The ignition of combustible material in the presence of a damp atmosphere

The ignition of damp combustible material is considered by treating both the heat transfer and mass transfer in a lumped approach, so that diffusive effects are ignored. However the phase changes of water vapour to liquid (or vice versa) are included and it is shown that condensation can be important in destabilising reactive material. This is apart 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 slight change in the atmospheric humidity can have a marked affect on the ignition characteristics of the material.