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Thermal effectiveness and entropy-exergy estimation in a tube with punched double V-winglets
(2026-06-01)
Jayranaiwachira, Nuthvipa
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Sripattanapipat, Somchai
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Promvonge, Pongjet
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Erfanian Nakhchi, Mahdi
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Skullong, Sompol
Vortex generators are effective devices for enhancing heat transfer rates in heating or cooling systems with minimal frictional losses via the production of streamwise vortices. This research effort presents the perforated double V-winglet (P-DVW) and looks at how it affects heat transmission and friction when mounted inside a heat exchange tube that is consistently heated for producing multiple vortices whereas its flow is turbulent. Optimizing thermal performance for increased energy savings and maximizing the Nusselt number ( Nu ) to minimize heat exchanger size are the major goals. Thermal characteristics, including generated entropy and exergy efficiency, are explored in depth. A Reynolds number (Re) that varies from 4760 to 29,270 is employed to explore the friction and thermal features of the tube. The P-DVW parameters encompass attack angles of α<inf>2</inf> = 15° and α<inf>1</inf> = 30°, four porosity ratios ( A <inf>h</inf>/ A <inf>w</inf> = 0, 0.0188, 0.0523, and 0.1026), and three pitch ratios, P<inf>R</inf>, (0.75, 1, and 1.25), while maintaining a constant winglet height. At P<inf>R</inf> = 0.75 and A <inf>h</inf>/ A <inf>w</inf> = 0, the P-DVW exhibits peak f and Nu values around 23.83 and 5.31 times bigger than those of the plain tube, accordingly. Further, under the specified conditions, it yields minimal entropy production, while the optimal exergy efficiency is roughly 0.9829. The thermal effectiveness of P-DVW is anticipated to reach its maximum at 2.55 with Nu<inf>R</inf> = 4.54 at A <inf>h</inf>/ A <inf>w</inf> = 0.0523 and P<inf>R</inf> = 0.75 to reveal its actual benefits. Furthermore, the correlations of f , Nu , and TEF were determined for the examined range of values.
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Augmentation of solar air heater effectiveness with flapped triangular-wings
(2025-12-01)
Promvonge, Pongjet
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Sripattanapipat, Somchai
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Jayranaiwachira, Nuthvipa
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Nakhchi, Mahdi Erfanian
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Skullong, Sompol
An experiment was conducted to identify the optimal method for enhancing the thermal effectiveness of a solar air heater duct utilizing flapped triangular-wing (FTW) vortex generators affixed to the absorber. The wings are structured in two configurations: backward FTW (B-FTW) and forward FTW (F-FTW), each incorporating a louver-flapped opening for lowering frictional loss. This study seeks to improve the Nusselt number ratio (Nu<inf>R</inf>) while lowering friction loss to optimize thermal effectiveness, hence minimizing the overall dimensions of thermal energy systems. The research findings focus on heat transmission (Nu) and frictional loss (f), encompassing thermal effectiveness across the entire range of Reynolds numbers (Re) from 5280 to 22,510. The FTW elements are configured in B-FTW and F-FTW forms, employing three relative pitches (P<inf>R</inf> = 0.75, 1.25, and 1.75) and five flap angles (θ = 0°, 35°, 45°, 65°, and 90°), while maintaining a constant attack angle (α = 45°) and a wing height ratio (B<inf>R</inf> = 1). The research findings demonstrate that the FTWs produce a significant increase in Nu contrasted to the smooth duct, which varies from 4.72 to 8.05 times, while the increase in f is approximately 13 to 68.1 times. For P<inf>R</inf> = 1.25, θ = 45°, and lower Re, the greatest thermal effectiveness factor (TEF) is roughly 2.87 for the F-FTW and 2.64 for the B-FTW, while Nu<inf>R</inf> is approximately 6.98 for the F-FTW and 6.29 for the B-FTW. This implies that the largest TEF is exclusively associated with the F-FTW, and therefore, the B-FTW should be averted in practice. Additionally, correlations are established and documented for the key quantities (Nu, f, and TEF).
