Jedsadaratanachai, Withada

Preferred name

Alternative Name

Jedsadaratanachai, W.

Main Affiliation

School of Engineering

withada.je@kmitl.ac.th

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Thermohydraulic Performance Improvement in Heat Exchanger Square Duct Inserted with 45° Inclined Square Ring
(2020-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
Thermal performance development, heat transfer structure, and flow behavior in the heat exchanger square duct equipped with a 45° inclined square ring are investigated numerically. The effects of flow blockage ratios and spacing ratios for the inclined square ring on fluid flow and heat transfer are considered. The Reynolds number (Re = 100-2000, laminar regime) based on the hydraulic diameter of the square duct is selected for the present work. The numerical domain of the square duct inserted with the 45° inclined square ring is solved with the finite volume method. The SIMPLE algorithm is picked for the numerical investigation. The heat transfer characteristics and flow topologies in the square duct inserted with the inclined square ring are plotted in the numerical report. The heat transfer rate, pressure loss, and efficiency for the square duct placed with the inclined square ring are presented in forms of Nusselt number, friction factor, and thermal enhancement factor, respectively. As the numerical results, it is detected that the heat transfer rate of the heat exchanger square duct inserted with the inclined square ring is around 1.00-10.05 times over the smooth duct with no inclined square ring. Additionally, the maximum thermal enhancement factor for the heat exchanger square duct inserted with the inclined square ring is around 2.84.
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Turbulent Airflow and Thermal Analysis in a Circular Tube Heat Exchanger Fitted With Turbulence-Inducing Vortex Generators (X-V Baffles)
(2025-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
The research presents an investigation into airflow configuration, thermal behavior, and convective heat transfer enhancement in a circular heat exchanger tube fitted with turbulence generators. These turbulence generators, referred to in this study as X-V baffles (XVBs), were developed to generate swirling flow within the heat exchanger tube, which is directly related to the enhancement of heat transfer rates and the overall performance of the heat exchanger. Additionally, the XVBs were designed with consideration for practical application and ease of maintenance in real-world industrial settings. The study examines the variables influencing airflow topology and thermal structure, including the blockage ratio (g/D = 0.05–0.20), pitch ratio (P/D = 1–2), flow direction (FD-VD and FD-VU), and types of turbulence generators (Type S and Type T XVBs). The research was conducted within the turbulent flow regime, with Reynolds numbers ranging from 3000 to 12,000 (Re = 3000–12000). The results are presented in terms of observed flow behavior within the test tube, such as cross-flow streamlines, streamwise flow streamlines, Nusselt number distribution, and fluid temperature distribution. The findings clearly show the formation of swirling flow in the heat exchanger tube when XVBs are installed. An increase in the blockage ratio and a decrease in the pitch ratio lead to a more intense swirling flow. The intensity of this swirling flow is directly correlated with the degree of disturbance in the thermal boundary layer (TH-BL). The maximum enhancements in Nusselt number and friction factor due to XVB installation are 7.24 and 58.01 times greater, respectively, compared to a smooth tube without XVBs. The maximum thermal enhancement factor (TEF) achieved is 2.27, obtained from the case with the Type T XVB at a blockage ratio of g/D = 0.05, a pitch ratio of P/D = 1, and a flow direction in the FD-VD configuration.
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Numerical Study of Turbulent Forced Convection in a Square Duct with Discrete X-V Inducing Turbulators (DXVIT)
(2025-04-01)
Boonloi, Amnart
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Jedsadaratanachai, Withada
This research is an extension study that applies a vortex generator previously developed and tested under laminar flow conditions to investigate its performance under turbulent flow conditions, covering the operating range of various heat exchanger systems. This type of vortex generator is called the discrete X-V inducing turbulator (DXVIT), which is derived from the V-baffle, known for its high heat transfer enhancement efficiency, combined with the structure of an orifice that provides durability and stability when installed in heat exchanger systems. The DXVIT is installed to modify the primary flow structure and disrupt the thermal boundary layer (ThBL), resulting in an increase in the convective heat transfer coefficient. This study examines the effects of DXVIT size, installation spacing, flow direction, and DXVIT type on the heat transfer and flow behavior under turbulent flow conditions with Reynolds numbers ranging from 3000 to 16,000. The investigation is conducted using numerical simulation methods. The results are presented in terms of flow and heat transfer behavior, along with an analysis of thermal performance using dimensionless parameters. The findings indicate that the heat transfer rate increases up to 5.29 times, and the thermal performance factor reaches 2.65 under the same pumping power conditions.
