Growths in the concentrations of radicals in reacting mixtures of hydrogen and oxygen. A study by analogue computer

Abstract

The times for various intermediate species to reach their quasi-steady-state concentrations in the thermal reaction between hydrogen and oxygen have been investigated using an analogue computer. Under second limit and slow reaction conditions, the growth curves of the species OH, O, H, HO₂ and H₂O were studied. The growth of all species to an overall steady-state with respect to reactants is controlled by the slowest reacting species H₂O₂, to which all the other species are linked in quasisteady-states. In a similar manner, the next slowest-reacting species HO₂ controls the growth of the other faster-reacting species. The times for OH, O, H, HO₂ and H₂O₂ to reach their quasi-steady-state concentrations are shown to be roughly 10^–6, 10^–4, 10^–3, 10^–1 and 100 sec respectively.

Computer predictions have been made of some of the experimental phenomena observed in aged B₂O₃-coated vessels. These phenomena have been attributed to a time-lag for H₂O₂ to reach its stationary concentration. This interpretation has been confirmed by direct computation. A brief assessment is made of the suitability of the analogue computer for investigating non-linearly branched kinetic chain systems involving one slow-reacting species.