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Augmented thermal effectiveness in solar air receiver with flapped curved winglets: Experimental and numerical analysis
(2025-12-01)
Sripattanapipat, Somchai
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Promvonge, Pongjet
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Jayranaiwachira, Nuthvipa
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Promthaisong, Pitak
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Nakhchi, Mahdi Erfanian
Thermal effectiveness was examined on a solar air receiver equipped with a new lengthwise vortex generator, namely a flapped curved winglet (FCW) mounted on the absorber, utilizing experimental and numerical approaches. Two arrays were employed to assemble two FCWs on the absorber at an angle of attack (α = 59.5°). The FCWs' V-tips were orientated upstream (VU-FCW) and downstream (VD-FCW). Air served as the working fluid, entering a constantly heat-fluxed channel at Reynolds numbers (Re) varying from 5280 to 22,510. Three relative winglet pitches (P<inf>R</inf> = P/H = 1.0–2.0), five winglet-mounted flap angles (β = 0° - 90°), and one winglet blockage ratio (b/H=B<inf>R</inf> = 0.6) were among the major factors. According to the findings, lowering P<inf>R</inf> and β greatly enhances the f (friction factor) and Nu (Nusselt number) of the two FCW arrays. The FCW with P<inf>R</inf> = 1.0 and β = 0° has the largest Nu and f values, approximately 8.3 and 77.39 times bigger than the smooth flat channel, as per the test data. The maximal thermal effectiveness factors (TEF) of the VD-FCW and VU-FCW were approximately 2.83 and 2.61, respectively, at comparable β = 45° and P<inf>R</inf> = 1.5. The f and Nu correlations in employing FCW were also provided. A 3D computational analysis employing the realizable k-ε turbulence model was conducted to examine heat transmission and flow patterns, with the corresponding measured data validating the expected results. The numerical and measured data sets yielded consistent results, and the FCW's heat transmission mechanism was also described.
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Thermal effectiveness analysis of heat exchange tube with staggered louver-punched V-baffles
(2024-12-01)
Promvonge, Pongjet
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Jayranaiwachira, Nuthvipa
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Promthaisong, Pitak
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Nakhchi, Mahdi Erfanian
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Skullong, Sompol
An experiment has been conducted to ascertain the optimal approach for enhancing the convective transmission of heat in a heat exchanger tube by periodically positioning staggered louver-punched V-baffle (SLVB) vortex generators on a perforated tape. The louver-punched V-baffles were staggered and set up with two patterns: V-apex directing upstream (VU) and downstream (VD), and each featured a louver-punched aperture to minimize friction loss. The aim of this work was to rise the thermal effectiveness as well as the Nusselt number ratio (Nu<inf>R</inf>) at optimal effectiveness in order to cut down on overall dimension of heat exchangers. Consequently, the research findings focused on behaviors of heat transmission and frictional loss, incorporating generated entropy, through a variety of Reynolds numbers (Re) spanning 29,270 to 4762. The SLVB elements were designed and placed in VU and VD forms using three relative pitches (P<inf>R</inf> = 0.5, 1.0, and 1.5) as well as six louver-flapped angles (θ = 0°, 10°, 20°, 30°, 45°, and 90°), all at the same attack angle (α = 52°), a baffle height ratio (B<inf>R</inf> = 0.3) and a louver size ratio (L<inf>R</inf> = 0.73). As demonstrated by the experiment, the θ = 20° generated the best heat transfer of all P<inf>R</inf> values, up to 6.55 times greater than the smooth tube, despite having a lower friction loss than the θ = 0° (solid baffle). At P<inf>R</inf> = 0.5, θ = 20° and smaller Re, the optimum thermal effectiveness factor (TEF) and Nu<inf>R</inf> values were, respectively, about 2.65 and 6.55 for the VU SLVB and 2.52 and 6.04 for the VD one. It implied that the TEF strategies can be utilized to anticipate the best effectiveness under identical scenarios. Also, correlations for the critical parameters, namely, Nu, f, and TEF, were estimated and documented.
