Strength Analysis Of Tubesheet And Study On Heat Transfer Performance Of Spiral Wound Corrugated Tube Heat Exchanger

Spiral wound corrugated tube heat exchangers use corrugated tubes as a high efficiency heat exchange tube instead of using the plain tubes in common wound tube heat exchangers,in order to utilize the advantages of both structures.In addition to heat transfer enhancement,periodical expansion and contraction of the cross section of the spiral wound corrugated pipe can reduce the dirt inside the pipe and provide larger heat exchange area.As a result,the equipment is compact and required space is saved.However,due to the few applications of this heat exchanger,various aspects still need to be studied.In this paper,taking the spiral wound corrugated tube heat exchanger as the research object,the strength of the heat exchanger tube plate and the heat transfer performance of the fluid are studied.The main work and contributions are as follows:(1)The integral heat exchanger model including spiral wound tube was established by using finite element analysis software ANSYS,and the supporting effect of tube bundle on tubesheet was analyzed numerically.Results show that the supporting effect of tube bundle on the tubesheet can be neglected.In order to further analyze the axial stiffness of spiral wound tubes,the equivalent coefficient of the elasticity modulus of spiral wound tubes is defined and fitted in this paper.(2)Numerical calculations of the stress intensity of the wrapped tube-to-tube heat exchanger tubesheet were carried out with the method of design by analysis.Results show that the maximum stress of the tubesheet appears at the arc transition section of the edge of the tubesheet,while the stress at other parts of the tubesheet is very small.Performing the lightweight design of tubesheet found that the bending stress at the center of tubesheet increases with the thinning of tubesheet.(3)Fluent software is used to study and compare the flow state and heat transfer enhancement characteristics of the fluid in spiral wound corrugated pipe and spiral wound plain pipe.It is found by comparing the streamline cloud picture,heat exchange cloud picture,temperature cloud picture,turbulent intensity cloud picture and average Nu number that the turbulent intensity of the fluid in spiral wound corrugated pipe is more intense,the fluid mixing is more sufficient,and the heat transfer effect is better than spiral wound plain pipe.(4)The structure parameters of spiral wound bellows on heat transfer are analyzed by single factor analysis.Results show that increasing the diameter of bellows,decreasing the winding radius,increasing the wave height h and decreasing the wave distance are helpful to enhance the heat transfer.Meanwhile,orthogonal test of the structure parameters of spiral wound corrugated pipe found that diameter d has the greatest influence on the heat transfer in the pipe,followed by wave distance p,wave height h and winding radius r,and winding pitch s has the smallest influence on the heat transfer in the pipe,which can be ignored basically.The optimal combination of structure parameters in the simulation range is obtained.In addition,the correlation of Nu number of fluid heat transfer in spirally wound corrugated pipe is fitted.(5)The heat transfer characteristics of shell-side fluid flow in spiral wound corrugated tube heat exchanger were numerically simulated.Effects of structural parameters on shell-side heat transfer were studied with single factor analysis as well as orthogonal test analysis.Results show that the diameter d,winding radius r and pitch s are the most important factors affecting shell-side heat transfer,and the wave distance p and wave height h are the least important factors.When designing the heat exchanger,the spiral wound heat exchanger tube with smaller diameter,winding radius and wave height,larger pitch and wave distance has the best heat transfer effect on shell side.