Promvonge, Pongjet

Preferred name

Promvonge, Pongjet

Alternative Name

Promvonge, P.

Main Affiliation

School of Engineering

pongjet.pr@kmitl.ac.th

Now showing 1 - 10 of 12

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Numerical heat transfer study of square duct equipped with novel flapped V-baffles
(2024-03-01)
Thianpong, Chinaruk
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Promvonge, Pongjet
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Skullong, Sompol
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Promthaisong, Pitak
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Nakhchi, Mahdi Erfanian
The paper describes a computational study of heat transfer enhancement inside a square duct with V-shaped flapped baffles located repeatedly on the bottom and top walls for fluid flowing with Reynolds numbers (Re) from 3000 to 21,000. The basic goal of this work is to attain the largest relative Nusselt number (Nu/Nu<inf>0</inf>) whilst maintaining the highest thermal performance to improve energy savings. A finite volume method was used in the computations, along with the Realizable k‒ε turbulent model. The variable baffle parameters considered first in the current simulation were the relative height/blockade ratio (B<inf>R</inf> = 0.05−0.2) and the flap angle of the baffle hole (β = 0° − 90°), while the fixed parameters included the attack angle (α = 60°), hole diameter ratio (d<inf>R</inf> = 0.5), and pitch ratio (P<inf>R</inf> = 0.5). To accomplish this goal, the previously mentioned parameters providing the best thermal performance were investigated further by extending the values of B<inf>R</inf> to 0.25−0.3, d<inf>R</inf> to 0.8 and α to 45°−30°. The simulation results indicate that the jet flowing from the flapped hole, as well as the vortices created by the baffle, can boost heat transfer and friction loss in comparison to the plain duct. In comparison, using a flapped baffle with β > 0° results in less friction loss, a greater thermal enhancement factor (TEF), and a higher Nusselt number than using a baffle with no flap. The first investigation disclosed that for B<inf>R</inf> = 0.2 and β = 20°, the greatest TEF of 2.19 with Nu/Nu<inf>0</inf> of 7.9 times are obtained. The extended study, on the other hand, showed that the highest TEF of roughly 2.49 with Nu/Nu<inf>0</inf> of 8.4 times are seen for α = 45°, d<inf>R</inf> = 0.8, B<inf>R</inf> = 0.25 and β = 20° at lowest Re. Thus, the flapped baffle provides a significant increase in Nu/Nu<inf>0</inf> and TEF over the baffle alone.
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Experimental and numerical thermal performance in solar receiver heat exchanger with trapezoidal louvered winglet and wavy groove
(2022-04-01)
Promvonge, Pongjet
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Promthaisong, Pitak
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Skullong, Sompol
A numerical and experimental study on the thermal–hydraulic performance of a solar receiver heat exchanger (SRH) equipped with a newly designed longitudinal-vortex generator, namely, trapezoidal louvered winglet and wavy groove placed on the absorber has been carried out. The relevant parameters included three pitch ratios of winglets/grooves (P/H = P<inf>R</inf> = 1, 1.5 and 2), four winglet blockage ratios (b/H = B<inf>R</inf> = 0.3–0.45) at a single attack angle of winglet/groove, α = 45°. The experimental outcome showed that the trapezoidal winglet (TW) together with the wavy groove at P<inf>R</inf> = 1, B<inf>R</inf> = 0.45 gives the greatest friction factor and the heat transfer around 108.1 and 9.35 times over the smooth SRH channel, respectively while that at P<inf>R</inf> = 1.5, B<inf>R</inf> = 0.4 provides the optimal thermal performance at about 2.6. To increase further the performance, the TW at optimal conditions was modified by punching the TW at its centroid to be a square-hole and then covering the back-end hole partially like a louver, called the trapezoidal louvered winglet (TLW). The TLW elements were mounted on the grooved absorber plate with eight louver angles (θ = 0°–90°). The investigation indicated that among the louver angles, the θ = 20° yields the greatest heat transfer up to 9.18 times above the smooth SRH whilst its friction loss is lower than the θ = 0°(solid-winglet). Hence, the TLW and wavy groove at θ = 20° provided the maximum thermal–hydraulic performance around 2.76. To understand the flow and thermal patterns, a 3D flow computation was also carried out and their results were validated with available measurements.
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Thermal performance in solar air heater with perforated-winglet-type vortex generator
(2018-08-01)
Skullong, Sompol
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Promthaisong, Pitak
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Promvonge, Pongjet
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Thianpong, Chinaruk
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Pimsarn, Monsak
