速冻隧道流场模拟及隧道的优化设计

发布时间：2019-06-05 23:41

【摘要】：从20世纪80年代开始,我国冷冻食品行业发展迅速,品种和数量与日俱增。速冻食品在冷却隧道内冷却时,受风速、风量影响很大,不合理设置会导致速冻食品表面的水分干燥升华、表皮破裂等缺陷。冷却隧道结构影响流场的均匀性,合理的隧道结构可以降低传送带内外侧的温度差,提高冷却效率,减少能源消耗。开展冷却隧道数值模拟可以预测食品的冷却效果,优化风速、风量等工艺条件及风机位置、折流板尺寸等隧道结构,为企业节省运行成本,提高速冻产品质量。本文应用FLUENT软件对一个速冻装置的冷却隧道进行数值模拟,分析冷却隧道内速度场和温度场随送风速度的变化规律,根据温差的变化确定最佳的送风速度。在这个较为合理的送风速度的条件下,增设折流板,进一步模拟分析冷却隧道结构对冷却效率改善的效果。通过本文的研究发现:(1)当送风速度由12m/s提高到13m/s、14m/s时,速度场中速度较低的区域范围有所减小,速度场的均匀性有所改善;当送风速度由14m/s提高到15m/s时,速度场的分布没有明显变化。(2)当送风速度由12m/s提高到13m/s、14m/s、15m/s时,温度场中温度最大值有所减小,低温区域的范围有所扩大,温度场的均匀性也有所改善。(3)在考虑冷量的充分利用和节能原则基础上,综合对速度场和温度场的分析可以得出,冷风机送风速度为14m/s时较为合理。(4)在送风速度为14m/s的前提下,加设折流板后速度场中速度较低的区域范围有所减小;温度场中低温区域的范围有所减小,传送带上内外侧温差减小。本文研究表明,冷却隧道送风速度以14m/s为佳,加设折流板可以进一步改善气流流场和温度场的分布均匀性。
[Abstract]:Since 1980 s, the frozen food industry in China has developed rapidly, and the variety and quantity are increasing day by day. When frozen food is cooled in the cooling tunnel, it is greatly affected by wind speed and air volume. Unreasonable setting will lead to moisture drying, sublimation, skin rupture and other defects on the surface of frozen food. The cooling tunnel structure affects the uniformity of flow field. Reasonable tunnel structure can reduce the temperature difference between the inner and outer sides of the conveyor belt, improve the cooling efficiency and reduce the energy consumption. The numerical simulation of cooling tunnel can predict the cooling effect of food, optimize the technological conditions such as wind speed and air volume, the position of fan, the size of baffle plate and so on, so as to save the operation cost and improve the quality of frozen products. In this paper, FLUENT software is used to simulate the cooling tunnel of a quick freezing device, and the variation of velocity field and temperature field with air supply velocity in cooling tunnel is analyzed, and the optimum air supply speed is determined according to the change of temperature difference. Under the condition of reasonable air supply speed, the baffle plate is added to further simulate and analyze the effect of cooling tunnel structure on the improvement of cooling efficiency. Through the research in this paper, it is found that: (1) when the air supply speed is increased from 12m/s to 13 m / s, the region range of the lower velocity in the velocity field decreases and the uniformity of the velocity field is improved when the air supply speed is increased from 13 m / s to 13 m / s; When the air supply speed increases from 14m/s to 15m/s, the distribution of velocity field does not change obviously. (2) when the air supply speed increases from 12m/s to 13 m, 14 m / s, 15 m / s, the maximum temperature in the temperature field decreases. The range of low temperature region is expanded, and the uniformity of temperature field is also improved. (3) on the basis of considering the principle of full utilization of cooling capacity and energy saving, the comprehensive analysis of velocity field and temperature field can be obtained. When the air supply speed of the chiller is 14m/s, it is more reasonable. (4) under the premise that the air supply speed is 14m/s, the range of the lower velocity in the velocity field is reduced when the baffle is added; The range of temperature field in the low temperature region decreases, and the temperature difference between the upper and outer sides of the conveyor belt decreases. The results show that the air supply speed of cooling tunnel is better than that of 14m/s, and the distribution uniformity of air flow field and temperature field can be further improved by adding baffle plate.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TS205

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