Chuwattanakul, Varesa
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Preferred name
Chuwattanakul, Varesa
Alternative Name
Chuwattanakul, V.
Main Affiliation
Email
varesa.ch@kmitl.ac.th
25 results
Now showing 1 - 10 of 25
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Item type:Publication, Effects of spiral start number and depth ratio of corrugated tube on flow and heat transfer characteristics in turbulent flow region(2019-08-01); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Experimental Study of the Effects of Inclusion of Rectangular-Cut Twisted Tapes on Heat Transfer and Pressure Drop in a Round Tube(2019-12-01); Eiamsa-ard, S.Twisted tape inserts were used as swirl generators in the flow through a tube for enhancing heat transfer. Twisted tapes have commonly been applied in many thermal applications used in industry. Several modified twisted tapes have been investigated for improving the thermal performance of heat exchangers. The effects in tubes with modified rectangular-cut twisted tape (RC-TT) inserts with various free-spacing ratios (s/w = 2.0, 2.5, 3.0, 3.5 and 4.0) and edge–width ratios (t/W = 0.1, 0.15, 0.2 and 0.25) on heat transfer and pressure losses are reported. The RC-TT used in this work had a fixed thickness of 1.2 mm, width of 60 mm, length of 2000 mm and twist ratio (y/W) of 3.0. Experiments were performed over a range of Reynolds numbers, 10,000 ≤ Re ≤ 20,000, using air as a test fluid. A tube with a classical/typical twisted tape was also tested for comparison. In all cases, the Nusselt number tended to increase with the Reynolds number, while the friction factor and thermal performance showed the opposite trend. For the rectangular-cut twisted tape inserts, the friction factor and Nusselt number decreased, while thermal performance increased with increasing free-spacing ratios (s/w) and edge–width ratios (t/W). Furthermore, the maximum thermal performance was achieved at the lowest free-spacing ratio (s/w), edge–width ratio (t/W) and Reynolds number (Re). - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effect of arc-shaped twisted-baffles on augmented heat transfer in a rectangular duct(2023-02-01); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Heat transfer evaluation of turbulent flows through gear-ring elements(2017-01-01); ; Heat transfer and friction loss characteristics in tubular heat exchangers with gear-ring turbulators (GR-Ts) have been experimentally and numerically investigated. The GR-Ts with different free-space length ratios (SR = s/D = 1.0, 2.0 and 3.0) and tooth numbers (N = 8, 16 and 24), were experimentally tested under constant wall heat flux in turbulent flow (Reynolds numbers from 6000 to 20,000). Air was used as the working fluid. The behaviors in a plain tube and the tube with a conventional ring turbulators (N = 0) were also studied for comparison. The results show that utilizing tubes with GR-Ts leads to the increases of heat transfer coefficient and pressure loss as compared to those associated with the use of a plain tube. Heat transfer enhancement and friction increase with decreasing free-space length ratio (SR) and tooth number (N). Among the investigated inserts, the conventional ring turbulators (N = 0) with free-space length ratio, SR = 1.0 give the highest heat transfer rate and friction factor at 2.7 times and 15.5 times of those of the plain tube. However, the maximum thermal performance factor of 1.3 is obtained by using the GR-Ts with the largest free-space length ratio and maximum tooth number (SR = 3.0 and N = 24). At SR = 3.0, the GR-Ts with tooth numbers (N) of 0, 8, 16 and 24 yield thermal performance factors up to 1.24, 1.26, 1.28 and 1.3, respectively. The numerical results are given for a better understanding of flow and heat transfer characteristics associated with the use of GR-Ts. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Impingement cooling by round jet with longitudinal swirling strip(2018-03-01) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Influence of delta-winged dual twisted tapes insertion on heat transfer and pressure drop characteristics(2015-01-01); Eiamsa-Ard, SmithThe article presents the heat transfer and friction factor characteristics of turbulent flow in a uniform wall heat flux tube inserted with delta-winged dual twisted tapes. The typical dual twisted tapes (DTs) with constant twist ratio of y/W = 3.0 and delta-winged dual twisted tapes with delta-winged attack angle of α = 30° and β = 30° were carried out. Influences of the delta-winged arrangements in (1) the parallel direction (DT-PW) and (2) the counter direction (DT-CW) on the thermal performance characteristics were also described. The experimental results found that the use of the dual twisted tapes with parallel wing arrangements (DT-PW) provide the heat transfer higher than those the typical dual twisted tapes (DTs) and dual twisted tapes with counter wing arrangements (DT-CW) around 6.6-7.3% and 5.5-8%, respectively, due to stronger of dual-swirling/turbulent flow leading to better fluid mixing between the core and near tube walls while the friction factor is increasing up to 10.9 times above the plain tube. The typical dual twisted tapes (DTs), dual twisted tapes with parallel wing arrangements (DT-PW) and dual twisted tapes with counter wing arrangements (DT-CW) performs the highest thermal performance factor up to 1.2, 0.9 and 0.85 at Reynolds number of 6000. