reactingFoam Enthalpy of Reaction Problem
 

Hello all,

I am doing a simulation which involves the decomposition of ethylene into hydrogen gas and carbon, according to the following reaction:

C2H4 --> 2H2 + 2C.

Now, this should be an exothermic reaction (the enthalpy of formation of ethylene is positive). However, reactingFoam seems to think it is an endothermic reaction (dQ is negative and large in magnitude where the reaction occurs).

I took all of the Cp coefficients for the thermo.compressibleGas file from the NASA Thermodynamic database, where Chemkin and the reactingFoam tutorial got there data.

Does anyone have any idea why reactingFoam might be calculating the wrong enthalpy of reaction?

Thank you.

if Q is negative, the reaction is exothermic, isn't it ?