A METHOD FOR DETERMINING CATALYTIC EFFICIENCY OF SURFACES.

A method is described which is used to determine numerically the relationship between the catalytic efficiency gamma of a surface and the heat transfer q through the surface in low Reynolds number flow of a partially dissociated gas. The work is motivated by the fact that heat transfer is easily measurable in the laboratory whereas catalytic efficiency is not. The approach is directed towards the derivation of a relationship between gamma and the surface concentration of free atoms c-o once this relationship is known, it is used to eliminate c-o from the expression relating gamma and q, obtainable from energy balance and from the kinetic theory of gases. To establish the required relationship between gamma and c-o, a mixed boundary value problem for the convective diffusion equation is formulated and solved numerically using an implicit, alternating-direction iteration procedure. The concentration of free atoms is determined not only along the surface, but also throughout the flow field. Results are obtained for a cylinder partially coated with a catalytic substance they reveal the effect of the velocity field and point out the need for better quantitative knowledge of the low Reynolds number flow. In addition, parameter values for the best experimental accuracy are delineated. Author