【作者】 孟继安；

【导师】 过增元；

【作者基本信息】 清华大学 ， 动力工程及工程热物理， 2003， 博士

【摘要】 高效节能技术特别是实用的高效强化传热技术广泛应用于石油、化工、能源、冶金、材料等工程领域以及航空、电子、核能等高科技领域。研究、发展和应用新型强化传热技术，将带来巨大的经济和社会效益。本文基于场协同强化原则，采用理论、数值方法和实验研究探求对流换热的强化与优化问题，在此基础上开发新的强化技术并在工业中获得应用。首先在粘性耗散一定的条件下以热量传递势容耗散取得极值为优化目标，运用变分方法导出了层流对流换热场协同方程。数值求解表明，管内层流对流换热的最优速度场为多纵向涡流态。然后，在理论上导出了紊流对流换热的整体换热性能与局域时均速度场和时均温度场的一般关系式，将对流换热的场协同强化原则扩展至湍流换热。这表明层流和湍流对流换的强化均可通过改善速度场和温度场的协同而获得。提出了采用多纵向涡强化管内对流换热的场协同强化方法，并进行了数值分析。结果表明，管内多纵向涡对层流和湍流换热的强化效果显著而流阻增加较少，具有优良的综合强化换热性能。根据理论和数值分析的结果，发明了两种多纵向涡强化换热管——交叉缩放椭圆管和不连续双斜内肋管，对其进行了实验和数值研究。交叉缩放椭圆管是通过椭圆截面的交叉变化诱导产生强烈的二次流和多纵向涡流，而不连续双斜向内肋管则是通过不连续的双斜向内肋对的作用形成强烈的多纵向涡。管内多纵向涡的存在改善了对流换热的速度场和热流场的协同程度，从而使换热获得了显著强化，而流阻增加较少。性能分析和比较表明，研发的两种新型强化换热管具有优良的综合换热强化性能。在此基础上开发了新型换热管的工业规模生产的制造工艺和设备，设计和制造出相应的新型换热器，并在整体性能实验的基础上将已其小批量应用于建筑和能源等领域，获得了较好的效果。由对流换热场协同强化原则指导研究开发的采用一次表面诱发多纵向涡强化传热技术，在换热器行业具有广阔的应用前景。更多还原

【Abstract】 The high-efficiency energy conservation techniques, especially, the practical high-efficiency heat transfer enhancement techniques, have a bright application in many engineering fields, such as petroleum, petro-chemistry, energy, metallurgy, material, aerospace, electronics, and nuclear energy. The researches on the development and application of heat transfer enhancement techniques will create immense economic and social benefits. Based on the field-coordinated enhancement principle, the enhancement and optimization for convective heat transfer are studied by theoretical analysis, numerical simulation and experiments in this dissertation. According to the analytical, numerical and experimental results, new heat transfer enhancement techniques are developed and applied in engineering. Firstly, under the condition of constant viscous dissipation, the field coordination equation was induced for steady laminar convective heat transfer by the conditional variational principle based on the extremum principle of heat transport potential capacity dissipation. The numerical solution shows that the optimal velocity field for laminar convective heat transfer in tubes is multi-longitudinal vortex flow. Secondly, the relation between Nusselt number and the local time-averaged velocity and temperature fields of turbulent convection was theoretically induced, which expands the field-coordinated enhancement principle to turbulent convective heat transfer. It shows that both laminar and turbulent convective heat transfer can be enhanced by improving the coordination between the velocity and temperature fields. Consequently, a field coordinated enhancement method by longitudinal vortex flow for convective heat transfer enhancement in tubes is presented. The numerical analysis indicates that that the multi-longitudinal vortex flow in tubes can markedly enhance both the laminar and turbulent heat transfer with less additional increase of flow resistance.Tow multi-longitudinal vortex enhanced tubes, the alternating elliptical axis tube (AEA-tube) and the discrete double-inclined ribs tube (DDIR-tube), are invented according to the theoretical and numerical analysis. The experimental and numerical studies on the two enhanced tubes are performed. The strong multi-longitudinal vortex flow in the AEA-tube is induced by alternating change of the elliptical cross-section, and for the DDIR-tube, the strong multi-longitudinal vortex flow is<WP=6>induced by the effect of the discrete double-inclined ribs. The existence of the multi-longitudinal vortices in tube improves the coordination between the velocity and heat flux fields for convective heat transfer, and remarkably enhances the heat transfer with less resistance increase. The performance analysis and comparison show that the two novel enhanced heat transfer tubes have excellent performance. After simulation and experiments for the new enhanced tubes, the processing technology and equipment for the novel enhanced tube were developed for industry manufacture, and the new heat exchangers with AEA-tubes are designed and manufactured, some novel heat exchangers have been successfully applied in the fields of architecture and energy, their energy conservation effect is remarkable.The enhancement techniques multi-longitudinal vortex induced by the primal surface change developed based on the field-coordinated enhancement principle will have broad application in heat exchangers.更多还原