扭曲管换热器管板的有限元分析

采用有限元分析软件ANSYS，对扭曲管换热器的管板在三种工况下的应力进行计算，分析了扭曲管轴向刚度削弱系数对管板应力强度及扭曲管轴向应力的影响。结果表明，扭曲管的轴向变形补偿能力优于普通直管，可以降低在温差载荷作用下管板中的应力，但会提高压力作用下的管板应力。在压力载荷作用下，扭曲管上的平均应力大小与普通直管差别不大，但扭曲管的轴向应力在管子横截面上的分布不均匀，局部的轴向应力远远高于平均应力水平，因此扭曲管抗疲劳和应力腐蚀开裂的能力不如直管。不同厚度的管板受扭曲管管束轴向刚度的影响不同，当管板厚度较小时，扭曲管管束轴向刚度的影响较大。

Finite Element Analysis of the Tubesheet of Twisted Tube Heat Exchangers

Finite element analysis with the software ANSYS was performed on the tubesheet of a twisted tube heat exchanger under three loading cases.Effects of the axial stiffness of the twisted tubes on the strength of the tubesheet were investigated.It is found that as the axial deformation compensation of the twisted tubes is better than that of the plain straight tube,stresses at the tubesheet are decreased when using twisted tubes under the thermal loading,but the stresses are increased under the pressure loadings. Although the average axial stress at the twisted tubes is almost the same as that at the straight tubes,the stress distribution at the cross section of the twisted tubes is not uniform and the maximum stress is much larger than the average stress,which implies that ability of the twisted tubes to resist fatigue or stress cor-rosion cracking is much weaker than the straight tubes.For different thickness of the tubesheet,the effect of the axial stiffness of the twisted tubes is different.The smaller the thickness of the tubesheet,the stron-ger the effect is.