THE IGNITION OF COMBUSTIBLE MATERIAL IN THE PRESENCE OF A DAMP ATMOSPHERE

The ignition of damp combustible material is considered by treating bo th the heat transfer and mass transfer in a lumped approach, so that d iffusive effects are ignored. However the phase changes of water vapou r to liquid (or vice versa) are included and it is shown that condensa tion can be important in destabilising reactive material. This is apar t from any effect due to wet reactions. In particular it is shown that if a lump of reactive material is initially dry and subcritical, a sl ight change in the atmospheric humidity can have a marked affect on th e ignition characteristics of the material.