scholarly journals Experimental studies on effect of bonding the twisted tape with pins to the inner surface of the circular tube

2014 ◽  
Vol 18 (4) ◽  
pp. 1273-1283 ◽  
Author(s):  
S. Selvam ◽  
Pr. Thiyagarajan ◽  
S. Suresh
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Experimental Studies ◽  
Twisted Tape ◽  
Constant Wall Temperature ◽  
Tube Heat Exchanger ◽  
Inner Surface ◽  
Fully Developed Turbulent Flow ◽  
Flow Experiments ◽  
Twist Pitch

Heat transfer and friction factor characteristics are studied for water flowing through the tube in tube heat exchanger for two different configurations, namely,(1) twisted tape with pins (TTP) and (2) twisted tape with pins bonded to the inner surface of the test section (TTPB). Experiments are carried out for different twist pitch to the width of the twisted tape ratios (y/w) for TTP and TTPB. But very few research works have been done based on the above mentioned heat transfer enhancement techniques. This paper presents the effect of twisted tape with pins on the heat transfer for a fully developed turbulent flow. Experiments are conducted by maintaining constant wall temperature. The heat transfer rate and pressure drop is found to be high for TTPB of y/w=3.33 when compared to all other configurations. The empirical correlations developed for different twisted tape with pins results in ?7.28% deviation for Nusselt number and ?7.16% for friction factor.

The Effect of Twisted-Tape Width on Heat Transfer and Pressure Drop for Fully Developed Laminar Flow

1996 ◽  
Vol 118 (3) ◽  
pp. 584-589 ◽  
Author(s):  
W. M. Chakroun ◽  
S. F. Al-Fahed
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Friction Factor ◽  
Twisted Tape ◽  
Constant Wall Temperature ◽  
Low Reynolds Number Flows ◽  
Temperature Boundary ◽  
Series Of Experiments

A series of experiments was conducted to study the effect of twisted-tape width on the heat transfer and pressure drop with laminar flow in tubes. Data for three twisted-tape wavelengths, each with five different widths, have been collected with constant wall temperature boundary condition. Correlations for the friction factor and Nusselt number are also available. The correlations predict the experimental data to within 10 to 15 percent for the heat transfer and friction factor, respectively. The presence of the twisted tape has caused the friction factor to increase by a factor of 3 to 7 depending on Reynolds number and the twisted-tape geometry. Heat transfer results have shown an increase of 1.5 to 3 times that of plain tubes depending on the flow conditions and the twisted-tape geometry. The width shows no effect on friction factor and heat transfer in the low range of Reynolds number but has a more pronounced effect on heat transfer at the higher range of Reynolds number. It is recommended to use loose-fit tapes for low Reynolds number flows instead of tight-fit in the design of heat exchangers because they are easier to install and remove for cleaning purposes.

scholarly journals Internal Flow Analysis of a Heat Transfer Enhanced Tube with a Segmented Twisted Tape Insert

Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 207 ◽  
Author(s):  
Gan Liu ◽  
Chen Yang ◽  
Junhui Zhang ◽  
Huaizhi Zong ◽  
Bing Xu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Friction Factor ◽  
Dominant Role ◽  
Length Ratio ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Constant Wall Temperature ◽  
Advantages And Disadvantages ◽  
Twist Ratio

A heat exchanger is a device that transfers unneeded heat from one region to another, and transferred heat may be fully reused, thus improving energy efficiency. To augment this positive process, many studies and investigations on automation technologies have been performed. Inserts are widely used in pipe flow for heat transfer enhancement, since they can break the boundary layer and promote the heat exchange. Segmented twisted tape, which is applicable in 3D printing, is a novel insert and has potential in heat transfer enhancement. To clarify its advantages and disadvantages, this research presents a numerical investigation of vortex flow and heat enhancement in pipes containing one segmented twisted element. Flow state and heat transfer behaviour are obtained by simulation under constant wall temperature with different Reynolds numbers, ranging from 10,000 to 35,000. The effects of geometric parameters, including twist ratio (P/D = 2.0, 3.3 and 4.6) and length ratio (L/P = 0.3, 0.5 and 0.7), on the Nusselt number (Nu) and friction factor (f) are investigated. Streamline and temperature distribution are presented. Meanwhile, local and overall heat transfer performance is compared with those of a smooth tube, and the overall performance is evaluated by performance evaluation factor (η). The results indicate that the twist ratio (P/D) plays a dominant role in heat transfer enhancement while the length ratio (L/P) also has considerable influence. It is shown that a segmented tape insert can increase the overall heat transfer rate by 23.5% and the friction factor by 235%, while local improvement along the tube can be 2.8 times more than the plain tube.

