Simulation Study On Enhanced Heat Transfer Performance Of Helically Wound Tube

The use of energy is inseparable from the use of heat exchangers.At present,manufacturers of LNG helically wound tube heat exchangers still use ordinary helically wound tubes as heat exchange components to manufacture heat exchangers,but they have problems of low heat transfer coefficient and large heat exchange area.The investigation found that there are few researches on the enhanced heat transfer technology of the helically wound tube.Therefore,it is necessary to study the enhanced heat transfer technology of the helically wound tube and put forward the enhanced heat transfer technology suitable for the helically wound tube.In this paper,the numerical simulation method was used to study the oval twisted helically wound tube and the two-start twisted helically wound tube.The significant factors that affect the flow and heat transfer characteristics of the two types of tube were determined by the method of factorial experiment,and the significant factor was analyzed.Firstly,the basic theory of single-phase flow and heat transfer is introduced.Based on the research status at home and abroad,two types of enhanced heat transfer technology are selected,and a new type of heat transfer-enhanced helically wound tube is established to establish physics and mathematics.The model uses ICEM software to generate grids,and performs grid-independent verification.Fluent software is used for numerical simulation.The simulation results are compared with the experimental results,and the accuracy of the model is verified.The number of criteria for evaluating the effect of enhanced heat transfer.Then introduced the basic theory of factorial experiment,analyzed the physical models of two types of enhanced tubes,and determined four structural parameters that affect the flow characteristics,heat transfer characteristics and comprehensive strengthening characteristics of the two types of reinforced tubes,according to relevant literature and engineering data.The level of each factor was set,two-level full-factor experiments were designed and performed,and factor analysis was used to analyze and determine the significant factors.It is pointed out that for the flow and heat transfer characteristics,the significant factors of both types of reinforced tubes are the distortion parameters.After that,the influence of significant factors on the oval twisted helically wound tube was analyzed.Using the established mathematical and physical models,the combination of multiple twist pitch and elliptic ratio was simulated at different Reynolds number levels,and the structural parameters were analyzed for in-tube flow characteristics,heat transfer characteristics,and the comprehensive enhanced characteristics.Through the analysis of the local flow field,the enhanced heat transfer mechanism of the oval twisted helically wound tube was studied.According to the results of the simulation experiment data analysis,the comprehensive enhancement factor was used as the evaluation criterion,the structural parameters were optimized,and the empirical formula for the flow and heat transfer within the simulated operating conditions was proposed.Finally,the influence of significant factors on the two-start twisted helically wound tube was analyzed.According to the analysis of the oval twisted method,the influence of structural parameters of the two-start twisted method was analyzed on the flow characteristics,heat transfer characteristics and comprehensive enhanced characteristics,and two types of enhanced tubes were compared.The characteristics of the two-start twisted method are applied to the heat transfer enhancement of the helically wound tube,and its structural parameters are optimized,and the flow and heat transfer empirical formulas are proposed.The research of this topic will provide a technical reference for the study of the heat transfer enhancement of the helically wound tube.