折流板开孔对换热器性能影响的分析研究

发布时间：2018-05-03 22:08

本文选题：PIV + 折流板开孔　；参考：《武汉工程大学》2015年硕士论文

【摘要】：管壳式换热器在现在换热设备中占据主要地位,其中单弓形折流板换热器以其结构简单,制造维护方便,传热效果好等优点被广泛采用。但是这种结构容易在折流板背根部产生死区,不利于壳程流体换热,且流体反复冲刷管束,容易产生列管振动,破坏换热管。对折流板开孔能够在一定程度上解决这类问题,但是有关单弓形折流板开孔对壳程的流动特性及换热特性的影响研究相对较少。本文主要利用实验与数值模拟两种方法来研究折流板开孔对换热器性能的影响。在实验部分中,本文利用新型PIV粒子测速技术做了大量的实验研究,探究了折流板不同开孔方式对管壳式换热器壳程流场的影响。结果表明截面上流体的速度随y轴位置的变化而变化,区域内速度成类似二次曲线分布。本文运用了区域平均涡量来表征壳程流场的流动性能,平均涡量越大,区域速度梯度就越大,越容易产生死区。通过分析不同的开孔方案,得到了不同区域的平均涡量,及其平均涡量随着折流板的间距的增大而增大,随着流量的增大而减小的规律,此外还得到了在同流量,同间距下的最佳开孔方案。在数值模拟中,利用FLUENT软件模拟了实验模型中壳程流体特性,分析比较了速度云图和速度截面图,得到了与PIV实验结果趋势相同的截面速度分布规律,截面速度分布呈现类似二次曲线分布,与实验结论一致,说明了结论的正确性。本文最后对实际工况参数下折流板开孔对换热器的换热影响展开了研究,利用最佳开孔方案和未开孔进行比较,研究表明折流板开孔后总换热系数有小幅降低,压降大幅度降低。在同压降下,折流板开孔后的总传热系数较未开孔得到了提高,工业设计中可以依此来对换热器进行折流板开孔设计,从而达到强化传热的目的。
[Abstract]:Shell and tube heat exchangers play an important role in the heat transfer equipment nowadays, among which the single bow baffle heat exchanger is widely used for its simple structure, convenient manufacturing and maintenance, good heat transfer effect and so on. However, this kind of structure is easy to produce dead zone at the back of baffle, which is unfavorable to the heat transfer of shell side fluid, and the fluid repeatedly scour the tube bundle, so it is easy to produce tube vibration and destroy the heat transfer tube. This kind of problem can be solved to some extent by opening the orifice of baffle plate, but the influence of single arch baffle orifice on the flow characteristics and heat transfer characteristics of shell side is relatively few. In this paper, experimental and numerical simulation are used to study the effect of baffle opening on the performance of heat exchanger. In the experiment part, a large number of experiments are done by using the new PIV particle velocity measurement technique, and the influence of different orifices of baffle plate on the flow field of shell and tube heat exchanger is investigated. The results show that the velocity of the fluid on the cross section varies with the position of the y axis, and the velocity in the region is similar to that of the conic. In this paper, the regional average vorticity is used to characterize the flowability of the shell flow field. The larger the average vorticity is, the larger the regional velocity gradient is, and the easier the dead zone is. Through the analysis of different open hole schemes, the average vorticity in different regions and its mean vorticity are obtained, which increase with the increase of baffle spacing and decrease with the increase of flow rate. In addition, the same flow rate is obtained. The best open hole scheme at the same distance. In the numerical simulation, the characteristics of the shell fluid in the experimental model are simulated by FLUENT software, the velocity cloud diagram and the velocity section diagram are analyzed and compared, and the section velocity distribution law of the same trend as the PIV experimental result is obtained. The section velocity distribution is similar to that of the conic curve, which is consistent with the experimental results, which shows the correctness of the conclusions. In the end of this paper, the effect of baffle opening on heat exchanger is studied under the actual operating conditions. The results show that the total heat transfer coefficient of baffle plate decreases slightly after opening, and the optimum open hole scheme is compared with that of non-perforated heat exchanger. The pressure drop is greatly reduced. Under the same pressure drop, the total heat transfer coefficient of the baffled plate after opening is improved compared with that of the non-perforated one, so the heat transfer can be enhanced by the design of the baffle hole in the industrial design.
【学位授予单位】：武汉工程大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.5

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