Promvonge, Pongjet

Preferred name

Promvonge, Pongjet

Alternative Name

Promvonge, P.

Main Affiliation

School of Engineering

pongjet.pr@kmitl.ac.th

Now showing 1 - 6 of 6

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Numerical study on heat transfer of turbulent channel flow over periodic grooves
(2008-08-01)
Eiamsa-ard, Smith
;
Promvonge, Pongjet
A numerical investigation of turbulent forced convection in a two-dimensional channel with periodic transverse grooves on the lower channel wall is conducted. The lower wall is subjected to a uniform heat flux condition while the upper wall is insulated. To investigate turbulence model effects, computations based on a finite volume method, are carried out by utilizing four turbulence models: the standard k - ε, the Renormalized Group (RNG) k - ε, the standard k - ω, and the shear stress transport (SST) k - ω turbulence models. Parametric runs are made for Reynolds numbers ranging from 6000 to 18,000 with the groove-width to channel-height ratio (B/H) of 0.5 to 1.75 while the groove pitch ratio of 2 and the depth ratio of 0.5 are fixed throughout. The predicted results from using several turbulence models reveal that the RNG and the k - ε turbulence models generally provide better agreement with available measurements than others. Therefore, the k - ε model is selected to use in prediction of this complex flow. In addition, the results of the heat transfer coefficient, friction factor, skin friction coefficient and thermal enhancement factor are also examined. It is found that the grooved channel provides a considerable increase in heat transfer at about 158% over the smooth channel and a maximum gain of 1.33 on thermal performance factor is obtained for the case of B/H = 0.75. This indicates that the reverse/re-circulation flow in a channel with transverse grooves can improve the heat transfer rate. © 2008 Elsevier Ltd. All rights reserved.
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Heat transfer and flowfriction behaviors in a channel with multiple 30° V-ribs
(2014-01-01)
Khanoknaiyakarn, C.
;
Jedsadaratanachai, W.
;
Promvonge, P.
The paper presents an experimental study on heat transfer and flow friction characteristics in a rectangular channel fitted with periodically rectangular V-ribs. The multiple V-rib turbulators are tested in the channel having an aspect ratio (width to height ratio), AR=10 and height, H= 30 mm, with three rib-to-channel height ratios (e/H=0.2, 0.3, and 0.4), two rib-pitch to channel-height ratios (PR=P<inf>1</inf>/H= 3 and 4) and a single attack angle (α=30°). The upper plate of channel is uniformly heated at a constant heat-flux. The experiment has been conducted by varying airflow velocity in order to obtain the Reynolds number range from 5000 to 24,000. The experimental results show a significant effect of the presence of the ribs on the heat transfer rate and pressure drop over the smooth channel. The measured data indicates that the V-rib turbulators with e/H = 0.4 and PR =3 yields the highest heat transfer rate and friction loss. All the V-rib turbulators perform much higher than the smooth channel with no rib. © 2014 Asian Institute of Technology.
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Heat transfer characteristics in a tube fitted with helical screw-tape with/without core-rod inserts
(2007-02-01)
Eiamsa-ard, Smith
;
Promvonge, Pongjet
Effects of insertion of a helical screw-tape with or without core-rod in a concentric double tube heat exchanger on heat transfer and flow friction characteristics are experimentally investigated. The heat exchanger has the outer and the inner tube diameters of 50 mm (D<inf>o</inf>) and 25 mm (D) where the cold and the hot waters used as the test fluids are in shell and tube sides, respectively. The stainless steel helical screw-tape has the geometrical dimensions of width (W) 17 mm with the clearance to the tube wall (D - W) / 2 = 4 mm. Thus, the insertion of the screw-tape in the tube is considered as a loose-fit. In the experiment, the loose-fit helical tape with or without core-rod, is inserted in the inner tube of the heat exchanger and the hot water enters the tube based on its Reynolds number in a range of 2000 to 12,000. The experimental results show that the increases in average Nusselt number of using the loose-fit, helical tape with and without core-rod are found to be 230% and 340%, respectively, over the corresponding plain tube. It is worth noting that for the loose-fit, helical tape without core-rod, the friction factor is around 50% less than that for the one with core-rod while the Nusselt number is about 50% higher. Furthermore, the enhancement efficiency of the helical screw-tapes varies between 1.00 and 1.17, 1.98 and 2.14, for the tapes with and without core-rod, respectively. © 2006 Elsevier Ltd. All rights reserved.
