| Enhanced heat transfer technology is widely used in the field of industrial production.How to improve the efficiency of heat exchangers has always been a research hotspot in the field of heat transfer.Based on the research of the corrugated pipe and the spiral twisted tape,a compound method of heat transfer enhancement by inserting the Left-Right twisted tape into corrugated pipe is proposed in this paper.This new type of enhanced heat transfer model is numerically simulated in laminar flow by using the software FLUENT ANSYS.The Reynolds number range from 400 to 1800 is selected for the simulated calculation.Water is used as the fluid medium,and the boundary condition of constant wall temperature is adopted.The heat transfer characteristics,resistance characteristics and comprehensive performance of the heat transfer model are evaluated by Nusselt number,friction coefficient and PEC value.Firstly,according to the different combinations of plain tube,corrugated tube,traditional twisted tape and Left-Right twisted tape,as well as the separate use of plain tube or corrugated tube,a total of six groups of models are established.Under the same conditions,different models are compared and studied.The results show that the heat transfer effect of the single corrugated tube is better than that of ordinary plain tube,but the effect of heat transfer enhancement is not significant.The heat transfer effect of the heat exchange tube can be greatly improved by inserting twisted tapes.The corrugated tube inserted with Left-Right twisted tapes has the highest heat transfer coefficient and the highest comprehensive performance PEC value.Secondly,the twisted ratio,width of the Left-Right twisted tape and the wave length and wave height of the corrugated tube are changed in this paper,and the effects of these structural parameters on the heat transfer characteristics,resistance characteristics and comprehensive heat transfer performance of the heat transfer model are studied.The results show that under the same Reynolds number,the heat transfer coefficient and friction resistance of the heat transfer model increase with the decrease of the twisted ratio of the Left-Right twisted tape,and the Left-Right twisted tape with smaller twisted ratio has higher comprehensive heat transfer performance.The heat transfer coefficient,friction resistance and PEC value of the heat transfer model decrease with the decrease of the width of the Left-Right twisted tape.Heat transfer effect of the corrugated tube inserted with Left-Right twisted tape will be weakened if the wave length and wave height is too large or too small.Among the models studied in this paper,the best comprehensive heat transfer performance is obtained when the model has the wave length of the 13 mm and the wave height of 2.5 mm.Finally,by changing the fitting positions between the Left-Right twisted tape and the corrugated tube,it is proved that the Left-Right junction of the twisted tape and the corrugated wave zone has strong disturbance in the flow field.When the Left-Right junction and the wave zone are in the same axial position,the heat transfer model has better heat transfer effect and comprehensive performance. |
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