An experimental and numerical study of turbulent convective heat transfer in a solar air heater duct with winglet-type vortex generators (WVGs) placed on the absorber plate is presented. Air as the test fluid enters the duct having a uniform wall heat-flux applied on the upper wall or the absorber plate with Reynolds number from 4100 to 25,500. Two types of WVGs are introduced: rectangular (RWVG) and trapezoidal (TWVG) WVGs, in order to create multiple vortex flows along the duct. The WVG parameters in the present study include two relative height (B<inf>R</inf> = e/H = 0.2 and 0.48), three longitudinal pitch ratios (P<inf>R</inf> = P<inf>l</inf>/H = 1, 1.5 and 2) and a single attack angle, α = 30°. The experimental result reveals that the RWVG with B<inf>R</inf> = 0.48 and P<inf>R</inf> = 1 provides the highest heat transfer and friction factor at about 7.1 and 109.5 times above the flat duct, respectively while the TWVG with B<inf>R</inf> = 0.2 and P<inf>R</inf> = 1.5 yields the maximum thermal performance around 1.84. Then, to improve the performance by reducing the substantial pressure loss, both the WVGs with B<inf>R</inf> = 0.48 and P<inf>R</inf> = 1.5 are modified to be perforated rectangular and trapezoidal winglet-type vortex generators (P-RWVG and P-TWVG) with four different punched hole/pore diameters (d = 1, 3, 5 and 7 mm) on their central area. The investigation indicates that among the perforated WVGs, the P-RWVG at d = 1 mm yields the highest heat transfer and friction factor up to 6.78 and 84.32 times higher than the smooth duct but the best thermal performance of about 2.01 is found for the P-TWVG with d = 5 mm. To explore the flow and heat transfer pattern, a 3D numerical flow simulation is performed and validated with available measurements where both the numerical and measured results are in good agreement.
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Thermal performance evaluation of a diamond-shaped roughened tube
(2025-12-01)
Chokphoemphun, Suriya
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Kamma, Panit
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Promvonge, Pongjet
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Promthaisong, Pitak
Thermal performance evaluation was examined numerically in a diamond-shaped roughened tube, which created recirculation and pair counter-rotation flows, which helped to disrupt the boundary layer, and increased fluid mixing led to improving the rate of heat transfer. The parameters studied, including relative depth ratio, e/D, DR, from 0.02 ≤ DR ≤ 0.14, and relative pitch ratio, p/D, PR, from 0.25 ≤ PR ≤ 1.5, under turbulent flow conditions, 3000 ≤ Re ≤ 20,000. Computed results included heat transfer (Nu/Nu<inf>0</inf>), frictional loss (f/f<inf>0</inf>) and thermal performance (in terms of thermal enhancement factor, TEF). The simulations showed that the velocity and heat transfer became fully developed periodic at around x/D ≈ 6–7.5. The pair counter-rotation flows increased the level of both the flow strength and the mixing of fluid, and disrupted the boundary layer, leading to an increase in heat transfer rate. The Nu/Nu<inf>0</inf>, f/f<inf>0</inf> and TEF were achieved in a range of 1.00–3.34, 1.21–24.00 and 0.69–1.56. The maximum TEF was found at 1.56 for DR = 0.08, PR = 0.50 and Re = 5000.
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Heat transfer augmentation in solar heat exchanger duct with louver-punched V-baffles
(2022-12-01)
Promvonge, Pongjet
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Promthaisong, Pitak
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Skullong, Sompol
A vortex generator's ability to create secondary flow and accelerate rapid fluid mixing allows it to effectively improve thermal performance in a solar heat exchanger duct. A newly created louver-punched V-baffle (LPVB) vortex generator was tested experimentally in the current study and the flow and thermal patterns were also investigated using a three-dimensional CFD simulation. The Realizable k–ε turbulence model was utilized in the simulation and the predictions were verified using experimental data and correlations. By directing the impinging air onto the duct's heated surface, the square louver on the baffle served the primary function of reducing pressure drag. Air was used as the test fluid, flowing at Reynolds numbers (Re) from 5300 to 23,000 into the constant heat-fluxed duct. On the heated wall that was set up by letting the V-apex direct upstream, the LPVBs with a 45° attack angle (α) were repeatedly positioned. There were two aspects to the current investigation. First, the optimal relative baffle pitches (P<inf>R</inf>) and louver angles (β) conditions were determined by looking at the LPVB characteristics, which included four β and three P<inf>R</inf> at a fixed relative louver size (L<inf>R</inf> = 0.5) and baffle height (B<inf>R</inf> = 0.4). Second, three relative louver sizes (L<inf>R</inf> = 0.3–0.9) were investigated at the optimal P<inf>R</inf> and β. According to the results, the solid-baffle friction loss is significantly reduced by the LPVB with β > 0° while the heat transfer is slightly lower. In the first part, the LPVB with P<inf>R</inf> = 1.5, β = 45° has the optimal performance while in the second part, the one with L<inf>R</inf> = 0.9 yields the greatest performance. A numerical flow model was computed to understand the flow and thermal patterns. The findings were verified using the available measurements, and there is close agreement between the experimental and numerical results.
