Influence of sawtooth twisted tape on thermal enhancement of heat exchanger tube

Boonsong Samutpraphut; Smith Eiamsa-ard; Varesa Chuwattanakul; Chinaruk Thianpong; Naoki Maruyama; Masafumi Hirota

Energy Reports (Mar 2023)

Influence of sawtooth twisted tape on thermal enhancement of heat exchanger tube

Boonsong Samutpraphut,
Smith Eiamsa-ard,
Varesa Chuwattanakul,
Chinaruk Thianpong,
Naoki Maruyama,
Masafumi Hirota

Affiliations

Boonsong Samutpraphut: Department of Mechanical Engineering, Mahanakorn University of Technology, Bangkok, 10530, Thailand
Smith Eiamsa-ard: Department of Mechanical Engineering, Mahanakorn University of Technology, Bangkok, 10530, Thailand; Division of System Engineering, Graduate School of Engineering, Mie University, Tsu, Mie, 514-8507, Japan
Varesa Chuwattanakul: School of Engineering, King Mongkut’s Institute of Technology Ladkrabang, Bangkok, 10520, Thailand; Corresponding author.
Chinaruk Thianpong: School of Engineering, King Mongkut’s Institute of Technology Ladkrabang, Bangkok, 10520, Thailand
Naoki Maruyama: Engineering Innovation Unit, Graduate School of Regional Innovation Studies, Mie University, Tsu, Mie, 514-8507, Japan; Division of Mechanical Engineering, Graduate School of Engineering, Mie University, Tsu, Mie, 514-8507, Japan
Masafumi Hirota: Division of Mechanical Engineering, Graduate School of Engineering, Mie University, Tsu, Mie, 514-8507, Japan

Journal volume & issue: Vol. 9
pp. 696 – 703

Abstract

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This article employs sawtooth twisted tapes to generate swirling flow and interrupted flowing disturbance in order to increase the level of heat transfer rate. The influences of the sawtooth twisted tape (S-TT) on enhanced heat transfer rate, friction factor and aerothermal performance index (API) behaviors are analyzed. The sawtooth twisted tapes (S-TTs) possessing constant pitch/twist ratio (y//W) of 3.0 and six sawtooth angles (α) of 20°, 30°, 40°, 50°, 60°, and 70° are assessed. Considering turbulent flow using air as the testing fluid, experiments were investigated at 6,000 < Re < 20,000 under boundary conditions of constant heat flux. According to the experimental findings, sawtooth twisted tape (S-TT) improves heat transfer rate and raises pressure loss with varying rates based on sawtooth angles (α). With the sawtooth twisted tape (S-TT) and 70° sawtooth angles, the optimum API of 1.33 is attained, while Nusselt number and friction factor are 32 and 0.135 at Re = 6,000. The recommended sawtooth twisted tape (S-TT) yields a highest Nusselt number of 78, which is 1.6 times greater than the typical twisted tape (TT) and 1.1 times greater than the plain tube. The combination of the TT and sawtooth patterns can be beneficial in terms of boosting heat transfer rate and API relating coupling of swirling flow and interrupted flowing disruption effects since the sawtooth twisted tape (S-TT) offers superior performance than the TT. Additionally, the heat exchanger tubes fitted with sawtooth twisted tape (S-TT) at sawtooth angles (α) of 20°, 30°, 40°, 50°, 60°, and 70° gain greater Nusselt number than the plain tube up to 158.3%, 162.2%, 166.1%, 171.7%, 179.7% and 186.2%, respectively.

Published in Energy Reports

ISSN: 2352-4847 (Online)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering
Website: http://www.journals.elsevier.com/energy-reports/

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