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Author: search.filters.author.Wongcharee, KhwanchitSubject: search.filters.subject.Heat transfer

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    Influence of divergence tapered V-baffles on heat transfer behaviors in a rectangular channel
    (2026-05-15)
    Keaitnukul, Warin
    ;
    Pingta, Supapat
    ;
    Phila, Arnut
    ;
    Wongcharee, Khwanchit
    ;
    Maruyama, Naoki
    This study examines the effects of Divergence Tapered V-Baffle (henceforth DT-VB) regarding the heat transfer and friction loss behavior within the rectangle-shaped duct. The baffle attack angles (α) were set at 45°, 60°, 75°, and 90°. The experimental results indicated that as Reynolds numbers increased, the Nusselt numbers exhibited an upward trend, while the friction values showed a corresponding decrease. The Nusselt number improved consistently as the attack angle decreased, with baffles at a 60° attack angle producing the highest friction loss, followed by those at 45°, 75°, and 90°. Among the configurations tested, the 45° attack angle demonstrated the best thermal performance due to its relatively low friction loss and enhanced heat transfer. The highest thermal performance factor (TPF) of 2.13 was attained at a 45° attack angle and a Reynolds number of 6,000.
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    Thermal evaluation of flow channels with perforated-baffles
    (2023-05-01)
    Eiamsa-ard, Smith
    ;
    Phila, Arnut
    ;
    Wongcharee, Khwanchit
    ;
    Pimsarn, Monsak
    ;
    Maruyama, Naoki
    The influences of perforated-baffles on the local Nusselt number (Nu) and thermo-hydraulic behaviors were comprehensively studied using thermochromic liquid crystal sheet. The perforated-baffles were designed in two forms: perforated-baffle (PB) and perforated-baffle with square wings (SW-PBs). Transverse solid baffles (TBs) were also tested for an assessment. All baffles had an identical height of 12 mm (e/H = 0.3). Experimental results showed that SW-PBs offered better Nu than PBs. It is also seen that PBs and SW-PBs caused lower pressure loss than TBs by around 20.49% and 13.98%, respectively. The reduction of friction loss was primarily due to the baffle perforation. In addition, the PBs yielded the thermal performance factors (TPF) up to 1.01 at the lowest Reynolds number of 6000.
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    Heat transfer visualization of swirling impinging jets using nozzle with centrally hollow helical-tape
    (2020-05-01)
    Eiamsa-Ard, Smith
    ;
    Kunnarak, Kengkla
    ;
    Wongcharee, Khwanchit
    ;
    Chuwattanakul, Varesa
    The present research was conducted to determine the heat transfer visualization of swirling impinging jets (SIJs) induced by nozzle with centrally hollow helical-tape using a thermochromic liquid crystal (TLC) sheet. The effects of jet-to-plate spacing ratios (L/D= 2.0, 4.0, 6.0 and 8.0) and Reynolds numbers (10,000 Re 20,000) on the radial uniformity and intensity of convective heat transfer were investigated. The experimental results of SIJs were compared with those of conventional impinging jets (CIJs). The formation of swirl flow of swirling impinging jet (SIJs) helped in improving the uniformity of local heat transfer or Nusselt number (Nu) and also average Nusselt number, as compared to those of conventional impinging jets (CIJs). Furthermore, the average Nusselt number (Nu) increased as jet-to-plate spacing ratio (L/D) decreased while Reynolds number (Re) increased for both conventional impinging jets (CIJs) and swirling impinging jets (SIJs). The highest Nusselt number (Nu) of swirling impinging jet (SIJ) was obtained at the jet-to-plate spacing ratio (L/D) of 4.0 and Reynolds number (Re) of 20,000. The maximum Nusselt number (Nu) of swirling impinging jet (SIJ) was higher than that of conventional impinging jets (CIJs) at similar conditions by around 5.3%.
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    Thermo-hydraulic performance of round tubes installed with double V-shaped winglet vortex generators: Effect of blockage ratio
    (2020-01-01)
    Samruaisin, Prachya
    ;
    Samutpraphut, Boonsong
    ;
    Wongcharee, Khwanchit
    ;
    Eiamsa-Ard, Smith
    ;
    Saysroy, Anucha
    Double V-shaped winglet vortex generators is proposed in the present research enhancing heat transfer and thermal-hydraulic performance factor. The numerical simulation was performed to study the effects of blockage ratios (e/D = 0.05-0.15) and Reynolds numbers (Re = 5000-15,000) on heat transfer rate, flow structure, local heat transfer, pressure loss and thermal-hydraulic performance factor characteristics. The double V-shaped winglets were installed in tandem arrangement on the top and bottom of tubes with constant pitch ratio of p/D = 1.0. Water was employed as the working fluid for Reynolds numbers ranging from 5000 to 15,000 under constant wall temperature boundary conditions. The numerical results demonstrated that the vortex generators induced swirling motion which helped in improving fluid flow mixing, leading to heat transfer enhancement with a moderate pressure loss penalty. Heat transfer and friction loss increased with increasing blockage ratio and Reynolds number while thermal-hydraulic performance factor showed opposite trend. The maximum thermal-hydraulic performance factor of 1.89 was obtained by using the vortex generator with the smallest blockage ratio (e/D) of 0.05 at the lowest Reynolds number of 5000.
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    INFLUENCE OF NONUNIFORM TWISTED TAPE ON HEAT TRANSFER ENHANCEMENT CHARACTERISTICS
    (2012-10-01)
    Eiamsa-ard, Smith
    ;
    Wongcharee, Khwanchit
    ;
    Promvonge, Pongjet
    An experimental study of heat transfer and friction factor characteristics in a circular tube fitted by twisted tapes with nonuniform twist ratios is reported. The twisted tapes are used as swirl generators playing roles as heat transfer enhancers. The nonuniform twisted tapes examined in the present work have (1) sequentially increasing twist ratios (SL), (2) sequentially decreasing twist ratios (LS), (3) repeatedly increasing-decreasing twist ratios (SL/SL), (4) repeatedly decreasing-increasing twist ratios (LS/LS), (5) intermittently increasing-decreasing twist ratios (SL→LS), and (6) intermittently decreasing-increasing twist ratios (LS→SL). In addition, three different typical twisted tapes with twist ratios of 3.0, 4.0, and 5.0 (TT) were also evaluated. Apparently, LS yields monotonically increasing swirling intensity and SL decreasing swirling intensity, resulting in lower heat transfer rate and friction factor than the other four nonuniform twisted tapes, which possess extra fluid fluctuation. However, among the tapes tested, the SL/SL offers the maximum thermal performance factor of around 1.03, which corresponds to Nusselt number of around 36% and friction factor of 3.57 times over those of the plain tube. © 2012 Copyright Taylor and Francis Group, LLC.