Experimental investigation of heat transfer and friction factor characteristics of thermosyphon solar water heater system fitted with spacer at the trailing edge of Left–Right twisted tapes

Jaisankar, S.; Radhakrishnan, T. K.; Sheeba, K. N.; Suresh, S.

doi:10.1016/j.enconman.2009.06.019

Cited by 93 publications

(34 citation statements)

References 15 publications

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“…These benefits are its easy installation, low cost and low maintenance [4,8]. The resistance to heat flow in a heat exchanger is broken by the disturbance introduced to the flow by the twisted-tape and therefore allow more heat to be transferred [3,9,10]. The enhancement of heat transfer in a tube fitted with twisted-tape is attributed to the reduction in hydraulic diameter, the secondary motion generated by the twisted tape, and the partitioning and blockage of the tube cross section by the tape [11].…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of heat transfer and fluid flow of water through a circular tube induced with divers' tape inserts

Oni

Paul

2016

Applied Thermal Engineering

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An investigation was carried out to analyse numerically heat transfer and flow characteristics of water through a circular tube induced with different twisted tapes. The aim is to know which of the tube designs gives the best performance when compared with a plain tube. Turbulent flow was considered, the walls of the tubes were under uniform wall heat flux, Reynolds number was between 5000 and 20000, and RNG κ-ε model was selected for the simulations. The shape of cuts on the tapes has effects on the performance of the induced tubes. The tube fitted with alternate-axis triangular cut twisted tape has the best performance as its Nusselt number and friction factor are 1.63 -2.18 and 2.60 -3.15 times respectively that of the tube fitted with plain twisted tape while its thermal performance factor is 1.35 -1.43 times that of the tube with plain twisted tape. New correlations were developed for the Nusselt number and friction factors, and reveal that the Nusselt number obtained from the new correlation agrees well with the correlation proposed by Thianpong et al. with a discrepancy of 2.21%. For the friction factor, the discrepancy is 3.01%.

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Section: Introductionmentioning

confidence: 99%

Numerical investigation of heat transfer and fluid flow of water through a circular tube induced with divers' tape inserts

Oni

Paul

2016

Applied Thermal Engineering

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“…The high heating performance of the heater was attributed to the roughness and darkness of the pot surface. The copper coil, covering the pot, also contributed to the maximum energy conversion during the heating process [9,10]. The reflected part of the radiative energy was trapped in the copper carrying the water.…”

Section: Resultsmentioning

confidence: 99%

Heating Performance Study on a Passive Solar Heater

et al. 2017

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Abstract.A passive thermosyphon heating system was designed, fabricated and tested for its thermal performance in semi-arid and four-season climate of Pakistan. The heating system design was based on a two-stage storage and natural thermosyphon circulation of the water. The objective of the study was to enhance the heating performance of the thermosyphon systems by using a semicircular steel pot collector, water carrying copper coil cover, two step water storage, and side mirror reflectors. The experiments were conducted during April to July 2014 when ambient temperature was reported to vary between 32ºC and 44ºC. In continuous flow mode operation, the hot water temperature remained between 46ºC and 78ºC. Since water temperature in the range of 45ºC to 50ºC is considered suitable for the domestic use, the presented design can easily reach the temperatures even higher than those acceptable for the domestic use.

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“…Experimental studies for tubes fitted with left-right twisted tape inserts of various twist ratios were examined to enhance the convective heat transfer rates of a thermosyphon solar water heater system (Jaisankar et al, 2008). The swirl flow was induced by left-right twisted tape in clockwise and counterclockwise directions inside the riser tube, which enhanced the heat transfer.…”

Section: Introductionmentioning

confidence: 99%

Augmentation of Turbulent Flow Heat Transfer in A Horizontal Tube with Varying Width Twisted Tape Inserts

Sarada¹,

Raju²,

Radha³

et al. 2012

Int J Automot Mech Eng

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The present work shows the results obtained from experimental investigations of the augmentation of turbulent flow heat transfer in a horizontal tube by means of varying width twisted tape inserts, with air as the working fluid. In order to reduce excessive pressure drops associated with full-width twisted tape inserts, with a lower corresponding reduction in heat transfer coefficients, reduced-width twisted tapes of widths ranging from 10 mm to 22 mm are used, which are lower than the internal diameter of the tube of 27.5 mm. Experiments were carried out for plain tubes with/without twisted tape inserts at a constant wall heat flux and different mass flow rates. The twisted tapes are of three different twist ratios (3, 4 and 5), each with five different widths (26 (full-width), 22, 18, 14 and 10 mm). The Reynolds number varied from 6000 to 13500. Both the heat transfer coefficient and pressure drop are calculated, and the results are compared with those of a plain tube. It is observed that with the inclusion of twisted tape inserts there is a significant increase in the heat transfer coefficients. Correlations are developed for friction factors and Nusselt numbers for a fully-developed turbulent swirl flow, which are applicable to full-width as well as reduced-width twisted tapes, using a modified twist ratio as the pitch to width ratio of the tape.

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Experimental investigation of heat transfer and friction factor characteristics of thermosyphon solar water heater system fitted with spacer at the trailing edge of Left–Right twisted tapes

Cited by 93 publications

References 15 publications

Numerical investigation of heat transfer and fluid flow of water through a circular tube induced with divers' tape inserts

Numerical investigation of heat transfer and fluid flow of water through a circular tube induced with divers' tape inserts

Heating Performance Study on a Passive Solar Heater

Augmentation of Turbulent Flow Heat Transfer in A Horizontal Tube with Varying Width Twisted Tape Inserts

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