大功率整流设备的复合结构自循环蒸发冷却系统特性研究

Self-circulating evaporative cooling is safe, effective and energy-saving. Different from the structure of single heat source in previous study and application, the high power rectifier equipment provides a system with composite structure. This research aims to carry out a systematic study on the characteristics of self-circulating evaporative cooling system for high power rectifier equipment, in the aspects of theory, numerical simulation and experimentation. Based on the coupled effects of driving force and flow resistance, an analytic model can be developed. Then the effects of design parameters and operational parameters on the self-circulation ability, the static flow instability, and cooling limit can be analyzed, based on the nonlinear bifurcation analysis theory. Simulate the flow and heat transfer in the complicated flow channels, analyze the gas-jam existing in a local area of the cooling channel and resulted abnormal high temperature, then the optimized design of flow channels can be proposed. Design and establish experiment model, and the conclusion of theoretical research and simulation can be verified. On the basis of experiment and nonlinear time series analysis methods, calculate the correlation dimension, the change of flow states can be analyzed as heat source increased, and then the dynamic characteristics of system can be analyzed. Finally, an optimization design method of the self-circulating evaporative cooling system with composite structure can be proposed. This research may offer the theoretical foundation for the application of evaporative cooling technology on high power rectifier equipment. Also, it may enrich the theory and the method of analysis about evaporative cooling technology.

自循环蒸发冷却是一种安全、高效、节能的冷却方法。不同于以往研究及应用中的单一结构热源，大功率整流设备具有复合热源结构。本课题拟通过理论、仿真和实验相结合的方式，对大功率整流设备的自循环复合结构蒸发冷却系统特性展开研究。基于自驱动力-流动阻力耦合关系，建立系统数学模型，利用非线性分岔理论分析系统自循环能力、静态不稳定性、冷却极限随设计参数和运行参数的变化规律。通过仿真模拟系统复杂流道内的流动换热，分析局部区域内的气堵问题及其导致的过热现象，提出流道优化方案。设计搭建模型，将理论和仿真的研究结果与实验数据进行比较验证；并在实验和非线性时序分析的基础上，计算关联维数，获得系统状态随热源变化的演化规律，进而分析系统的动态特性。最终，提出具有普适性的针对复合结构自循环蒸发冷却系统的设计方法。本项目的研究将为蒸发冷却技术在大功率整流设备上的应用奠定理论基础，同时也将进一步丰富蒸发冷却理论和研究方法。

自循环蒸发冷却技术是一种安全、高效、节能的冷却方法。针对其在大功率整流设备上的应用，本项目开展具有复合结构的自循环蒸发冷却系统特性研究。首先基于分布式热源分析，分析系统循环动力和流动阻力的动态耦合平衡关系，构建了最小并联单元系统模型和方程；通过非线性理论分析系统随热负荷变化的静态演化特性，并针对系统典型参数分析其对系统特性的影响规律；然后依据以上理论分析结果针对240kVA三相桥式整流器提出自循环蒸发冷却系统设计方案，基于局部阻力和仿真结果分析局部并联管路设计方案对系统特性的影响，完成局部优化；之后依据以上成果设计并搭建试验平台开展试验研究，验证理论分析结果，掌握复合结构自循环蒸发冷却系统随热负荷演化的运行性能；同时探索将非线性分析模型用于系统动态性能分析，基于关联维数开展系统不同试验条件和热负荷区间内的动态性能分析。本项目研究工作为蒸发冷却技术在大功率整流设备上的应用奠定了基础，同时也为复合结构自循环蒸发冷却系统的优化设计和运行提供了参考。