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Effect of rotating twisted tape on thermo-hydraulic performances of nanofluids in heat-exchanger systems

Qi, Cong; Wang, Guiqing; Yan, Yuying; Mei, Siyuan; Luo, Tao

Authors

Cong Qi

Guiqing Wang

YUYING YAN YUYING.YAN@NOTTINGHAM.AC.UK
Professor of Thermofluids Engineering

Siyuan Mei

Tao Luo



Abstract

Stable TiO2-H2O nanofluids are prepared and their stabilities are studied. An experimental set for studying the heat transfer and flow characteristics of nanofluids is established. Heat transfer and flow characteristics of TiO2-H2O nanofluids in a circular tube with rotating and static built-in twisted tapes are experimentally investigated and compared. An innovative performance evaluation plot of exergy efficiency is developed and the exergy efficiency of tube with rotating and static built-in twisted tapes filled with nanofluids is analyzed in this paper. The results indicate that the combination of rotating built-in twisted tape and TiO2-H2O nanofluids shows an excellent enhancement in heat transfer, which can increase the heat transfer by 101.6% compared with that of in a circular tube. The effects of nanoparticle mass fractions (ω= 0.1%, 0.3% and 0.5%) and Reynolds numbers (Re = 600–7000) on the heat transfer and flow characteristics of TiO2-H2O nanofluids are discussed. It is found that there is a critical Reynolds number (Re = 4500) for the maximum value of relative heat transfer enhancement ratio. The comprehensive performance of the experimental system is analyzed. It can be found that the comprehensive performance index of the experimental system firstly increases and then reduces with Reynolds number, and it can reach 1.519 at best. However, for the performance evaluation of exergy efficiency, the coupling of rotating twisted tape and nanofluids deteriorates the exergy efficiency. Also, it can be found that the exergy efficiency of the circular tube with twisted tape is greater than that of circular tube under the same pumping power and pressure drop, but it shows deterioration under the same mass flow rate.

Citation

Qi, C., Wang, G., Yan, Y., Mei, S., & Luo, T. (2018). Effect of rotating twisted tape on thermo-hydraulic performances of nanofluids in heat-exchanger systems. Energy Conversion and Management, 166, https://doi.org/10.1016/j.enconman.2018.04.086

Journal Article Type Article
Acceptance Date Apr 22, 2018
Online Publication Date May 3, 2018
Publication Date Jun 15, 2018
Deposit Date May 8, 2018
Publicly Available Date May 4, 2019
Journal Energy Conversion and Management
Print ISSN 0196-8904
Electronic ISSN 0196-8904
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 166
DOI https://doi.org/10.1016/j.enconman.2018.04.086
Keywords Nanofluids; Rotating twisted tape; Heat transfer enhancement; Nanoparticle mass fraction; Exergy efficiency
Public URL http://eprints.nottingham.ac.uk/id/eprint/51610
Publisher URL https://doi.org/10.1016/j.enconman.2018.04.086
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0





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