Experimental and Numerical Study on Flow Resistance and Bubble Transport in a Helical Static Mixer

Abstract

Flow resistance and bubble transport in a helical static mixer were studied experimentally and numerically. The inline mixer increases the volume fraction of gas in liquids by breaking bubbles into smaller sizes with a micrometer size in the flow experiments. The gas–liquid flow was simulated by a combination of computational fluid dynamics and Taylor expansion methods of moments. The friction factor of the helical static mixer is much smaller than that of the Kenics static mixers. The pressure drop increases with the Reynolds number, and the increment is larger when the Reynolds number is higher. The equidistant pressure drop increases with the argument of Reynolds number, and increases when the pitch decreases from upstream to downstream. The energy expenditure increases significantly when the variable-pitch coefficient is too small. The bubble geometric mean diameter decreases and the geometric standard deviation increases when the gas–liquid fluid flows through the mixer. The variable pitch structure enhances the bubble breakup effectively. The change of the bubble size decreases with the argument of the Reynolds number. The effect of the mixer has a limitation on breaking the bubbles.

Single and two‐phase flows in a horizontal pipe with a Kenics static mixer: Effect of pressure drop on mixing

“…A new correlation was proposed (Equation ()) with R 2 (coefficient of determination [COD]) = 0.95. Equation () deviates by ±15% at most from the correlation proposed in Table 2 [ 37 ] and ±13% from the modified experimental friction factor (fm exp). [ 41,42 ] The difference between our experimental results and the correlations proposed by various authors was reduced after taking into account the influence of the geometric parameters of the KSM, such as porosity and hydraulic diameter. The remaining gap can be explained by the effect of the pipe diameter and the relative roughness.…”

“…Single‐phase pressure drops with and without mixers, Kenics with six elements, were measured using a multi‐tube manometer. The comparative evolution (Figure 4) of the experimental data of this work using the Darcy friction factor (a method used for a modified KSM [ 40 ] ) with correlations established from friction factors determined pipe diameters of 12.7 mm, [ 35 ] 21 mm [ 36 ] as well as 30 mm, [ 36 ] and 20 mm [ 37 ] with aspect ratios of, respectively, 2.5, 2, and 1.5 showed that the modified pressure drop factor (Equation ()) [ 41,42 ] calculated using the experimental pressure drop values, the hydraulic diameter influenced by the presence of KSM (Equation ()), [ 37 ] and the porosity of KSM has the same shape as the Darcy coefficient reduced by a factor of 1.9 . It was also noticed that the modified pressure drop factor was very close to the correlation mentioned in Table 2, [ 37 ] for 8110 < Re L < 18 940, which is equivalent to 4870 < Re h < 11 362.…”

Process Intensification in Chemical Reaction Engineering

“…Several advantages make them suitable to replace the classical equipment, among which are lower space requirements and energy demand thanks to the absence of moving parts. Further benefits include low operational costs, increased process safety, and better selectivity with respect to the reduction of byproducts reduction thanks to mixing intensification [43,45,46]. This has led to various applications in several fields, e.g., chemistry, pharmaceuticals, food, polymers, and water treatment.…”

The Influence of Groove Structure Parameters on the Maximum Flow Resistance of a Rectangular Narrow Channel

“…Nho et al [19] studied the total pressure losses of narrow channels with 11 different types of top structures incorporating ribs on the in-line turbine cascades, and found that the total pressure loss was smallest at the top of the double ribs and the slope groove on the pressure side. Fangyang Yuan [20] studied the flow resistance and bubble transport in a helical static mixer, and found that the pressure drop increases with the Reynolds number, and the increment is larger when the Reynolds number is higher. Ostanek and Thole [21] studied the loss in pressure drop along different forms of ribs, and identified a large loss of pressure of ribs with edges.…”