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Entrance pressure drop of extruder dies increased with a decrease in the ratio of barrel-to-die diameter during the extrusion of corn. For the low Reynolds number flow studied (1.77 x 10?3≤ Re ≤ 9 x 10?5) the viscous component, obtained from Weissberg's analysis, contributed 2% to 40% of the entrance pressure drop and increased as the barrel-to-die diameter ratio decreased. The friction factor for laminar fully developed flow through the die followed the expression f = 16/Re'. Fully developed flow within the die was achieved at a die length-to-diameter ratio of 9. 相似文献
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Finite Element Modeling of Fluid Flow, Heat Transfer, and Melting of Biomaterials in a Single-screw Extruder 总被引:1,自引:0,他引:1
L.J. Wang G.M. Ganjyal D.D. Jones C.L. Weller M.A. Hanna 《Journal of food science》2004,69(5):E212-E223
ABSTRACT: A mathematical model was developed to simulate non-isothermal plug flow of granular starch in feed zone, melting in transition zone, and non-Newtonian melt flow in metering zone and die channel during single-screw extrusion processing. The maximum deviations between the predicted and experimental pressure at the die entrance, product temperature at the die entrance, and minimum residence time were about 20%, 2.5%, and 8%, respectively, of the measured values when the barrel temperatures were 50°C in the feed zone and 120°C in the rest zones. The deviations were within 40%, 4%, and 15%, respectively, of the measured values when the barrel temperatures were 50°C in the feed zone and 140°C in the rest zones. Simulations were carried out to investigate the operating characteristics of an extruder, the melting degree, and profiles of pressure and bulk temperature during extrusion. 相似文献
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利用ANSYS有限元分析软件对PP熔体在双螺杆挤出机非啮合并列型螺纹元件中的流动进行了三维非等温非牛顿流场分析,求出了速度场、压力场、温度场的基本规律以及螺杆特性曲线的分布。计算结果对实际生产具有一定的指导意义。 相似文献
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A model was developed consisting of a modified Plank's equation to estimate phase change time and two unsteady state cross-product heat transfer equations for estimating precooling and tempering times. It accurately predicted total time to proceed from an initial temperature above the freezing point to a final temperature of ?18°C. A correction factor was developed and incorporated in the P term in Plank's equation to correct for the effect of initial and freezer medium temperatures and heat transfer coefficients. The model, tested over a broad range of freezing conditions, had a mean absolute error of 5.9% in predicted values relative to experimental values. 相似文献
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运用inventor9软件对食品挤压成型机中螺杆进行了三维参数化建模,分析了参数化建模的过程和技术要点,并由螺杆的模型生成了关联的工程图,提高了螺杆的系列化设计和变异设计的效率和质量,对inventor软件在其他产品设计中的应用有很重要的意义。 相似文献
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郭建旭 《中国服装(北京)》2004,(17):78-85
Helmut Newton——这位西方服装史上以“性”为主题的一代时装摄影大师,就这样还带着人们对他的热切期望突然地死去了,同时他的摄影风格也因此随他而去了。经过了半个世纪的锤炼,Helmut Newton的摄影艺术风格已经日臻成熟,在“窥淫”(Voyerism)摄影艺术风格的道路上已经没有人能够与他相提并论…… 相似文献
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《纺织学会志》2013,104(1-6):243-250
Abstract In fabric beam dyeing, it is difficult to apply the dye uniformly to the fabric because the fabric remains stationary while dye liquor is circulated through it. The uniformity of the liquor flow profile is critical to obtain uniform shade. This study used Computational Fluid Dynamics to determine how using metal collars and end-caps affect the liquor flow profile through the fabric during dyeing. This research found that placing the collars a distance of about 30% of the winding height under each side of the fabric gave the most uniform liquor flow profile of any collar position. In addition, the use of end-caps gave more uniform liquor flow than did the use of collars. A more uniform liquor flow profile would be expected to provide a more level dyeing. 相似文献
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在管零件制造行业中,弯管是最常用的加工方式之一.管件在弯曲过程中,当弯曲变形程度过大时,弯曲中性层的外层管壁会产生过度变薄,甚至导致破裂;最内侧管壁将增厚,甚至失稳起皱;同时,断面会产生畸变.呈椭圆形.因此外侧减薄量、内侧的波浪度、截面的椭圆度是必须严格控制的3个加工缺陷.通过对管件在绕弯方式下受力变形的理论分析与研究,提出并设计了适用于绕弯加工管件的组合模具,通过该组合模具来控制上述的3个变形.最后,采用装配了该组合模具的CNC(Computerized Numerical Control,电脑数值控制)弯管机进行试验,试验结果显示,该组合模具有效地解决了弯管过程中的缺陷,取得了良好的效果. 相似文献
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蓖麻饼粕含有毒素,不适宜作饲料,所以常用作肥料,在当今世界饲料蛋白短缺的情况下,尤其是蓖麻饼粕生产国出现了饲料蛋白缺乏的情况,蓖麻饼粕的饲用就显得很重要。联合国工业研究中心(UNIDO)和美国得克萨斯A&M大学食品研究和发展中心共同研究,找到了一些脱除蓖麻饼粕毒素的经济、简单的方法。1削弱蓖麻饼粕毒素CB-1A作用的有效方法蓖麻饼粕含有3种毒素即:a)蓖麻籽的白朊———一种有毒蛋白;b)蓖麻碱———一种毒性生物碱;c)被称为CB-IA的烈性过敏反应源。蓖麻籽的白朊在脱溶过程中很容易被破坏掉,蓖麻… 相似文献
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分析固定模拉拔与辊模拉拔药芯焊丝的不同变形特点和工艺特点。辊模拉拔药芯焊丝生产工艺可行,它对改善焊丝质量满足生产需要具有实际意义和理论价值。 相似文献
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本文讨论了零件参数设计与制造成本的关系。利用概率的理论 ,假设各零件的参数服从正态分布 ,从而给出非线性规划问题的目标函数。参数标定值的选取是离散的 ,用计算机数值计算能力采用网格搜索最优解。并结合实例 ,介绍了食品挤压机双螺杆零件参数的优化设计 相似文献
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米糠挤压设备的研究开发 总被引:2,自引:0,他引:2
米糠是一种营养丰富、生理功能卓越的食品原料 ,本文分析了米糠挤压的特点 ,从米糠挤压的预处理、喂料、输送、挤压及粉碎的全过程进行分析研究 ,探讨了改善米糠挤压性能的设备设计 ,并且利用了计算机辅助设计 相似文献