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Heat transfer enhancement in a tube with combined conical-nozzle inserts and swirl generator
(2006-11-01)
Promvonge, P.
;
Eiamsa-ard, S.
The enhancements of heat transfer characteristics in a uniform heat flux circular tube fitted with conical nozzles and swirl generator are experimentally investigated. In this research, the conical nozzles, assumed as a turbulator/reverse flow generator, are placed in a model pipe line through which air as working fluid is passed. Three different pitch ratios (PR) of conical-nozzle arrangements in the test tube are introduced with PR = 2.0, 4.0 and 7.0 in each run. In addition, the snail is also employed to provide swirling flow at the inlet of the test tube. It is found that each application of the conical nozzle and the snail can help to increase considerably the heat transfer rate over that of the plain tube by about 278% and 206%, respectively. The use of the conical nozzle in common with the snail leads to a maximum heat transfer rate that is up by 316%. Correlation equations for Nusselt number, friction factor and performance evaluation criteria to assess the real benefits in using the turbulators and swirl generator of the enhanced tube are determined. © 2006 Elsevier Ltd. All rights reserved.
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Heat transfer in square duct fitted diagonally with angle-finned tape-Part 1: Experimental study
(2012-05-01)
Promvonge, Pongjet
;
Skullong, Sompol
;
Kwankaomeng, Sutapat
;
Thiangpong, Chinaruk
The paper presents an experimental study on turbulent flow and heat transfer characteristics in a square duct fitted diagonally with 30° angle-finned tapes. The tested duct has a square section and uniform heat-fluxed walls and the flow rate of air used as the test fluid is presented in terms of Reynolds number from 4000 to 23,000. The angle-finned straight tape in the present work is newly invented without previous investigations available. The insertion of the finned tape is performed with three ratios of fin pitch to duct height (PR= P/. H) at the fin attack angle of 30° with respect to the main flow direction. The finned tape inserted diagonally in the duct is expected to generate a longitudinal vortex flow pair through the heated duct. Influences of five fin-to-duct height ratios (BR= b/. H= 0.1-0.3) for each fin pitch on thermal and flow friction characteristics of the inserted duct are investigated. The experimental result shows that at smaller fin pitch spacing, the finned tape with BR= 0.3 provides the highest heat transfer and friction factor but the one with BR= 0.2 and PR= 1.0 yields the best thermal performance. The thermal performance of the newly invented finned tape turbulator is found to be much higher than that of the wire coil/twisted tape turbulator. © 2012 Elsevier Ltd.
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Heat transfer and turbulent flow friction in a circular tube fitted with conical-nozzle turbulators
(2007-01-01)
Promvonge, Pongjet
;
Eiamsa-ard, Smith
The paper deals with an experimental study of the influence of conical-nozzle turbulator inserts on heat transfer and friction characteristics in a circular tube. In the present work, the turbulators are placed in the test tube section with two different types: (1) diverging nozzle arrangement (D-nozzle turbulator) and (2) converging nozzle arrangement (C-nozzle turbulator). The turbulators are thoroughly inserted inside the tube with various pitch ratios, PR = 2.0, 4.0, and 7.0. The Reynolds number based on the bulk average properties of the air is in a range of 8000 to 18,000 and the experimental data obtained are compared with those obtained from the plain tube and from the literature. The experimental results reveal that increasing the Reynolds number at a given pitch ratio of the turbulators leads to the significant increase in Nusselt number indicating enhanced heat transfer coefficient due to rising convection as the flow increases. However, the friction factor at a given Reynolds number considerably increases with the reduction of pitch ratio and Reynolds number. The D-nozzle arrangement, creating stronger reverse/turbulence flow, provides higher the heat transfer rate and friction factor than the C-nozzle arrangement. The heat transfer rates obtained from using both nozzle-turbulators, in general, are found to be higher than that from the plain tube at a range of 236 to 344%, depending on Reynolds number and the turbulator arrangements. In addition, proposed correlations from the present experimental data for Nusselt number and friction factor are also presented. © 2006 Elsevier Ltd. All rights reserved.

Promvonge, Pongjet

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