Residence time distribution in screw extruders

Abstract

A companion article (Chen and Hu, 1993a) discussed a statistical theory that for a system consisting of two closed subsystems, the residence time density (RTD) functions of the two subsystems will bestatistically independent, ifa two-dimensional perfect mixing exists at the subsystem boundary. In this case, the overall RTD function is related to that for individualsubsystems through the convolution integral. This theory has been validated experimentally using two die-screw combinations.Based on this theory, a predictive RTD model for an intermeshing counterrotating twin-screw extruder has been developed. The screw in the longitudinal direction has been treated as C-chambers in series. The overall RTD of leakage flows has been calculated from the RTDs of these individual chambers and then converted into the RTD of the extruder. The predicted RTD has been tested against experimental results with success.

Residence‐time distribution model for twin‐screw extruders

“…Ž . Chen et al 1993 , developed a theory that involves the superposition of RTD functions of different screw sections with two-dimensional perfect mixing at the boundaries. Based on this theory, Chen et al developed a predictive RTD model for an intermeshing counterrotating twin-screw extruder, which treats the screw as a set of individual turns connected in series, with the RTD from each turn assumed to be statistically independent of each other.…”

Series solutions for viscous and viscoelastic fluids flow in the helical rectangular channel of an extruder screw

“…However, the point we would like to make is that if even for a constant shear viscosity fluid, the Parallel Plate Model is found to be inaccurate, then it is going to be inaccurate also for a shearthinning fluid because the flow of an inelastic fluid in a screw channel will retain some of the features of a Newtonian fluid flow [31].…”

Acceleration of Chemical Reaction in Reactive Extrusion Accompained by Devolatilization

“…(2), and f(t) is the RTD function. A statistical method was introduced to relate the overall RTD in a screw extruder to the RTDs in its appropriately divided elements [18]. For n elements with RTD functions f 1 (t), f 2 ,(t), .…”