ABSTRACT
Fully dimensionalised terms have been retained, but most of thermal ignition theory has been developed by grouping and non-dimensionalising parameters. Thermal runaway can also occur in substances that can undergo exothermic decomposition, such as fertilisers. The more general problem arises from the failure to recognise that stockpiles of material which are capable of undergoing exothermic oxidation cannot be increased in size indefinitely without promoting ‘thermal runaway’. Spontaneous, thermal ignition in a closed system implies that the whole volume is simultaneously involved in the phenomenon. The criterion for occurrence of an explosion must therefore be related to the net rate of heat gain or loss in a volume element of the reacting system. Whichever treatment is appropriate for any particular system, governed by the temperature, density and geometry, but there is a potential combustion hazard when materials that are capable of undergoing exothermic oxidation are stored or transported in bulk.
