Local and global dispersion effects in Couette-Taylor flow .2. Quantitative measurements and discussion of the reactor performance

For the first time, the extent to which laminar and turbulent Couette-Taylor flow (CTF) combine a limited axial dispersion with a high local mixing intensity has been quantified by simultaneously measuring the inter-vortex flux and the tangential dispersion. The correlations for the tangential dispersion indicate that the local mixing intensity of CTF is of the same order of magnitude as in coiled pipe flow. The axial dispersion was measured in such a way that the dispersion enhancing or reducing effects which originate from the slow intra-vortex transport were eliminated. This allowed the comparison of the measurements in this study with recent theoretical calculations of the inter-vortex flux in 2D-periodic flows. The variation of the inter-vortex flux with D-mol(1/2) shows that in the laminar regime the inter-vortex Aux can be described by the penetration model. A mechanism for the axial dispersion in the turbulent regime is also proposed. By comparing the ratios of the local and global dispersion coefficients, it is quantitatively shown that for CTF the local mixing intensity can be increased with a relatively smaller increase in axial dispersion than for conventional flow types.