Research On Numerical Simulation Approach For Strength And Rigidity Analysis Of Spiral Plate Heat Exchanger

Spiral plate heat exchanger has compact structure and efficient heat transfer rate,small floor area,flexible operation,strong self-cleaning ability,low price,convenient manufacturing and installation,and is widely used.As the spiral plate heat exchangers with large size and high parameters are increasingly used,how to accurately design the equipment is getting more and more concerned.In this thesis,the strength and stiffness of the plates of a spiral plate heat exchanger are studied based on the finite element method with focus on the numericall simulation approach.The main work and conclusions are as follows:(1)Regarding the difficulties of numerical simulating the whole structure of a spiral plate heat exchanger,the feasibility of simplifying the finite element model of the whole spiral plates with multi-layer channels into the model with a single-layer channel is proposed and verified,and for strength analysis of spiral plates,the model can be further simplified into 6×6 substructure model,which greatly simplified the finite element model of the spiral plates.(2)Based on the 6×6 substructure model of spiral plates,the stress classification method and limit analysis method are used to perform the linear elastic stress intensity analysis and limit load analysis.Effects of the material parameters and geometric parameters on the pressure loading capacity of the spiral plate are studied,which provides a reference for the optimal design of the spiral plate.The results show that the limit bearing capacity of the spiral plate can be effectively improved by changing the yield strength,wall thickness and the distance between columns.(3)Based on buckling analysis with both the single-layer channel model and substructure model,the ability of the spiral plate to bear external load is studied,and the effects of material parameters and geometric parameters are investigated.The results show that for the local buckling,the substructure model is effective to calculate the critical pressure of the spiral plate.Wall thickness,distance between columns and elastic modulus of materials have a great influence on the buckling of spiral plates.Increasing the wall thickness and reducing the distance between columns can effectively improve the ability of spiral plates to bear external loads.However,reducing the elastic modulus of materials caused by high temperature will decrease the rigidity of spiral plates;(4)Both design-by-rules and design-by-analysis were applied to calculate the allowable pressure of the spiral plate.By comparing the results,it is found that design-by-rules is more conservative.Although the two design methods find that effects of the spiral plate diameter and wall thickness on the allowable pressure are the same,the influences of the distance between the spacing columns are quite different.With decreasing the spacing,the allowable pressure obtained by design-by-analysis remarkably increased while that by design-by-rules increased slowly,implying that in this aspect,the design-by-rule is too conservative.