Abstract The rotary air preheater is one of the leading heat exchangers to be employed in steam power plants. However, thermal stress induced deformation of the rotor significantly decreases the efficiency of preheating system. The countercurrent arrangement of hot flue gas and cold air is the direct cause of greater temperature difference across the rotor, which leads to a mushroom deformation, and then serious problems of air leakage and mechanical friction. In this study, a numerical investigation was newly performed by the analysis modules of Fluid Flow (FLUENT) and Static Structural through ANSYS Workbench to couple heat transfer and thermal stress deformation in the rotary air preheater. Porous media method along with the local non-equilibrium thermal model was adopted to accurately obtain the temperature distributions of both matrix and gas. Good agreements were yielded by comparing the simulation results and experimental data. The effects of operational and structural parameters, i.e., the temperature difference between the hot and the cold ends, the rotation angle, the height, and the radius on thermal deformation behavior of the entire rotor were investigated in detail. The droopy deformation at the hot and the cold ends increases with the temperature difference and radius, whereas increasing the height of rotor has the opposite influence. With the rotation of matrix, the maximum droopy deformation is located at the entrance of flue gas section and the minimum occurs when reaching the air section. Furthermore, a series of formulas were presented with nonlinear curve fitting to evaluate the deformation amount, which were proved to be of excellent accuracy and can be a better guidance for the seal system of the preheater.

中文翻译：

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回转式空气预热器传热与变形耦合的数值分析

摘要 回转式空气预热器是蒸汽发电厂采用的主要换热器之一。然而，转子的热应力引起的变形显着降低了预热系统的效率。热烟气与冷空气逆流布置是转子两端温差较大的直接原因，从而导致蘑菇形变形，进而出现严重的漏风和机械摩擦问题。在这项研究中，流体流动 (FLUENT) 和静态结构分析模块通过 ANSYS Workbench 进行了新的数值研究，以耦合旋转空气预热器中的传热和热应力变形。采用多孔介质法结合局部非平衡热模型，准确获得基体和气体的温度分布。通过比较模拟结果和实验数据，产生了良好的一致性。详细研究了运行参数和结构参数，即冷热端温差、旋转角度、高度和半径对整个转子热变形行为的影响。热端和冷端的下垂变形随着温差和半径的增加而增加，而转子高度的增加则产生相反的影响。随着基体的旋转，最大下垂变形位于烟气段入口处，到达空气段时发生最小。此外，还提出了一系列公式，通过非线性曲线拟合来评估变形量，