Hello Rob,nI tried using another species in the mixture-coal. Still, the error persists. Since I kept Cp constant, the Cp value is >0. But the divergence is still there.nThe temperature of phase-2 (mixture-coal) is attached. Also when I change the operating conditions (T = 1023) so that the reactor temperature is 1073 K. But that is not reflected from contours. Should I patch the temperature for the entire domain as an input to the operating temperature of the reactor?nn