Effect of turbulence induced shear on micro-mixing in a vertically aligned high-shear rate Taylor-Couette flow reactor

The impact of shear rate variation (employing different rotational speeds of the inner cylinder) on micro-mixing efficiency in a vertical aligned Taylor-Couette flow reactor (TCR) has been studied. The iodate-iodide reaction system was used to measure the segregation index, and CFD modelling was employed to analyse the hydrodynamics, in particular the turbulence induced shear characteristics within the Taylor-Couette flow reactor. As the shear rate (γ̇[Formula presented]) in the TCR increases from 3110-6220 s⁻¹, the segregation index decreases from 0.114 to 0.044, corresponding to a micro-mixing time reduction from 0.0049 s to 0.0018 s. The results have indicated that as the shear rate increases, the turbulence induced shear within the reactor is enhanced, leading to a decrease in the segregation index. By comparing the experimental data with those previously published, it was demonstrated that the micro-mixing in such vertically aligned TCR is strongly correlated with turbulence induced shear, reflected by changes in the micro-mixing time. CFD modelling results on power consumption have revealed that an increase in the power consumption will result in higher shear rate, consequently giving out a reduction in the segregation index. A new correlation was proposed to estimate the micro-mixing time. By considering the local turbulence dissipation rate and its corresponding occupied spatial volume fraction, where the turbulence dissipation rate surpasses the average turbulent dissipation rate in the TCR, it was found that that the micro-mixing time is inversely proportional to the ratio of the local turbulence dissipation rate to the average turbulence dissipation rate in the TCR.