Axial dispersion in coiled tubular reactors

Dispersion coefficient and moment analysis of flow injection analysis peaks

“…Many workers have examined the effect of manifold design and experimental parameters upon the response curve in an attempt to develop a more accurate measure of dispersion in a flow injection system. Coiling of the tubing has been shown to introduce additional mechanisms of transport (10)(11)(12)(13) that obscure the significance of D. Additionally, as the FIA manifold becomes more complex in design, any available theory becomes increasingly inadequate in attempts to predict the behavior of the system. Vanderslice et al (6) first showed that the solute diffusion coefficient and tube radius directly affect dispersion.…”

Oscillatory control of sample dispersion in a continuous flow system

“…The greater the number of times this event occurs, the more uniform is the distribution of velocities of the fluid streamlines and the more similar to the plug-flow type is the transport process. 5,6 A higher efficiency in controlling dispersion is observed when knotted or knitted reactors are employed instead of coils. This can be attributed to more frequent changes in the flow direction for the former types: knitted reactors produce changes in a periodic way, whereas knotted reactors act by randomly disturbing the flow direction.…”

“…These results show that shaking is more efficient at low flow rates in contrast to coiling or knotting that work better at higher values. 6,9 Hence, for the disturbed straight reactor, reducing the flow rate at a constant reactor length is a way to increase the number of times the flow direction is changed. An analogy with current strategies (coiled, knotted reactors) can be found when the coiling factor or the number of knots per unit length is increased.…”

“…Different types of reactors such as packed, helically coiled and three-dimensional disoriented (serpentines, knotted or knitted) have been reported, showing different advantages and disadvantages depending on the operational conditions. [4][5][6][7][8][9] Some strategies other than the modification to the reactor shape and dimensions have been reported. Cardwell et al 10 used a vibrating reed mixer for improving the mixing of sample and reagents in the determination of the acidity of wines by discontinuous flow analysis.…”

Catalytic Hydrogenation of Carbon Dioxide to Methane in Wall‐Cooled Fixed‐Bed Reactors‡

“…This model has already been investigated and published 17–21 and assumes uniformity of porosity and fluid velocity over the cross section of the bed (plug flow). The α w model uses an effective radial thermal conductivity ( λ rad ), which is considered to be constant in the radial direction up to the internal reactor wall, and introduces an additional heat transfer coefficient directly at the wall ( α w ) to account for weaker heat transfer close to the wall.…”