Thermal performance in solar air heater with perforated-winglet-type vortex generator

Skullong, Sompol; Promthaisong, Pitak; Promvonge, Pongjet; Thianpong, Chinaruk; Pimsarn, Monsak

doi:10.1016/j.solener.2018.05.093

Cited by 128 publications

(20 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The passive method is effective for convective heat transfer enhancement without the aid of external equipment [8]. Recent investigations have been done to study the potential applications of different inserts including wire coils [9,10], vortex generators [11][12][13][14], and twisted tapes [15][16][17][18] for several solar thermal applications. However, few researchers have investigated the optimal configurations of inserts applied to SWH at the moderate temperature of the working fluid [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Parametric optimization of a stamped longitudinal vortex generator inside a circular tube of a solar water heater at low Reynolds numbers

et al. 2021

View full text Add to dashboard Cite

Solar Water Heater (SWH) has low efficiency and the performance of this type of device needs to be improved to provide useful and ecological sources of energy. The passive techniques of augmentation heat transfer are an effective strategy to increase the convective heat transfer coefficient without external equipment. In this way, recent investigations have been done to study the potential applications of different inserts including wire coils, vortex generators, and twisted tapes for several solar thermal applications. However, few researchers have investigated inserts in SWH which is useful in many sectors where the working fluid operates at moderate temperatures. The longitudinal vortex generators (LVG) have been applied to promote heat transfer enhancement with a low/moderate pressure drop penalty. Therefore, the present work investigated optimal geometric parameters of LVG to enhance the heat transfer for a SWH at low Reynolds number and laminar flow, using a 3D periodical numerical simulation based on the Finite Volume Method coupled to the Genetic Algorithm optimization method (NSGA-II). The LVG was stamped over a flat plate inserted inside a smooth tube operating under a typical residential application corresponding to Reynolds numbers of 300, 600, and 900. The geometric parameters of LGV were submitted to the optimization procedure which can find traditional LVG such as rectangular-winglet and delta-winglet or a mix of them. The results showed that the application of LGVs to enhance heat transfer is an effective passive technique. The different optimal shapes of the LVG for all Reynolds numbers evaluated improved more than 50% of heat transfer. The highest augmentation heat transfer of 62% is found for the Reynolds number 900. However, the best thermo-hydraulic efficiency value is found for the Reynolds number of 600 in which the heat transfer intensification represents 55% of the pressure drop penalty.

show abstract

Section: Introductionmentioning

confidence: 99%

Parametric optimization of a stamped longitudinal vortex generator inside a circular tube of a solar water heater at low Reynolds numbers

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Gupta et al [16] reported a heat transfer increase of 34% by the VGs with holes arranged in common-flow-up configuration compared with the corresponding case without VGs. Skullong et al [17] studied the rectangular and trapezoidal VG pairs punched with holes and great heat transfer enhancement was obtained by the trapezoidal VGs due to the downward common vortex flow to the solar absorber plate. Sinha et al [18] studied the effect of combined VG arrays with different configurations on the performance of a plate-fin heat exchanger.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

View full text Add to dashboard Cite

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.

show abstract

“…The conclusions revealed that a combination of DWVGs and ribs improves the thermo-hydraulic performance of the solar system around 22%. Skullong et al [37] studied numerically and experimentally the turbulent flow characteristics and thermal efficiency in solar heaters fitted by penetrated winglet vortex generators. They observed that vortex generators with a hole diameter of d=1mm have higher heat transfer rates compared with larger hole diameters.…”

Section: Introductionmentioning

confidence: 99%

Turbulent Flows Inside Pipes Equipped With Novel Perforated V-Shaped Rectangular Winglet Turbulators: Numerical Simulations

Nakhchi

Rahmati

2020

Journal of Energy Resources Technology

View full text Add to dashboard Cite

In this study, computational simulations have been performed to investigate the turbulent characteristics and energy consumption through heat exchanger tubes equipped by new perforated V-shaped rectangular winglet (PVRW) turbulators. The effects of the holes intensity on the velocity and temperature contours are additionally investigated. The Reynolds number, hole diameter ratio, and the number of holes selected are in the range of 5000 ≤ Re ≤ 18,000, 0 ≤ DR ≤ 0.40, and 0 ≤ N ≤ 14, respectively. Renormalization group (RNG) k–ε turbulent model which is a finite volume solver is utilized for the computational fluid dynamics (CFD) simulation. It was noticed that the proposed perforated turbulators could considerably intensify the thermal performance compared to typical VRW inserts. It is found that the recirculating flow generated by the PVRW augments the fluid mixing and transfers the heat from the pipe walls to the core of the tube. The simulations illustrate that the amount of heat transfer enhances 25.2% reducing the DR from 0.4 to 0.13 at Re = 18,000 and N = 14. Also, using PVRW turbulators with N = 7 and DR = 0.26 augments the average Nusselt number around 354.3% compared to the circular pipe without inserts. The highest thermal efficiency parameter of η = 2.25 could be obtained at Re = 5000 for the heat exchangers fitted by vortex generators with N = 14 and DR = 0.26.

show abstract

Thermal performance in solar air heater with perforated-winglet-type vortex generator

Cited by 128 publications

References 39 publications

Parametric optimization of a stamped longitudinal vortex generator inside a circular tube of a solar water heater at low Reynolds numbers

Parametric optimization of a stamped longitudinal vortex generator inside a circular tube of a solar water heater at low Reynolds numbers

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

Turbulent Flows Inside Pipes Equipped With Novel Perforated V-Shaped Rectangular Winglet Turbulators: Numerical Simulations

Contact Info

Product

Resources

About