Major results for micromixing

As mentioned above, to determine one value for fM needs an experimental curve of X, versus u0 for the case where the impinging velocity m() is taken as the governing variable. The plot of a set of typical data is indicated in Fig. 10.12. From the curve the critical point at which Xs turns from a varying value to a small constant is found at u -0.184 m/s. With the known reaction rate constant at 298 K, the micromixing time can be calculated as 

In comparison, the micromixing time in a general stirred tank reactor (STR) ranges from 500 to 1000 ms. If it is noted that the impingement zone in the SCISR occupies only a small volumetric fraction (less than 20% of the total), the value of 192 ms for the micromixing time in the SCISR indicates clearly that impinging streams do promote micromixing very efficiently. 

The data determined for the micromixing time, rM, from various curves are illustrated in Fig. 10.13, which meet approximately the relationship below  

The reason for the decrease in the micromixing time with the increase in impinging velocity is clear a higher impinging velocity implies an increased energy dissipation rate and thus more efficient micromixing. 

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