A study of residence time distribution in co-rotating twin-screw extruders. Part II: Experimental validation

In the first part of this paper, a new approach to model the residence time distribution (RTD) in a co-rotating twin-screw extruder was proposed. It consists of coupling a continuum mechanics approach with a chemical engineering one, yielding an RID curve without any fitting parameter. However, the choice of ideal reactors that depict the behavior of each particular profile is not evident. In this second part, we present an experimental study based on two types of extruder (Leistritz 30-34 and Clextral BC45), different screw profiles and two measurement techniques (off-line and in-line). Global, partial and local RTD curves were obtained, both experimentally and by means of a deconvolution technique. This series of experiments permitted the definition of the best association between ideal reactors and screw elements. Using this association, a comparison has been made between experimental results and theoretical calculations. A good agreement was generally obtained in terms of the RTD shape, delay time, mean residence time and variance.