(Microsoft Word - \343\355 \346\323\307\343\355 \346\324\320\35472-82) Al-Khwarizmi Engineering Journal Al-Khwarizmi Engineering Journal, Vol. 14, No. 4, December, (2018) P.P. 72- 82 Experimental and Numerical Investigation for Simulation of Thermophysical Properties for Polypropylene 575 Polymer Melts in Single Screw Extruder May M. Ismail* Sami D. Salman** Shatha K. Muallah*** *,**,*** Department of Biochemical Engineering / Al-Khwarizmi College of Engineering /University of Baghdad *Email: maymunir766@gmail.com **Email: sami.albayati@gmail.com ***Email: shatha_engr@yahoo.com (Received 13 February 2018; accepted 15 April 2018) https://doi.org/10.22153/kej.2018.04.003 Abstract A numerical model for Polypropylene 575 polymer melts flow along the solid conveying screw of a single screw extruder under constant heat flux using ANSYS-FLUENT 17.2 software ha s been conducted. The model uses the thermophysical properties such as Viscosity, thermal conductivity, Specific heat and density of polypropylene 575 that measured as a function of temperature, and residence time data for process simulation. The numerical simulation using CFD models for single screw extruder and the polymer extrusion was analysed for parameters such as (thermal conductivity, specific heat, density and viscosity) reveals a high degree of similarity to experimental data measured. The most important outcome of this study is that geometrical, parameter and conditions have been obtained from the simulation used to minimize the size, cost and time of operation for extruder. Keywords: Ansys Fluent, CFD, Single Screw Extruder, Numerical Simulation, Polymer melt, Polypropylene575, Solid Works, Thermophysical properties. 1. Introduction The production procedure of polymer slides begins in an extruder, where extrusion is a process of production long products of Constant cross- section (sheets, rods, pipes, wire insulation, coating films). Identifying of rheological behaviour for polymers is necessary for finding the best or most favourable situation of melt processing, like temperature, rate of flow, and for estimating the desirable machine capacity [1]. Many different laws have been used to describe the flow of these complex material such as power law, Bingham law, Bird-Carreau law and Carreau-Yasuda law [2]. Simulation software is applied to enhance the turnaround times, productivity, quality, and resource employment in polymer processing. However, the feasibility of a simulation software is extremely dependent on the reliability of the material data and models in its database, the skilfulness of the employer, and on the understanding of the material behaviour [1]. This study deals with the single screw extruder design for polymeric processing using (CFD) software ANSYS FLUENT 17.2, while the geometrical creation by using SOLID WORKS 2016 [2]. Fig. (1) Show the commercial single screw extruder and Fig. (2a) Show the schematic diagram of single screw extruder. May M. Ismail Al-Khwarizmi Engineering Journal, Vol. 14, No. 4, P.P. 72- 82 (2018) 73 Fig. 1. Single screw extruder equipment (SJ30 / 28). Fig. 2a. Schematic diagram of the extruder. 2. a Experimental Setup Fig. 2b. Schematic diagram of the extruder with setup details. 2. b Experimental Work The experiments were carried out to study the effects of thermophysical properties such as (viscosity, thermal conductivity, specific heat and density) for Polypropylene 575 through single screw extruder at a different flow rate, variable rpm and constant heat flux (7803.571 w/m2), to see more details show Fig. (2b). The physical and thermophysical properties of the polymer were measured as a function of temperature by (AR-G2) rotational rheometer, (plate-plate) geometry [3, 4] (TCi thermal conductivity analysers), and DSC equipment [5]. The data obtained from this equipment was used as polynomial equation then employed as input data for simulation process as illustrated in the equations (A-D) below. Fig. (3) Shows the experimental behaviour of thermophysical properties for polypropylene 575 at different temperature. µ = 0.2905T2 - 294.5T + 76012 ... (a) K = 8E-06T2 - 0.0081T + 2.2014 ... (b) Cp = -0.1036T2 + 102.73T – 22458 ... (c) ρ = -0.0184T2 + 17.98T - 