高参数换热器管板热应力分析模型的研究

Study on Analytical Models of Thermal Stress in Tube Sheet of Heavy Duty Heat Exchanger

常规的管板设计方法是用等效无孔实心板来代替多孔管板,采用比较简单的公式、曲线、图表进行设计计算,但是这些计算无法准确考虑管板温度差引起的热应力。目前常用有限元方法,通过施加温度载荷和对流载荷计算得到管板的温度场,进而求出管板的温差应力,但计算结果的准确性一直是许多研究者关注的问题。采用有限元方法,以U型管式换热器管板为例,分别按给定管板表面温度、给定流体温度和管板表面传热膜系数、包含温度场在内的流固耦合三种分析模型计算得到管板的温度场,进而对比分析了不同模型对管板热应力计算结果的影响。研究结果为管板强度的精确设计提供了借鉴。

Conventional method of tube sheet design is with the perforated plate replaced by the equivalent imperforated plate, using relatively simple formula, curve and charts for the calculations of design. However, these calculations could not get the thermal stress of tube sheet caused by temperature difference. At present, the temperature of the tube sheet surface, and the bulk temperature and the heat transfer film coefficient were assumed to get the temperature fields using the finite element method. Then the thermal stress fields of the tube sheet are obtained. However, the accuracy of the results is concerned by many re- searchers. Three analytical models were applied first to calculate the temperature field of a U - tube heat exchanger using the finite element method. In the three models, the temperature of the tube sheet surface, the bulk temperature and the heat, transfer film coefficient, and the fluid - solid coupled heat trans- fer simulation were assumed, respectively. Then the thermal stress fields of the tube sheet were obtained in the temperature fields calculated above. The results show the effect of different analytical models on the simulation of the thermal stress field, serving as a reference for accurate tube sheet design.