振荡热管内的气液相变及其运行特征分析

发布时间：2018-06-03 06:19

本文选题：振荡热管 + 相变传热传质　；参考：《南昌大学》2016年硕士论文

【摘要】：在上个世纪90年代,Akachi发明了一种传热效率极高的热管,命名为振荡热管。振荡热管有着热超导体的美称,其显著的传热效率甚至比任意一种金属还要高,因而备受科研工作者的青睐。然而到目前为止,大多数研究仍停留在现象观测上,关于振荡热管的运行机理及流动特性还没有完整的理论认识,所以本文尝试通过数值模拟研究寻找答案。振荡热管的研究属于典型的气液两相流类型,该类研究的关键在于准确的捕捉到气液相界面。本文尝试以VOF方法捕捉界面,结合相变传热理论处理气液之间传热传质,选用连续表面力(CSF)模型计算表面张力,引用Kistler提出的动态接触角模型计算管内工质的动态接触角。基于此,建立了较为准确处理振荡热管内气液相变的二维数学模型,并在Fluent平台上对单环闭式振荡热管进行了数值模拟,直观研究分析了振荡热管中气液相变传热传质。振荡热管模拟过程分为两个阶段:初始化阶段和加热运行阶段。针对数值模拟中振荡热管初始化的特殊性,详细描述了其初始化过程,并比较了三种真空度对初始化的影响;研究了加热以后气泡的生长、运动状况以及分布情况;分析了气泡变化与传热之间的关系;关注了液相工质内流动状况;分析了动态接触角模型对振荡热管模拟的重要性。最后着重以气泡/塞为研究对象,分析气泡运动特性、工质流动特性以及振荡热管振荡特性,针对振荡热管的运行特征进行分析研究,更好的了解和认识振荡热管运行机理。
[Abstract]:In the 1990 s, Akachi invented a highly efficient heat pipe named oscillating heat pipe. Oscillating heat pipe has the reputation of thermal superconductor, its remarkable heat transfer efficiency is even higher than any metal, so it is favored by researchers. However, up to now, most of the studies are still focused on the observation of phenomena, and there is no complete theoretical understanding of the operating mechanism and flow characteristics of the oscillatory heat pipe, so this paper attempts to find out the answer by numerical simulation. The research of oscillatory heat pipe belongs to the typical gas-liquid two-phase flow. The key of this kind of research is to capture the gas-liquid interface accurately. In this paper, the interface is captured by VOF method, and the heat and mass transfer between gas and liquid is treated with the theory of phase change heat transfer. The continuous surface force model is used to calculate the surface tension, and the dynamic contact angle model proposed by Kistler is used to calculate the dynamic contact angle of the working fluid in the tube. Based on this, a 2-D mathematical model for dealing with the gas-liquid phase change in oscillatory heat pipe is established, and the numerical simulation of single-loop closed oscillating heat pipe is carried out on the Fluent platform. The heat and mass transfer of gas-liquid phase variation in oscillatory heat pipe is studied intuitively. The simulation process of oscillating heat pipe is divided into two stages: initialization stage and heating operation stage. Aiming at the particularity of oscillating heat pipe initialization in numerical simulation, the initialization process is described in detail, and the effects of three kinds of vacuum on initialization are compared, and the growth, motion and distribution of bubbles after heating are studied. The relationship between bubble change and heat transfer is analyzed, the flow situation in liquid phase is concerned, and the importance of dynamic contact angle model to the simulation of oscillating heat pipe is analyzed. Finally, the bubble / plug is taken as the research object to analyze the characteristics of bubble motion, working fluid flow and oscillatory heat pipe oscillation. The operating characteristics of oscillating heat pipe are analyzed and studied to better understand and understand the operating mechanism of oscillating heat pipe.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK124

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