Study of the process of hydrogen-oxygen combustion at a refractory surface

When a fuel burns near a ceramic surface it is possible to achieve more effective ignition of the fuel mixture than in the case of ignition in free space. The mechanism of combustion near a ceramic surface can be studied most easily and reliably in relation to the low-pressure hydrogen-oxygen reaction, as the hydrogen homogeneous combustion mechanism is most reliable under these conditions. The aim of the study was to determine the nature of the effect of ceramic surfaces on low pressure hydrogen-oxygen combustion by simultaneously recording the product of the reaction--water and the hydrogen and oxygen atoms by gas-phase EPR. This approach made it possible to demonstrate the presence of heterogeneous branching accompanied by the escape of radicals into the chamber. The introduction of ceramic inserts into the control reactor is accompanied by a substantial increase in the water concentration, heating of the insert surface, and a fall in the atom concentration. Simultaneous recording of the active centers, products and reaction heating shows that the process of effective hydrogen burnup on the three surfaces investigated proceeds mainly in accordance with the catalytic mechanism and is not associated with the activating effect of the surface on the homogeneous combustion rate.