Development of new correlations for heat transfer and friction loss of solid ring with combined square wing twisted tape inserts heat exchanger tube

Experimental examination is carried out to study the turbulent heat transfer and fluid-flow characteristics in circular heat exchanger tube using combined wing with solid ring twisted tape inserts. A series of experiments has been performed with the range of Reynolds number varied from 3000 to 21000, number of twisted taped inserts, NTT, varied from 1.0 to 4.0 with constant value of other twisted tape parameters such as rings pitch ratio, dR /DT = 1.0, wing pitch ratio, PW /WT = = 3.0, and wing depth ratio, Wd /WT = 1.67. Based on the examined, turbulent heat transfer and fluid-flow in wing with combined solid ring twisted tape inserts results are compared with plain circular tube under same operating conditions. The experimental results show that the heat transfer is increased around 5.66 times than plane circular heat exchanger tube. The thermal and hydrodynamic performance parameter based on equal pumping power, ?p, was found to be highest for NTT = 3.0. The optimum value of thermal and hydrodynamic performance has been found to be 2.74 for Reynolds mumber of 3000 within the range of the parameters investigated. Multiple wings with solid rings twisted tape inserts have been also shown to be thermally as well as hydraulically better in comparison to other similar twisted tape insert geometries.

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Experimental determination of enhancement of heat transfer in a multiple square perforated twisted tape inserts heat exchanger tube

Experimental Heat Transfer ◽

10.1080/08916152.2017.1397814 ◽

2017 ◽

Vol 31 (2) ◽

pp. 85-105 ◽

Cited By ~ 16

Author(s):

Amar Raj Singh Suri ◽

Anil Kumar ◽

Rajesh Maithani

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Experimental Determination ◽

Twisted Tape ◽

Heat Exchanger Tube ◽

Enhancement Of Heat Transfer ◽

Exchanger Tube

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Sensitivity Analysis of a Heat Exchanger Tube Fitted With Cross-Cut Twisted Tape With Alternate Axis

Journal of Heat Transfer ◽

10.1115/1.4042780 ◽

2019 ◽

Vol 141 (4) ◽

Cited By ~ 14

Author(s):

M. E. Nakhchi ◽

J. A. Esfahani

Keyword(s):

Heat Transfer ◽

Sensitivity Analysis ◽

Reynolds Number ◽

Heat Exchanger ◽

Thermal Performance ◽

Diameter Ratio ◽

Design Parameters ◽

Twisted Tape ◽

Heat Exchanger Tube ◽

Exchanger Tube

Numerical simulations are used to analyze the thermal performance of turbulent flow inside heat exchanger tube fitted with cross-cut twisted tape with alternate axis (CCTA). The design parameters include the Reynolds number (5000<Re<15,000), cross-cut width ratio (0.7<b/D<0.9), cross-cut length ratio (2<s/D<2.5), and twist ratio (2<y/D<4). The objective functions are the Nusselt number ratio (Nu/Nus), the friction factor ratio (f/fs), and the thermal performance (η). Response surface method (RSM) is used to construct second-order polynomial correlations as functions of design parameters. The regression analysis shows that heat transfer ratio decreased with increasing both the Reynolds number and the width to diameter ratio of the twisted tape. This means that the twisted tape has more influence on heat transfer at smaller inlet fluid velocities. Sensitivity analysis reveals that among the effective input parameters, the sensitivity of Nu/Nus to the Reynolds number is the highest. The results reveal that thermal performance enhances with increasing the width to diameter ratio of the twisted tape (b/D). The maximum thermal performance factor of 1.531 is obtained for the case of Re=5000, b/D=0.9, s/D=2.5, and y/D=4.

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