3491.1 ... (d) In addition, the laboratory experiments were carried out on the laboratory extruder as illustrated in Fig. (1). The experiments were conducted using Chinese extruder in Babil governorate, this part of the work involves conducting the practical experiments on the polypropylene 575 and simulating these experiments, then validates the results with the experimental work, table (1) Shows the overall data of single screw extruder. May M. Ismail Al-Khwarizmi Engineering Journal, Vol. 14, No. 4, P.P. 72- 82 (2018) 74 (a) (b) (c) (d) Fig. 3. The thermophysical properties of polypropylene 575 at different temperature. (a)Viscosity. (b) thermal conductivity. (c) Specific heat. (d) Density. Table 1, Overall data for the practical part of single screw Extruder. 3. Polymer Used In this research, polypropylene 575 was used because it has a good mechanical and physical properties, such as an excellent insulator, therefore, it was used in an electrical industry, melting point ranging between (157-171) ℃, and in clinical filed due to low moisture absorption [6]. As well as polypropylene 575 is strongly influenced by the length and size of chain likewise increasing the length of chain which leads to enhancing melting point temperature because of increasing the joint between the chains [7,8]. Total feed in Kg m Total feed rate Kg/s N Screw Speed rpm Heat flux inlet W/m2 Heat flux outlet W/m2 Temperature of inlet polymer °C Temperature of polymer outlet °C Setting Temperature °C 0.25 1.812*10-4 10 7803.571 7203.57 23 157 160 0.25 2.193*10-4 20 7803.571 7626.1 23 153 160 0.25 3.472*10-4 30 7803.571 7633.48 23 148 160 0.25 5.952*10-4 40 7803.571 7750 23 143 160 0.5 2.6*10-4 10 7803.571 7201.72 23 178 180 0.5 3.33*10-4 20 7803.571 7310.335 23 175 180 0.5 4.39*10-4 30 7803.571 7540.455 23 171 180 0.5 5.56*10-4 40 7803.571 7575.45 23 168 180 May M. Ismail Al-Khwarizmi Engineering Journal, Vol. 14, No. 4, P.P. 72- 82 (2018) 75 4. Simulation Process Based on practical experiments, it is know that the increasing usage of (CFD) packages Computational Fluid Dynamics to study the flow of complex melting polymer in different processing and complex devices need some usable material modelling technique. For this purpose, it is necessary to study the model describing the behaviour of polymer melting specifically. As well as, the commercial CFD packages supply only some liner model such as (the model of the linear viscous body for viscous fluids) [9, 10]. For incompressible fluids, all CFD packages simulation started from the governing equations for continuity and momentum [11]. The arithmetical models using the commercial CFD software’s (SOLID WORKS 2016) for model creation, table (2) shows the dimensions of single screw extruder and (ANSYS FLUENT 17.2) used and evaluated against the experimental findings to validate the observed results. Three steps of the CFD Simulation Process including pre-processing, solving and post-processing steps are followed to analyse the fluid flow and heat transfer model. Pre- processing is the first stage in analysing and building a CFD model which taking place before the numerical solution process. In this step, the model geometries of single screw extruder were created and identified based on the boundary types, then the domain of benefits was divided into smaller segments which known as a grid (mesh) generation. This stage is the most important and the most time-consuming step in the CFD process. ANSYS FLUENT meshing has been used as a result of its simplicity and flexibility in application [12]. While in the solver step, the definition of material, operating conditions and boundary condition at an inlet, outlet, and across the whole fluid flow were selected. Pressure-based solver (PBCS) was selected to solve the governing equations for heat transfer and flow. The PBCS solver can be used for a broad range of flow regimes from low-speed incompressible flow to high-speed compressible flow and hence was selected. The precise identification of the properties, parameters, the appropriate models for the solution methods, accuracy and convergence are very important factor to get a realistic solution [13]. As well as post-processing is the last step of the CFD process where the results with their parameters can be extracted and analysed using meaningful graphics, vector plots, contour plots, animations and reports. Numerous of commercial post-processing packages are available to view results for analysis [14]. Table 2, Dimension of screw. 