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Research Papers: Heat Transfer Enhancement

# Enhancement and Prediction of Heat Transfer Rate in Turbulent Flow Through Tube With Perforated Twisted Tape Inserts: A New Correlation

[+] Author and Article Information
J. U. Ahamed

Department of Mechanical Engineering, Chittagong University of Engineering and Technology (CUET), Chittagong 4349, Bangladeshjamal239@yahoo.com

M. A. Wazed1

Department of Engineering Design and Manufacture, University of Malaya (UM), 50603 Kuala Lumpur, Malaysiaawazed@gmail.com

S. Ahmed

Department of Engineering Design and Manufacture, University of Malaya (UM), 50603 Kuala Lumpur, Malaysiaahmed@um.edu.my

Y. Nukman

Department of Engineering Design and Manufacture, University of Malaya (UM), 50603 Kuala Lumpur, Malaysianukman@um.edu.my

T. M. Y. S. Tuan Ya

Department of Engineering Design and Manufacture, University of Malaya (UM), 50603 Kuala Lumpur, Malaysiatyusoff@um.edu.my

M. A. R. Sarkar

Department of Mechanical Engineering, Bangladesh University of Engineering and Technology (BUET), Dhaka 1000, Bangladeshrashid@me.buet.ac.bd

1

Corresponding author.

J. Heat Transfer 133(4), 041903 (Jan 14, 2011) (9 pages) doi:10.1115/1.4002635 History: Received March 08, 2010; Revised September 11, 2010; Published January 14, 2011; Online January 14, 2011

## Abstract

An experimental investigation has been carried out for turbulent flow in a tube with perforated twisted tape inserts. The mild steel twisted tape inserts with circular holes of different diameters (i.e., perforation) are used in the flow field. An intensive laboratory study is conducted for heat transfer and pressure drop characteristics in the tubes for turbulent flow with various airflow rates. Heat transfer and pressure drop data are engendered for a wide range Reynolds number $(1.3×104–5.2×104)$. Tube wall temperature, pressure drop, air velocity, and its temperature are measured both for plain tube and for tube with perforated twisted tape inserts. Heat transfer coefficients, Nusselt number, pumping power, and heat transfer effectiveness are calculated for both cases. Experimental results showed that perforated twisted inserts of different geometry in a circular tube enhanced the heat transfer rate with an increase in friction factor and pumping power for turbulent flow. The pumping power, heat transfer coefficient, and effectiveness in the tube with the twisted tape inserts are found to increase up to 1.8, 5.5, and 4.0 times of those for the plain tube for same Reynolds number, respectively. Finally, a correlation is developed for prediction of the heat transfer rate for turbulent flow through a circular tube with perforated twisted tape inserts.

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## Figures

Figure 1

Schematic diagram of the experimental facility

Figure 2

Cross section of the test section with perforated twisted tape inserts

Figure 3

X-section of the test section with insulations

Figure 4

Schematic diagram of the hole position in the plate

Figure 5

Location of pitot tube for velocity measurement (R is the radius of the whole tube)

Figure 6

Axial location of thermocouple for wall temperature

Figure 7

Radial location of thermocouple for outlet bulk fluid temperature

Figure 8

Effects of perforation of the twisted tape insert on Nusselt number at different Reynolds numbers

Figure 9

Variation of the average heat transfer coefficient for different inserts (porous and nonporous inserts) at different Reynolds numbers

Figure 10

Variation of wall and bulk temperatures along the axial distance for different perforation of insert at Reynolds number around 29,670

Figure 11

Variation of the pressure drop for inserts having different perforation at different Reynolds numbers

Figure 12

Variation of the friction factor along axial distance for smooth tube

Figure 13

Variation of the friction factor along axial distance for the tube with the perforated twisted tape having porosity Rp=4.6%

Figure 14

Variation of the experimental data with the predicted data for different porosity of twisted tape inserts (Rp from 2.5% to 20.8%)

Figure 15

Goodness of fit of the correlation (Eq. 11)

Figure 16

ln(Nu/Pr0.33) versus ln(Re) graph for different porosity of twisted tape inserts (Rp from 2.5% to 20.8%) considering single series

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