Analysis on heat transfer and pressure drop of fin-and-oval-tube heat exchangers with tear-drop delta vortex generators

Lu, Gaofeng; Zhai, Xiaoqiang

doi:10.1016/j.ijheatmasstransfer.2018.07.148

Cited by 25 publications

(7 citation statements)

References 33 publications

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“…In contrast, this secondary flow is noted observed with the installation of the convex strips. Meanwhile, the installation of the convex strips increases the fluid velocity in the gap between the tube and convex strips owing to the narrowing of the channel cross‐sectional area, which increases the fluid velocity 31 . The changes in the flow patterns due to the installation of four and eight convex strips can be analyzed in detail by expressing the flow field in the horizontal plane ( Y = 0.92 mm), as shown in Figure 8.…”

Section: Resultsmentioning

confidence: 99%

Heat transfer intensification with field synergy principle in a fin‐and‐tube heat exchanger through convex strip installation

Syaiful

Wicaksono

et al. 2022

Engineering Reports

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Improvement of heat transfer using surface protrusion (convex strip) has been effective recently. Surface protrusion is able to improve flow mixing which increases the rate of heat transfer. Therefore, this study aims to improve the heat transfer in a fin-and-tube heat exchanger by fitting convex strips around the tubes. Three-dimensional modeling was carried out by placing four and eight convex strips around the staggered tubes at a constant temperature of 106 • C. The turbulent k-ε model was applied at a Reynolds number range of 3438-15,926.The results of the study indicate that tubes with eight convex strips demonstrated a heat transfer improvement of 40.46%, compared to that with four convex strips. In this case, the TEF is 6.27% higher than the four convex strips. In addition, the synergy angle in the eight convex strips configuration was 0.13% lower than that of the four convex strips configuration. Meanwhile, the flow resistance in the tubes with eight convex strips configurations was 30.96% higher than that of the four convex strips.

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Section: Resultsmentioning

confidence: 99%

Heat transfer intensification with field synergy principle in a fin‐and‐tube heat exchanger through convex strip installation

Syaiful

Wicaksono

et al. 2022

Engineering Reports

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“…From Figure 11, it can be observed that the decrease in the longitudinal vortex on a single VG pair is caused by viscous dissipation, as the fluid flows downstream. However, the longitudinal vortex was enhanced again with the addition of VG pairs [10]. Figures 11 (a)-(c) show that the installation of seven pairs of CxDWP and CDWP increased the longitudinal vortex intensity by 36.9% and 185.23%, respectively, against DWP Re = 689 with an attack angle of 20º at x/L = 0.21.…”

Section: Longitudinal Vortex Intensitymentioning

confidence: 96%

“…Through three-dimensional (3D) modeling, Naik and Tiwari [9] studied the effect of winglet locations on heat transfer features in fin and tube heat exchangers using inline RWPs, and observed that the Nusselt number (Nu) and secondary flow intensity (Se) peaked at ∆Y = ± 1.25 and attack angle (β) = 45°, which are mounted in the downstream area adjacent to the tube. Lu and Zhai [10] numerically analyzed the heat transfer and pressure drop on a fin and oval tube heat exchanger using a tear-drop delta VG, found that the tear-drop delta GV outperforms plain delta VG, and investigated the mechanism of the advantage in the light of Se and field synergy principle.…”

Section: Introductionmentioning

confidence: 99%

Effect of Attack Angle of Concave and Convex Winglets Vortex Generators on Thermal-Hydraulic Performance of Fin and Tube Heat Exchangers with Field Synergy Principle

Syaiful¹,

Yunianto²,

Salsabila³

et al. 2021

IJHT

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In fin and tube heat exchangers, the gas passing through the fin has a lower thermal conductivity than the fluid passing through the tube. The low thermal conductivity brings a high thermal resistance, which suppresses the heat transfer rate. A common practice to enhance fin-side heat transfer is to generate longitudinal vortex by mounting vortex generators (VGs) on the fin. This paper aims to investigate how longitudinal vortex generator (LVG) improves heat transfer and pressure drop. Numerical simulations were carried out to analyze three types of VGs. The installation of VGs was varied with the attack angle changing from 10°, 15°, to 20° with a 1-3-4-7 VG arrangement on the tube. The flow velocity was expressed in Reynolds number (Re) between 364 and 689. The enhancement of heat transfer rate and improvement of pressure drop were analyzed between three types of VG, three different attack angles, and four types of winglet installation, compared to baseline. The simulation results show that the highest convective heat transfer coefficient (84.85%) was achieved by the VG composed of seven concave delta winglet pairs (CDWPs) at the attack angle of 20° and Re = 689; CDWP VG provides the highest heat transfer improvement among all cases.

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“…Sarangi and Mishra [21] studied the location of VGs in common flow up configuration and reported that the VGs near the central tube were effective at heat-transfer enhancement. Lu and Zhai [22] numerically studied the performance of tear-drop VGs in common flow up. They found that tear-drop VGs can enhance the heat transfer with a negligible increase in the pressure drop.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Flow Symmetry and Heat Transfer of Winglet Pair in Common Flow Down Configuration

et al. 2020

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The effect of transverse pitch between a pair of delta-winglet vortex generators arranged in a common flow down configuration on the symmetrical flow structure and heat-transfer performance was numerically investigated. The results showed that symmetrical longitudinal vortices form a common flow down region between the vortices. The fluid is induced to flow from the top towards the bottom of the channel in the common flow region, which is advantageous to the heat transfer of the bottom fin. The vortex interaction increases and the vortex intensity decreases along with the decrease in transverse pitch of vortex generators. Vortex interaction has a slight influence on pressure penalty. The Nusselt number decreases with increasing vortex interaction. The vortices gradually attenuate and depart from each other during the process of flowing downward. A reasonable transverse pitch of delta-winglet vortex generators in a common-flow-down configuration is recommended for high thermal performance.

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Analysis on heat transfer and pressure drop of fin-and-oval-tube heat exchangers with tear-drop delta vortex generators

Cited by 25 publications

References 33 publications

Heat transfer intensification with field synergy principle in a fin‐and‐tube heat exchanger through convex strip installation

Heat transfer intensification with field synergy principle in a fin‐and‐tube heat exchanger through convex strip installation

Effect of Attack Angle of Concave and Convex Winglets Vortex Generators on Thermal-Hydraulic Performance of Fin and Tube Heat Exchangers with Field Synergy Principle

Characteristics of Flow Symmetry and Heat Transfer of Winglet Pair in Common Flow Down Configuration

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