Catalytic combustion in a tube with electrical discharge: Preliminary measurements of augmented reaction rates [4]

Since Senftleben¹ first indicated that in the presence of electric fields, heat transfer rates may be increased substantially beyond natural convection values, correlations have been proposed relating electric field and fluid flow parameters to film coefficients of transfer. The 'corona wind', which exists in a non-uniform electric field before spark breakdown, can be used to alter the hydrodynamics of convective diffusion processes such that an augmentation of transport rates in wall boundary layers can be achieved ^2-6. Corona wind augmentation of wall reactions, particularly catalytic combustion processes, has not previously been considered ^7,8, but as catalytic combustion is a convective diffusion process, the superposition of the corona wind on the flow field near the catalytic surface may augment overall reaction rates by increased mixing. For very rapid surface reactions, where molecular diffusion inhibits the overall rate and lowers overall rate constants, corona wind augmentation may limit the effects of diffusion and, thereby, increase catalyst effectiveness. Improvements in the overall rate constant, or mass transfer coefficient, would be useful in many areas, including air pollution control, energy conservation, and the design of compact, controlled heat flux catalytic combustors. We report here our test of the catalytic combustion of hydrogen at one atmosphere on platinised alumina in a flow reactor with a uniformly accessible catalyst surface. By this experimental design we may be able to obtain reaction rate data from the kinetically controlled to the diffusion limited regimes of combustion owing to the high activity of hydrogen on metallic platinum. A uniformly accessible catalyst surface also permits analysis of the reaction rate data using either one- or two-dimensional approaches.