In order to develop an overall process model, the heat of reaction
must be combined with the rate of reaction and the other transport
equations. There are two common theories regarding the heat
associated with pyrolysis. One is that the pyrolysis of the woody
biomass to non-condensable gases, volatiles, and char is assumed to
be a series of endothermic reactions
second approach, the char formation process is
exothermic, while the condensable and non-condensable gas formation
process is endothermic