Axial dispersion in laminar flow of polymer solutions through coiled tubes

Abstract

SynopsisThe results of an experimental study on axial dispersion in laminar flow of non-Newtonian fluids through helical coils are reported. The ranges of variables covered are 10.5 < X < 220,0.6 < n < 1.0, 0.1 < N R~~ < 140, and 0.04 < 7 < 2.2. The condition for the applicability of Taylor's dispersion model is also reported. It is found that coiling results in a dispersion reduced over that in a straight tube.

Residence time distribution of a purely viscous non-Newtonian fluid in helically coiled or spatially chaotic flows

“…For this Reynolds numbers range, the flow in the chaotic twisted pipe arrangement can be considered as fully chaotic in the whole section of the apparatus [15,19]. In this case, the dispersed plug flow model has been found suitable for a correct prediction of the RTD of the liquid, both in the chaotic and in the helically coiled systems [15], confirming previous experimental works dedicated to the latter configuration [9,10,21].…”

“…These properties present a significant advantage for the mixing of very viscous or fragile fluids for which turbulence generation can cause damages and increase pumping costs due to pressure drops. The idea of generating a spatial (Lagrangian) chaotic behavior from a deterministic flow by simple geometrical perturbations has attracted much attention in recent years [18][19][20], mainly because of its potential application in mixing devices [21][22][23]. The geometrical perturbation induces complex three-dimensional chaotic trajectories in which particles can visit a large number of positions in physical space.…”

Residence time distributions of power law fluids in motionless mixers

“…Concentrations varied from 0.5 g/L to 2.0 g/L, giving power law constants in the range of 0.607 to 0.725. Other fluid properties have been reported previously (Saxena and Nigam, 1981).…”

“…The tracer was a red dye and was detected colorimetrically. Details have been previously reported (Saxena and Nigam, 1981). Figure 1 shows the data from nine separate runs with polymer concentrations of 0.5, 1 .O, and 2.0 g/L and with mean residence times between 26.7 and 49.6 minutes.…”

Residence Time Distribution Study of a Living/Controlled Radical Miniemulsion Polymerization System in a Continuous Tubular Reactor

“…Theoretical RTDs have been derived using Dean's flow equations for laminar flow in helical tubes,21, 22 and there have been numerous experimental studies that describe RTD details for diffusion‐free laminar flow23 and axial dispersion in laminar flow24, 25 for Newtonian and non‐Newtonian26 systems, including polymer solutions 27. Most of these studies have been done using step tracer experiments, as opposed to the pulse tracer method that was used in the study.…”