Temperature rise during endothermic reaction

hebe2u · April 4, 2019, 03:04

Hi!

I'm trying to simulate the thermal decomposition(pyrolysis) of urea(CH4N2O) into ammonia(NH3) and isocyanic acid(HNCO).
This is endothermic reaction, △H>0.
However, in the result of this simulation, the temperature increases.
(There is no heat source.)
I defined the reference specific enthalpy -3.9e6 J/kg for urea, -4.75e5 J/kg for ammonia, -2.76e6 J/kg for isocyanic at 25 C and 1 atm.

What should I check more to simulation the endothermic reaction?

Thank you!

ghorrocks · April 4, 2019, 05:27

FAQ: https://www.cfd-online.com/Wiki/Ansy..._inaccurate.3F

Are you sure your simulation is converged?

April 4, 2019, 03:04	Temperature rise during endothermic reaction	#1
hebe2u New Member Mia Join Date: Apr 2013 Posts: 3 Rep Power: 13	Hi! I'm trying to simulate the thermal decomposition(pyrolysis) of urea(CH4N2O) into ammonia(NH3) and isocyanic acid(HNCO). This is endothermic reaction, △H>0. However, in the result of this simulation, the temperature increases. (There is no heat source.) I defined the reference specific enthalpy -3.9e6 J/kg for urea, -4.75e5 J/kg for ammonia, -2.76e6 J/kg for isocyanic at 25 C and 1 atm. What should I check more to simulation the endothermic reaction? Thank you!

April 4, 2019, 05:27		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	FAQ: https://www.cfd-online.com/Wiki/Ansy..._inaccurate.3F Are you sure your simulation is converged? __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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