Non-Isothermal Simulation of Melting Process in Twin Screw Extruder Based on Two Typical Screw Configurations

2011 ◽  
Vol 130-134 ◽  
pp. 2273-2279
Author(s):  
Chang Liang ◽  
Bing Luo ◽  
Kui Sheng Wang
Keyword(s):  
Liquid Fraction ◽  
Melting Process ◽  
Melting Zone ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Twin Screw Extruders ◽  
Twin Screw ◽  
Higher Temperature ◽  
Study Heat Transfer ◽  
Screw Extruders

In this study, heat transfer and melting process in a co-rotating twin screw extruder are studied based on two typical screw configurations, screw element and kneading blocks staggered 45°. In order to estimate the melting ability of two configurations quantitatively, FEM software, FLUENT is adopted to simulate the cases. It could be concluded that kneading blocks have higher temperature rise and more liquid fraction than screw element, and it takes less time and less distance for kneading blocks to finish melting. Simulation results also show that kneading blocks have more viscous dissipation than screw element. Therefore, we can come to the conclusion that the kneading blocks are more suitable for the melting zone of co-rotating twin screw extruders.

scholarly journals The Comparison of Water Absorption Analysis between Counterrotating and Corotating Twin-Screw Extruders with Different Antioxidants Content in Wood Plastic Composites

2011 ◽  
Vol 2011 ◽  
pp. 1-4 ◽  
Author(s):  
Mohd Hafizuddin Ab Ghani ◽  
Sahrim Ahmad
Keyword(s):  
Water Absorption ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Wood Plastic Composites ◽  
Twin Screw Extruders ◽  
Plastic Composites ◽  
Study Results ◽  
Significant Difference ◽  
Twin Screw ◽  
Screw Extruders

Water absorption is a major concern for natural fibers as reinforcement in wood plastic composites (WPCs). This paper presents a study on the comparison analysis of water absorption between two types of twin-screw extruders, namely, counterrotating and corotating with presence of variable antioxidants content. Composites of mixed fibres between rice husk and saw dust with recycled high-density polyethylene (rHDPE) were prepared with two different extruder machines, namely, counterrotating and corotating twin screw, respectively. The contents of matrix (30 wt%) and fibres (62 wt%) were mixed with additives (8 wt%) and compounded using compounder before extruded using both of the machines. Samples were immersed in distilled water according to ASTM D 570-98. From the study, results indicated a significant difference among samples extruded by counterrotating and corotating twin-screw extruders. The counterrotating twin-screw extruder gives the smallest value of water absorption compared to corotating twin-screw extruder. This indicates that the types of screw play an important role in water uptake by improving the adhesion between natural fillers and the polymer matrix.

Analysis on Melting Mechanism in the Cross Section of Co-Rotating Twin Screw Extruder

2012 ◽  
Vol 548 ◽  
pp. 571-575
Author(s):  
Chang Liang ◽  
Kui Sheng Wang ◽  
Bing Luo
Keyword(s):  
Viscous Dissipation ◽  
Cross Section ◽  
Liquid Fraction ◽  
Melting Process ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Solid Materials ◽  
Positive Displacement ◽  
Twin Screw ◽  
Hot Melt

In this paper, melting process in a co-rotating twin screw extruder was studied based on two dimensional melting model of flow field cross section. Positive displacement conveying characteristic in the melting section was assumed and melting process of each section was regarded as the result of time evolution. Procedure of melting was analyzed according to experiments and numerical simulations, both indicating that solid materials in the flight zones would melt firstly and carcass wrapped in the middle of melt would be molten finally. Liquid fraction contours showed that flow of hot melt played an important role in the melting process of cross section. Four types of melting mechanisms were summarized, in which viscous dissipation heat was discussed in detail, showing that viscous dissipation contributed about 10%-30% to the total energy needed during melting. Screw speed affected viscous dissipation significantly, while heating flux of barrel had little influence on it.

