Research On Characteristics Of Heat Exchanger Tube With Short Twisted Tape Under The Influence Of Pulsing Flow

In this paper,the tape that less than half the length of the tube and pulsing stream is as the main object,for finding out exactly parameters of the most favorable heat transfer structure parameters.The short tape in the heat pipe among heat transfer enhancement technology is a main trend,because it has some characters,such as low flow resistance,less material consumption,the simple structure,being easy to rotate and so on.Then importing the pulse flow,and to study the flow field of short twisted tape tube under the influence of pulsing flow.From the two aspects of the interpolation structure and flow field,find exact structural parameters and flow parameters that apply in actual production.This paper introduced the main research progress of the short twisted tape heat tube at home and abroad and the main principles of enhanced heat transfer technology of pulsing flow are introduced.The characteristics of flow field and heat transfer effect are studied in this paper,and the main results are obtained:Combined with the results of previous scholars,the heat transfer mechanism and the flow field of short twisted tape tube under the influence of pulsing flow were furtherly studied,by studying flow velocity and flow resistance law in the theoretical part of the paper,with field synergy principle as the foundation,according to the heat transfer enhancement mechanism of pulsation flow,to analyze the flow field of short twisted tape tube,and considering the degree of collaboration with the heat flow and velocity field,to improve heat transfer efficiency from the view of optimized design.Setting up model by FLUENT software to analyze and calculate in numerical simulation of this paper,the flow field of short twisted tape tube under the influence of pulsing flow were studied,it can be concluded that the fluid velocity contours,pressure contours and temperature images in the tube and so on,then to anslyze data by after-treatment,summarized the structure type of the Nu heat transfer coefficient correlation and structural type of drag coefficient correlation,fiding that the effect of reverse ratio Y on the heat transfer coefficient of Nu can be ignored approximately,and finding that flow resistance decreases when reverse ratio Y=5,the tape length L from 400 mm to 500mm;and from numerical simulation results,it is found that the amplitude of the pulsing flow is the key factor to influence the heat transfer of the short tape tube.In the experiments,using particle image velocimetry(PIV),builting the water circulation system,the PIV experiment that velocity field and vorticity field of short twisted tape tube under the influence of pulsing flow was carried out.The results show that fluid in pipe flow effect was best when the reverse ratio Y=5,length;and the increase of pulsing flow amplitude also have to improve the effect of heat transfer enhancement obviously.