槽式光热发电系统中真空集热管失效机理及其寿命预测方法研究

The failure of solar vacuum receiver is the primary ongoing issue for the parabolic trough solar power systems. It is the precondition of improving the reliability and fatigue lifetime of solar vacuum receiver to deeply theoretical study the failure mechanism and life predication method. In the project, the high temperature failure mechanism of structure of solar vacuum receiver will be firstly studied. Using temperature, flow and thermal stress field coupling method to establish the 3- dimensional numeral simulation of solar vacuum receiver. The theoretical study and experimental verification will be combined to explore the forming regularity of thermal stress and fatigue property of the metal absorber, bellows and glass-to-metal seals. On the other hand, this research focuses on vacuum failure mechanism. The high temperature hydrogen permeation model and experiment will be established to explore the mechanism of hydrogen permeation. The variation of the residual gases with temperature and time in the annular space will be analyzed by the numerical simulation of rare gas flow and heat transfer. The characteristic curve of the temperature with vacuum failure can be concluded. Finally, the structure fatigue life prediction model and vacuum life prediction model will be established. Applying the corresponding high temperature accelerated life testing method and the least square method to analyze and evaluate the lifetime and reliability of the solar vacuum receiver. The research results can present the theoretical foundation of how to effectively relieve the failure problem of solar vacuum receiver and improve its operation reliability in the parabolic trough solar power station.

真空集热管失效一直是槽式光热发电系统中最主要的问题，对其失效机理及寿命预测方法进行深入理论研究是提高其可靠性和寿命的前提基础。本课题拟首先开展真空集热管结构高温失效机理研究，通过真空集热管温度场、流场与应力场的多场耦合三维数值模拟与实验研究，探索金属内管、波纹管及玻璃与金属封接等关键部件的热应力及疲劳失效特性；其次开展真空失效机理研究，建立集热管高温渗氢模型与实验测试，探索其氢气渗透机理；开展集热管在高温加热时残气分析，揭示环形空间气体成分、分压随温度与时间变化规律；通过对环形空间稀薄气体流动与传热数值模拟与实验，得出集热管温度-真空失效特性曲线；最后建立真空集热管结构高温疲劳寿命预测模型和真空寿命预测模型，通过建立相应高温加速寿命测试方法，利用最小二乘法进行加速寿命实验统计与分析，实现集热管的寿命预测与可靠性评价，为有效缓解真空集热管失效问题及提高其在槽式电站运行可靠性提供理论依据。

真空集热管失效一直是槽式光热发电系统中最主要的问题，对其失效机理及寿命预测方法进行深入理论研究是提高其可靠性和寿命的前提基础。本项目针对真空集热管的失效机理及其寿命预测方法开展研究，涉及到传热、结构力学及真空等多个交叉学科领域，该项目的研究对促进相关学科发展具有一定的理论意义和应用价值。本项目的研究工作和成果主要包括：.1）建立了真空集热管在周向非均匀聚光条件下整管温度场、流场与应力场耦合的三维数值模型，分析了集热管整管能流密度、温度和热应力分布规律及其分布对集热管结构失效规律影响；开展了集热管在系统中温度和热应力的实验测试与数值模拟验证；分析了在各种工况下，真空集热管中关键部件的温度和热应力变化规律及其结构失效特性，提出其热应力及结构失效的消减机制与措施。.2) 建立了真空集热管结构疲劳寿命评价方法和测试平台，对集热管的金属内管、波纹管和玻璃与封接处开展了相应疲劳寿命测试研究，分析和评价了真空集热管结构疲劳寿命。 .3）通过对集热管出气、漏气、吸气和氢气渗透机理的理论与实验研究，探索了集热管真空失效机理，提出了降低真空集热管真空失效、提高真空寿命的措施。.4）建立了真空集热管的真空寿命预测数学模型，并建立了真空集热管残余气体测试平台及其寿命评价方法，分析了不同运行年限的集热管内残余气体种类和气体分压强，探索了集热管内残余气体随温度与时间变化规律，对集热管的真空寿命进行了评价和预测。.5）建立了基于真空集热管热损增加率作为失效判定标准的集热管综合寿命预测方法，研究了真空集热管环形空间稀薄气体传热机理，并通过实验和数值模拟分析了环形空间气体成分、真空分压对集热管的热损影响规律；完成了真空集热管热损与集热管温度、环形空间气体压强和气体成分间相互关系分析，实现了真空集热管的综合寿命预测与评价，为有效缓解真空集热管失效问题及提高其在槽式电站运行可靠性提供科学理论支撑。