Study On Heat Transfer Characteristics Of Fluid-Solid Two-Phase Flow In Spiral Slices Inserted Condenser Tube

In response to the depletion of fossil energy and energy and environmental pollution,all countries in the world have formulated strategies for energy development,making the economy sustainable,achieving efficient use of resources,and continuously improving the environment.Heat exchangers are widely used in petroleum,chemical,energy and pharmaceutical industries.Heat exchangers are the basic equipment for the equipment manufacturing industry.Heat exchangers that are more economical,better,cleaner,and safer in production and use are the foundation for sustainable development.Increasing the heat transfer efficiency of the heat exchanger and preventing the fouling of the heat transfer surface is important measures to improve the heat transfer efficiency,and have important practical and social benefits for the country’s sustainable development strategy.This paper uses a composite enhanced heat transfer technique for liquidsolid two-phase flow in a tube with spiral slices insert.Work on the impact on this technology on the heat transfer performance of the tube.This paper briefly introduces the basic theory of inserting the spiral piece and passing solid particles to achieve the composite heat transfer enhancement of the tube,which provides a theoretical basis for the later numerical simulation.The parameters such as the height of the spiral slice,the pitch of the spiral slice,the spacing of the spiral slice,the volume concentration of the solid particles and the particle diameter,which affect the heat transfer performance of the tube were optimized by numerical calculation.The optimized parameter combination was obtained.The following is the main work carried out in this paper and the results of the research.Firstly,build a suitable mathematical model according to the actual engineering problems of the heat exchange tubes.After the meshing of the computing domain is completed,the calculation domain of the threedimensional physical model of the heat transfer tube was numerically simulated by Fluent software.The effect of inserting the spiral slice and adding solid particles on heat transfer performance and resistance performance of the heat exchange tube was studied.A comprehensive evaluation index was established to comprehensively evaluate the heat transfer performance of the heat transfer tubes.Secondly,using Fluent software,the heat transfer characteristics and resistance characteristics of the tubes in which the spiral slices were inserted and the solid particles were added were numerically simulated.The influence of the height of the spiral slice,the pitch of the spiral slice,the space of the spiral slice,the volume concentration of the solid particles and the particle diameter on the heat transfer and the resistance of the tube were analyzed.Combined with the analysis of the comprehensive evaluation criteria,the effects of the above five parameters on the comprehensive heat transfer performance of the tube with spiral slices inserted and particles added are comprehensively considered.It has been found that the insertion of the spiral slice of the tube causes the rotation of the fluid to promote radial mixing.The perturbation of the fluid by the solid particles and the collision of the particles on the wall created the disturbances in the temperature boundary layer and the velocity boundary layer.Heat transfer performance is enhanced while resistance performance is improved.The heat transfer performance of the tube with spiral slice inserted and particle added is significantly enhanced compared to the smooth tube.It provides a reference direction for the optimization research of various structural parameters of heat exchange tubes.Finally,based on the orthogonal test method,the parameters such as the height of the spiral slice h,the pitch of the spiral slice s,the space of the spiral slice l,the volume concentration of the solid particles c and the particle diameter d were optimized.The results show the influence of various parameters on the heat transfer performance of the tube with spiral slices and particle added.The pitch of the spiral slice has the greatest influence.This is followed by the diameter of the particles and the height of the spiral slice.Then there is the spacing of the spiral slices and the concentration of the particles.Based on the model structure and the range of parameters studied in this paper,the pitch of the spiral has the greatest influence on the comprehensive performance of the heat transfer tube.The effect of the space of the spiral slices and the concentration of the particles of the comprehensive performance of the tube is similar.The optimal combination of parameters affecting the comprehensive performance of the heat transfer tube is obtained when the following conditions are set for each parameter.The height of the spiral piece was 4 mm,the pitch of the spiral piece was 60 mm,the pitch of the spiral piece was set to 400 mm,the volume concentration of the particles was 5%,and the particle diameter was 1.2 mm.Combined with the analysis of the velocity field and temperature field of the numerical calculation results,the comprehensive performance of the tube under this combination of parameters is indeed significantly improved.