【作者】 刘情超；

【导师】 谭鹤群；

【作者基本信息】 华中农业大学 ， 农业机械化工程， 2011， 硕士

【摘要】 随着饲料工业这个行业的发展,越来越多的饲料生产厂家对干燥技术和设备提出了更高的要求。为了适应生产厂家的要求,干燥设备的设计和研发也偏向于大型化、系列化、低能耗。多层立式干燥器一种新型干燥器,它的特点是：一是干燥室内无机械运动部件,日常维护少。二是可连续运行,效率高、产量大(产能≥10t/h)。三是干燥器体积巨大,造价高昂。饲料生产中干燥过程是个很重要的环节,多层立式干燥器向干燥室内送风方式是底部送风和两侧送风。对送风方式以及热风在干燥室内的流动状态进行研究,可以为立式干燥器的优化和改进提供参考依据。本文先对膨化饲料的热特性进行了研究,然后利用计算流体力学(CFD)对多层立式干燥器中的热风流动情况进行数值模拟,具体研究如下：1)试验材料选用某饲料生产厂的3种膨化饲料(002、556、561),用KD2 PRO热特性分析仪测量膨化饲料在3种初始温度T℃(25℃、35℃、45℃)和8种含水率水平M下的导热系数λ。得出了导热系数关于含水率、温度的二元回归方程是：2)用质量体积法测量2种膨化饲料(556、561)的孔隙率,2种饲料颗粒外形是比较规则的圆柱体。通过研究的孔隙率可以看出,膨化饲料颗粒的大小对其孔隙率的影响不是很大。膨化饲料堆积体常被看成一个整体,实际上颗粒之间存在很多的空隙,而且颗粒表面也存在气孔,还有颗粒之间也有相互的挤压作用,使得堆积体的表面张力会偏大,这些孔隙也不容易被检测出来,所以得到的孔隙率测量值会偏小。孔隙率在本文是干燥室建模的关键参数之一3)建立了立式干燥器干燥室内的模型,重点研究了干燥过程中底部送风方式和两侧送风方式,得出了干燥室内的风压矢量图、风压分布图、风速矢量图、风速分布图。通过对模型数值的分析和研究,发现采用底部送风方式干燥室模型最佳的干燥区域是：X=0-400mm, Y=0-750mm和X=1500-2400mm, Y=1300-2400mm。采用两侧送风方式干燥室模型最佳干燥区域是：X=0-100mm, Y=0-500mm,和X=1800-2400mm, Y=1300-2400mm。更多还原

【Abstract】 Along with the development of feed industry, drying technology and equipment were put forward higher request by more and more feed producers. In order to adapt to the manufacturer’s request, the design and research of dryer equipment focus on hugeness, serration, low energy consumption. Multi-storey vertical dryer is a new type of dryer, Its characteristic is:dry room with no mechanical parts, and daily maintenance need less; running continuously, high efficiency, high capacity≥10t/h;expensive. Drying is an important link in the feed manufacturing process, Air distribution mode in multi-storey vertical dryer is bottom air supply and sides supply. In this paper, following Patten of hot air in dryer chamber was researched; provide the reference to the optimization and improvement of vertical dryer.Firstly the thermal characteristics of expanded feed were studied, and then the air flow condition of multilayer vertical dryer was simulated by using computational fluid dynamics (CFD). Specific research as follows:1) Test material was a factory 3 expanded feed (002、556、561), using KD2 PRO thermal characteristic analyzer measure thermal conductivityλof expanded feed at initial temperature T(25℃、35℃、45℃)and 8 kinds of moisture content M. Thermal conductivity relations of coefficient were found out.2) Using quality volume method measure the porosity of expanded feed (556、561), two expanded feed’ grain appearance are cylinder. Through the research of porosity, expanded feed grain size affect porosity smaller. Expanded feed together is often as a whole, actually there are many gaps between particles. Surface exists hole, make the surface tension become larger. These pore also not easily detected, so the values of porosity measured is small.3) Vertical dryer dry indoor model was established, the way of ventilation air side supply and bottom supply was focused on. The dry indoor air pressure distribution vector diagram, air pressure, wind velocity vector diagram, wind velocity distribution were found out. By anglicizing and researching numerical model, found out the best dry area of ventilation dry room model of bottom air supply is:X=0-400mm, Y=0-750mm and X=1500-2400mm, Y=1300-2400mm is best, the best dry area of dry room model of Sides supply is:X=0-100mm, Y=0-500mm and X=1800-2400mm, Y=1300-2400mm.更多还原