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Synergistic thermo-hydraulic performance of hybrid winged–wavy rib and dimpled cooling channels for EV battery thermal management
(2026-09-01)
Kaewchoothong, Natthaporn
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Sengchuai, Kiattisak
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Gonsrang, Sarawut
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Oo, Ye Min
This study presents a numerical investigation of the thermo-hydraulic performance of a hybrid winged–wavy rib and dimpled cooling channel for electric vehicle (EV) battery thermal management under the Reynolds number range of 10,000–50,000. This study focuses on the unresolved interaction between longitudinal vortices generated by the wings and recirculation induced by dimples, which has not been systematically measured in prior hybrid cooling-channel studies. The influence of wing inclination angle on flow structure, vortex dynamics, heat transfer characteristics, and pressure loss is analyzed. The results showed that integrating winged ribs with wavy geometries and dimples generated strong longitudinal vortices and secondary flows, thereby enhancing near-wall mixing and disrupting the thermal boundary layer. As the wing inclination angle decreased from 90° to 30°, both the intensity and spatial extent of the vortical structures increased significantly. The 30° configuration produced the strongest vortex–dimple interaction, yielding local Nusselt number ratios (Nu/Nu<inf>o</inf>) of approximately 4.0–4.5, while the area-averaged Nusselt number was enhanced by up to 36.2% compared to the wavy-rib baseline configuration. This improvement was accompanied by an increase in the friction factor of approximately 61.9%, indicating a notable hydraulic penalty associated with intensified flow disturbance. Despite the increase in pressure loss, the 30° configuration demonstrated the highest thermo-hydraulic performance among the investigated cases, achieving a thermal performance factor approximately 12.1% higher than that of the wavy-rib baseline. These findings highlight the critical role of vortex–recirculation coupling in heat transfer enhancement and provide useful design guidance for compact air-cooled battery thermal management systems.
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Curved lancet pin-fin geometry effects on convective performance in microchannels
(2026-07-01)
Kaewchoothong, Natthaporn
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Oo, Ye Min
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Gonsrang, Sarawut
Efficient thermal management in compact cooling systems requires enhancement techniques that improve heat transfer while minimizing pressure penalties, particularly under transitional flow conditions. However, the effects of curvature-controlled pin-fin geometries in microchannel flows at moderate Reynolds numbers (Re = 1000–5000) remain insufficiently understood. In this study, a three-dimensional numerical investigation was conducted to evaluate the thermo-hydraulic performance of a microchannel heat sink equipped with curved lancet pin-fins. Four inclination angles (45°, 60°, 75°, and 90°) were systematically examined. A smooth channel was used as a baseline for comparison. The results showed that curvature-induced flow redirection significantly altered vortex structures, enhanced near-wall mixing, and suppressed large-scale wake regions. Among the tested configurations, the 45° case provided the best performance, increasing the area-averaged Nusselt number by up to 16.7% compared with the 90° case, while simultaneously reducing the friction factor by approximately 1.36%. As a result, the thermal performance factor improved by up to 16.9%, indicating a favorable balance between heat transfer enhancement and pressure loss. The novelty of this work lies in the systematic evaluation of curvature-angle effects on lancet-type pin-fins under transitional Reynolds-number conditions in confined microchannels. The findings provide new physical insight into curvature-controlled flow mechanisms and offer practical guidance for the design of compact cooling systems with improved thermo-hydraulic efficiency.
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Integrated design of wavy-rib and inclined pin-fin channels for high-efficiency thermal management
(2026-06-01)
Kaewchoothong, Natthaporn
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Oo, Ye Min
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Gonsrang, Sarawut
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Cheputeh, Ni Asri
A stationary numerical investigation was conducted to examine the thermo–hydraulic characteristics of a hybrid wavy rib–inclined pin-fin channel. The study aims to clarify the fundamental interaction mechanisms between rib-induced secondary flow and pin-fin orientation under non-rotating conditions, providing a baseline understanding relevant to internal cooling concepts. The governing parameters include Reynolds number ( Re = 10,000–50,000) and pin-fin inclination angle ( α = 45°–90°), while the channel aspect ratio is maintained at 1:1. The results indicate that heat transfer enhancement is controlled by the coupling between rib-generated periodic secondary vortices and inclination-dependent pin-induced vortex structures. The inclined pin-fins redistribute momentum in the streamwise and cross-stream directions, modifying vortex coherence, impingement location, and boundary-layer renewal. Among the tested configurations, the 75° inclination produced the most balanced vortex interaction, resulting in the highest area-averaged Nusselt number. Compared with the wavy-rib-only channel, the 75° case enhanced heat transfer by up to 10.53% and exceeded the performance of other orientations within the investigated range. Although the absolute Nusselt number increased with Reynolds number for all cases, the relative enhancement and thermal performance factor decreased at higher Reynolds numbers due to the increasing dominance of bulk inertial transport over geometry-induced mixing. The 75° configuration achieved the most favorable overall thermo–hydraulic performance, providing a compromise between sustained vortex-induced heat transfer and moderated pressure penalty.