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Experimental and numerical heat transfer study of turbulent tube flow through discrete V-winglets
(2020-04-01)
Promvonge, Pongjet
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Promthaisong, Pitak
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Skullong, Sompol
The article presents an experimental and numerical investigation on heat transfer augmentation in a tubular heat exchanger inserted with discrete-V-winglet (DW) tape. Air entered the DW-inserted tube having a uniform wall heat flux in a turbulent flow regime, Reynolds number from 4200 to 25,800. Two arrangements of DWs: V-tip pointing upstream (V-up) and downstream (V-down) were introduced with three relative winglet heights (R<inf>B</inf>=b/D = 0.1, 0.15 and 0.2) and four relative winglet-pitches (R<inf>P</inf>=P/D = 0.5, 1.0, 1.5 and 2.0), all at a single angle of attack, α = 30°. Effects of those parameters on the heat transfer/Nusselt number (Nu) and friction factor (f) were examined. Also, a novel thermal-performance enhancement factor (TEF) was put forward. The experimental result has shown that at a given R<inf>B</inf>, the smallest pitch length (R<inf>P</inf>=0.5) yields the highest f and Nu. The DW with R<inf>B</inf>=0.2 and R<inf>P</inf>=0.5 has the maximum Nu and f of about 3.8 times and 18.8 times, respectively whereas the one with R<inf>B</inf>=0.15 and R<inf>P</inf>=1.0 gives the highest TEF of about 1.99 and 2.02 for the V-up and V-down, respectively. Moreover, the DW provides higher TEF than the typical V-winglet as expected. To explore the mechanism of heat transfer, a numerical model of the inserted-tube flow was carried out and the numerical result was validated and found in favorable agreement with available measurement. Flow structures and heat transfer patterns from the simulation such as temperature contours and streamlines including the Nusselt number contours were also proposed.
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Effect of louvered curved-baffles on thermohydraulic performance in heat exchanger tube
(2023-02-01)
Jayranaiwachira, Nuthvipa
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Promvonge, Pongjet
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Thianpong, Chinaruk
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Promthaisong, Pitak
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Skullong, Sompol
The paper presents an experimental study of convection enhancement in a tube heat exchanger using louvered curved-baffle (LCB) vortex generator (VG). The heat transfer and pressure loss of air as a working fluid, flowing in an isothermal-fluxed tube were measured having Reynolds numbers (Re) between 4760 and 29,300. The LCB elements were arrayed on two tape sides in a V-shape with a 30° attack angle. At a fixed baffle height, the LCB had three axial pitch ratios (PR) from 0.5 to 1.5 and six louver angles (θ) from 0° to 90°. Thermal enhancement factor (TEF), Nusselt number (Nu), and friction factor (f) are often utilized to analyze the effect of VG geometrical variables on thermohydraulic performance. The measured results demonstrated that the LCB-inserted tube has a significantly larger Nu and f than a plain tube functioning alone, and that the Nu and f tend to rise when PR and θ decline. Using the LCB increases Nu and f by approximately 2.59-4.66 and 3.8-39.37 times, respectively. The maximal TEF is achieved for the LCB at PR = 1, θ = 45° and lower Re. Empirical correlations for Nu and f were evaluated and found to fit measured data well, with discrepancies by ± 9% and ±10%, respectively.
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Numerical heat transfer in a solar air heater duct with punched delta-winglet vortex generators
(2021-08-01)
Promvonge, Pongjet
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Promthaisong, Pitak
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Skullong, Sompol
