Analysis of Large Deformation and Thermal Stress of the Helical Tube-in-Tube Heat Exchanger
Method of the"fluid-solid"conjugate heat transfer unidirectional coupling with"thermo-solid"was employed to ana-lyze convective heat transfer characteristics of the helical tube-in-tube heat exchanger,the thermal expansion and the influence of the large deformation on thermal stress calculation.The results show that fluid particles subjected to influence of centrifugal force of the helical tube and annulus generate secondary flow mixing and enhance heat transfer of the outer side of helical tube,temperature of the outer side of helical tube is lower than that of the inner side of the same section;under the high temperature heat transfer condition,the helical tube has significant deformation due to thermal expansion,and the deformation is at the same order of magnitude as thickness of the tube wall,and the thermal stress calculation of the helical tube-in-tube heat ex-changer belongs to the problem of large deformation,and the result of nonlinear calculation of large deformation finite element is larger than that of linear calculation of small displacement,and is more in line with the actual.Lastly,to reduce thermal stress as the optimization goal,the orientation of T-joint arrangement of helical tube-in-tube heat exchanger was optimized,the ther-mal stress of the radial arrangement T-joint is reduced by about 1/3 compared with that of the axial arrangement.
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