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Thermal performance evaluation of a channel with twisted baffles installed: Effect of twisted baffle arrangement
(2026-03-01)
Eiamsa-ard, S.
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Pingta, S.
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Phila, A.
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Woncharee, K.
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Chamoli, S.
This research aims to introduce newly designed twisted baffle for enhancing heat transfer in solar air heater. This study examined the thermo-hydraulic performance of converging twisted baffles (C-TBs) and diverging twisted baffles (D-TBs) with different numbers of loops (n = 2, 4, 6, and 8) over a Reynolds number range (Re) of 6000–24,000. The results demonstrated that both converging twisted baffles and diverging twisted baffles significantly enhanced heat transfer compared to a smooth channel. The Nusselt number, friction factor, and thermal performance factor (TPF) increased as the number of loops decreased, attributed to stronger flow reattachment. Specifically, twisted baffles with 2, 4, 6, and 8 loops enhanced Nu by approximately 2.29–3.43, 2.02–3.05, 1.77–2.74, and 1.61–2.48 times, respectively, while the friction factor increased by 5.19–5.71, 4.61–5.01, 4.06–4.43, and 3.73–4.06 times, respectively. For a given number of loops, diverging twisted baffles consistently provided higher heat transfer enhancement than converging twisted baffles, albeit with slightly increased friction losses. Across the investigated range, the 2-loop diverging twisted baffles exhibited the best overall performance, achieving the highest Nusselt number ratio (Nu/Nu<inf>SC</inf> where Nu<inf>SC</inf> is the Nusselt number of the smooth channel) of 3.43 and a maximum thermal performance factor of 1.92 at Reynolds number of 6000, establishing it as the optimal configuration among those tested. This research contributes valuable design guidelines for selecting optimal baffle configurations, thereby supporting the development of more energy-efficient solar thermal systems.
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Thermal performance enhancement of a circular tube fitted with inclined perforated disk inserts
(2026-03-01)
Mehta, Rajesh
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Gupta, Anirudh
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Kumar, Nitin
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Eiamsa-ard, Smith
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Thianpong, Chinaruk
Heat exchangers are crucial devices in industries, and enhancing their thermal performance while controlling pressure losses remains a significant challenge. This paper examines the idea that inclined perforated disk (IPD) inserts can be effectively used to improve heat transfer in circular tubes with constant heat flux conditions at acceptable levels of hydraulic penalties. Turbulent airflow with Reynolds numbers (Re) ranging from 5000 to 21,000 was examined in experiments, and three perforation indices (PI = 0.21, 0.24, and 0.27) were tested to determine the effects of hole density on thermal and hydraulic performance. Evidence showed that the Nusselt number (Nu) had been improved by over 86 % compared to plain tubes, with the thermal enhancement factor (TEF) reaching as high as 1.53 at PI = 0.27 and Re = 5000. Particle swarm optimization (PSO) and neural network modelling multi-objective optimization were used to test the results of the experiment and determine the best operating conditions at PI = 0.21. The paper has demonstrated that inclined perforated disk inserts can form a viable passive method for enhancing the efficiency of heat exchangers, as the swirl and jet flow patterns created by the perforations effectively break the thermal boundary layer, thereby increasing the rate of convective heat transfer.
