Optimization Study Of Spirally Grooved Tube Shape Based On Genetic Algorithm And Surrogate Model

Spiral grooved tube is a kind of low-cost,simple structure and high-efficiency heat exchange element,which has been widely used in energy,petroleum,chemical and other industries.In this paper,the spiral groove tube is the research object,and the method of CFD numerical simulation is used to explore the enhanced heat transfer mechanism of the spiral groove tube.The optimization design framework based on genetic algorithm and surrogate model was used to optimize the groove shapes of single-head and double-head spirally grooved tubes,and an optimized spirally grooved tube with good enhanced convective heat transfer performance was obtained.The reliability of this optimized design framework is verified,and a new idea is provided for the optimization study of the enhanced heat transfer performance of the spirally grooved tube.In this paper,numerical simulation methods are used to compare and analyze the flow field characteristics of single-phase flow heat transfer in spirally grooved tubes and smooth tubes,and explore the enhanced heat transfer mechanism of spirally grooved tubes.The numerical simulation results are verified with the previous experimental results to ensure the reliability of the numerical simulation method.Studies have shown that the fluid flow in the spirally grooved tube presents a spiral forward,which produces a larger secondary flow and a stronger longitudinal vortex on the cross section perpendicular to the main flow.Based on the analysis of the field synergy theory,it is found that the field synergy angle in the spirally grooved tube is smaller than that of the smooth tube,and the field synergy between the velocity field and the temperature field is better than that of the smooth tube,and the convective heat transfer performance is better.In this paper,an optimal design framework of spirally grooved tubes based on genetic algorithm and surrogate model is proposed.The groove shape of single end and double end spirally grooved tubes is optimized respectively with the comprehensive heat transfer performance as the optimization objective,and the optimized spirally grooved tubes with improved comprehensive heat transfer performance are obtained.In the optimization study,a spline curve based on control points was used to parametrically describe the groove shape of the spiral grooved tube,the data obtained by orthogonal experiment design and CFD calculation was used to train a surrogate model,and the genetic algorithm was combined to find the groove shape with the best comprehensive performance.The surrogate model is used in the optimization design framework to replace a large number of CFD calculations,which saves computing resources and improves the efficiency of the optimization process.This paper also compares and analyzes the flow field characteristics and heat transfer characteristics of the single-phase flow heat transfer in the optimized spirally grooved tube and the original spirally grooved tube.It is found that compared with the original spiral grooved tube,the optimized spiral grooved tube has flat groove shape,smaller secondary flow and longitudinal vortex intensity,but more uniform turbulent kinetic energy distribution and lower flow resistance;its field synergy performance is equal to or slightly higher than that of the original spiral grooved tube,and its heat transfer capacity is equivalent to that of the original spiral grooved tube.Therefore,the comprehensive heat transfer performance of the optimized grooved spiral grooved tube is greatly improved.