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Numerical investigations on flow structure and heat transfer in a square duct equipped with double V-orifice
(2020-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
Numerical predictions on heat transfer characteristic, flow topology and thermal performance assessment in a square duct are presented. The passive technique, insertion of the vortex generator, is opted to develop the heat transfer rate in the square duct heat exchanger. The vortex generator of the present research is Double V-Orifice (DVO). The square duct equipped with DVO is tested with various parameters. The influences of DVO height, b, to the duct height, H, or b/H, gap spacing between the outer edge of the orifice and the duct wall, s, to the duct height or s/H and flow directions (tip-pointing-Downstream and tip-pointing-Upstream) on flow pattern and heat transfer profile are considered for laminar flow regime with similar pitch, P, to duct height or P/H of 1. The Reynolds number, Re, based on the hydraulic diameter, D<inf>h</inf>, of the square duct around 100 – 2000 is discussed. The numerical model is solved with the commercial software (finite volume method). As the numerical result, the square duct inserted with the DVO offers greater Nusselt number, Nu, than the plain duct around 1.00 – 14.80 times. The maximum thermal enhancement factor, TEF, for the square duct inserted with the DVO is found to be about 3.60 depended on s/H, b/H and flow direction. The flow and heat transfer profiles in the square duct inserted with the DVO are also illustrated.
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IMPACT OF THREE DIFFERENT DOUBLE BAFFLE DESIGNS ON THE THERMAL PERFORMANCE OF SQUARE DUCTS
(2022-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
CFD analyses of flow characteristics and heat transfer topology in a heat exchanger duct (HXD) placed with three various configurations of the double V-baffles (DVB) are reported. Parameters of interest are DVB height ratios (b/H = 0.05 – 0.25), gap spacing ratios (g = 0.05 – 0.40), flow directions (+x,-x), and DVB configurations (Type I, II and III). Laminar flow with Reynolds numbers (based on the inlet conditions) between 100 – 2000 is measured. The present problem is solved with the finite volume method (a commercial program). Fluid flow and heat transfer characteristics in the tested duct are described. Thermal assessments of the tested duct are also presented. Simulation results showed that the installation of the DVB in the HXD results in higher heat transfer rate due to the creation of the vortex flow and the disturbance of the thermal boundary layer (TBL). Different flow structures and heat transfer behavior are observed when gap spacing ratios, flow directions and DVB shapes are changed. In addition, the type II DVB provides the highest TEF of 3.55 at b/H = 0.10, g/H = 0.25 for the-x flow direction.
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Numerical Investigations of Laminar Air Flow and Heat Transfer Characteristics in a Square Channel Inserted with Discrete X-V Baffles (XVB)
(2023-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
Thermal performance enhancement in a square channel heat exchanger (HX) using a passive technique is presented. Vortex turbulator insertion in a square channel HX as a passive technique is selected for thermal improvement. The vortex turbulator of interest is discrete X-V baffles (XVB). The discrete XVBs are inserted in the square channel with the main aim of generating vortex flow. The vortex flow generated can support the enhanced convective heat transfer coefficient and also enhance HX performance. Effects of baffle configuration (type A and B),bafflesize(w/H= 0.05, 0.10, 0.15 and 0.20), baffle distance (e/H = 1, 1.5 and 2) and flow direction (±xairflow paths) on fluid flow and thermal topologies are numerically investigated by using a commercial code. As shown by the numerical results, the predicted flow configuration with the discrete XVB insertions, which include impinging and vortex streams, is found through the HX channel. The perturbing thermal boundary layer and greater air blending are also found through the HX channel inserted with the discrete XVB. These mechanisms promote and augment the convection heat transfer coefficient, heat transfer rate and rise thermal potentiality. The maximum Nusselt number of the channel with the baffles inserted is 11.01 times upper than that of the smooth channel, while the greatest thermal performance factor (TPF) is observed to be around 3.45.
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Investigations of Air-Flow Configuration, Heat Transfer Behavior and Thermal Performance in Heat Exchangers with XVB-Type Turbulence Generators Under Turbulent Flow Conditions
(2025-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
