reactingFoam Enthalpy of Reaction Problem

Cyberholmes · August 17, 2011, 18:15

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.

zeppos10 · August 23, 2011, 06:23

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

August 17, 2011, 18:15	reactingFoam Enthalpy of Reaction Problem	#1
Cyberholmes New Member Join Date: Jun 2011 Posts: 29 Rep Power: 15	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.

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August 23, 2011, 06:23		#2
zeppos10 New Member bas mannaerts Join Date: Aug 2011 Location: Wageningen, NL Posts: 1 Rep Power: 0	if Q is negative, the reaction is exothermic, isn't it ?