The Study On Heat Transfer Enhancement Of The Interpolation-tubular Air Pre-heater With Semi-elliptic Cylinder Shell Vortex Generator

Air pre-heater is one components of boiler equipment. It works in the field wherethe temperature of gas is lowest of all components that be heated in the boiler. Atpresent most used is smooth pipes air pre-heater. It has problems of the low heattransfer efficiency and low temperature corrosion. From the perspective of energysaving and recovery and utilization on waste heat, we should strengthen the heattransfer process and improve the tube wall temperature. It is considered that takingaction to improve heat transfer coefficient between gas and pipe will contribute to thesolution of these problems. Papers on the basis of referring to in the related literature,comparing several different measures on tube heat transfer enhancement, puttingforward a interpolation-tubular air pre-heater with semi-elliptical cylinder shell vortexgenerator.Interpolation-tubular heat transfer pipe with semi-elliptical cylinder shell vortexgenerator using a small tube insert in a bigger pipe with bottom closing. Small tubeouter wall arranged longitudinal vortex generators. Through the analysis, it is agreedthat semi-elliptic cylinder shell vortex generators has better streamline, small flowresistance, and good heat strengthening performance. Comparing to other scholarsstudy the measures on tube heat transfer enhancement, interpolation-tubular heattransfer pipe may double heat transfer enhancement. Taking it to apply to the airpre-heater can improve greatly the heat transfer coefficient between gas and pipe, andreach that the tube is not easy to fouling. But also improve the tube wall temperature,which reduce the extent and speed of the low temperature corrosion. So it is suitablefor replacing the smooth pipe to transform tubular air pre-heater.This paper based on the fluid mechanics and heat transfer theory, using numerical simulation method, taking the interpolation-tubular heat transfer pipe withsemi-elliptic cylinder shell vortex generator as the object to study. Air longitudinalflow inside pipe, gas lateral flow out pipe. Studying the flow and heat transfercharacteristics of interpolation-tubular heat transfer pipe with semi-elliptic cylindershell vortex generator, finding the main factors that influence the heat transferperformance of the semi-elliptic cylinder shell vortex generator and optimizing thestructure of the vortex generator.In terms of theoretical guidance, combining heat transfer, advanced heat transferand fluid mechanics correlation theory. Discussing the occurrence mechanism oflongitudinal vortex, and the mechanism of longitudinal vortex heat transferenhancement. Analysing convective heat transfer of field synergy theory, flow controlequation, boundary layer theory and boundary condition.On the numerical simulation, using FLUENT study respectively the high aspectratio, angle of dip, angle of attack, spacing and arrangement of the semi-ellipticcylinder shell vortex generators, which influence its the flow and heat transferperformance. Proving when vortex generator double row layout, the enhanced heattransfer effect is superior to the single. Coming to conclusion: the heat transferenhancement performance of vortex generator is better when the high aspect ratiov=0.5, angle of dip α=15°, angle of attack β=60°, and spacing S=100mm. To obtain amore accurate and better comprehensive effect vortex generators structure parameterson heat exchange, valuing in its superior range to conduct overall optimization withorthogonal test. Finally getting a group of better structure parameters(v=0.46,α=13°,β=55°,s=90mm).