共查询到17条相似文献,搜索用时 199 毫秒
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目的:提高单螺杆挤出机的混合性能和工作效率.方法:设计了一种利用行星轮组件和混合元件的同轴渐加速单螺杆,利用Ansys/cfx对其流道进行了三维流场分析,得到了宏观压力场、速度矢量图、速度流线图以及轴向速度变化曲线并与传统单螺杆进行了对比,结果:随着螺杆转速的不断变大,物料在机筒内停留时间变短,渐加速螺杆的挤出效率得以提高20%~25%,使得耗能大大减少,由于捏合块的存在,物料在捏合块处被反复挤压,使得渐加速型单螺杆在增加产能的同时混合性能又可以得到保证.结论:同轴渐加速单螺杆高速旋转的捏合块可使物料混合更充分,且能缩短物料在螺杆中的停留时间,提高产量. 相似文献
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针对普通单螺杆挤出机剪切混合模式单一、工作性能差等问题,研究设计一种新组合型单螺杆。采用SolidWorks建模,ANSYS/CFX有限元分析和对比试验的方法;形成新组合型单螺杆流道整体压力差高于传统单螺杆1.22 MPa左右,物料在进出强剪切段过程中有回流产生,强剪切段物料输送速度较传统单螺杆加快0.012 m/s左右的结果;得出新组合型单螺杆挤出机在80?160 r/min的转速下,物料停留时间较传统单螺杆挤出机缩短5%?12%的试验结论。研究为高性能单螺杆挤出机的优化创新提供理论依据。 相似文献
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为了明确和量化同向全啮合双螺杆挤出机各螺杆元件的功能,增加配置用于生产植物基肉双螺杆挤出机螺杆的合理性,以低温脱脂花生蛋白粉的物性参数为条件,对SLZ36型挤出机的3种元件长度为32 mm的螺杆元件双头螺旋元件、5啮合盘啮合元件及3齿形盘齿形元件的剪切速率、混合指数、物料停留时间、最大剪切应力分布进行仿真分析。采用Solidworks软件建立元件的几何模型,应用Gambit软件进行模型的网格划分及网格质量分析,在Polyflow软件中进行数值模拟,通过Fieldview软件对仿真结果进行后处理分析。结果表明:通过混合指数分析得到3种螺杆元件对物料的混合性能大小为齿形元件>啮合元件>螺旋元件;通过物料停留时间分析得到3种螺杆元件的轴向混合性能大小为齿形元件>螺旋元件>啮合元件;通过剪切速率及平均最大剪切应力分析得到对物料的剪切性能大小为啮合元件>螺旋元件>齿形元件。进行植物基肉双螺杆挤出机螺杆组合时,针对目前整个螺杆配置螺旋元件最多的情况,在进行物料更换时可以合理地配置啮合元件以增加螺杆剪切能力,配置齿形元件以增加螺杆的混合能力。 相似文献
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目的:探究啮合同向双螺杆挤出机不同螺杆构型对流场的影响,改善聚乳酸的材料性能。方法:应用Solidworks软件建立双头螺纹元件的几何模型,在Polyflow中进行数值模拟,借助Fieldview软件对仿真结果进行后处理分析,并对比剪切速率场、压力场、速度场、黏度场以及停留时间分布曲线RTD,得出螺槽深度对流场的影响。结果:在中心距相同的情况下,通过改变螺纹元件的外径和内径之比改变螺槽深度,在相同的工艺条件下,同向双螺杆流道内各物理场以及混合性能均存在较大差异;与构型二相比,构型一的剪切作用更强,但构型二的建压能力更好;挤出过程中,构型二轴向混合能力较好但自清洁能力较差,而构型一轴向混合能力较差、自清洁能力较好。结论:螺槽深度的改变对流道混合性能有着一定影响且存在规律性,可有效指导双螺杆挤出机螺纹元件的设计。 相似文献
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The flow of plasticized maize starch in a co-rotating twin screw extruder was simulated by using computational fluid dynamics (CFD). Sensitivity of the simulation to the selected viscosity model was analyzed. The results suggest that about 16 times increase in zero shear viscosity has no influence on the flow, whereas a slight change in viscosity at the shear thinning region leads to significant increase in pressure drop along the mixing zone of extruder. Simulation results were validated quantitatively by experimental data. Furthermore, the flow type and profile in the extruder were discussed by using the influence of screw speed and screw configuration as exemplary process parameters. To evaluate the dispersive mixing efficiency, material specific critical capillary number was implemented into particle tracking simulations. Maximum shear stress generated at the tip of the screws was used to calculate the maximum capillary ratio, and therefore to determine the dispersive mixing efficiency. The results show that increase in screw speed led to better dispersive mixing, although the generated shear stresses decreased. To investigate the influence of screw geometry, two different screw configurations were simulated. The results show that the dispersive mixing efficiency can be improved by using reverse kneading blocks at which more particles are exposed to high shear stresses. 相似文献
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《Journal of food engineering》1988,8(3):157-172
The residence time distributions in the feed zone of a counter-rotating, twin-screw extruder processing maize grits, were measured by means of a 64Cu tracer. The detection system was mounted above the transport zone of the extruder. Three different screw pairs were investigated. The residence time distribution measurements were analysed by means of an axial mixing model developed for a twin-screw extruder. The feed rate was found to be the most important variable affecting the average residence time. The average residence time was inversely proportional to the screw speed. Measurements could be simulated by assuming backmixing action over approximately 15% of the axial length of the screw. Geometrical devices in these screw pairs, such as kneading zones and so-called drossel zones (high-shear throttle valves), resulted in a significant increase in the average residence time. Their action can be simulated by means of an axial plug-flow model. 相似文献
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The effect of different extrusion operating parameters on air bubble entrapment during twin‐screw extrusion of amylopectin half‐products was studied. A ZSK‐30 twin‐screw corotating extruder with a slit die attached to the discharge end of the extruder to cool the extrudate to prevent water vapor puffing was used. The extrusion parameters investigated were screw speed (150, 300 and 500 rpm), mass flow rate (1.67 and 3.33 g s?1), native versus pregelatinized amylopectin, screw configuration (with or without kneading blocks), and moisture content (32 and 35%, w.b.). The parameters that exerted the greatest effect on air bubble entrapment during twin‐screw extrusion are the type of amylopectin used, mass flow rate and screw speed. On the other hand, in the ranges studied screw configuration and moisture content did not show any significant effect on air bubble entrapment. Explanations for these results are interpreted with the aid of the barrel fill length mechanism proposed by Cisneros and Kokini (2001). 相似文献
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利用双螺杆食品挤压机对棉籽饼粕进行了挤压脱除棉酚的试验,考察了加工参数对脱毒效果的影响。结果表明:增大螺杆转速,脱毒效果变好;减小含水量,脱毒效果变好;增大螺杆转速,产量增大;增大含水量,产量增大;捏合盘的加入能有效改善脱毒效果,捏合盘长度和位置是影响脱毒效果的显著因素。试验结果还表明,双螺杆挤压机用于棉籽饼粕挤压脱毒,效果十分显著。 相似文献