Chuwattanakul, Varesa
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Preferred name
Chuwattanakul, Varesa
Alternative Name
Chuwattanakul, V.
Main Affiliation
Email
varesa.ch@kmitl.ac.th
4 results
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Item type:Publication, Intensification of convective heat transfer and heat exchanger performance by the combined influence of a twisted tube and twisted tape(2019-09-01); Eiamsa-Ard, S.Twisted tubes and twisted tapes are swirl flow generators utilized for increasing thermal performance. The combined effects of twisted tubes and twisted tapes on heat transfer, pressure drop and thermal performance were experimentally investigated. Experiments were performed using a trapezoidal shaped twisted tube and twisted tapes having various twist ratios (y/w=2.0, 3.0, 4.0 and 5.0). Water was used as the test fluid in a turbulent regime (4500<Re<16,000). A simulation of velocity, temperature contours and local Nusselt number plots was also performed to gain information about fluid flow and heat transfer. The results of the combined devices are studied with those of a smooth circular tube and a twisted tube alone, for comparison. The experimental results show that at a given Re, the Nusselt number (Nu), friction factor (f) and thermal performance of a twisted tube mounted with a twisted tape are consistently higher than those of the twisted tube alone and a smooth circular tube. Additionally, the heat transfer, friction loss and thermal performance factor increase with a reduction of the twist ratio (y/w) since the tape with a smaller y/w gives stronger and more consistent swirl flow. - 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, Influence of three-start spirally twisted tube combined with triple-channel twisted tape insert on heat transfer enhancement(2016-04-01); ; In the present article, heat transfer enhancement by three-start spirally twisted tube combination with triple-channel twisted tape is studied numerically using RNG k-ε turbulence model. Influences of the tape width ratio (w/D = 0.1, 0.25, 0.34 and 0.5) and tube/tape arrangement (belly-to-belly and belly-to-neck arrangements) are described. The numerical results of a twisted tube without tape and a circular plain tube are also given for comparison. The results are reported in terms of velocity field, temperature field, turbulent kinetic energy, local Nusselt number distribution, average Nusselt number, pressure loss and thermal performance factor. It is found that heat transfer and friction factor increase with tape width ratio. At a given tape width, the systems in belly-to-neck arrangement are more efficient for heat transfer enhancement than the ones in belly-to-belly arrangement. The three-start spirally twisted tubes with twisted tapes in belly-to-neck arrangement at w/D = 0.1, 0.25 and 0.34 give higher Nusselt numbers than the twisted tube without tape up to 1.2%, 21% and 36%, respectively. The twisted tubes with triple-channel twisted tape in belly-to-belly arrangement provide higher Nusselt numbers than the twisted tube without tape up to 1.23%, 6.7%, 10% and 17%, respectively. The superior heat transfer of the combined devices in belly-to-neck arrangement (especially at large w/D) is attributed to the stronger interaction between the swirling flows induced by the tubes and those induced by the tapes. Moreover, the systems in belly-to-neck arrangement cause lower friction loss than the ones in belly-to-belly arrangement. Thus, the systems in belly-to-neck arrangement yield higher thermal performance factors. Among the studied cases, the twisted tube combined with triple-channel twisted tape in belly-to-neck arrangement at w/D = 0.34 possesses the maximum thermal performance of 1.32 at Reynolds number of 5000. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Influence of regularly spaced quadruple twisted tape elements on thermal enhancement characteristics(2018-06-01); ; The present work explores the heat transfer, pressure loss and thermal enhancement factor (TEF) behaviors of a tube fitted with regularly spaced quadruple twisted tape elements (RS-QTTs). The effects of free space ratio and twisted tape arrangement (co, counter and cross arrangements) were investigated in turbulent flow regime. Experiments were carried out using all twisted tapes with constant twist ratio of 2.5 under constant heat flux condition. The results show that RS-QTTs in all arrangements yield lower heat transfer rate and cause lower friction loss than full-length quadruple twisted tapes (QTTs) due to the weaker swirling intensity caused by the decaying of swirling flow. Heat transfer rates given by the RS-QTTs with s/y of 0.5, 1.0, 1.5 and 2.0 are lower than those given by the QTTs by around 6.2%, 8.13%, 10.6% and 12.8%, respectively. For RS-QTTs, heat transfer rate, friction loss and TEF increase with decreasing s/y. Over the range reported, the RS-QTTs in cross-arrangement with s/y = 0.5 gives heat transfer rate up to 6.6% over than that of the QTTs and the maximum TEF of 1.27. Moreover, the flow and thermal behaviors were also numerically studied for a better understanding on heat transfer mechanism.