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Thermodynamic performance analysis of a round tube fitted with gradient quadruple twisted tapes
(2026-03-01)
Samruaisin, Prachya
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Liengsirikul, Sathaporn
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Thianpong, Chinaruk
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Chuwattanakul, Varesa
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Chamoli, Sunil
Air-cooled heat exchangers employing twisted-tape passive inserts exist in many forms; however, designing tapes that are practical to manufacture while enhancing heat transfer without incurring excessive pressure drop remains challenging. This study therefore introduces gradient quadruple twisted tapes (GQTT), which gradually vary the pitch across four tapes to control swirl and mix along the tube. In addition, the turn count changes in steps along the four tapes, which triggers extra turbulence near each change and keeps the flow well mixed downstream. This simple and manufacturable pattern aims to boost heat transfer while keeping the added friction under control. Our objective is to evaluate whether GQTT can improve overall performance while keeping the pressure drop within a practical range, in comparison with a plain tube and a constant-turn tape. A realizable k-ε turbulence model, rigorously validated against benchmark data, was applied to eight GQTT variants and benchmarked against a plain tube and a constant-turn tape for Reynolds numbers (Re) between 5000 and 19,000. Spatial second-order schemes, grid-independence testing, and strict residual criteria ensured solution accuracy. Among the candidates, the descending-opposite-pitch configuration (Ds-OPSD) consistently delivered the highest performance. First-law analysis reveals a peak thermal performance factor (TPF) of 1.42 at Re = 5000, equating to a 42 % gain in overall thermo-hydraulic efficiency over the plain tube, with the Nusselt number (Nu) climbing from 57.5 to 100 across the examined Re window. Second-law metrics corroborate this superiority. At the same Re of peak TPF, the Ds-OPSD cuts exergy destruction from 291.4 to 62 W (≈79 % reduction versus the plain tube and ≈22 % versus the constant-turn tape). Total entropy generation remains minimal and nearly constant (S<inf>total</inf> ≈ 0.206–0.212), while the Bejan number stays high (≈0.999–0.971), indicating that the enhancement is achieved without excessive frictional penalties.
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Influence of perforated twisted tapes with vortex generator wings on heat transfer performance and entropy in a heat exchanger tube
(2026-01-01)
Mehta, Rajesh
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Gupta, Anirudh
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Kumar, Nitin
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Eiamsa-ard, Smith
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Pimsarn, Monsak
This study conducts an investigative exploration of thermal and hydraulic performance regarding hybrid inserts which combine perforated twisted tapes with vortex generator wings mounted inside circular tubes. The insert design makes use of both swirl flow and secondary vortex generation which breaks up the thermal boundary layer and boosts convective heat transfer rates. During this investigation, researchers utilized water as the working fluid at Reynolds number (Re) from 3000 to 21,000 to study the effect of three perforation diameter ratio (d/D) 0.143, 0.19, and 0.238 and respective Vortex generator (VG) edge cut ratio (a/D) 0.143, 0.19, and 0.238. Nusselt number (Nu) reach 182.3 % and thermal enhancement factor (TEF) achieve 1.68 at Re = 15,000 when using the enhanced tube compared to a smooth tube. The industrial application of larger VG openings at standard spacing produced a beneficial relationship between thermal performance and flow resistance when the pressure rise reached 345 %. The analysis of entropy generation showed heat transfer irreversibility gave way to frictional irreversibility when both perforation dimension and Re became larger. System design optimization prerequisites involved trade-offs which met Bejan number (Be) analysis trends. The Random Forest machine learning model combined with ANN and Linear Regression models contributed to thermal parameter prediction (Nu, f, TEF) by delivering a predictive accuracy level with less than 6.6 % deviation. The research leads to vital knowledge needed for developing compact heat exchangers integrating passive enhancement methods.
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Influence of Delta Winglets on Improving heat transfer and friction factor characteristics in tubular heat exchanger
(2025-05-19)
Ruengpayungsak, K.
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Samruaisin, P.
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Kaewkosum, P.
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Pingta, S.
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Wongcharee, K.
