Analysis Of Vibration And Heat Transfer Characteristics Of A Improved Planar Elastic Tube Bundle In Heat Exchanger

The elastic bundle heat exchanger replaces the traditional rigid element with an elastic heat transfer element,and uses fluid-induced vibration of the internal elastic tube bundle to achieve composite enhanced heat transfer,which opens up a new research direction for the application of passive enhanced heat transfer technology in the heat exchanger.However,due to the influence of the internal bundle structure,the effect of vibration-enhanced heat transfer at low flow rates is not obvious.Therefore,the structure of the elastic tube bundle is improved,and the calculation model of heat exchanger flow-solid-thermal coupling is established to analyze the vibration characteristics and heat transfer mechanism of the improved elastic tube bundle under the shell process fluid induction.The following is a summary of the main research work and conclusions of this paper.(1)Based on the traditional planar elastic pipe bundle,the structure is improved and the corresponding finite element model is established.The modal analysis of the improved planar elastic tube bundle is carried out by ANSYS,and the inherent frequencies of each order of the improved elastic tube bundle and the corresponding vibration patterns are obtained.Compared with the traditional planar elastic bundle,this bundle has smaller inherent vibration frequencies and is more likely to generate vibrations under the impact of a slower flowing fluid.(2)Taking the improved planar elastic pipe bundle as the research object,the calculation model of fluid-solid-thermal coupling is established,and the influence of shell flow rate on the vibration correspondence and heat transfer characteristics of the improved elastic pipe bundle is studied.The results show that with the increase of the fluid flow rate of the shell range,the vibration pattern of the improved planar elastic pipe bundle gradually changes from the out-plane vibration of the vertical pipe bundle to the in-plane vibration in the plane,and the vibration of the elastic tube bundle induced by the shell fluid can achieve enhanced heat transfer,and the heat transfer coefficient increases with the increase of the flow rate.At the same time,the influence of the wall thickness and outer diameter of the pipe bundle on the vibration and heat transfer characteristics of the pipe bundle are also analyzed.The influence of the impact direction of the shell range fluid on the vibration correspondence and heat transfer characteristics of the tube bundle is also analyzed,which lays a foundation for the subsequent study of the installation mode of the tube bundle in the heat exchanger.(3)Based on the study of the vibration response mechanism of the improved single-row elastic tube bundle,the vibration-enhanced heat transfer mechanism of the improved multi-row elastic tube bundle under various conditions is explored.The study shows that when the shell fluid flow rate increases,the heat transfer coefficient of each row of the elastic tube bundles also increases,but the vibration-enhanced heat transfer performance induced by the shell fluid of the improved elastic tube bundle gradually decreases.When the tube row spacing increases,the heat transfer coefficients of the elastic tube bundle heat exchanger under vibration and non-vibration conditions decrease,but the PEC value of the elastic tube bundle heat exchanger increases,and the vibration-enhanced heat transfer is more effective.The installation angle of the bundle has a greater impact on the vibration response,and at the same time has an impact on the heat transfer performance of the elastic bundle heat exchanger,when the bundle installation angle is-10°,the heat transfer coefficient of the elastic bundle heat exchanger is the largest,but the enhanced heat transfer performance of the heat exchanger is the lowest.Figure [55] table [12] reference [87]...