Experimental study on effect of heat transfer enhancement for single-phase forced convective flow with twisted tape inserts

• Published in: International journal of heat and mass transfer Vol. 106; pp. 877 - 883
• Main Authors: Man, Changzhong, Lv, Xiaogang, Hu, Jingwei, Sun, Peiyan, Tang, Yunbang
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.03.2017; Elsevier BV
• Subjects: Cold water; Convective flow; Cooling; Dual-pipe heat exchanger; Fluid dynamics; Fluid flow; Heat exchangers; Heat transfer; Heat transfer enhancement; Hot water; Inserts; Nusselt number; Reynolds number; Turbulence; Turbulent flow; Twisted tape insert; Heat transfer enhancement; Dual-pipe heat exchanger; Twisted tape insert; Turbulent flow
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2016.10.026

•A new type of twisted tapes is introduced in this paper which is seldom investigated before.•Characteristics of heat transfer and friction of the new type of twisted tapes are studied compared with typical twisted tapes and plain tube.•Comprehensive performance of the ACCT tape is evaluated and the results show that it has a prominent performance on heat transfer enhancement.•All deviations in experiment and calculation are kept within a small range. In this paper, experimental investigation on heat transfer and friction characteristics of dual-pipe heat exchanger for single-phase forced convective flow with alternation of clockwise and counterclockwise twisted tape (ACCT tape) and typical twisted tape (TT tape) inserted in the inner tube has been carried out. And effects of different lengths of twisted tapes on heat transfer enhancement were studied through a circular tube using water as testing fluid in turbulent conditions with a range of Reynolds number between 3000 and 9000. In the dual-pipe heat exchanger, hot water was cooled in the inner tube and cold water was as cooling fluid between the inner tube and the outer tube. The results showed that the ACCT tapes performed better on heat transfer enhancement than the typical twisted tapes and the best effect appeared with the full-length (l=2400mm) ACCT tape insert in comparison with the twisted tapes of other lengths. The maximum values of PEC (performance evaluation criteria) with the full-length ACCT tape insert reached 1.42 in experimental flowing conditions. Empirical correlations for Nusselt number and friction factors were established and found to fit the experimental data with a deviation within 8%.