Thermal behaviors in a round tube equipped with quadruple perforated-delta-winglet pairs

Skullong, Sompol; Promvonge, Pongjet; Thianpong, Chinaruk; Jayranaiwachira, Nuthvipa

doi:10.1016/j.applthermaleng.2016.12.082

Cited by 68 publications

(22 citation statements)

References 45 publications

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“…The average friction factor in the inner tube with the addition of the DWT with Rb = 0.28, 0.35, and 0.42 increased by 11.8, 13.4, and 15.5, respectively, compared with the much lower friction factor values of the LS and plain tube, although the values of LS were slightly better those of the plain tube. Rb = 0.42 showed the highest f value, which may be attributed to the increased surface area (solid-winglet/tape) that induced a larger recirculation zone behind the winglet, leading to higher vortex strength, higher turbulence intensity, and an enhanced friction factor [28]. …”

Section: Effect Of Blockage Ratio On Friction Factormentioning

confidence: 99%

“…As is shown in Figure 6, a higher R b produces a higher Nu. The higher R b generated strong flow circulation and separation for higher turbulence intensity leading to higher heat-transfer performance [28] the heat-transfer rate [25]. The Nusselt numbers of the tube with DWT and LS insertions were higher than those of the plain tube.…”

Section: Validation Of the Plain Tubementioning

confidence: 99%

Section: Validation Of the Plain Tubementioning

confidence: 99%

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Impact of Blockage Ratio on Thermal Performance of Delta-Winglet Vortex Generators

et al. 2018

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Abstract:The impact of double-sided delta-winglet tape (DWTs) inserts on convective heat transfer and friction behaviors in a tube was experimentally investigated. Three DWTs with ratios of winglet-height (b) to inner tube diameter (d i ) called blockage ratio (R b ) of 0.28, 0.35 and 0.42 were tested and their performance was compared to that of a longitudinal strip and plain tube under similar test flow conditions. Experiments were conducted over a wide range of flow rates, 3.35 × 10 −5 -8.33 × 10 −5 m 3 /s, which correspond to 5500 ≤ Reynolds number (Re) ≤ 14,500 in the 14.3 mm i.d. tube. The results revealed that using DWTs dramatically increased the Nusselt number (Nu) by as much as 364.3% and the friction factor (f ) by 15.5 times compared with those of a plain tube. Thermal performance (η) increased with a corresponding increase in R b . The highest thermal performance (η) obtained was 1.4. Showing a notable improvement on the thermal performance of the system, DWTs are proposed as a favorable insert device.

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Section: Effect Of Blockage Ratio On Friction Factormentioning

confidence: 99%

Section: Validation Of the Plain Tubementioning

confidence: 99%

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Impact of Blockage Ratio on Thermal Performance of Delta-Winglet Vortex Generators

et al. 2018

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“…Many new types of turbulence promoters have been developed recently. Comment types are: twisted tapes [20][21][22][23][24], winglets tapes [25,26], circular rings [23,27], horseshoe baffles [28], Advances in Heat Exchangers helical inserts [29], and coil wires [30]. The optimization of their design for improving thermohydraulic performance has been the focus of research.…”

Section: Turbulence Promoters For Tubular Geometriesmentioning

confidence: 99%

“…The modification of basic insert geometries is done seeking to improve on its thermohydraulic performance as is the case of the delta-winglet tape where a considerable augmentation of the heat transfer and friction factor rate has been reported [25,26]. Some other geometries exhibit improved thermal performance but at the cost of considerable increase of pressure drop.…”

Section: Turbulence Promoters For Tubular Geometriesmentioning

confidence: 99%

Use of Heat Transfer Enhancement Techniques in the Design of Heat Exchangers

Picón‐Núñez¹,

Melo-González²,

Castillo³

2019

Advances in Heat Exchangers

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Heat transfer enhancement refers to application of basic concepts of heat transfer processes to improve the rate of heat removal or deposition on a surface. In the flow of a clean fluid through the tube of a heat exchanger, the boundary layer theorem establishes that a laminar sublayer exists where the fluid velocity is minimal. Heat transfer through this stagnant layer is mainly dominated by thermal conduction, becoming the major resistance to heat transfer. From an engineering point of view, heat transfer can be enhanced if this stagnant layer is partially removed or eliminated. In single-phase heat transfer processes, three options are available to increase the heat transfer rate. One of them is the choice of smaller free flow sectional area for increased fluid velocity bringing about a reduction of the thickness of the laminar sublayer. A second option is the engineering of new surfaces which cause increased local turbulence, and the third option consists in the use of mechanical inserts that promote local turbulence. The application of these alternatives is limited by the pressure drop. This chapter describes the concept of heat transfer enhancement and the ways it is applied to the development of new heat exchanger technology.

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The effect of triangular shutter type flow deflector perforated baffle plate on the thermofluid performance of a heat exchanger

Rahman

2023

Heat Trans

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The study aimed to investigate the heat transfer (HT) properties of a tubular heat exchanger (HX) by using innovative baffle plate arrangements. The newly designed baffle plate was circular with triangular openings and adjustable triangular flow deflectors. These deflectors were strategically placed at the inlet of the HX to create a swirling flow downstream. Three baffle plates were installed along the flow direction with different length‐to‐diameter ratios (pitch ratios) to assess their impact on HT, pressure drop, and thermal enhancement factor. The study compared these results with a smooth channel under varying Reynolds numbers (16,500–29,500). The findings revealed that both the pitch ratio (0.6–1.2) and the inclination angle of the deflectors (30⁰–50⁰) significantly affected the HX's performance. Notably, the baffle plate with a deflector inclination angle of 30° and a pitch ratio of 1 showed a remarkable average improvement of 36.5% compared to other angles and ratios.

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Thermal behaviors in a round tube equipped with quadruple perforated-delta-winglet pairs

Cited by 68 publications

References 45 publications

Impact of Blockage Ratio on Thermal Performance of Delta-Winglet Vortex Generators

Impact of Blockage Ratio on Thermal Performance of Delta-Winglet Vortex Generators

Use of Heat Transfer Enhancement Techniques in the Design of Heat Exchangers

The effect of triangular shutter type flow deflector perforated baffle plate on the thermofluid performance of a heat exchanger

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