Research On Flow And Heat Transfer Characteristics Of Corrugated Inner Fin Tube With Plugged Core

The development of different types of high-efficiency heat exchange equipment has become an important way to reduce energy consumption.Based on the research of the inner fin tube,a new type of corrugated inner fin tube with plugged core is carried out in this study.By optimizing and improving the fin structure into a corrugated shape,not only did it increase the total heat exchange area,but it changed the flow direction and resistance distribution of the fluid.In order to reduce the thermal resistance of the air near the wall and improve the effects of finned tube heat transfer,the disturbance of the fluid to the boundary layer was reinforced.The simulation calculation method is used to study the flow resistance and heat transfer performance of the corrugated inner fin tube with plugged core in this study.The following conclusions were drawed:（1）The heat transfer performance and flow resistance of the corrugated inner fin tube with plugged core and the straight fin tube with plugged core are comparatively studied,and the turbulent kinetic energy,velocity vector and temperature cloud diagram on different sections of the inner fin tube are studied and analyzed.The study found that compared with the core-plugged straight finned tube,the core-plugged corrugated inner finned tube has stronger heat transfer performance,with an average increase of 24.33%in comprehensive heat transfer performance,and the flow resistance is significantly higher than that of the core-plugged straight fin tube.An increase of 19.26%.（2）The main structural parameters of corrugated inner finned tube with blocked core were studied by single factor analysis method.The results showed that the heat transfer performance and resistance loss of the corrugated inner fin tube with plugged core increase with the increase of wave height A;the wavelength L is changed.The effect of thermal characteristics is roughly the same as that of A.It increases with the increase of L.For flow resistance,when the Reynolds number is low,it first decreases and then increases.When the Reynolds number is greater than 3653,the flow resistance gradually decreases as L increases.In addition,the heat transfer performance gradually decreases with the increase of the thickness t,and the resistance loss shows Decrease first and then increase,and the minimum value is taken at the thickness t=0.2 mm.Then,the multi-objective optimization design of the corrugated inner fin tube with plugged core was carried out,and the influence of the structural parameters of wave height A,wavelength L and thickness t on the heat transfer performance and flow resistance of the corrugated inner fin tube with the plugged core was comprehensively investigated,and the optimal structural parameters of the corrugated inner fin tube It is A=0.85 mm,L=9 mm,t=0.15 mm,and the objective function heat transfer factor j=0.01825,friction factor f=0.03481,comprehensive performance F_TEF=0.05575 under optimal structural conditions;finally,the sensitivity of the structural parameters is analyzed,and the heat transfer characteristics Mainly affected by wavelength,flow resistance is mainly affected by wave height,and wavelength and fin thi ckness have relatively high sensitivity to overall performance.（3）The influence of the number of fins on the corrugated inner fin tube with the plugged core was studied.The results showed that the heat transfer factor j,the friction factor f,and the comprehensive performance F_TEF increase with the increase of the number of fins.Analysis of the heat transfer mechanism through cloud diagrams showed that the more fins,the better the heat transfer effect s of the corrugated tube with plugged cores.Then,the heat transfer performance and flow resistance of the corrugated inner fin tube with corrugated core in two different arrangements of fins arranged in order and staggered are compared.The study found that when Re is smaller,the heat transfer factor j and the overall performance F_TEF of the fin in order and staggered are not much different,but as Re increases,the heat transfer factor j and the overall performance F_TEF of in-line fins are gradually higher than the that of staggered fins.The friction factor f is always higher than that of the fins in-line.Finally,a comparison of the heat transfer performance and flow resistance laws of flat corrugated and curved corru gated finned tubes shows that the heat transfer factor j and comprehensive performance F_TEF of flat corrugated core-plugged fin tubes are higher than that of curved corrugated structures,and with Re increases the gap between the two and gradually decrease;The difference in friction factor is small,which the flat corrugated structure is slightly higher than the curved corrugated.