5. Assumption for Simplification of Model The assumptions which were considered for simulation the model are as following: (i) The polymer fluid was assumed as Non-Newtonian having a pseudo plastic characteristic and incompressible fluid, (ii) The fluid flow was assumed as a laminar flow due to the rpm of screw was very low and there is no slippage between fluids and the cylinder wall, (iii) The heat flux was assumed constant with negligible radiation effects, (iv) The particles were presumed to be spherical and single phase model was used, and (v) The thermos-physical properties of fluids were variable with temperatures [15]. The following governing equations for cylindrical coordinates have been used for simulation [16]. Continuity equation: ( ) ( ) ( ) 1 1 0 r v r v t r r r v z z ρ ρ θρ θ ρ ∂ ∂∂ + + ∂ ∂ ∂ ∂ + = ∂ … (1) Momentum equation: 2 22 2 2 2 2 ( ) 1 [ ( ( )) 1 2 ] r r r r r z r r r v t r r z r p r r r r r r g r z r θ θ θ νν ν ν ν ρ ν ν θ µ ν ννν ρ θ θ ∂ ∂ ∂ ∂ + + ⋅ + − = ∂ ∂ ∂ ∂ ∂ ∂ ∂ − + ⋅ ∂ ∂ ∂ ∂∂∂ + ⋅ + − ⋅ + ∂ ∂ ∂ … (2) Extruder length(mm) L/D Ratio Shaft diameter(mm) Screw diameter(mm) Cylinder diameter(mm) Pitch (mm) Screw speed(rpm) Weight capacity(Kg) 1000 28 14 30 35.7 25 10-40 1-8 May M. Ismail Al-Khwarizmi Engineering Journal, Vol. 14, No. 4, P.P. 72- 82 (2018) 76 2 2 2 2 2 ( ) 1 [ ( ) 1 ] z z z z z z z z r z t r r z vp r z r r r g r z ν νν ν νθ ρ ν ν θ µ ν ν ρ θ ∂ ∂∂ ∂ + + ⋅ + = ∂ ∂ ∂ ∂ ∂∂ ∂ − + ⋅ ⋅ + ∂ ∂ ∂ ∂ ∂ ⋅ + + ∂ ∂ … (3) Energy equation: 2 1 1 T T C p k r t r r r T T k k g r z z ρ ϕ ϕ ∂ ∂ ∂ = + ∂ ∂ ∂ ∂ ∂ ∂ ∂ + + ∂ ∂ ∂ ∂                 … (4) 6. Results Temperature Contour planes were displayed illustrated in the following figuers. Fig. (4) A-D at heat flux of 7803.571 W/m2 and 250 gm as a weight and Fig. (8) A-D but at 500 gm as a weight, represents Contour planes of the temperature distribution along the extruder with revolution per minute ranging between (10-40) rpm. Increase rpm led to reduction in residance time, which affects the heating of polypropelene 575 material within the extruder.It can also be observed that the temperature of the material increased to a certain extent inside the extruder and then decreased very slightly in few degrees before the material started to exit out of extruder .This is can be seen clearly, especially when the rpm increased, where the loss in temperature increased. Also it can be inferred that temperature of polymer near the screw surface and near the barrel wall is the highest. The polymer material in the middle has lower temperature [15]. Fig. (5) A-D at a heat flux of 7803.571 W/m2 and 250 gm as a weight and Fig. (10) A-D with 500 gm as a weight, represent Contour planes of the density behavior along the extruder at rpm ranging between (10-40). Where increasing temperature led to increase density to a certain extent, this is observed especially when increasing the rpm. Because of the interstitial materials that contain air between their granules, it is known that by increasing the temperature leads to an increase in the density of these materials, because when the temperature increases these grains begin to melt, which leads to reducing the volume with the mass constant, thus led to increase density [17]. Fig. (6) A-D at heat flux 7803.571 W/m2 and 250 gm as a weight and, Fig. (11) A-D but with 500 gm as a weight, represent Contour planes of the viscosity behavior along the extruder at rpm ranging between (10-40). Where Increase temperature led to decreasing the viscosity and this is clearly observed in the practical results when the viscosity decreased by increasing the temperature. Fig. (7) A-D at heat flux 7803.571 W/m2 and 250 gm as a weight, and Fig. (12) with 500 gm as a weight, represent Contour planes of the thermal conductivity behavior along the extruder at rpm ranging between (10-40). Where increasing the temperature led to slightly decreasing in thermal conductivity because of polymeric materials used