Pimsarn, Monsak
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Pimsarn, Monsak
Alternative Name
Pimsarn, M.
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Email
monsak.pi@kmitl.ac.th
12 results
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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, 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, Influence of a double vortex chamber on temperature reduction in a counter-flow vortex tube(2021-12-01); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Influence of bed height and drying temperature on shrimp drying characteristics using a fluidized-bed dryer(2023-08-01) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Heat transfer enhancement by tapered twisted tape inserts(2015-10-01); ; Nanan, K.The effects of inserted tapered twisted tapes, their taper angle and twist ratio on heat transfer rate, pressure drop and thermal performance factor characteristics have been reported. The experiments were carried out by using the tapered twisted tapes with 4 different taper angles which θ= 0.0° (typical twisted tape), 0.3°, 0.6° and 0.9°. At each taper angle, the tapered twisted tapes were twisted at three different twist ratios (y/W) of 3.5, 4.0 and 4.5. All tapes were tested under turbulent flow regime for Reynolds numbers between 6000 and 20,000. A twist ratio is defined as the ratio of twist length (y) to twisted tape width at the large end (W). The plain tube was also tested for comparison. Heat transfer enhancement and friction loss increased with decreasing taper angle and twist ratio. Thermal performance factor tended to increase with increasing taper angle and decreasing tape twist ratio. For the present range, the tube with the tape with taper angle (θ) of 0.9° and twist ratio (y/W) of 3.5 yielded the maximum thermal performance factor of 1.05 at Reynolds number (Re) of 6000. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Heat transfer characteristics of a swirling impinging air jet emerging from a triple spiral-corrugated nozzle with a twisted tape installed(2022-07-01) - 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, Heat transfer augmentation through the use of wire-rod bundles under constant wall heat flux condition(2013-11-01); ; Eiamsa-ard, S.This article reports an experimental investigation on heat transfer, friction factor and thermal performance characteristics of turbulent flow (6000. ≤. Re≤. 20,000) in heat exchanger tubes with wire-rod bundles as flow turbulators. The experiments were carried out at three different pitch ratios (P/D) of 1.0, 1.5 and 2.0 and three wire-rod number per bundle (N) of 4, 6 and 8. The experimental results show that Nusselt number increases with increasing Reynolds number and wire-rod number per bundle, and decreasing pitch ratio (P/D) of the turbulators. As compared to the results of the tube without wire-rod (the plain tube), heat transfer rate and friction factor are respectively increased in ranges of 3.5 to 68.8% and 156 to 353%, depending on the operating conditions. At the same pumping power, the use of wire-rod turbulators results in thermal performance factor up to 1.02 times of those of the plain tube. In addition, the correlations that developed from the present experimental data for Nusselt number, friction factor and thermal performance factor are also presented. © 2013 Elsevier Ltd. - 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. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Parametric study on thermal enhancement and flow characteristics in a heat exchanger tube installed with protruded baffle bundles(2019-11-01); ; Influence of protruded baffle turbulators (P-BTs) on turbulent convective heat transfer rate and thermal performance behavior in round tubes was experimentally studied. The following geometrical parameters of P-BTs were considered (i) spacing ratio (SR = s/D<inf>ob</inf> = 1.0–3.0), (ii) diameter ratio (DR = d/D<inf>ob</inf> = 0.2–0.4), (iii) baffle orientation angle (θ = 0° (without rotation), 60°, 120° and 180°), and (iv) Reynolds number (Re = 6000 to 20,000). Air was used as working fluid at Prandtl number of Pr = 0.71. The plain tube data was examined for comparison with tube installed with protruded baffle turbulators (P-BTs). The experimental results obvious that increasing baffle orientation angle (θ), increasing diameter ratio (DR) and decreasing spacing ratio (SR) lead to the significant increases in heat transfer (Nu) and pressure loss (f). It can be also reveal that thermal performance (η) at a given Re considerably increases with the increasing spacing ratio (SR) and the reduction of diameter ratio (DR) and baffle orientation angle. The P-BTs with larger baffle orientation angle, induce stronger vortex ring and longitudinal vortex behind the baffles, give higher the thermal performance. Furthermore, all of empirical correlations (Nu, f and η) were derived as a function of Re and the protruded baffle turbulator (P-BT) geometry parameters including spacing ratio (SR), and protrusion-diameter ratio (DR).