Numerical Simulation Of Turbulent Heattransfer Of Supercritical Fluid In A Helically Tube

With the shortage of energy in today’s society,people are increasingly aware of the energy conservation,the world’s countries are actively looking for enhanced heat transfer technology,in order to reduce energy waste.Now is to strengthen the heat transfer is a comprehensive engineering research topic,especially single-phase convection heat transfer.Spiral coil is a passive hardening technology.The spiral coil is a highly efficient heat exchanger that has a compact structure and is widely found in piping systems,heat exchangers,nuclear power and other power plant systems in a variety of mechanical devices.The fluids in the supercritical state exhibit good flow and heat transfer characteristics and are widely used in many fields such as aerospace engineering,refrigeration engineering and power plants.Therefore,the supercritical fluid heat transfer characteristics have been one of the focuses in the field of energy.In this paper,CFD simulation of the flow and heat transfer process of supercritical fluid in the spiral coil is carried out to analyze the structural parameters and boundary conditions of the spiral coil.Influence of Heat Transfer Characteristics in Spiral Coil.The first chapter mainly introduces the background of the research,the current situation of domestic and foreign research and the content of this paper.The second chapter mainly introduces the establishment of the model,the division of the grid,through the grid independence analysis,and finally determine the guarantee accuracy and timeliness of the calculation gridIn the third chapter,the physical properties of supercritical fluids are introduced,and the fluid properties of the supercritical fluid are greatly changed.By analyzing the variation of the physical parameters with temperature in detail,the supercritical calculation is calculated based on the CFD secondary development.Fluid physical proceduresIn the fourth chapter,the numerical simulation of the heat transfer characteristics of CO₂ in the spiral coil under supercritical pressure is introduced.The influence of the diameter,pitch,gravity and mass flow on the heat transfer characteristics is compared respectively.In chapter five,the numerical simulation of the heat transfer characteristics of methane in the spiral coil under supercritical pressure is introduced.The effects of the diameter,pitch,the presence or absence of gravity and the mass flow on the heat transfer characteristics are compared respectively.Compare it with CO₂ heat transfer characteristics.Through the numerical simulation results,the following conclusions are obtained: the diameter of the coil can be reduced and the heat transfer coefficient can be improved.The higher the heat flux density is,the higher the heat transfer efficiency is.The spiral coil pitch and the influence of gravity on heat transfer not big.At the same time compared the methane and CO₂ in the spiral coil heat transfer process,the two are very different.