Plasticating Single-Screw Extrusion

2006 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Solid Polymer ◽  
Heat Of Fusion ◽  
Screw Extruder ◽  
Twin Screw Extruders ◽  
Single Screw ◽  
Single Screw Extrusion ◽  
Single Screw Extruder ◽  
Single Screw Extruders ◽  
Twin Screw ◽  
Screw Extruders

There are two types of extruder: (1) single-screw extruders and (2) twin-screw extruders. The single-screw extruder is one of the most important pieces of equipment in the processing of thermoplastic polymers. Accordingly, during the past three decades, many attempts have been made to analyze the performance of single-screw extruders using different degrees of mathematical sophistication (Cox and Fenner 1980; Donovan 1971; Edmondson and Fenner 1975; Elbirli et al. 1983, 1984; Halmos et al. 1978; Han et al. 1991a, 1991b, 1996; Lee and Han 1990; Lindt 1976; Lindt and Elbirli 1985; Shapiro et al. 1976; Tadmor 1966; Tadmor and Klein 1970; Tadmor et al. 1967). There are two types of single-screw extruders: (a) plasticating and (b) melt-conveying. The plasticating single-screw extruder conveys a solid polymer from the feed section to the melting section, where most of the melting (or softening) occurs, and then transports the melted or softened polymer to a shaping device (e.g., dies and molds). The meltconveying extruder does not include a melting section; it simply transports an already softened polymer to a shaping device (e.g., rubber extruder). Single-screw extruders are used for various purposes, such as melting and pumping, compounding with an additive(s) or filler, cooling and mixing, removing residual monomers or solvents in polymer (i.e., polymer devolatilization), and cross-linking reactions. Single-screw extruders are simple to operate and relatively inexpensive as compared with twin-screw extruders. However, there are situations where a single-screw extruder cannot function as effectively as a twin-screw extruder. In the design of plasticating single-screw extruders, one needs information on (1) the physical and thermal properties of polymers (e.g., friction coefficient between the solid polymer and barrel wall, thermal conductivity of polymer, specific heat as a function of temperature, melting point of polymer, and heat of fusion of polymer) and (2) rheological properties of polymers as functions of shear rate and temperature. Due to the complexity involved in the design of extruders, it is highly desirable for one to establish relationships between material variables and processing variables.

Steady and Transient Flow of a Non-Newtonian Chemically Reactive Fluid in a Twin-Screw Extruder

2001 ◽  
Author(s):  
W. Zhu ◽  
Y. Jaluria
Keyword(s):  
Steady State ◽  
Response Time ◽  
Transient Flow ◽  
Transient Behavior ◽  
Operating Conditions ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Twin Screw ◽  
Calculated Velocity ◽  
Screw Extruders

Abstract The flow of chemically reactive non-Newtonian materials, such as bio-polymers and aciylates, in a fully intermeshing, co-rotating twin-screw extruder is numerically investigated. A detailed study of the system transient behavior is carried out. The main transient aspects, including response time, variation of system variables, and instability of operation, are studied for both single- and twin-screw extruders. The effect of a time-dependent variation in the boundary conditions is studied. The coupling due to conduction heat transfer in the screw barrel is found to be very important and is taken into account for single-screw extruders. In the absence of this conjugate coupling, the response time is much shorter. Several other interesting trends are obtained with respect to the dependence of the transient response on the fluid, materials, and operating conditions. Steady state results are obtained at large time. The calculated velocity distributions in the screw channel are compared with experimental results in the literature for steady state flow and good agreement has been obtained. The numerical results show that not all desired operating conditions are feasible. The calculated results for transient transport agree with the few experimental observations available on this system. These results will be useful in the design, control and optimization of polymer extrusion processes.

scholarly journals Experimental and Numerical Simulation Study of Devolatilization in a Self-Wiping Corotating Parallel Twin-Screw Extruder

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2728
Author(s):  
Masatoshi Ohara ◽  
Yuya Sasai ◽  
Sho Umemoto ◽  
Yuya Obata ◽  
Takemasa Sugiyama ◽  
...  
Keyword(s):  
Surface Area ◽  
Flow Rate ◽  
Volatile Component ◽  
Volatile Components ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Surface Renewal ◽  
Twin Screw Extruders ◽  
Renewal Model ◽  
Twin Screw

