Cantera reactor change in enthalpy of system

[Antariksh Patel]

Hi guys, 

I am trying to find how the mass fractions and the enthalpy of the system changes with a step of 1 microsecond and I am trying to do this using a IDealGasConstPressureReactor. However I am not getting the results I should (i know what i should get from some other work) and it seems like there is negligable change in the system. Does anyone have any ideas? I have attatched the code bellow.

t = 1*10**-6 # Time step size

#for i in np.arange(no_points): # Mabye i can make this fast by taking stuff out the loop #

gas = ct.Solution("GRI12.yaml")  # create a default GRI-Mech 3.0 gas mixture

gas.HPX = -8.11741605e+05, ct.one_atm, "H2:4.84696761e-04, H:3.67735198e-08, O:8.28486505e-08, O2:1.39780208e-01, OH:8.98867449e-07, H2O:5.93006471e-02, HO2:8.64347184e-05, H2O2:3.06804698e-05 , C:7.20296866e-20 , CH:3.18642075e-15, CH2:3.78751570e-10, CH2(S):2.03115950e-11, CH3:1.04947051e-05, CH4:2.71408855e-02, CO:1.33276760e-02, CO2:3.14464669e-02, HCO:1.43914696e-08, CH2O:5.21917402e-04, CH2OH:2.31522396e-10, CH3O:7.97217973e-06, CH3OH:7.74571720e-05, C2H:5.95324446e-15, C2H2:1.67765778e-05, C2H3:2.18436408e-10, C2H4:2.97896465e-04, C2H5:4.95170037e-07, C2H6:5.24363320e-04, HCCO:1.30502110e-10, CH2CO:3.18984103e-06, HCCOH:1.53179021e-08, N2:7.26940692e-01, AR:0"  # set gas to an interesting state

reac = ct.IdealGasConstPressureReactor(gas)  # create a reactor containing the gas

sim = ct.ReactorNet([reac])  # add the reactor to a new ReactorNet simulator

#print(gas.enthalpy_mass)  # view the initial state of the mixture (state summary will be printed to console)

#print(gas.Y[13])

gas()

test1 = gas.enthalpy_mass

sim.advance(t)  # advance the simulation to the specified absolute time, t = 1 sec

#print(gas.enthalpy_mass)  # view the updated state of the mixture, reflecting properties at t = 1 sec

#print(gas.Y[13])

gas()

test2 = gas.enthalpy_mass

print(test1-test2)

[Ray Speth]

Hi,

For a closed system at constant pressure, the enthalpy is constant. The answer Cantera gives you should correspond to that, within some small integration tolerances.

Regards,

Ray