This study employs numerical modeling using the finite volume method to analyze airflow and thermal structures when vortex flow (VTF) generators are installed in heat exchanger square ducts (HX-SD). The VTF generator used in this study is the X-V baffle (XVB), which is designed to enhance heat transfer rates. The XVB is an evolution of the V-baffle, a type of VTF generator known for its efficiency in improving heat transfer. It features an X-shaped structure (considered in the cross-sectional (CS) plane, y-z plane) to further optimize the design. The present research investigates the effects of XVB thickness, represented by the thickness ratio (b) to the HX-SD height (H) or hydraulic diameter (Dh) (b/H), with B-R values ranging from 0.05 to 0.20. Additionally, three XVB configurations (Types A, B, and C) are examined, along with two airflow directions: AFD-VD (airflow direction – V-Downstream) and AFD-VU (airflow direction – V-Upstream). The investigation focuses on turbulent flow conditions, analyzing air velocity within a Reynolds number range of Re = 3,000 to 16,000. The results indicate that VTF is generated throughout the HX-SD due to the pressure difference caused by flow obstruction from the XVB in all cases examined. By enhancing air mixing and disrupting the thermal boundary layer (Th-BL), the induced VTF significantly increases the heat transfer rate. The maximum observed increase in heat transfer was 7.95 times higher than that of a smooth, empty duct.
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Three-Direction Type of Diffuser-Shaped Vortex Generator Development for the Wind Solar Tower
(2025-01-01)
Sudsanguan, Anan
;
Boonloi, Amnart
;
Jedsadaratanachai, Withada
This study explored the use of diffuser shapes to enhance the performance of a solar updraft tower. A diffuser-shaped vortex generator, a simple device requiring no structural modifications to the tower, was installed at the chimney outlet. The generator transformed crosswind into a vortex, increasing the updraft velocity. This study employed finite element methods and numerical models to validate the results alongside physical experiments. Both approaches focused on the crosswind velocity and vortex generator height to determine an optimal semi-opening angle for the diffuser shape. The experimental results revealed that an 8° diffuser-shaped vortex generator with a height of h<inf>vg</inf> = 2D achieved the greatest updraft enhancement, increasing the speed by 86.89% compared to the prototype tower. The enhancement was found to increase proportionally with the generator’s angle and height.
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Heat Transfer Potentiality and Flow Behavior in a Square Duct Fitted with Double-Inclined Baffles: A Numerical Analysis
(2021-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
Numerical analysis of heat transfer mechanisms and flow topologies for the heat exchanger square channel (HESC) installed with the double-inclined baffles (DIB) is reported. The main objective of the present research is to study the influences of DIB height to duct height (b/H=0.05-0.30), DIB distance to duct height (P/H=1-1.5), and flow attack angle (α=30° and 45°) on the flow topologies, heat transfer features, and thermal performances. The Reynolds numbers (based on the entry HESC around 100-2000) are analyzed for the present problem. The numerical models of the HESC installed with the DIB are solved with finite volume method (commercial code). The simulated results of the HESC installed with the DIB are reported in forms of flow topologies and heat transfer characteristics. The Nusselt numbers (Nu), friction factors (f), and thermal enhancement factors (TEF) of the HESC placed with the DIB are offered. As the numerical results, it is seen that the DIB produces the vortex streams and impinging streams in all cases. The vortex streams and impinging streams disturb the thermal boundary layer on the HESC walls that is a key motive for the growth of heat transfer rate. The best TEF of the HESC installed with the DIB is about 3.87 at P/H=1, α=30°, Re=2000, and b/H=0.15. Additionally, the TEF contours, which help to design the HESC inserted with the DIB, are performed.
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3D-numerical predictions of flow structure and heat transfer behavior in heat exchanger tubes inserted with different patterns of double-V baffles
(2022-11-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
3D-simulation of convective heat transfer and laminar flows at an isothermal wall of a circular tube heat exchanger (CTHE) inserted with different configurations of double-V baffles (DVB) are presented. The insertion of DVB is done with the objective to produce vortex flows and impinging flows to perturb the thermal boundary layer (TBL) over the isothermal wall, thus increasing convective heat transfer coefficient and efficiency. Various DVB parameters which contribute to the best thermal efficiency are considered. Effects of six DVB shapes (Type A-F), DVB height (b/D = 0.05-0.30) and flow directions (+x, -x) on air stream and thermal mechanisms with Reynolds number within 100-2000 (calculated with the inlet condition) are compared. Simulation results of flow structure (streamline structures in transverse planes) and heat transfer characteristics (fluid temperature distributions and local Nusselt number (Nux) contours) are reported. Insights into the flow pattern and heat transfer are key to improve heating and cooling system performance. The improvement of the CTHE inserted with the DVB is presented in terms of the Nusselt number (Nu) and the thermal enhancement factor (TEF), while the pressure loss is presented by the friction factor (f). Simulation results show that the DVB creates vortex and impinging flow over the surface of the circular tubes in the CTHE of all investigated tests. The best TEF and the best Nusselt number ratio are 3.55 and 22.42, respectively.

Jedsadaratanachai, Withada

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