und Temperatur deutlich geringer
        %50-60 Celsius und lediglich 5 bar.
  %  end
  %Simulationszeit verlängern
%end

[Torsten]

However the Matlab toolbox doesnt contain this function.

Which function do you mean here ?

[Long Runjia Yu]

https://cantera.org/stable/python/zerodim.html#cantera.ReactorNet.sensitivities

This one for example for zero dimensional reactors or this one which was used in the example script I have given in the original question https://cantera.org/stable/python/onedim.html#cantera.FreeFlame.get_flame_speed_reaction_sensitivities

[Torsten]

You should try to convince your instructor that the simulations should be done in the python environment if sensitivity analysis is needed. It will become unnecessarily complicated and time-consuming if you are forced to dive into the internals of the cantera software for this - time that can be spent better for other problems.

[Yifeng Tang]

If you prefer to use Python packages while in MATLAB, it's possible. See https://www.mathworks.com/help/matlab/call-python-libraries.html

[Long Runjia Yu]

Thank you very much for your answer. I was not aware of this aspect of Matlab.

Does this effectively mean that with a py. prefix i get to use Python package functions without ever leaving my Matlab script?

[Yifeng Tang]

That's my understanding, although I've used it only in very limited cases, like using an existing .py script to import data in certain format.

The documentation page should have plenty of examples you can follow.

I've also seen lots of videos on this topic: https://www.mathworks.com/videos/search.html?q=python&page=1