Simulation of Turbulent Heat Transfer in a Tube Fitted with Twisted Tape Placed Separately from the Tube Walls

2015 ◽  
Vol 751 ◽  
pp. 245-250 ◽  
Author(s):  
Niwat Piriyarungroj ◽  
Smith Eiamsa-ard ◽  
Pongjet Promvonge ◽  
Petpices Eiamsa-Ard ◽  
Chinaruk Thianpong
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Friction Factor ◽  
Transfer Rate ◽  
Reynolds Numbers ◽  
Turbulent Heat Transfer ◽  
Twisted Tape ◽  
Turbulent Heat ◽  
Clearance Ratio ◽  
Constant Wall Temperature

The effects of loose-fit twisted tape (LFT) on the heat transfer rate, friction factor, fluid phenomena and thermal performance of a tube under constant wall temperature are examined. It is observed that apart from the rise of Reynolds number, the reduction of the clearance ratio (c/D) leads to an increase in the heat transfer and pressure loss. According to the numerical results, the heat transfer and friction factor in the tubes with loose-fit twisted tape (LFT) for the smallest clearance ratio of c/D = 0.05 are higher those other clearance ratios. In addition, the thermal performances of clearance ratio c/D = 0.05 are found to be higher than those other clearance ratios (c/D) for all Reynolds numbers examined.

scholarly journals The Effect of Twisted Tape Width on Heat Transfer and Pressure Drop for Fully Developed Laminar Flow

1995 ◽  
Author(s):  
Walid M. Chakroun ◽  
Sami F. Al-Fahed
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Friction Factor ◽  
Twisted Tape ◽  
Constant Wall Temperature ◽  
Low Reynolds Number Flows ◽  
Temperature Boundary ◽  
Series Of Experiments

A series of experiments was conducted to study the effect of twisted-tape width on the heat transfer and pressure drop with laminar flow in tubes. Data for three twisted-tape wave lengths each with five different widths have been collected with constant wall temperature boundary condition. Correlations for the friction factor and Nusselt number are also available. The correlations predict the experimental data to within 10 % to 15 % for the heat transfer and friction factor, respectively. The presence of the twisted tape has caused the friction factor to increase by a factor of 3 to 7 depending on Reynolds number and the twisted-tape geometry. Heat-transfer results have shown an increase of 1.5 to 3 times that of plain tubes depending on the flow conditions and the twisted-tape geometry. The width shows no effect on friction factor and heat transfer in the low range of Reynolds number but have a more pronounced effect on heat transfer at the higher range of Reynolds number. It is recommended to use a loose-fit tapes for low Reynolds number flows instead of tight-fit in the design of heat exchangers because they are easier to install and remove for cleaning purposes.

scholarly journals Thermal-Hydraulic Studies on the Shell-and-Tube Heat Exchanger with Minijets

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3276 ◽  
Author(s):  
Jan Wajs ◽  
Michał Bajor ◽  
Dariusz Mikielewicz
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Waste Heat ◽  
Experimental Studies ◽  
Convection Heat Transfer ◽  
Test Facility ◽  
Experimental Investigations ◽  
Transfer Coefficients ◽  
Tube Heat Exchanger ◽  
Shell And Tube

In this paper a patented design of a heat exchanger with minijets, with a cylindrical construction is presented. It is followed by the results of its systematic experimental investigations in the single-phase convection heat transfer mode. Based on these results, validation of selected correlations (coming from the literature) describing the Nusselt number was carried out. An assessment of the heat exchange intensification level in the described heat exchanger was done through the comparison with a shell-and-tube exchanger of a classical design. The thermal-hydraulic characteristics of both units were the subjects of comparison. They were constructed for the identical thermal conditions, i.e., volumetric flow rates of the working media and the media temperatures at the inlets to the heat exchanger. The experimental studies of both heat exchangers were conducted on the same test facility. An increase in the heat transfer coefficients values for the minijets heat exchanger was observed in comparison with the reference one, whereas the generated minijets caused greater hydraulic resistance. Experimentally confirmed intensification of heat transfer on the air side, makes the proposed minijets heat exchanger application more attractive, for the waste heat utilization systems from gas sources.

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