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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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Analysis of exergy and heat transfer in a tube fitted with flapped V-baffles
(2024-07-01)
Jayranaiwachira, Nuthvipa
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Promvonge, Pongjet
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Tongyote, Paritkavin
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Skullong, Sompol
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Nakhchi, Mahdi Erfanian
Vortex generator is a device that shows promise in generating streamwise vortices that can be utilized for boosting the rate of heat transmission inside a cooling/heating system with a relatively smaller penalty in terms of friction loss. The primary goal of the current research is to maximize the comparative Nusselt number ratio (Nu/Nu<inf>0</inf>) to be as large as possible to lower the size of the system while keeping thermal performance as high as feasible to save more energy. Thus, in the current study, the impacts of inserting the flapped V-baffle vortex generator (FBVG) on the thermal effectiveness improvement of a round tube were experimentally investigated. At a fixed attack angle (α = 60°) and baffle blockage ratio (B<inf>R</inf> = b/D = 0.3), the geometrical behaviors of FBVGs placed periodically along two edges of a straight tape were six different flap angles (θ = 0°, 25°, 35°, 45°, 65° and 90°) and three ratios of baffle pitches (P/D = P<inf>R</inf> = 2.0, 1.5, and 1.0). The current V-baffles, which were positioned on both tape edges, were designed to reduce friction loss caused by interrupting the central core flow when placed on both tape sides. The measurement results focused on the friction loss and thermal behaviors, including exergy and entropy analyses for Reynolds number from 4750 to 29,270. In the findings, the Nusselt number and friction factor of FBVG at θ = 0° and P<inf>R</inf> = 1 are, respectively, up to 5.6 and 35.24 times larger than those of the smooth tube. The entropy generation (S˙<inf>gen</inf>′) seems to decline as θ and P<inf>R</inf> increase, with the smallest S˙<inf>gen</inf>′ found at θ = 0° and P<inf>R</inf> = 1 for lower Re. The FBVG has the greatest exergy efficiency (η<inf>Ex</inf>) at θ = 0° and P<inf>R</inf> = 1. To find the true benefits of FBVG, its thermal performance is estimated and seen to reach a maximum at about 2.44 with Nu<inf>R</inf> = 4.65 at θ = 45° and P<inf>R</inf> = 1. The optimal scenario at θ = 25° and P<inf>R</inf> = 1 was preferred, however, since it yielded the largest Nu<inf>R</inf> = 5.42 at TEF = 2.39.
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Heat transfer analysis in a tube contained with louver-punched triangular baffles
(2024-06-01)
Jayranaiwachira, Nuthvipa
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Promvonge, Pongjet
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Promthaisong, Pitak
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Nakhchi, Mahdi Erfanian
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Skullong, Sompol
The present research assesses the thermal effectiveness of a heat exchange tube incorporating louver-punched triangular baffle (LPTB) vortex generators under turbulent conditions. For Reynolds numbers between 4760 and 29,270, the heat transfer and flow behaviors in the consistent heat-fluxed tube equipped with LPTBs were studied numerically and experimentally. A single baffle height/blockage ratio (b/D = B<inf>R</inf> = 0.25) and relative baffle pitch (P/D = P<inf>R</inf> = 1) were used for both baffle attack angles, (α) 30° and 45°, along with three louver size ratios (e/b = L<inf>R</inf> = 0.24–0.56) as well as five louver angles (θ = 0°, 20°, 30°, 45°, 60°, and 90°). The results show that as the L<inf>R</inf> and θ values decrease, the Nusselt number (Nu) and friction factor (f) of the LPTB rise owing to the improved fluid mixing process generated by streamwise vortices with stronger turbulence kinetic energy. The LPTB with L<inf>R</inf> = 0 and θ = 0° provides the greatest f and Nu of about 22.18 and 5.1 times, respectively, although the one with L<inf>R</inf> = 0.24 and θ = 45° has the largest TEF of about 2.39 and 2.5 for the α = 30° and 45° LPTBs, respectively. Furthermore, an examination into the thermal and flow patterns was conducted through a three-dimensional computation; the validation of the numerical and experimental data yielded satisfactory results. Using measured data, the f and Nu correlations of the α = 30° and 45° LPTBs were additionally established.
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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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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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LPG Leakage Risk Predictions from an IoT-Based Detection System Using Machine Learning
(2023-01-01)
Lorthong, Saksiwa
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Janjarassuk, Udom
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Jayranaiwachira, Nuthvipa
LPG has the potential to ignite and explode if it spills since it is a flammable gas. Explosions and flames caused by LPG leaks can damage or kill people who are working in the hazardous area. The industrial sector currently lacks efficient warning systems to identify and anticipate leaks, necessitating efficient equipment to identify and monitor gas leaks. This work aims to investigate and identify a device designed to detect and keep track of LPG leaks by utilizing straightforward yet efficient IoT technologies. The experimental and carefully vetted data are applied to build an Artificial Neural Network (ANN) model for predicting the risk of gas leaks. Gas leaks in the workplace are monitored, alerted to, and controlled by using gas detection systems based on IoT technology. The dataset is then submitted to factor analysis for feature selection, which made use of the model's expertise from its examination of the information gathered from the detecting device in the Cloud system. Several measures were utilized to evaluate the model, including Accuracy, Precision, Recall, F1-Score and Area Under the Curve (AUC). The investigation led to clustering the Risk Ranking Number into three levels, which were then utilized in conjunction with the Risk Matrix to evaluate risk. The net processing time was 1.34 minutes, and the forecast accuracy was 96.05%. This study will assist in improving the model that establishes the alarm system's alert level.

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