Numerical Study on Enhanced Heat Transfer by Twisted Tape Inserts inside Tubes

The present describes the numerical study on the single-phase enhanced convective heat transfer effect with single twisted tape insert, double twisted tape insert and triplex twisted tape insert as inserts in heat exchange tubes. The second order discrete FVM method was used, and the wall surface enhancement equations were used to analyze the heat transfer and flow characteristics of air inside the tube in the heating process, the result was compared with the classical empirical equation, and it showed an error within ±15%. The study results show that the TTI of three types can enhance the heat transfer ability of fluid by 1.8-4.5 times; and the three types of TTI's also showed different characteristics in the resisting effect to flow of fluids. The resistance can increase by 8.7-6.0 times with a single TTI, by 14.4-9.4 times with a double TTI, and by as high as 21.2-13.7 times with a triplex TTI.