换热管内插组合扭带强化传热实验与数值模拟研究

发布时间：2018-07-02 23:49

本文选题：组合扭带 + 强化传热　；参考：《广西大学》2015年硕士论文

【摘要】：换热器是工业传热的关键设备,应用强化传热技术改善其传热性能是节能环保的有效途径。换热管内插入自旋扭带不仅可以强化管内传热,而且具有在线防垢的作用。本文以水为介质,对换热管内插入组合扭带的强化传热进行了实验与数值模拟研究,并与开孔扭带和空管作对比分析。实验结果表明：内插入组合扭带管的压力降、传热系数和努塞尔数都得到了提高。其中,压力降扭带管比空管提高了23.2%～37.9%；传热系数扭带管比空管平均提高了16.39%～38.88%,组合扭带管比开孔扭带管平均提高了19.49%；努塞尔数扭带管比空管平均提高了13.01%～20.38%,组合扭带管比开孔扭带平均提高了6.52%。换热管内插入组合扭带的传热综合性能评价因子Φ都大于1,Φ值最高达到1.16,有效地实现了传热强化。数值模拟结果表明：组合扭带管内的流体为三维螺旋轨迹流动,边界层流体速度大于空管和开孔扭带管,且边界层速度比空管平均提高了5.03%16.68%,比开孔扭带管平均提高了1.20%～3.37%,减薄了管内流体边界层厚度。组合扭带管内流体的三维螺旋流动、二次流以及边界层速度的提高是换热管传热强化的主要原因。组合扭带管的传热系数随着扭带宽度、扭率和错开率的减小而增大,内表面传热系数变化总体呈现由进口到出口的不断减小趋势。换热管管壁的温度分布随管壁半径呈对数形式分布,且温度大小由外向内逐级递减。
[Abstract]:Heat exchanger is the key equipment for industrial heat transfer. It is an effective way to save energy and protect environment by applying enhanced heat transfer technology to improve its heat transfer performance. The insertion of spin-torsion band in the heat transfer tube can not only enhance the heat transfer in the tube, but also have the effect of on-line anti-scaling. In this paper, the experimental and numerical simulation of heat transfer enhancement by inserting a combined torsion band into a heat exchanger pipe is carried out in water medium, and the results are compared with that of an open-hole torsional belt and an empty tube. The experimental results show that the pressure drop, heat transfer coefficient and Nusselle number of the intercalated combined torsion tube are improved. The heat transfer coefficient of the tube is increased by 16.39 and 38.88 than that of the empty tube, and the average increase of the combined tube is 19.49 compared with that of the open-hole torsion tube, and the pressure drop tube is 23.2and 37.9m higher than that of the empty tube, and the heat transfer coefficient of the tube is increased by 16.39 and 38.88, and the average value of the combined tube is 19.49. The average value of the Nussel number torsion tube is 13.01% and 20.38% higher than that of the empty tube, and the combined torsion band tube is 6.52% higher than the open-hole torsion band. The comprehensive heat transfer performance evaluation factor 桅 is greater than 1, and the maximum value of 桅 is 1.16, which can effectively realize heat transfer enhancement. The numerical simulation results show that the fluid in the combined torsion tube is a three-dimensional spiral trajectory flow, and the velocity of the boundary layer fluid is larger than that of the empty tube and the open-hole torsion tube. The velocity of the boundary layer is 5.03 / 68 higher than that of the empty tube and 1.20 / 3.37, respectively, and the thickness of the fluid boundary layer in the pipe is reduced. The three dimensional helical flow secondary flow and the increase of boundary layer velocity are the main reasons for the heat transfer enhancement of the combined torsional tube. The heat transfer coefficient of the combined torsion tube increases with the decrease of the width of the torsion belt, the torsion ratio and the staggered opening rate, and the variation of the heat transfer coefficient of the inner surface presents a decreasing trend from the inlet to the outlet. The temperature distribution of the heat transfer tube wall is logarithmic with the radius of the tube wall, and the temperature decreases progressively from outside to inside.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.5

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