振动流化床干燥过程微观传热的数值模拟
发布时间：2018-07-29 13:24
【摘要】：振动流化床干燥器作为一种干燥设备对湿态散状物料的干燥优点很多,主要表现为床层物料在激振力作用下实现抛掷,可明显降低进口热空气用量,而且振动作用可改变颗粒在床层上的分布,避免了颗粒结块,并可改善颗粒空隙度。但是振动流化床内部的流动和传热过程复杂,目前关于其流动和传热的理论研究并不多见。论文总结了目前国内振动流化床干燥设备的研究现状,利用Solidworks和PHOENICS软件建立了振动流化床微观传热过程的计算模型,然后用PHOENICS软件对微观模型进行了较详细的数值模拟。研究发现,在计算条件允许范围内床层厚度越大、进口风速越低用于干燥的气体热量利用率增加,进口气流温度升高热风流过颗粒群后温度降低越明显,传热效率随粒径减小稍有增大,筛网表面颗粒排布密度、排布形式等对微观传热也会产生不同程度的影响。在瞬态条件下通过编制MOF文件,利用运动物体方法实现了筛网的振动运动,对近筛网流动进行了动态分析,得到了动态的流场、压力场分布,由瞬态的计算可知由于筛网的振动,筛网附近出现反流,流动阻力系数发生变化,速度流场变得复杂,由于算法和计算机硬件制约,振动对传热的作用需进一步研究。论文研究结果对提高振动流化床干燥机的传热性能有一定的参考价值。
[Abstract]:As a kind of drying equipment, the vibratory fluidized bed dryer has many advantages in drying wet dispersed materials, which mainly shows that the bed material is thrown under the action of exciting force, and the amount of imported hot air can be reduced obviously. The vibration can change the distribution of particles on the bed, avoid the agglomeration of particles, and improve the porosity of particles. However, the flow and heat transfer processes in vibratory fluidized beds are complex, and the theoretical research on the flow and heat transfer is rare. In this paper, the present research situation of vibratory fluidized bed drying equipment in China is summarized. The calculation model of micro heat transfer process of vibratory fluidized bed is established by using Solidworks and PHOENICS software, and then the detailed numerical simulation of the micro model is carried out by PHOENICS software. It is found that the larger the bed thickness is, the lower the inlet wind speed is, and the lower the heat efficiency of the inlet air is, the more obvious the temperature decreases after the inlet air temperature rises and the hot air flows through the particle group. The heat transfer efficiency increases slightly with the decrease of particle size, and the distribution density and distribution form of the particles on the surface of the screen also have different effects on the microcosmic heat transfer. Under the transient condition, the vibration motion of the sieve mesh is realized by the method of moving object by compiling the MOF file. The dynamic analysis of the flow near the screen is carried out, and the distribution of the dynamic flow field and pressure field is obtained. From the transient calculation, it can be seen that because of the vibration of the screen mesh, the reverse flow around the screen, the change of the flow resistance coefficient and the complexity of the velocity flow field, the effect of vibration on heat transfer needs to be further studied because of the restriction of algorithm and computer hardware. The results of this paper have some reference value for improving the heat transfer performance of vibratory fluidized bed dryer.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB4
[Abstract]:As a kind of drying equipment, the vibratory fluidized bed dryer has many advantages in drying wet dispersed materials, which mainly shows that the bed material is thrown under the action of exciting force, and the amount of imported hot air can be reduced obviously. The vibration can change the distribution of particles on the bed, avoid the agglomeration of particles, and improve the porosity of particles. However, the flow and heat transfer processes in vibratory fluidized beds are complex, and the theoretical research on the flow and heat transfer is rare. In this paper, the present research situation of vibratory fluidized bed drying equipment in China is summarized. The calculation model of micro heat transfer process of vibratory fluidized bed is established by using Solidworks and PHOENICS software, and then the detailed numerical simulation of the micro model is carried out by PHOENICS software. It is found that the larger the bed thickness is, the lower the inlet wind speed is, and the lower the heat efficiency of the inlet air is, the more obvious the temperature decreases after the inlet air temperature rises and the hot air flows through the particle group. The heat transfer efficiency increases slightly with the decrease of particle size, and the distribution density and distribution form of the particles on the surface of the screen also have different effects on the microcosmic heat transfer. Under the transient condition, the vibration motion of the sieve mesh is realized by the method of moving object by compiling the MOF file. The dynamic analysis of the flow near the screen is carried out, and the distribution of the dynamic flow field and pressure field is obtained. From the transient calculation, it can be seen that because of the vibration of the screen mesh, the reverse flow around the screen, the change of the flow resistance coefficient and the complexity of the velocity flow field, the effect of vibration on heat transfer needs to be further studied because of the restriction of algorithm and computer hardware. The results of this paper have some reference value for improving the heat transfer performance of vibratory fluidized bed dryer.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB4
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