2528df0f75
These changes make it unnecessary to copy header files around during the build process, which tends to confuse IDEs and debuggers. The headers which comprise Cantera's external C++ interface are now in the 'include' directory. All of the samples and demos are now in the 'samples' subdirectory.
114 lines
3.3 KiB
Matlab
114 lines
3.3 KiB
Matlab
function periodic_cstr
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%
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% Periodic CSTR
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%
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% This example illustrates a CSTR with steady inputs but periodic
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% interior state. A stoichiometric hydrogen/oxygen mixture is
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% introduced and reacts to produce water. But since water has a
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% large efficiency as a third body in the chain termination reaction
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%
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% H + O2 + M = HO2 + M
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%
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% as soon as a significant amount of water is produced the reaction
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% stops. After enough time has passed that the water is exhausted from
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% the reactor, the mixture explodes again and the process
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% repeats. This explanation can be verified by decreasing the rate for
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% reaction 7 in file 'h2o2.cti' and re-running the example.
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%
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% Acknowledgments: The idea for this example and an estimate of the
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% conditions needed to see the oscillations came from Bob Kee,
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% Colorado School of Mines
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%
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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help periodic_cstr
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% create the gas mixture
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gas = IdealGasMix('h2o2.cti');
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% pressure = 60 Torr, T = 770 K
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p = 60.0*133.3;
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t = 770.0;
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OneAtm = 1.01325e5;
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set(gas,'T', 300.0, 'P', p, 'X', 'H2:2, O2:1');
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% create an upstream reservoir that will supply the reactor. The
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% temperature, pressure, and composition of the upstream reservoir are
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% set to those of the 'gas' object at the time the reservoir is
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% created.
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upstream = Reservoir(gas);
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% Now set the gas to the initial temperature of the reactor, and create
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% the reactor object.
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set(gas, 'T', t, 'P', p);
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cstr = Reactor(gas);
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% Set its volume to 10 cm^3. In this problem, the reactor volume is
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% fixed, so the initial volume is the volume at all later times.
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setInitialVolume(cstr, 10.0*1.0e-6);
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% We need to have heat loss to see the oscillations. Create a
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% reservoir to represent the environment, and initialize its
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% temperature to the reactor temperature.
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env = Reservoir(gas);
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% Create a heat-conducting wall between the reactor and the
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% environment. Set its area, and its overall heat transfer
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% coefficient. Larger U causes the reactor to be closer to isothermal.
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% If U is too small, the gas ignites, and the temperature spikes and
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% stays high.
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w = Wall;
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install(w, cstr, env);
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setArea(w, 1.0);
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setHeatTransferCoeff(w, 0.02);
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% Connect the upstream reservoir to the reactor with a mass flow
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% controller (constant mdot). Set the mass flow rate to 1.25 sccm.
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sccm = 1.25;
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vdot = sccm * 1.0e-6/60.0 * ((OneAtm / pressure(gas)) * ( temperature(gas) / 273.15)); % m^3/s
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mdot = density(gas) * vdot; % kg/s
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mfc = MassFlowController;
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install(mfc, upstream, cstr);
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setMassFlowRate(mfc, mdot);
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% now create a downstream reservoir to exhaust into.
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downstream = Reservoir(gas);
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% connect the reactor to the downstream reservoir with a valve, and
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% set the coefficient sufficiently large to keep the reactor pressure
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% close to the downstream pressure of 60 Torr.
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v = Valve;
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install(v, cstr, downstream);
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setValveCoeff(v, 1.0e-9);
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% create the network
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network = ReactorNet({cstr});
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% now integrate in time
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tme = 0.0;
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dt = 0.1;
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n = 0;
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while tme < 300.0
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n = n + 1;
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tme = tme + dt;
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advance(network, tme);
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tm(n) = tme;
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y(1,n) = massFraction(cstr,'H2');
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y(2,n) = massFraction(cstr,'O2');
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y(3,n) = massFraction(cstr,'H2O');
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end
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clf
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figure(1)
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plot(tm,y)
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legend('H2','O2','H2O')
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title('Mass Fractions')
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