HEV Static Mixer

Figure 5-17 Path lines, colored by velocity magnitude, illustrating the flow through an HEV static mixer.

Bakker A., N. Cathie, and R. LaRoche (1994a). ModeUng of the flow and mixing in HEV static mixers, presented at the 8th European Conference on Mixing, Cambridge, Sept. 21-23 Inst. Chem. Eng. Symp. Sen, 136, 533-540. 

Chandavimol, M., D. Randall, M. Vielhaber, and G. K. Patterson (1991b). Gas dispersion in a liquid in twisted ribbon and HEV static mixers, presented at the AIChE Annual Meeting, Dallas. 

Most manufacturers of static mixers have published (either in sales literature or in the technical literature) design methods for pressure drop. The pressure drop design methods, from Myers et al. (1997) for the Kenics HEM and Kenics HEV mixers are presented. The Darcy friction factor for the standard HEV mixer, Ntr = 2, L/D = 1, (with X/D = 3 downstream pipe) is presented in Figure 10.31. The friction factor is not given below Nrc = 1,000 because the HEV mixer should not be used for Nrc < 3,000. 

In addition, Chandavimol et al. (1991a,b) have estimated the kinetic rate at which the bubbles go from initial size to the maximum equilibrium size as a function of energy dissipation. The rate of dispersion was found to be approximately proportional to energy dissipation rate. [See Figure 7-24 for a comparison of bubble breakup rate between vortex (HEV) and spiral (KMS type) static mixers.] In general, the equilibrium drop size is reached in a few pipe diameters. However, the drop size distribution is narrowed as the simultaneous processes of drop breakup and coalescence are continued, depending on the mixer design and fluid properties. See also Hesketh et al. (1987, 1991). 

Figure 7-24 Comparison of overall correlation of bubble breakup rate for vortex (HEV) and spiral (KMS) static mixers. (Data from Chandavimol et al., 1991b.)...

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