Devolatilization is an important process for separating and removing unnecessary residual volatile substances or solvents during the production of polymers using twin-screw extruders. Latinen proposed a surface renewal model to determine the concentration of volatile components in the extrudate of a single-screw extruder. When a twin-screw extruder is used to calculate the concentration, it is necessary to use the exposed surface area of the resin in the starved region of Latinen’s model, which, however, is difficult to estimate. In our previous work, we numerically determined resin profiles of the screws using the 2.5D Hele–Shaw flow model and the finite element method, which helps in estimating the surface area of devolatilization. In this study, we numerically analyzed the volatile concentration of the extrudate in a self-wiping corotating twin-screw extruder using Latinen’s surface renewal model along with our resin profile calculation method. The experimental results of the concentrations of the volatile component (toluene) in the extrudate of polypropylene agreed well with its numerical calculation with a relative error of 6.5% (except for the data of the lowest rotational speed). Our results also showed that decreasing the flow rate and increasing the pump capacity were effective for removing the volatile component. The screw pitch of a full-flight screw was not affected by the devolatilization efficiency with a fixed flow rate and screw speed.

Approach to develop a screw configuration for compounding solid fillers on a twin screw extruder using the example of polyethylene-layered silicate masterbatches

2011 ◽  
Vol 31 (5) ◽  
Author(s):  
Walter Michaeli ◽  
Athanassios Elas ◽  
Florian Puch
Keyword(s):  
Material Properties ◽  
High Density Polyethylene ◽  
Layered Silicate ◽  
Practical Method ◽  
Screw Extruder ◽  
Twin Screw Extruders ◽  
Twin Screw ◽  
Number Of Publications ◽  
Available Information ◽  
Screw Extruders

Abstract The high potential of layered silicate improving material properties of plastics has been discussed in a significant number of publications. However, homogeneously dispersing it with twin screw extruders is demanding. Available information on optimum screw configuration is contradictory. In this investigation, we develop a practical method for individually designing and optimising extruder sections. This method is applied for designing extruder sections for compounding masterbatches of high-density polyethylene and layered silicate. We found out that for best dispersion, dispersing sections should only be partially filled with melt. Thus, only right-handed kneading elements should be applied.

Numerical Simulation of Mixing Performance of Intermeshing Co-Rotating Tri-Screw and Twin-Screw Extruders

2012 ◽  
Vol 468-471 ◽  
pp. 2211-2214 ◽  
Author(s):  
G. Wang ◽  
X.Z. Zhu ◽  
Chun Yi Sun
Keyword(s):  
Shear Rate ◽  
Polymer Melt ◽  
Polymer Processing ◽  
Mixing Efficiency ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Twin Screw Extruders ◽  
Mixing Performance ◽  
Twin Screw ◽  
Dispersive Mixing

Parallel arranged tri-screw extruder (PATSE) is a new machine of polymer processing and first manufactured in recent years in China. Compared with the traditional twin-screw extruder, PATSE adds a screw, and added an intermeshing region. It is well known that material going though intermeshing region will acquire higher shear rate and stretching rate, which is beneficial to mixing processing. In order to know the mixing performance in cross-section for PATSE, polymer melt flow field simulation and mixing simulation were conducted on PATSE with 2D model and a Carreau flow model to evaluate velocity profiles, particle trajectories, max shear rate, max stretching rate, dispersive mixing, distributive mixing, segregation scale, length of stretch, mixing efficiency with the commercial CFD package Polyflow and compared with those of twin screw extruder (TSE). The results show that PATSE has better mixing performance than TSE.

Simulation and Experiment of the Motion Characters in Twin-Screw Extruder

2015 ◽  
Vol 799-800 ◽  
pp. 528-532
Author(s):  
Li Xue Zhu ◽  
Hong Yu Wei ◽  
Shao Ming Luo ◽  
Chun Fang Zhao
Keyword(s):  
Fluid Flow ◽  
Flow Field ◽  
Velocity Distribution ◽  
Melting Process ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Distribution Rules ◽  
Twin Screw ◽  
Simulation And Experiment

In the paper, a velocity and fluid flow status of the melting process in twin-screw extruder were analyzed. To explore the optimum producing parameters of expanding food, several models of the flow field and velocity of twin-screw extruder were created with fake plastic Newton fluid. Then the velocity distribution rules in the cavity space were simulated. With the valuable verification of experiments, the results showed that, the velocity distribution near the inner wall is uniform, and increases at the delivery of the extruder. The velocity rises in the teeth root than in the top of the screws. At the mesh field, the velocity was changed frequently. The experiment of popped extrusion verified the simulation conclusion.

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