Chuwattanakul, Varesa

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Preferred name
Chuwattanakul, Varesa
Alternative Name
Chuwattanakul, V.
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Email
varesa.ch@kmitl.ac.th

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    Investigation of turbulent thermal-hydraulic behaviors of a heat exchanger tube with U-cut twisted-tape
    (2025-03-01)
    Wongcharee, K.
    ;
    Chuwattanakul, V.
    ;
    Chamoli, S.
    ;
    Maruyama, N.
    ;
    Hirota, M.
    This study examines the influences of U-cut twisted tapes (U-TTs) on thermal-hydraulic behaviors in a circular tube with uniform heat flux. The geometric parameters studied include six U-cut ratios (s/t = 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0) and two twist ratios (y/w = 3.5 and 4.0). Experimental results revealed that their U-cut ratios highly influenced heat transfer enhancement. U-TTs with U-cut ratios (s/t) of 0.5, 1.0, 1.5, and 2.0 achieved higher Nusselt numbers than conventional twisted tapes (TTs). In contrast, U-TTs with larger U-cut ratios (s/t = 2.5 and 3.0) showed reduced Nusselt numbers. However, friction losses with all U-TTs were consistently higher than those with TTs. Due to their excellent heat transfer enhancement, U-TTs with s/t ratios of 0.5 and 1.0 exhibited significantly higher thermal performance factors (TPF) than conventional TTs. The highest TPF, 1.28, was achieved by U-TTs with an s/t ratio of 0.5 and a y/w of 3.5 at a Reynolds number of 6000.
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    Heat transfer of swirling impinging jets with TiO2-water nanofluids
    (2017-01-01)
    Wongcharee, K.
    ;
    Chuwattanakul, V.
    ;
    Eiamsa-ard, S.
    An experimental work has been carried out to study the heat transfer of swirling impinging jets (SIJs) with TiO<inf>2</inf>-water nanofluids using thermochromic liquid crystal technique. Experiments were carried out at constant jet-to-target spacing ratio (L/D) of 1.0, 2.0, 3.0 and 4.0 for Reynolds numbers from 5000 to 20,000 by using nanofluids with TiO<inf>2</inf>concentrations of 0.5%, 1.0%, 1.5%, 2.0% and 2.5% by volume, twisted tapes with twist ratios (y/W) of 4.0, 5.0, 6.0 and 7.0. Conventional impinging jets (CIJs) and swirling impinging jets (SIJs) with pure water were also tested, for comparison. At similar operation conditions, swirling impinging jets (SIJs) offer superior heat transfer to conventional impinging jets. It is also found that the nanofluids with concentrations of 0.5%, 1.0%, 1.5% and 2.0% by volume give higher Nusselt numbers than the base fluid (water) while the one with concentration of 2.5% shows opposite result. Over the studied range, the optimum condition where the maximum Nusselt number is achieved at TiO<inf>2</inf>-water nanofluids with concentration of 2.0% by volume and y/W = 6.0.
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    Influence of CuO/water nanofluid concentration and swirling flow on jet impingement cooling
    (2017-11-01)
    Wongcharee, K.
    ;
    Chuwattanakul, V.
    ;
    Eiamsa-ard, S.
    CuO/water nanofluids were applied in swirling impinging jets for heat transfer enhancement. Swirling flow was induced by twisted tape inserts with twist ratios (y/w) of 1.43, 2.86 and 4.28. Impinging jets were injected at three different ratios of jet-to-plate spacing to nozzle diameter (H/d) of 2, 3 and 4. Nanofluids with CuO concentrations of 2.0%, 3.0% and 4.0% by volume were comparatively tested with water (a base fluid) for Reynolds numbers ranging from 1600 to 9400. Experimental results reveal that the nanofluids with concentrations of 2.0 and 3.0% by volume yield higher Nusselt numbers than the base fluid while the one with concentration of 4.0% shows opposite result. At the ratio of jet-to-plate spacing/nozzle diameter (H/d) of 2, Nusselt number slightly increases with decreasing twist ratio (y/w). However, at the ratios of jet-to-plate spacing/nozzle diameter (H/d) of 3 and 4, Nusselt number increases with increasing twist ratio. Over the studied range, the optimum condition is found at H/d = 2, y/w = 1.43, and nanofluid concentration of 2.0% by volume.