【作者】 吴华新；

【导师】 周松；

【作者基本信息】 哈尔滨工程大学 ， 动力机械及工程， 2009， 博士

【摘要】 随着社会经济技术的发展与进步,能源日益有限。强化传热技术,高效、节能的产品备受瞩目。研究强化传热技术,设计开发新颖的、紧凑的高效换热装置,成为一个具有理论和实践意义的重要课题。本论文的主要内容是研究基于一次表面换热原理的空气一水介质波纹板式换热器的流动与传热特性。在广泛调研国内外的板式换热器与燃气轮机回热器应用一次表面实现高效传热的理论研究、实验研究、数值模拟和模型研制的基础上,将一次表面引入到空气-水换热过程,拓展了一次表面换热装置的应用领域。在研究中先将传统的水一水介质波纹板式换热器改装成空气一水换热器,进行实验,通过与光管式、翅片管式紧凑型换热器的传热与流阻的权威数据进行比较,表明一次表面波纹板式换热装置具有结构紧凑与低流动阻力的特征,利用一次表面可实现空气-水之间的高效传热。一次表面波纹板上波纹的凸起与凹陷不仅可促进无源的扰动,还可阻断边界层发展。带有倾角的波纹板叠合放置,板间形成的流道是复杂的空间结构,针对其特点,本研究建立了描述空气在波纹板间的流动与传热过程的数学模型。通过数值求解27种可代表一次表面形面特征的物理模型,比较了波纹形状、波纹高度及波纹倾角对空气在波纹板间传热与流动的影响,以高对流换热系数与小流动阻力作为指标,初选了几种高效的一次表面。又以面积最佳传热因子j/f/与体积最佳传热因子E作为后续评价依据,实现优中选优。研究中从波纹的不等截面积流道理论出发,创新性地提出了不等高度波纹的方法。通过实验证明该方法可进一步缩小了两侧流体的热容比,提高换热效率。并将实验结果与模拟的数据进行了比较,对建立的数学模型实现了验证,表明用于模拟的数学模型能够满足本研究的需要。研究中还对不锈钢波纹板的防冻性能进行了实验研究,实验中测定了水在不锈钢表面最高结冰温度,波纹板的凸凹结构可破坏冰在波纹板表面的附着,具有防结冻的功能。以实验为依据,建立了水在波纹板间的三维静止结冰与流动结冰的数学模型,进行了模拟计算,分析了水在波纹板间结冰过程中温度变化与相变界面移动规律,有助于改进波纹板的设计。本研究为一次表面及其类似介质的紧凑、高效换热装置的设计与开发提供了依据,拓展了一次表面的应用,具有一定的理论与实践价值。更多还原

【Abstract】 With the development of society economy and technology, demand of energy resources grew day by day. Under the condition of limited energy resources, enhanced heat transfer, efficient and energy-saving technologies, product applications had been paid a great deal of attention. The study of the process of enhanced heat transfer technology and designing the novel compact heat exchanger devices had became an important problem with theoretical and practical meaning.The main contents of this paper were the studying of air-water medium corrugated plate heat exchanger flow resistance characteristics according to the principle of primary surface heat transfer. The two successful cases of plate heat exchanger and gas turbine regenerator which applied primary surface to transfer heat efficiently were extensively researched including theory study, experiment study, numerical simulation and model development. Then the efficiently primary surface was introduced to the field of air-water heat transfer, which expanded the application scope of primary surface.The traditional water-water plate heat exchanger was converted into air-water heat exchanger and the experimentation was carried out. Through comparing with the heat transfer and flow resistance authority data of smooth tube and finned tube compact heat exchangers, the results demonstrated that the primary surface corrugated plate heat exchanger had the characteristics of low flow resistance and compact construction and could transfer heat efficiently between water and air.The salient and depression of the primary surface corrugated plates were not only the promotion of passive disturbance, but also could block the development of boundary layer. The corrugated plates with inclination angle were congruently placed; the flow passage had a complex space structure. In view of these characteristics, the basic laws-the mass conservation, momentum conservation, energy conservation and the basic theory of turbulence were adopted in the study to establish the mathematical model of air flowing and transferring heat between the corrugated plates. Through solving 27 physical models which could represent the shape and surface characteristics of the primary surface, the impact of air transferring heat and flowing between the corrugated plates by corrugation shape, corrugation height and corrugation inclination angle were compared. The indexes of high convective heat transfer coefficient and low flow resistance were selected and several efficient primary surfaces were primarily chosen. The area best heat transfer factor j/f and volume best heat transfer factor E were taken as the follow-up estimation basis to select the best one.The method of differ height corrugation was put forward innovatively on the basis of differ section theory. The experimentation proved that this method could reduce the heat capacity ratio of the fluid on both sides further and improved the heat transfer efficiency. The numerical simulation data and experimental results were compared and the mathematical model was validated satisfying the request of this study.The anti-frozen performance of stainless steel corrugated plates was also experimented studied. The minimum icing temperature of water on the stainless steel surface was determined; the convex-concave structure could block the ice adhering on the surface of corrugated plates and had a certain anti-frozen function. The three-dimensional processes of water statically freezing and flow freezing between the corrugated plates were simulated; the temperature variation and phase change interface moving law were analyzed, which could be used in the improvement of corrugated plates.This study provided the basis and method guidance to the design and development of air-water primary surface and similarly the compact, efficient heat exchange equipment, which expanded the scope of application and had a certain theoretical and practical value.更多还原