Kwankaomeng, Sutapat
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Kwankaomeng, Sutapat
Alternative Name
Kwankaomeng, S.
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sutapat.kw@kmitl.ac.th
5 results
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Item type:Publication, Heat transfer augmentation in a wedge-ribbed channel using winglet vortex generators(2010-02-01); ; Experimental investigations have been carried out to study the effect of combined wedge ribs and winglet type vortex generators (WVGs) on heat transfer and friction loss behaviors for turbulent airflow through a constant heat flux channel. To create a reverse flow in the channel, two types of wedge (right-triangle) ribs are introduced: wedge ribs pointing downstream and pointing upstream. The arrangements of both rib types placed inside the opposite channel walls are in-line and staggered arrays. To generate longitudinal vortex flows through the tested section, two pairs of the WVGs with the attack angle of 60° are mounted on the test channel entrance. The test channel has an aspect ratio, AR = 10 and height, H = 30 mm with a rib height, e/H = 0.2 and rib pitch, P/H = 1.33. The flow rate in terms of Reynolds numbers is based on the inlet hydraulic diameter of the channel ranging from 5000 to 22,000. The presence of the combined ribs and the WVGs shows the significant increase in heat transfer rate and friction loss over the smooth channel. The Nusselt number and friction factor values obtained from combined the ribs and the WVGs are found to be much higher than those from the ribs/WVGs alone. In conjunction with the WVGs, the in-line wedge pointing downstream provides the highest increase in both the heat transfer rate and the friction factor while the staggered wedge pointing upstream yields the best thermal performance. © 2009 Elsevier Ltd. All rights reserved. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Heat transfer in square duct fitted diagonally with angle-finned tape-Part 2: Numerical study(2012-05-01); ; Thiangpong, ChinarukA numerical work has been conducted to examine turbulent flow and heat transfer characteristics in a three-dimensional isothermal-fluxed square-duct fitted diagonally with 30°-angle finned tapes. The computations are based on the finite volume method with the SIMPLE algorithm implemented. The air flow and heat transfer characteristics in the duct are presented for Reynolds number (Re) in a range of 4000 to 20,000. In the current study, a straight tape with 30°-angled fins mounted repeatedly on both sides is inserted diagonally into the test duct to generate a pair of longitudinal counter-vortices in assisting chaotic flow mixing in the duct including vortex-induced impingement (VI) effect. Effects of fin blockage ratio (BR= b/. H) and pitch ratio (PR= L/. H) on heat transfer and pressure drop behaviors in the duct are investigated and the results of the finned tape insert are compared with available measurements. The computation reveals that predicted results from the finned tape insert are in good agreement with measured data. The study indicates that the vortex flow can help to induce impingement/reattachment flows (VI effect) on the duct walls leading to drastic increase in the heat transfer rate over the duct. The rise of the BR and the reduction of the PR results in the increase in Nusselt number and friction factor values. The maximum thermal performance is found to be 1.95 for using the finned tape at BR= 0.2 and PR= 1 whereas the Nusselt number ratio is about 4.5 at lower Re. © 2012 Elsevier Ltd. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Numerical heat transfer study of turbulent square-duct flow through inline V-shaped discrete ribs(2011-12-01); ; A numerical work has been conducted to examine turbulent periodic flow and heat transfer characteristics in a three dimensional square-duct with inline 60° V-shaped discrete thin ribs placed on two opposite heated walls. The isothermal-flux condition is applied only to the upper and lower duct walls while the two sidewalls are insulated, similar to internal passage cooling of gas turbine blades. The computations are based on the finite volume method with the SIMPLE algorithm for handling the pressure-velocity coupling. Air is the working fluid with the flow rate in terms of Reynolds numbers ranging from 10,000 to 25,000. The numerical result is validated with available square-rib measured data and found to agree well with measurement. The computation reveals that the ribbed duct flow is fully developed periodic flow and heat transfer profiles at about x/ D=7-11 downstream of the inlet. Effects of different rib height to duct diameter ratios, BR, on thermal characteristics for a periodic ribbed duct flow are investigated. It is found that a pair of counter-rotating vortices (P-vortex) caused by the rib can induce impingement/attachment flows on the walls leading to greater increase in heat transfer over the test duct. In addition, the rise of BR values leads to the increase in heat transfer and friction loss. The maximum thermal performance is around 1.8 for the rib with BR=0.0725 where the heat transfer rate is about 4.0 times above the smooth duct at lower Reynolds number. © 2011 Elsevier Ltd. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Thermal behavior in solar air heater channel fitted with combined rib and delta-winglet(2011-07-01); ; Effects of combined ribs and delta-winglet type vortex generators (DWs) on forced convection heat transfer and friction loss behaviors for turbulent airflow through a solar air heater channel are experimentally investigated in the present work. Measurements are carried out in the rectangular channel of aspect ratio, AR=10 and height, H=30mm. The flow rate is presented in the form of Reynolds numbers based on the inlet hydraulic diameter of the channel ranging from 5000 to 22,000. The cross-section shape of the rib placed on the absorber plate to create a reverse-flow is an isosceles triangle with a single rib height, e/H=0.2 and rib pitch, P<inf>l</inf>/H=1.33. Ten pairs of the DW with its height, b/H=0.4; transverse pitch, P<inf>t</inf>/H=1 and three attack angles (α) of 60°, 45° and 30° are introduced and mounted on the lower plate entrance of the tested channel to generate longitudinal vortex flows. The experimental results show that the Nusselt number and friction factor values for combined rib and DW are found to be much higher than those for the rib/DW alone. The larger attack angle of the DW leads to higher heat transfer and friction loss than the lower one. In common with the rib, the DW pointing upstream (PU-DW) is found to give higher heat transfer rate and friction loss than the DW pointing downstream (PD-DW) at a similar operating condition. In comparison, the largest attack angle (α=60°) of the PU-DW yields the highest increase in both the Nusselt number and friction factor while the lowest attack angle of the PD-DW provides the best thermal performance. © 2011 Elsevier Ltd. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Thermal characteristics in a tube fitted with inclined vortex rings(2014-01-01); The paper presents an experimental study on the heat transfer, pressure loss and thermal performance characteristics in a round tube fitted repeatedly with inclined vortex ring (VR) under a uniform wall heat flux. Periodically VRs are inserted into the tube with a view to generating vortex flows that assist to increase the heat transfer rate of the tube. The airflow rate in terms of Reynolds number is ranging from 5000 to 25,000. Measurements are carried out for the VR with a single blockage ratio, BR= e/D = 0.1 and an attack angle, α = 20°, at fourVR pitch ratios, PR= P/D = 0.5, 1.0, 1.5 and 2.0. The variations of heat transfer and pressure loss are presented in the form of mean Nusselt number and friction factor respectively. The experimental results show that the use of the VRs leads to the considerable increase in heat transfer and friction factor values in comparison with the smooth tube. The VRs at PR = 0.5 provides the highest heat transfer and friction factor. © (2014) Trans Tech Publications, Switzerland.