Study On Properties Of Mixing Elements In Melt Conveying Zone Of Intermeshing Counter-Rotating Twin Screw Extruder

Some properties, such as forced transportation, narrow residence time distribution, good self-cleaning and small shear force etc, were behaved in intermeshing counter-rotating twin screw extruder. Because people had less study on its mixing theory, its applications were limited in narrow range in the industry. To improve mixing capabilities of intermeshing counter-rotating twin screw extruder and applied limit, some new kinds of mixing elements were introduced.Pin-barrel element was introduced in intermeshing counter-rotating twin screw extruder in the first part of this paper. The 3D Newtonian isothermal flow of normal screw element and pin-barrel element including pins of different numbers, rows, space between two pins on the barrel was simulated. With the numerical simulation of dynamic flow fields by particle tracking analyze method and statistical analyses, residence time distribution and max shear rate distribution were analyzed. The results of numerical analyses showed that intermeshing counter-rotating twin screw extruder with pin-barrel provides better distributive and dispersive mixing than intermeshing counter-rotating twin screw extruder without pin.VCR element was introduced in melting transport zone of intermeshing counter-rotating twin screw extruder in the second part of this paper. The 3D Newtonian isothermal flow of normal double-thread screw element, normal triple screw element and VCR element was simulated. With the numerical simulation of dynamic flow fields by particle tracking analyze method and statistical analyses, residence time distribution and max shear rate distribution were analyzed. The results of numerical analyses showed that normal double-thread screw element has the best dispersive mixing effect and normal triple screw element take the second place, VCR element is the weakest among these mixing elements. The numerical analyses also showed that VCR element has the best distribute mixing effect and normal double-thread screw element take the second place, normal double-thread screw element is the weakest among them.The results of the experiments of the second part of the paper showed that the comparison of the mixing elements is consistent with the numerical analyses. This result also mean that the numerical analyze methods can be applied on the processing of the design of the new mixing elements.