Thianpong, Chinaruk

Preferred name

Thianpong, Chinaruk

Alternative Name

Thianpong, C.

Main Affiliation

School of Engineering

chinaruk.th@kmitl.ac.th

Now showing 1 - 10 of 13

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Heat transfer augmentation in a wedge-ribbed channel using winglet vortex generators
(2010-02-01)
Chompookham, Teerapat
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Thianpong, Chinaruk
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Kwankaomeng, Sutapat
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Promvonge, Pongjet
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.
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Entropy generation and thermal performance of tubular heat exchanger fitted with louvered corner-curved V-baffles
(2023-02-01)
Jayranaiwachira, Nuthvipa
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Promvonge, Pongjet
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Thianpong, Chinaruk
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Skullong, Sompol
The current article deals with an experimental study on entropy generation analysis and thermohydraulic performance of a uniform heat-flux tube equipped with louvered corner-curved baffle tape (LCBT). Air was drawn into the inserted tube for the Reynolds number (Re) between 4760 and 29,300. The V-shaped LCBT arranged by V-tip in downstream direction was introduced with three baffle pitch ratios (P<inf>R</inf> = 1–2) and six louver angles (θ = 0–90°) for a fixed attack angle (α) of 30° and baffle height ratio (B<inf>R</inf> = 0.25). The impacts of investigated parameters on the thermal enhancement factor (TEF), Nusselt number (Nu), friction factor (f), and total entropy generation (S˙<inf>gen</inf>′) were examined. The measurements showed that the LCBT with the smallest values of P<inf>R</inf> = 1, θ = 0° give the largest Nu and f at about 4.4 and 19.2 times above the plain tube values, respectively. However, the greatest TEF around 2.23 was seen for employing the LCBT at P<inf>R</inf> = 1, θ = 45°. The entropy analysis also showed that the S˙<inf>gen</inf>′ is found to decline with the increment of P<inf>R</inf> and θ, whereas the minimal S˙<inf>gen</inf>′is at P<inf>R</inf> = 1, θ = 0° for lower Re but at P<inf>R</inf> = 1, θ = 45° for higher Re. Furthermore, the Nu and f empirical correlations for employing LCBTs were also proposed.
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Thermal characterization in a circular tube fitted with inclined horseshoe baffles
(2015-01-22)
Promvonge, Pongjet
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Tamna, Sombat
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Pimsarn, Monsak
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Thianpong, Chinaruk
In the present study, the influence of inclined horseshoes baffles placed repeatedly in a tubular heat exchanger on heat transfer rate, friction factor and thermal enhancement factor are experimentally determined. The horseshoe baffle elements with an inclination angle of 20° were inserted periodically into the test tube at three different baffle-pitch ratios (P<inf>R</inf> = 0.5, 1.0 and 2) and -width or blockage ratios (B<inf>R</inf> = 0.1, 0.15 and 0.2). The experiment was conducted in the test tube having a uniform heat-fluxed wall by varying turbulent airflow to obtain Reynolds number in a range of 5300-24,000. The experimental results revealed that the tube fitted with inclined horseshoes baffles provides considerable improvement of the heat transfer rate over the plain tube around 92-208% while the friction factor is increased at about 1.76-6.37 times. To access the real benefits for the inclined horseshoes baffles inserted in plain tube, thermal performance factor is examined and found to be in the range of 1.34-1.92 at which the maximum obtained at P<inf>R</inf> = 0.5 and B<inf>R</inf> = 0.1 is considerably higher than that for published inserted devices. Correlations for Nusselt number and friction factor for the oblique horseshoe-baffled tube are also proposed.
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Thermal performance of heat exchanger tube inserted with curved-winglet tapes
(2018-01-25)
Skullong, Sompol
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Promvonge, Pongjet
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Thianpong, Chinaruk
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Jayranaiwachira, Nuthvipa
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Pimsarn, Monsak
The paper deals with the effect of curved-winglet (CW) inserts on thermal and flow behaviors in a constant heat-fluxed tube. A straight tape is used to support the 45° CWs mounted repeatedly on both tape sides to generate two pairs of longitudinal counter-rotating vortices along the test tube in order to assist the chaotic flow mixing and to disrupt the boundary layer leading to faster rate of heat transfer. The airflow and heat transfer behaviors in the tube are examined for Reynolds number (Re) in the range of 4150–25,400. The curved-winglet tape (CWT) parameters involved are the winglet attack angle of 45° three relative winglet heights (b/D = B<inf>R</inf> = 0.1, 0.2 and 0.3) and winglet pitches, (P/D = P<inf>R</inf> = 0.5, 1.0 and 2.0). The investigation reveals that the maximum thermal enhancement factor (TEF) of the CWT is about 1.62 at B<inf>R</inf> = 0.1 and P<inf>R</inf> = 1.0. For further improvement, the CWT at B<inf>R</inf> = 0.1 and P<inf>R</inf> = 1.0 is modified by punching the CW to be the perforated-curved-winglet tape (P-CWT) to reduce the pressure loss. The P-CWT characteristics include five different punched hole diameters (d = 1.0, 1.5, 2.0, 2.5 and 3.0 mm). The experimental results show that TEF of all the P-CWTs is higher than that of the CWT and the maximum TEF of 1.76 higher than the CWT around 9% is found for d = 1.5 mm. To understand the flow pattern and heat transfer mechanism, a three-dimensional CFD investigation is also performed and for validation, the good agreement between numerical and experimental results is found. For experimental data, empirical correlations for Nu, f and TEF for the CWT and P-CWT inserts are also determined.
