Energy Transfer screws

Several different designs are available at the entry to the ET and VBET sections depending on the application. 

Extrudate samples from a melting-mixing experiment were also collected for the ET screw at screw speeds ranging from 30 to 150 rpm using the experimental method described in Section 8.4.1. The ET screw used was the 63.5 mm diameter 

The same ET section of the screw used for the Maddock solidification and cross-sectional views was numerically simulated using an LDPE resin at a screw speed of 

Similar particle releases are shown for views perpendicular to the screw axes by Fig. 14.13. The particles in these views are spaced evenly with time, and thus more space between the particles indicates higher velocities. The spacing, however, is 

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The first wave-dispersion-type screw was developed and patented by Kruder in 1975 [18], and the device was trademarked as the Wave screw. Numerous other wave dispersion screws were developed later based on Kruder s design. The term wave dispersion screw refers to screws with metering sections that have two or more channels with a flight between them that is selectively undercut to allow the dispersion of solid polymer fragments and molten resin. Several commercially available screws utilize this type of technology and are discussed in this section. These screws include Double Wave screws, Energy Transfer screws. Variable Barrier Energy Transfer screws, DM2 screws, and Fusion screws. 

In variable depth mixers, the channel depth of the mixer is varied to obtain improved mixing. An example of a variable depth mixer is the double wave screw shown in Fig. 8.81 and the energy transfer screw see Fig. 12.23. Another example is the Pulsar mixing section shown in Fig. 8.103. 

Figure 7.23 Energy transfer and VB energy transfer screws. (Reproduced with permission from J.A. Myers and R.A. Barr in Proceedings of the 60th SPE Annual Conference - ANTEC 2002, San Francisco, CA, USA, 2002, Paper No.251.

In blown film trials comparing a barrier screw and an energy transfer screw, and VB energy transfer screw, the latter outperformed the others in the extrusion of LLDPE and LLDPE blends with regards to both output rate and melt temperature. The extruder screw was 88.9 mm diameter, with 30 1 L/D. 

Figure 5.16 Heat flux response for HIPS. The positive heat flux show/n here is for energy transferred from inside of the barrel to the outside. The discharge pressure and screw speed were maintained at 1 MPa and 50 rpm, respectively...

The heat transferred through the barrel wall over the channel, Ej, is given by Eq. 7.83. A heat transfer expression could also be written for energy transferred from the molten polymer to the barrel over the flight iand and also from the melt to the screw surface. 

Two screws were designed with Energy Transfer (ET) sections from Robert Barr, Inc. [31], and the screws were labeled by Dow as ET-1 and ET-2. The original... 

Figure 14.2 Schematic for an Energy Transfer (ET) screw (courtesy of Jeff A. Myers of...

Somers, S.A., Spalding, M.A., Dooley, J., and Hyun, K.S., Numerical Analysis of the Thermal Mixing Effects of an Energy Transfer (ET) Screw Section, SPE ANTEC Tech. Papers, 41, 222 (1995)... 

Four-Channel Energy Transfer Cooling Screws... 

Plastification of polymeric material requires energy to be transferred from an outside source into the material. In the twin-screw extruder, this energy transfer occurs through both mechanical and thermal mechanisms. However, as the extruder gets larger, the surface to volume ratio decreases significantly. Therefore, mechanical energy transfer is the dominant mechanism for plastification. 

The percussive effect of high intensity vibrations generated in an extruded polymer melt can be influenced by ultrasonic oscillations. The periodic shift in the pressure generated by the action of the screw affects the processed material and the energy transferred to the... 

In the screw preheat zone in particular, and at the onset of plastification, microwave technology offers promising solutions to the process engineering problems in extruder design mentioned above. Energy transfer in this technology does not involve heat conduction and makes for an efficient transfer of energy into the compacted bulk powder materials with poor heat conductance properties present in the extrude in this phase of the plastification process (For details, see Diemert [20]). 

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