as an insulator. The phonon transport is the main mechanism for interaction of heat energy with each other and with subatomic particles [18]. Drag Phonon is the increase in effective mass of electrons conduction or valence holes due to interactions with crystal lattice in moving the electron. As an electron moves the past atoms in the lattice, its polarizes or charge distorts the nearby lattice. This effect leads to an electron decrease (as may be the case, hole) mobility, which results in a thermal conductivity decreased [19]. Fig. (8) A-D at heat flux 7803.571 W/m2 and 250 gm as a weight, and Fig. (13) A-D with 500 gm as a weight, represent Contour planes of the specific heat behavior along the extruder at rpm ranging between (10-40). Where increasing the temperature led to increase in specific heat. Specific heat capacity is a measuring of substance ability to absorb heat. The heat first goes to increase the kinetic energy of the molecules. These molecules also can store energy in rotation and vibration. As heats up the substance, the average kinetic energy of molecules increases. The collisions impart energy enough to allow rotation occur. Then rotation contributes to internal energy and raises the specific heat capacity of material [20]. It is clearly shawn in Fig. (14 & 15) a, b, c, & d that a significant matching between the experimental results and the results of process simulations with a slight difference. This difference resulting from the degree of complexity of the form "Single screw extruder" and the process of mesh generation. May M. Ismail Al-Khwarizmi Engineering Journal, Vol. 14, No. 4, P.P. 72- 82 (2018) 77 Fig. 4. Temperature Contour plane at 250 gm. Fig. 5. Density Contour plane at 250 gm. Fig. 6. Viscosity Contour plane at 250 gm. Fig. 7. Thermal conductivity Contour plane at 250 gm. Fig. 8. Specific heat Contour plane at 250 gm. Fig. 9. Temperature Contour plane at 500 gm. May M. Ismail Al-Khwarizmi Engineering Journal, Vol. 14, No. 4, P.P. 72- 82 (2018) 78 Fig. 10. Density Contour plane at 500 gm. Fig. 11. Viscosity Contour plane at 500 gm. Fig. 12. Thermal conductivity Contour plane at 500 gm. Fig. 13. Specific heat Contour plane at 500 gm. (a) (b) May M. Ismail Al-Khwarizmi Engineering Journal, Vol. 14, No. 4, P.P. 72- 82 (2018) 79 (c) (d) Fig. 14. Thermophysical properties of polypropylene 575 for experimental and simulation results at different temperature (a)Viscosity, (b) thermal conductivity, (c) Specific heat, (d) Density. (a) (b) (c) (d) Fig. 14. Thermophysical properties of polypropylene 575 for experimental and simulation results at different temperature (a) Viscosity, (b) thermal conductivity, (c) Specific heat, (d) Density. May M. Ismail Al-Khwarizmi Engineering Journal, Vol. 14, No. 4, P.P. 72- 82 (2018) 80 7. Conclusion The numerical values showed closer fitting to the experimental values in the extruder. Where viscosity and thermal conductivity decreased with increasing temperature along the extruder. While the specific heat and density increased with temperature increased along the extruder. Consequently, this study was successfully validated by CFD simulation for single screw extruder. Acknowledgments The authors would like to thank Al-Furat General Company for Chemical Industries and Pesticides, in Babil governorate for serving and helpful work in the laboratory. 8. References [1] Johanna Aho, "Rheological Characterization of Polymer Melts in Shear and Extension : Measurement Reliability and Data for Practical Processing", A Ph.D thesis for the degree of Doctor of Materials Science inTampere University of Technology, Finland, ISSN1458-8045, (2011). [2] Ram Y. and Chumporn N., "Finite Element Modeling for the Design of a Single Screw Extruder for Starch-Based Snack Products", vol. III, pp. 8–11, (2010). [3] Shatha K. Muallah, "Experimental Determination of the Elastic and Viscous Behavior of Polycarbonate Melts at Different Temperatures and Their Relationship to the Steady State Viscosity via the Cox-Merz Rule", Iraqi J. Chem. Pet. Eng., vol. 15, no. 2, pp. 49–59, (2014). [4] Shatha K., Sami D. and May M., "Experimental Investigation on Rheological Characterization of ecovio ® F Film C2203biopolymer Melts", International