Theory of Ignition of a Reactive Solid by Constant Energy Flux

Abstract

A study was made of the numerical solutions of the equations representing heating of a reactive, homogeneous, opaque solid by a constant flux of energy. Depletion of reactants was considered. Critical conditions for attainment of ignition were defined in terms of behavior of the surface temperature due to self heating after termination of external heating. For a wide range of physical and chemical parameters, it was found that: (1) critical conditions were relatively insensitive to reaction order; (2) the critical ignition temperature has an upper limit approximately equal to the adiabatic solid phase reaction temperature; (3) for activation energies below a critical value, typically 20 kcal/mole, heating cannot produce ignition unless the adiabatic thermal explosion time of the solid is unacceptably short; (4) critical ignition conditions are correlated to an accuracy of 4 % by empirical expressions including the physical and chemical properties and based on simple heat balance arguments.