重力式热管数值模拟及结构优化

发布时间：2018-01-13 08:45

本文关键词：重力式热管数值模拟及结构优化　出处：《西华大学》2015年硕士论文　论文类型：学位论文

【摘要】：热管通过较小的轴向截面远距离导热的优良导热特性而广为人知,在我国碳钢-水热管换热器应用相对普遍。热管的传热强化也是学界研究的热点之一,然而,目前多数课题对热管传热性能的研究大多围绕于热管通过较小截面的优良导热性能的研究上。在涉及重力式热虹吸管的数值模拟换热强化分析文献中,结合场协同理论提出对策的较少。而且同时具备结合过增元理论特质,并且不拘泥于传统热管的轴截面优良导热性能的相关理论文献相对较少。本课题研究的对象为重力式热虹吸管径向热阻对传热性能的影响,并且结合过增元提出的场协同理论进行数值分析,提出新式的重力式热虹吸管结构。计算机数值仿真技术对于热虹吸管内部传热性能和流动过程的分析是一种不可或缺的重要方法。有限元法和现有的强化换热理论结合,为提高热管换热性能提出的改进措施提供可靠的数值仿真结果。将数值仿真结果进行量化分析,对不同结构的换热性能提出合理预测。本课题尝试提出一种设计方案以提高重力式热虹吸管换热设备的能源利用率。结合重力式热虹吸管内部流场的分析,研究周向热阻,针对周向换热强化提出一种内部扰流结构。该扰流结构主要用于重力式热虹吸管的蒸发段的径向传热强化。本课题的研究过程在借鉴前人研究的理论基础上,提出新的换热扰流结构,谋求一种新的换热强化思路。借助FLUENT软件强大的数值模拟功能,对封闭式两相热虹吸流热交换器内部的耦合场模拟基础上,同时结合了清华大学过增元的场协同理论对重力式热虹吸管周向换热强化进行研究。根据对数值仿真结果的分析,为重力式热虹吸管的换热强化提出可行的传热强化结构。课题研究成果被同时应用于两项专利的申报。本课题提出一种新的内螺旋翅片扰流结构,该结构具备两个显著特征尺寸,锥角和螺旋升角。对于这种内插有锥度的内扰流件的两个参数,分别提出一组参数供比较:锥角有α=12.33°,30°,45°,60°,螺旋升角有β=10.37°,14.036°,25.91°。通过CFD数值仿真分别比较两组结构参数对管内的传热与阻力特性的影响,对于不同锥度下数值仿真结果量化分析显示:数值仿真结果显示对应锥角α=60°的阻力系数,fh数值变化范围为0.013~0.37。30°阻力系数较之60°锥角增加0.460~0.592倍。综合EEC-Re曲线、EEC-α曲线以及紊流工况各参数换热性能,在锥度为30°时模型的强化效果较理想。对于不同锥度下数值仿真结果量化分析显示:数值模拟结果中强化管的EEC最大值在升角为25.91°处取得。综合全段Re数来看EEC-Re曲线,升角25.91°强化效果较为理想。分析EEC-β曲线,可知25.91°的强化效果较为理想。对于该内扰流结构件,最终选取的最优参数为:锥角α=30°、升角β=25.91°。
[Abstract]:Heat pipe is widely known for its good thermal conductivity characteristics of long distance heat conduction with small axial section and is widely used in carbon steel-water heat pipe heat exchangers in China. The heat transfer enhancement of heat pipe is also one of the hot spots in academic circles. At present, most of the research on heat transfer performance of heat pipe is focused on the excellent thermal conductivity of heat pipe passing through a smaller section, in the literature of heat transfer enhancement analysis involving gravity thermosyphon pipe. Combined with the field synergy theory, few of the proposed countermeasures, and at the same time has the characteristics of the combined superfluous theory. And there are few theoretical literatures about the good thermal conductivity of axial section of traditional heat pipe. The object of this research is the influence of radial thermal resistance on heat transfer performance of gravity thermosyphon tube. In addition, the field synergy theory proposed by superinitiator is used for numerical analysis. A new structure of gravimetric thermosyphon pipe is proposed. The computer numerical simulation technique is an indispensable and important method for the analysis of heat transfer performance and flow process in the thermosyphon tube. Finite element method and existing enhanced heat transfer mechanism. On union. In order to improve the heat transfer performance of heat pipe, it provides reliable numerical simulation results. The numerical simulation results are analyzed quantitatively. Reasonable prediction of heat transfer performance of different structures is put forward. In this paper, a design scheme is proposed to improve the energy efficiency of gravity thermosyphon heat exchanger, and the analysis of internal flow field of gravity thermosyphon tube is carried out. Research on circumferential thermal resistance. An internal scrambling structure is proposed for circumferential heat transfer strengthening. The structure is mainly used for the radial heat transfer enhancement of the evaporation section of gravity thermosyphon. The research process of this subject is based on the theory of previous studies. A new heat transfer scrambling structure is proposed to seek a new way of heat transfer enhancement. With the help of the powerful numerical simulation function of FLUENT software, the coupling field in the closed two-phase thermosyphon heat exchanger is simulated. At the same time, combined with the field synergy theory of the superelement of Tsinghua University, the circumferential heat transfer enhancement of the gravity thermosyphon is studied. The numerical simulation results are analyzed. A feasible heat transfer enhancement structure is proposed for the heat transfer enhancement of gravity thermosyphon. The research results are applied to the application of two patents at the same time. A new internal helical fin scrambling structure is proposed in this paper. The structure has two remarkable characteristic dimensions, cone angle and spiral angle. For the two parameters of this kind of internal spoiler with taper interpolation, a set of parameters are put forward for comparison: the cone angle is a 12.33 掳/ 30 掳. The spiral angle was 10.37 掳and 14.036 掳. The effects of two sets of structural parameters on the heat transfer and resistance characteristics of the tube were compared by CFD numerical simulation. Quantitative analysis of numerical simulation results under different taper shows that the resistance coefficient corresponding to the cone angle 伪 = 60 掳is shown by the numerical simulation results. The variation range of FH value is 0.013 掳0.37.30 掳resistance coefficient is 0.460,0.592 times higher than that of 60 掳cone angle. The comprehensive EEC-Re curve is obtained. The EEC- 伪 curve and the heat transfer performance of each parameter in turbulent condition. When the taper is 30 掳, the enhancement effect of the model is better. The quantitative analysis of the numerical simulation results under different taper shows that:. In the numerical simulation results, the maximum value of EEC of the strengthened tube is obtained at the rising angle of 25.91 掳. The EEC-Re curve can be seen from the whole section re number. By analyzing the curve of EEC- 尾, we can see that the strengthening effect of 25.91 掳is better. The optimum parameters are as follows: cone angle 30 掳, rising angle 尾 25. 91 掳.
【学位授予单位】：西华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK172.4

【相似文献】