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Enhanced thermal effectiveness of square duct with V-type double-baffles: Numerical study
(2024-09-01)
Promvonge, Pongjet
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Sripattanapipat, Somchai
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Thianpong, Chinaruk
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Skullong, Sompol
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Promthaisong, Pitak
The article puts forward three-dimensional computational research on heat transmission augmentation within a square channel containing 45o V-type double-baffles positioned on the lower and top parts at regular intervals in the turbulence zone for Reynolds numbers (Re) that vary from 3000 to 20,000. The primary goal of this research is to increase the thermal effectiveness and relative Nusselt number (Nu/Nu<inf>0</inf>), in order to conserve energy and reduce the size of the heating or cooling system. The simulations utilize a finite volume approach in common with the SIMPLE algorithm, whereas the turbulent model used is the realizable k–ε. The baffles are designed to be separated vertically for reducing pressure loss. Both single V-baffles and double V-baffles have four relative pitches (PR = 0.4, 0.5, 0.6, and 1.0) and height/blockage ratios (BR = 0.05, 0.1, 0.15, and 0.2), with a fixed attack angle (α) of 45o. The computational findings show that both V-baffles are capable of producing the primary vortices, but only the double V-baffles have the ability to provide the impinging streams onto the wall, cooling the region behind the baffles. This suggests that the double V-baffles not only boost heat transmission but also reduce frictional loss. When compared to a single V-baffle, the double ones enhance heat transfer by an average of 1.04–9.94% while decreasing frictional loss by an average of 9.88–31.73%. The thermal effectiveness factor (TEF) of the double V-baffles ranges from 1.03 to 3.21, and its peak value of around 3.21 is for PR = 0.4, BR = 0.05, at lower Re.
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Heat transfer and turbulent flow friction in a round tube with staggered-winglet perforated-tapes
(2016-04-01)
Skullong, Sompol
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Promvonge, Pongjet
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Thianpong, Chinaruk
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Pimsarn, Monsak
The article deals with thermal and flow resistance characteristics in a tubular heat exchanger fitted with staggered-winglet perforated tapes (WPT). The experiment was conducted in the test tube having a constant wall heat-flux for turbulent airflow, Reynolds number (Re) from 4180 to 26,000. The aim of using the WPT is to generate longitudinal vortex flows to disrupt thermal boundary layer on the tube wall and to provide stronger fluid mixing. The WPT having an winglet inclination angle of 30° was inserted into the test tube at five different winglet blockage ratios (B <inf>R</inf> = 0.1, 0.15, 0.2, 0.25 and 0.3) and three winglet pitch ratios (P <inf>R</inf> = 0.5, 1.0 and 1.5). To find an optimum thermal performance condition, the effect of B <inf>R</inf> and P <inf>R</inf> on the heat transfer and pressure loss due to flow friction in the tube is examined. The experimental results reveal that Nusselt number (Nu) and friction factor (f) for the WPT increase with the increment of B <inf>R</inf> but the reduction of P <inf>R</inf> . The highest thermal enhancement factor (TEF) of 1.71 is achieved by utilizing the WPT with B <inf>R</inf> = 0.15, P <inf>R</inf> = 1.0 at Re = 4180. Compared to staggered-winglet typical non-perforated tape (WTT), the WPT yields the TEF of about 1.2 times higher than the WTT. Correlations of Nu, f and TEF for the WPT and the WTT are also proposed.
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Thermal behaviors in a round tube equipped with quadruple perforated-delta-winglet pairs
(2017-01-01)
Skullong, Sompol
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Promvonge, Pongjet
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Thianpong, Chinaruk
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Jayranaiwachira, Nuthvipa
