Jedsadaratanachai, Withada

Preferred name

Alternative Name

Jedsadaratanachai, W.

Main Affiliation

School of Engineering

withada.je@kmitl.ac.th

Now showing 1 - 5 of 5

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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
;
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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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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Enhancing convective heat transfer coefficient in a circular heat exchanger tube mounted with modified V-orifice (MVO): CFD analysis and correlations
(2026-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
This study investigates the airflow dynamics and heat transfer (HT) profiles in a circular heat exchanger tube (CHET) mounted with a modified V-orifice (MVO) acting as a turbulator/vortex generator, which is a passive technique to enhance HT. A numerical modeling approach based on the finite volume method using a commercial software package was employed to provide detailed insights into the air flow profile, which is essential for the design of both the turbulator and the CHET system. The MVO is a turbulator derived from the orifice concept, an established engineering device, and has been adapted in combination with a V-shaped structure to effectively generate vortices and enhance HT. Key parameters expected to influence the flow and HT behavior were investigated. These include the ratio of the MVO thickness, b, to the CHET diameter, D (referred to as the blockage ratio, B-R), which was studied in the range of 0.05–0.30, and the ratio of the MVO spacing, P, to the CHET diameter (pitch ratio, P-R), which was considered at values of 1, 1.5, and 2. Attack angles of 30°, 45°, and 60° were examined for both + x and–x flow directions. The study covered turbulent flow conditions corresponding to Reynolds numbers in the range of 3,000–16000, representative of the operating conditions at the CHET inlet. The results indicate that MVO installation in the CHET acts as a flow obstruction, generating a pressure difference that induces vortex formation. These vortices play a key role in modifying the HT behavior, resulting in increased convective HT coefficients. The outcomes are summarized in forms of dimensionless variables. The highest observed HT enhancement reached 9.93 times that of the plain CHET, while the maximum thermal enhancement factor (TEF) was 1.92, obtained at an attack angle of 30°, P-R = 1, B-R = 0.25, in the +x fluid-flow direction at Re = 3,000.
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Investigations of thermal behavior, flow structure, and performance in a circular tube heat exchanger fitted with diamond-shaped orifice (DSO): a CFD assessment
(2025-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
This study numerically investigates the enhancement of heat exchanger performance using a passive technique based on vortex generation. The proposed enhancement device, termed a diamond-shaped orifice (DSO), is a modified configuration that combines a conventional orifice plate with a conical ring. The DSO is inserted into a circular tube to modify the flow structure and induce strong vortices, thereby promoting convective heat transfer and improving the overall thermal performance. The effects of key geometric parameters, including the attack angle (α = 20°, 30°, and 45°), flow blockage ratio (FBR = 0.05–0.30), and pitch ratio (PRT = 1–2), are systematically examined under turbulent airflow conditions with Reynolds numbers ranging from 3,000 to 20,000. The results reveal that incorporating the DSO generates intense swirling flow, which effectively disrupts the thermal boundary layer and enhances the convective heat transfer coefficient. The maximum Nusselt number improvement reached 7.16 times that of a plain tube, while the highest thermal enhancement factor (TEF) attained was 1.77, indicating a substantial improvement in heat exchanger performance without additional active energy input.

Jedsadaratanachai, Withada

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