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Influence of sawtooth twisted tape on thermal enhancement of heat exchanger tube(2023-03-01); ; Maruyama, NaokiThis article employs sawtooth twisted tapes to generate swirling flow and interrupted flowing disturbance in order to increase the level of heat transfer rate. The influences of the sawtooth twisted tape (S-TT) on enhanced heat transfer rate, friction factor and aerothermal performance index (API) behaviors are analyzed. The sawtooth twisted tapes (S-TTs) possessing constant pitch/twist ratio (y//W) of 3.0 and six sawtooth angles (α) of 20°, 30°, 40°, 50°, 60°, and 70° are assessed. Considering turbulent flow using air as the testing fluid, experiments were investigated at 6,000 < Re < 20,000 under boundary conditions of constant heat flux. According to the experimental findings, sawtooth twisted tape (S-TT) improves heat transfer rate and raises pressure loss with varying rates based on sawtooth angles (α). With the sawtooth twisted tape (S-TT) and 70° sawtooth angles, the optimum API of 1.33 is attained, while Nusselt number and friction factor are 32 and 0.135 at Re = 6,000. The recommended sawtooth twisted tape (S-TT) yields a highest Nusselt number of 78, which is 1.6 times greater than the typical twisted tape (TT) and 1.1 times greater than the plain tube. The combination of the TT and sawtooth patterns can be beneficial in terms of boosting heat transfer rate and API relating coupling of swirling flow and interrupted flowing disruption effects since the sawtooth twisted tape (S-TT) offers superior performance than the TT. Additionally, the heat exchanger tubes fitted with sawtooth twisted tape (S-TT) at sawtooth angles (α) of 20°, 30°, 40°, 50°, 60°, and 70° gain greater Nusselt number than the plain tube up to 158.3%, 162.2%, 166.1%, 171.7%, 179.7% and 186.2%, respectively. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Thermal and swirl flow topologies in a twisted square duct with a multi-twisted tape installed(2020-01-01); Eiamsa-Ard, SmithThis paper presents 3D numerical investigation of the turbulent flow and heat transfer characteristics of a twisted square duct installed with multi-twisted tapes. Air was used as the working fluid with flow rates in terms of Reynolds numbers ranging from 3000 to 20,000. The effects of (1) multi-twisted tape width ratios (w/H) of 0.2 to 1.0 and (2) the number of channels (N = 2 and 4) on heat transfer and flow mechanisms were studied at constant twist ratio of y/D = 3.5. The numerical results showed that twisted square duct combined with twisted tape caused swirl flows which effectively promoted fluid mixing and provided heat transfer over those of both a straight smooth square duct and twisted square duct. Increasing w/H led to increases in both heat transfer and the friction factor. At a given multi-twisted tape width ratio (w/H), the heat transfer and friction factor with N = 4 were higher than those with N = 2, while thermal enhancement factor showed the opposite trend. A maximum thermal enhancement factor of 1.93 was obtained at tape width ratio of w/H = 1.0, channel number of N = 2 and Re = 3000. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Intensification of thermo-hydraulic performance in heat exchanger tube inserted with multiple twisted-tapes(2018-05-25); ; The present work presents the thermo-hydraulic characteristics in the heat exchanger tube inserted with multiple-twisted tapes (M-TT). Multiple-twisted tapes consisted of a larger twisted tape and small twisted tapes which were placed along with the larger twisted tape. The study encompassed 6 different twist ratios of the small twisted tapes (y/w = 2.5, 5, 10, 15, 20 and 25) and 5 different numbers of the small twisted tapes (N = 2, 3, 4, 5 and 6). Experiments were conducted under uniform wall heat flux condition by using air as the testing fluid for Reynolds numbers from 6000 to 20,000. A large single twisted tape in a tight-fit form (T-TT) and that in a loose-fit form (L-TT) were tested as the reference cases for comparison. The experimental results found that the use of multiple-twisted tapes (M-TT) with N = 3, 4, 5 and 6 leads to the considerable increases in heat transfer enhancement and friction factor as compared to those of single twisted tape. For multiple twisted tapes (M-TT), Nusselt number (Nu), friction factor (f) and thermo-hydraulic performance factor (η) increase with increasing number (N) and decreasing twist ratio (y/w) of small twisted tapes. The maximum thermo-hydraulic performance factor of 1.2 is obtained by the use of M-TT with N = 6 and y/w = 2.5. In addition, the numerical work on flow and thermal behaviors was also performed for a better understanding of heat transfer mechanisms. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Evaluation of aerothermal performance of a round tube with regularly-spaced multi-channel twisted tape elements installed(2024-06-01); ;