J. of Research and Scince, vol. 6, no. 9, pp. 1247– 1254, (2017). [5] M. Kuzmanovi, L. Delva, L. Cardon, and K. Ragaert, "The Effect of Injection Molding Temperature on the Morphology and Mechanical Properties of PP / PET Blends and Microfibrillar Composites". pp. 3–18, (2016). [6] Ammar Al-Baldawi, S. K. M. and O. W., "Thermo-Rheological Investigation and Modeling of the Shear Viscosity of Polypropylene above the Melting Temperature",Al-Khwarizmi Eng. J., vol. 9, No. 4, pp. 12–23, (2013). [7] C.Maier, T.Calafut, "Polypropylene: The definitive user`s guide and data book", ISBN: 9781-1-884207-58-7, Plastic design Library, New York (1998). [8] R. Zhuet et al, "Microstructure and mechanical properties of Polypropylene/Poly (methyl methacrylate)Nano composite prepared using Supercritical carbon dioxide", Macromolecules, 44, 6103-6112 (2011). [9] A. Al-Baldawi, H. Damanik, S. Turek, and O. Wuensch, "Comparison of Improved FE/FV Methods in the Context of Simulating Jet Extrusion Processes", Proceedings of the 1st Int. Con. on Thermo-Mechanically Graded Materials, ISBN: 978-3-942267-58-8, 225- 230 (2012). [10] A. Al-Baldawi and O. Wünsch, "Simulating of a pressing process of a viscoelastic polymer melt, Proceedings in Applied Mathematics and Mechanics", 12, 471-472 (2012). [11] A. Al-Baldawi, "Modellierung und Simulation viskoelastischer Polymerschmelzen", ISBN: 978-3-89958- 598-8, Kassel University Press, Kassel (2012). [12] Steffe, J. F., "Rheological Methods in Food Process Engineering", 2nd Edition: Freeman Press, East Lansing, Michigan, (1996). [13] Eesa, M. and Barigou, M., "Enhancing radial temperature uniformity and boundary layer development in viscous Newtonian and non- Newtonian flow by transverse oscillations": A CFD study. Chemical Engineering Science, 65(6), 2199-2212, (2010). [14] Tian S., "CFD Modeling Of Oscillatory Perturbed Advection In Viscous Flows", A Ph.D thesis, School of Chemical Engineering, The University of Birmingham, (2015). [15] Manohar Baalaganapathy and Periasamy C., "Computational Fluid Dynamics Simulation of Single Screw Extruders In Cable Industries ". International Journal of Research in Engineering and Technology 5 (3): pp. 85–89, (2016). [16] R. B. Bird, W. E. Stewart, and E. N. Lightfoot, “Transport Phenomena”, Hand book, 2nd edition, Wiley: NY, (2002). [17] Jinping Qu, Baoshan Shi, and Hezhi He, "Influence of Vibration on Density of Polymer Solid Granules in Single Screw Extruder". Polymer Plastics Technology and Engineering, 46: pp. 233–237. doi: 10.1080/03602550601152911, (2007). [18] I.A. Tsekmes, R. Kochetov, P.H.F. Morshuis, and J.J Smit, "Thermal Conductivity of May M. Ismail Al-Khwarizmi Engineering Journal, Vol. 14, No. 4, P.P. 72- 82 (2018) 81 Polymeric Composites: A Review", IEEE International Conference on Solid Dielectrics, Bologna, Italy, pp. 678–681, (2013). [19] Kittel Charles, "Introduction to Solid State Physics", 7th Ed., John Wiley and Sons, Inc. (1996). [20] Vargha- Butler, A. Wilhelm and Hasan A., "Specific heats of polymer powders by differential scanning calorimetry". Traduit par le journal, Vol. 60: pp. 1853–1856, (1982). )2018( 72-82، صفحة 4د، العد14دجلة الخوارزمي الهندسية المجلم مي منير اسماعيل 82 وليبروبيلين التحقيق التجريبي والعددي لمحاكاة الخصائص الحرارية الحرارية للبوليمر الذائب ب البرغي الواحد يفي الطارد ذ ٥٧٥ ***شذى كاظم معله **سامي داوود سلمان *مي منير اسماعيل جامعة بغداد /كلية الهندسه الخوارزمي /ةاالحيائي ةالكيميائي ةقسم الهندس*،**،*** maymunir766@gmail.com :البريد االلكتروني* sami.albayati@gmail.com :البريد االلكتروني** shatha_engr@yahoo.com :البريد االلكتروني*** الخالصة الذي يتدفق على طول الطارد الذي يكون ذا مسمار مفرد تحت كمية حرارة معلومة ، معدل تدفق ٥٧٥النموذج العددي للبوليمر الذائب بولي بروبلين ). يستخدم النموذج الخصائص الريولوجية للبوليمرالذي TNEULF-SYSNA ١٧٫٢ه بأستخدام برنامج (ؤدورة بالدقيقة مختلفة حيث تم اجرامتغير، وكذلك و ارة) لمعامالت مثل درجة الحرDFCدالة لدرجة الحرارة لمحاكاة العمليات التجريبية. حيث تم تحليل نتائج المحاكاة العددية بأستخدام نموذج (بوصفه يقاس حد النتائج المهمة لهذا البحث أالتوصيليه الحرارية وكذلك الكثافه حيث اثبتت درجة عالية من التشابه مع البيانات التجريبية المقاسة. وو الكثافه النوعيةو اللزوجة تم الحصول على الشكل الهندسي وتحديد ظروف العمل لتقليل التكلفة ووقت التشغيل.