Model residence time distribution

FIGURE 15.12 An arbitrary residence time distribution modeled as PFRs in parallel. 

In order to obtain a residence-time distribution model, E(B), for flow through a vessel of... 

D. Glasser and R. Jackson. A Generalized residence time distribution model for a chemical reactor. In 8th International Symposium on Chemical Reaction Engineering, I.Ch.E. Symposium Series No. 87, page 535, 1984. 

There are various ways to classify mathematical models (5). First, according to the nature of the process, they can be classified as deterministic or stochastic. The former refers to a process in which each variable or parameter acquires a certain specific value or sets of values according to the operating conditions. In the latter, an element of uncertainty enters we cannot specify a certain value to a variable, but only a most probable one. Transport-based models are deterministic residence time distribution models in well-stirred tanks are stochastic. 

Mathematical models can also be classified according to the mathematical foundation the model is built on. Thus we have transport phenomena-bas A models (including most of the models presented in this text), empirical models (based on experimental correlations), and population-based models, such as the previously mentioned residence time distribution models. Models can be further classified as steady or unsteady, lumped parameter or distributed parameter (implying no variation or variation with spatial coordinates, respectively), and linear or nonlinear. 

B. Drop Size and Residence Time Distribution Models. 236... 

Maier and Lambla (1995) model the conversion of a nonylphenyl ethoxylate (NP8) onto a pre-maleated ethylene-propylene mbber (EPR-ma) along the reactive extmder by using a kinetics model derived from batch experiments and a residence-time-distribution model. Mathematically this model is given by the equation ... 

Puaux et al. (2006) isocyanurate) (PUIR) with axial dispersion residence-time-distribution model. residence-time distributions are predicted... 

Since the particles retain their identity in the reactor and the rate equations are nonlinear, a residence time distribution model will be used. The particle slip velocity was found to be negligible as compared with the liquid-phase circulation velocities, which govern the dispersion coefQcient. It will be assumed that the axial dispersion coefficients for the solid and liquid phases are practically the same. Thus, the exit age distribution for the solid particles can be found by following the procedure for the liquid phase. 

Drop size and residence time distribution models... 

An interesting alternative way could consists in fitting analytically the Residence Time Distribution model defined by Eq.25 on the velocity distribution model defined by Eq. 5 ... 

The first approach, which considers a single phase, proposes conventional multiphase flow models, such as ideal flow, dispersion, and residence time distribution models. The second approach, which takes into account two phases as bubble and emulsion, suggests different governing equations for each phase and considers a term for describing mass interchange between the two phases. 

Gao J, Walsh GC, Bigio D, Briber RM, Wetzel MD (1999) Residence-Time Distribution Model for Twin-Screw Extruders, AIChE Journal 45(12) pp 2541 Godavarti S, Karwe MV (1997) Determination of specific mechanical energy distribution on a twin-screw extruder. Elsevier 67 277-287... 

Residence time distribution (RTD) is a classical tool in the prediction of the comportment of a chemical reactor provided that the reaction kinetics and mass transfer characteristics of the system are known, the reactor performance can be calculated by combining kinetic and mass transfer models to an appropriate residence time distribution model. RTDs can be determined experimentally, as described in classical textbooks of chemical reaction engineering (e.g. Levenspiel 1999). RTD experiments are typically carried out as pulse or step-response experiments. The technique is principally elegant, but it requires the access to the real reactor system. In large-scale production, experimental RTD studies are not always possible or allowed. Furthermore, a predictive tool is needed, as the design of a new reactor is considered. 

Glasser, D. and R. Jackson. A Generalized Residence Time Distribution Model for a Chemical Reactor. Instn. Chem. Engrs. Symp. Series 87 (1984) 535. 

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