The flow topology and thermohydraulic performance of a novel designed punched delta-winglet (P-DW) placed on the absorber of a solar air heater duct are numerically explored. The effects of geometrical parameters, namely, the relative winglet pitch, PR = 1-2 and the relative punched hole size, dR = 0-0.583 at a single value of blockage ratio, BR = 0.48 and attack angle, α = 30° on thermal characteristics are proposed for Reynolds number from 4000 to 24,000. Among several turbulence models, the simulation has shown that the realizable k-ϵ turbulence model is favorable with respect to measurements. For flow patterns, the P-DW produces several counter-spinning vortices helping induce the impinging jets onto the absorber surface whilst for thermal behaviors, the decline of PR and dR leads to the rise in the friction factor (f) and Nusselt number (Nu). The P-DW provides greater Nu and f than the plain flat plate by 17.1-78.21 and 3.92-5.9 times, respectively and gives the highest performance around 2.1. Further, the P-DW is modified by covering the punched hole partially with a circular flap, called the flapped delta-winglet (F-DW) and this F-DW yields the greatest performance around 2.16 higher than the P-DW about 2.9%.
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Enhanced thermal performance in solar receiver duct with louver-punched V-type winglets: Numerical and experimental study
(2025-03-01)
Suchatawat, Maturose
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Sripattanapipat, Somchai
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Promthaisong, Pitak
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Skullong, Sompol
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Promvonge, Pongjet
An experimental and computational research was performed to explore the augmentation of turbulent convection in a solar receiver channel by utilizing louver-punched V-type winglets (LPVWs) that were fixed to the absorber plate. The simulation utilized the realizable k-ε turbulent model, and the predicated outputs were verified by the relevant measured data. At a fixed attack angle (α) of 45°, the LPVW components were mounted on the absorber with the V-tip facing downstream. Using the LPVW, the newly developed absorber is intended to boost thermal performance by generating multiple flows of longitudinal vortices that induce impinging air streams onto the absorber, thereby enhancing heat transmission. The louvered hole on the winglet serves to reduce pressure loss while preserving the primary vortices. In the current investigation, the winglet parameters consisted of a single relative winglet height (B<inf>R</inf> = 0.4), four louver size ratios (R<inf>L</inf> = e<inf>1</inf>/b = 0.9, 0.7, 0.5, and 0.3), and five louver-flapped angles (β = 90°, 60°, 45°, 30°, and 0°). The LPVW with β > 0° substantially reduced the solid-winglet (β = 0°) friction loss, whereas the heat transmission was slightly declined, as indicated by the results. The solid winglet (β = 0°) exhibited the largest frictional loss and heat transmission, with values approximately 6.3 and 48.2 times the smooth flat duct, respectively. The optimal performance of the LPVW was roughly 2.58, at R<inf>L</inf> = 0.9 and β = 45° Furthermore, empirical correlations for heat transmission and frictional loss were established for this solar receiver duct system. To investigate the heat transmission and flow patterns, a 3-dimensional numerical simulation was implemented, and the predictions were verified against the measured data. The findings were in good accord between the numerical and measured data. For greater thermal performance, the LPVW is reconfigured by altering the locations of the louver holes. The revised LPVW exhibits a peak TEF of 2.7 at β = 35°, l<inf>2</inf>/l<inf>1</inf> = 0.15, l<inf>3</inf>/l<inf>1</inf> = -0.15 and R<inf>L</inf> = 0.9, about 4.65 % superior than the initial analysis.
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Numerical Heat Transfer Investigation in a Solar Receiver Heat Exchanger Channel with Punched Elliptical-Winglet Vortex Generators
(2021-01-01)
Promthaisong, Pitak
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Promvonge, Pongjet
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Khanoknaiyakarn, Chitakorn
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Skullong, Sompol
Thermal performance in a solar receiver heat exchanger (SRX) channel with punched elliptical-winglet vortex generator (P-EW) mounted on the absorber plate is numerically examined for Reynolds number (Re) ranging from 4000 to 24,000. In the present simulation, the P-EW characteristics included three ratios of winglet pitches (P<inf>R</inf> = 2.0, 1.5 and 1.0) including four sizes of the perforated-holes (nondimensional hole diameter, d<inf>R</inf>= 0.0, 0.25, 0.417 and 0.583) at one value of the attack angle (α =30°) and relative height (B<inf>R</inf>= 0.48). The computation reveals that employing P-EW generally yields considerably large friction factor (f) and Nusselt number (Nu) than the flat-plate channel alone. The use of smaller hole size causes the rise in Nu and f. It is noticeable that counter-spinning vortices pairs generated by the multiple P-EW can induce the impinging flow onto the absorber plate together with the air jet coming out of the hole, leading to the rise in the heat transfer rate greater than the smooth flat-plate channel. The highest thermal performance of about 1.9 was seen for the one with P<inf>R</inf> = 1.5 and d<inf>R</inf> = 0.417.

Promvonge, Pongjet

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