The article deals with an experimental investigation of enhancing convective heat transfer in a heated circular tube with pairs of perforated-delta-winglets placed repeatedly on a perforated-cross-tape (PW-XT). The perforated-delta-winglets are placed in inline array and a triangular-hole is punched on each winglet to reduce the friction loss. The aim at using the PW-XT insert is to produce streamwise-vortex flows in the tube to reduce the thickness of thermal boundary layer and to increase fluid mixing of the flow. The involved winglet parameters are composed of relative winglet height or blockage ratio, (B<inf>R</inf> = b/D = 0.1, 0.15, 0.2 and 0.25) and relative winglet pitch or pitch ratio, (P<inf>R</inf> = P/D = 0.5, 1.0, 1.5 and 2.0) and those are performed at a single delta-winglet inclination/attack angle, α = 30° and a winglet porosity ratio, A<inf>p</inf>/A<inf>w</inf> = 0.359 for Reynolds number from 4180 to 26,000. The present results of heat transfer and pressure loss displayed in terms of respective Nusselt number (Nu) and friction factor (f) show that Nu increases with increasing B<inf>R</inf>but with decreasing P<inf>R</inf>. Nu for the PW-XT insert is in a range of 1.96–5.06 times while f increases around 2.06–35.68 times above the plain tube alone. To estimate the real merits of the PW-XT, the thermal enhancement factor (TEF) is evaluated and found to be a maximum around 1.902 at B<inf>R</inf> = 0.15, P<inf>R</inf> = 1.0. In comparison, the PW-XT gives considerably higher TEF than the typical four delta-winglet pairs placed on the cross-tape (TW-XT) having the highest TEF around 1.72.
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Effect of trapezoidal louvered winglets on increased heat transfer and exergy in tubular heat exchanger
(2024-10-01)
Promvonge, Pongjet
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Thianpong, Chinaruk
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Jayranaiwachira, Nuthvipa
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Nakhchi, Mahdi Erfanian
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Skullong, Sompol
The effect of inserting a trapezoidal louvered winglet tape (TLWT) into a uniformly heat-fluxed tube on its thermal effectiveness was studied experimentally. The exergy and entropy analyses for turbulent flows, as well as frictional loss and thermal features, were highlighted as key aspects of the experimental finding for the Reynolds number which measured between about 4700 and 30,000. Because fixing baffles to the curved shape of tube wall presented a challenge, the baffles were consequently positioned on double surfaces of a flat tape. Six values of the louver angle (θ<inf>1</inf> = 0°, 25°, 30°, 45°, 60°, and 90°) and three values of the relative pitch of winglet (P<inf>R</inf> = 1.0, 1.5, and 2.0) were employed in the arrangement of TLWTs, with the V-apex oriented upstream (V-up). Each of these had only a fixed height (B<inf>R</inf> = 0.25) and angle of attack (α = 30°). The winglets were utilized to induce streamwise vortices which can hinder the boundary layer formation, while the louvered openings were adopted to lessen pressure drop without significantly impacting the primary vortices. The experiment results disclosed that the smallest θ<inf>1</inf> and P<inf>R</inf> produced the largest relative friction factor (f<inf>R</inf>) and Nu<inf>R</inf>, which were about 13.57 and 4.04 times higher, while P<inf>R</inf> = 1 and θ<inf>1</inf> = 45° provide the greatest TEF of about 2.27. The greatest exergy efficiency (η<inf>Ex</inf>) resulting from the TLWT was reached at θ<inf>1</inf> = 0°, but the generation of entropy (S˙<inf>g</inf>′) dropped with lowering θ<inf>1</inf> and Re. A further examination, however, showed that the best scenario with α = 60° and staggered arrays is more desirable since it yields the largest TEF of 2.45 at θ<inf>1</inf> = 45° and P<inf>R</inf> = 1. For the range of parameters under consideration, the Nu and f correlations were additionally established.
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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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Experimental and numerical study on heat transfer enhancement in a channel with Z-shaped baffles
(2012-08-01)
Sriromreun, Parkpoom
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Thianpong, Chinaruk
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Promvonge, Pongjet
The influence of baffle turbulators on heat transfer augmentation in a rectangular channel has been investigated experimentally and numerically. In the experiment, the baffles are placed in a zigzag shape (Z-shaped baffle) aligned in series on the isothermal-fluxed top wall, similar to the absorber plate of a solar air heater channel. The aim at using the Z-baffles is to create co-rotating vortex flows having a significant influence on the flow turbulence intensity leading to higher heat transfer enhancement in the tested channel. Effects of the Z-baffle height and pitch spacing length are examined to find the optimum thermal performance for the Reynolds number from 4400 to 20,400. The Z-baffles inclined to 45° relative to the main flow direction are characterized at three baffle- to channel-height ratios (e/. H= 0.1, 0.2 and 0.3) and baffle pitch ratios (P/. H= 1.5, 2 and 3). The experimental results show a significant effect of the presence of the Z-baffle on the heat transfer rate and friction loss over the smooth channel with no baffle. The Nusselt number, friction factor and thermal performance enhancement factor for the in-phase 45° Z-baffles are found to be considerably higher than those for the out-phase 45° Z-baffle at a similar operating condition. The in-phase 45° Z-baffle with larger e/. H provides higher heat transfer and friction loss than the one with smaller e/. H while the shorter pitch length yields the higher Nu, f and TEF than the larger one. The numerical work is also conducted to investigate the flow friction and heat transfer behaviors in the channel mounted with the 45° Z-baffles, and the numerical results are found in good agreement with experimental data. © 2012 Elsevier Ltd.

Thianpong, Chinaruk

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