Research On The Flat Strip-insert With Oblique Teeth To Self-rotate With Fluid Power And Enhance Heat Transfer In Tubes

Based on the systemic analyses of the technologies to remove orprevent fouling on heat transfer surface in the world, a compound heattransfer enhancement insert of ingenious structure is invented andresearched. It can solve the problems that fouling or scale grows easilyon tube inside wall and the convective heat transfer coefficient is low inheat transfer tubes at low flowing velocity. The insert's structure ischaracterized that oblique teeth are distributed equally on both surfacesof the fiat strip-insert and there are notches in staggered arrangement oneach side. Directed by the teeth and notch, the fluid in tubes must flowspirally. The kinetic moment is created to remove fouling acted on theinsert by the spirally flowing fluid. In the meantime, an additional forcemoment is made when the fluid push the oblique teeth. Thus, the overallforce moment is great enough to make the insert self-rotate and removefouling at low flowing velocity. Due to the teeth throttle and strong eddy,the convective heat transfer is effectively enhanced. This insert can bemade by injection molding because its basic structure is a flat strip. Thecost will be low and the quality will be good.In the systemic study of the compound technology, the kineticmoment formula of the insert self-rotation is obtained though thetheoretical analysis of dynamics. This formula can be the guide for thestructure optimization and engineering application. The main factors toaffect heat transfer enhancement are analyzed quantitatively andapproximately through theoretical calculation. In the optimization ofstructure parameters, the experimental and theoretical analyses arecombined.The study shows that the force moment of self-rotation is increasedby 116ï¼…compared with the present insert technology, i.e. twisted strip.The new technology can be also used in those heat exchangers at lowerflowing velocity. The ability of fouling removal is great enough. Theaverage enhancement of heat transfer is as great as 93.6ï¼…. The flowingresistance is in the range of industry permission. It is of great significance of engineering application.