Heat transfer rate and pressure drop characteristics are two critical constraints that substantially influence the advancement of solar air heaters. The thermal efficacy of these systems is significantly improved by factors such as flow configurations, thermal mechanisms, and geometric modifications. The integration of insertion in turbulators is a common method to improve heat transfer efficiency in solar air heaters. This article presents heat transfer and thermal efficiency in a tubular heat exchanger incorporating Delta winglet (DW). The thermal transfer and pressure drop of air as a working fluid in a tube with a constant heat flux were quantified for Reynolds numbers (Re) between 6000 and 20,000. The DW elements were positioned on two tape sides in a configuration with attack angles (θ) of 30°, 45°, and 60°. Delta winglet height ratios (h/D=0.10) and pitch ratios (p/D=0.1) were examined. Data from the current smooth or plain tubes were also analyzed for comparative purposes. According to the experimental results, the tube with this inserted has a much higher Nusselt number (Nu) and friction factor (f) than a plain tube. Both Nu and f increase as θ decrease. The DW enhances Nu and f by approximately 2.51-3.04 times and 5.21-7.16 times, respectively. The maximum TEF of 1.34 is achieved at an attack angle of 30° and a Reynolds number of 6000. The statistical correlations for Nu f and TEF were analysed and demonstrated a strong fit to the observed data, with discrepancies of ±4%, ±5% and ±3%, respectively. This design improves the conservation of energy in heat exchanger tube applications.
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Thermohydraulic performance evaluation of a heat exchanger mounted with oval inclined twisted rings
(2025-03-01)
Samruaisin, P.
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Chuwattanakul, V.
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Thapmanee, P.
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Kumar, M.
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Naphon, P.
This research examines the effects of oval inclined twisted rings (I-TRs) on thermal performance characteristics. Heat transfer enhancement, friction factor, and thermal enhancement factor tests were conducted under uniform wall heat flux with Reynolds numbers (Re) varying from 6000 to 20,000. A systematic investigation was carried out to examine the influence of different pitch ratios (p/D) and oval-ring inclination angles (θ) on thermal enhancement factor (TEF). The experimental results reveal that the Nusselt number increases with decreasing pitch ratio (p/D) and inclination angle (θ) of the I-TRs. At p/D = 1.5, the Nusselt numbers are approximately 8.59 % to 18.78 % higher than those for I-TRs with p/D values of 2.0 and 2.5. At the smallest inclination angle, θ = 30°, the Nusselt numbers are approximately higher than those at θ = 45°, 60°, 75°, and 90° by around 1.56 %, 7.21 %, 13.74 %, and 27.14 %, respectively. At a p/D ratio of 1.5 and an inclination angle of θ = 30°, the resulting thermal enhancement factor (TEF) consistently exceeds unity across the entire Reynolds number (Re) range. In contrast, for other geometries and configurations, some TEF values fall below unity at higher Re. Within the studied range, the highest TEF of 1.12 is achieved at θ = 30°, p/D = 1.5, and Re = 6,000. The key finding suggests that the performance of the thermal system is highly dependent on both the configuration and operational conditions.
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Enhanced thermal effectiveness of square duct with V-type double-baffles: Numerical study
(2024-09-01)
Promvonge, Pongjet
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Sripattanapipat, Somchai
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Thianpong, Chinaruk
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Skullong, Sompol
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Promthaisong, Pitak
The article puts forward three-dimensional computational research on heat transmission augmentation within a square channel containing 45<sup>o</sup> V-type double-baffles positioned on the lower and top parts at regular intervals in the turbulence zone for Reynolds numbers (Re) that vary from 3000 to 20,000. The primary goal of this research is to increase the thermal effectiveness and relative Nusselt number (Nu/Nu<inf>0</inf>), in order to conserve energy and reduce the size of the heating or cooling system. The simulations utilize a finite volume approach in common with the SIMPLE algorithm, whereas the turbulent model used is the realizable k–ε. The baffles are designed to be separated vertically for reducing pressure loss. Both single V-baffles and double V-baffles have four relative pitches (PR = 0.4, 0.5, 0.6, and 1.0) and height/blockage ratios (BR = 0.05, 0.1, 0.15, and 0.2), with a fixed attack angle (α) of 45<sup>o</sup>. The computational findings show that both V-baffles are capable of producing the primary vortices, but only the double V-baffles have the ability to provide the impinging streams onto the wall, cooling the region behind the baffles. This suggests that the double V-baffles not only boost heat transmission but also reduce frictional loss. When compared to a single V-baffle, the double ones enhance heat transfer by an average of 1.04–9.94% while decreasing frictional loss by an average of 9.88–31.73%. The thermal effectiveness factor (TEF) of the double V-baffles ranges from 1.03 to 3.21, and its peak value of around 3.21 is for PR = 0.4, BR = 0.05, at lower Re.

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