Residence Time Theory

Abstract

The intellectual roots of residence time theory date back to 1908 and, thus, span the 100-year history of Industrial & Engineering Chemistry. The theory was created, developed, and extended by chemical engineers. It permeates chemical engineering in general and chemical reaction engineering in particular. It also has found widespread utility in the geosciences, environmental engineering, medicine, and biology. This paper provides an overview of the theory and gives some new results here and there.

Hydrodynamics and residence time distribution of liquid flow in tubular reactors equipped with screen-type static mixers

“…This concept has been in place for over a hundred years [15] and became widely used after the work of Danckwerts in the early 1950's [15,16]. Residence time distribution (RTD) is an indicator of the macro-mixing in the reactor as it measures features of ideal or non-ideal flows associated with bulk flow patterns, and knowledge concerning its characteristics would therefore offer the ability to adapt the reactor/contactor design to meet specific process requirements.…”

Self-similarity of fluid residence time statistics in a turbulent round jet

“…The instantaneous value of the residence time of an element of material is described in the following as the elementary age and denoted by a * (t), with the corresponding mass denoted by m * . A number of experimental and numerical approaches have been developed previously in order to characterise and model residence time distributions, as described in the popular text book by Levenspiel (1999) and in a recent review by Nauman (2008), and these methods are applied routinely in, among others, the process industry.…”

“…Instead, elementary-age distributions can be modelled by Lagrangian tracking of material elements (Mackley & Saraiva 1999), provided that the effects of Brownian and turbulent motions are accounted for accurately, at least in a statistical sense. Rather than simulating the molecular dynamics directly, random walk procedures (Mackley & Saraiva 1999;Nauman 2008) and Langevin equations (Langevin 1908;Haworth & Pope 1986) have been used to take account of molecular and turbulent contributions to the transport of the elementary age.…”

A Particulate Method for Determining Residence Time in Viscous Flow Processes

“…It appears that the curves are very smooth in comparison to the one established for a Newtonian fluid by Nauman. [30] In addition, no perceptible influence of the power law index can be discerned. Table 4 shows the number of optimal classes obtained by the minimization of the least square criterion [Equation (21)], which varies in the range 40-189 in a non-monotonic fashion with respect to the power law index.…”

“…In a legacy review paper, Nauman [22] suggests to 'modify CFD codes to allow easy, accurate, and semi automatic determination of RTD in laminar flows'. Keeping this in mind, our motivation is to revisit the methodology of RTD calculation using the particle tracking technique.…”