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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Numerical assessments of flow pattern and heat transfer profile for the round tube equipped with different configurations of the dual-inclined baffle
(2021-10-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
Numerical studies of the heat exchanger tube (HXT) equipped with the dual-inclined baffle (DIB) on fluid streams and heat transfer profiles are reported. The DIB configurations can be separated into three types: 1. The DIB is inserted in the middle of the HXT called “type I″, 2. The DIB is placed on the HXT wall called “type II” and 3. The combination of the type I and II DIB called “type III”. The three DIB types are designed with the main purpose to create three different flow profiles. The influences of DIB height with a single pitch distance (P/D = 1) and DIB attack angle of 30° for heat transfer characteristics and fluid streams are discussed in a laminar flow region at Re = 100–2000 (considered at the entry condition). The numerical problem of the HXT inserted with the DIB is solved with a commercial code (the finite volume method). The computation domain is validated to confirm the reliability and accuracy of the simulated results. The flow configurations: streamlines in transverse planes (y-z planes), and heat transfer behaviors: temperature contours in transverse planes (y-z planes) and local Nusselt number contours (Nu<inf>x</inf>), in the HXT equipped with the DIB are proposed in the simulated-result section. The relations of the average Nusselt number ratio (Nu/Nu<inf>0</inf>), friction factor ratio (f/f<inf>0</inf>) and thermal enhancement factor (TEF) with the Reynolds numbers in the HXT inserted with the DIB are presented. As the simulated results, the equipment of the DIB in the HXT brings upper heat transfer rate and thermal performance than those of the smooth tube because of the creations of the vortex streams and impinging streams. The different flow profiles are detected when varying the DIB types that impact for the variations of the heat transfer profile. For the studied range, the increased heat transfer rate in the HXT installed with the DIB is observed to be around 1.03–17.46 times above the plain tube depended on the DIB type, DIB blockage and Reynolds number. Additionally, the maximal TEF of 3.70 is found for the type II DIB at b/D = 0.25 and Re = 2000.
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Performance improvement in a heat exchanger tube using discrete X–V baffle (DXVB) turbulators
(2024-02-01)
Boonloi, Amnart
;
Lewpiriyawong, Nuttawut
;
Jedsadaratanachai, Withada
Thermal performance improvement in a heating tube (HT) using discrete X–V baffle (DXVB) as turbulators is presented. The DXVB is designed with three main goals: 1. To decrease the pressure drop in the tested tube and 2. To increase the mixing quality in the heat exchanger tube and 3. To produce powerful vortex flows. Lower pressure drop, generated vortex flows and higher mixing quality will augment a heat transfer rate and thermo-hydraulic efficiency. This study examines effects of DXVB structures, DXVB distances and placements on laminar air flow and thermal structure with Reynolds number from 100 to 2000. The current problem is numerically investigated using the finite volume technique of a commercial program/code (ANSYS-FLUENT V.2022). The created model of the HT fitted with the DXVB is numerically validated. From the numerical results, the DXVB installed affects the air flow structure in the tested tube. The vortex streams are observed. The change in fluid flow influences thermal characteristics. The vortex streams destroy some parts of the thermal boundary layer and help to increase mixing quality. These perturbed thermal boundary layer (TB-layer) and better mixing quality are two important factors that contribute to convective heat transfer enhancement. In addition, the maximum heat transfer rate and pressure loss are 10.17 and 45.75 times upper than that in the circular plain tube, respectively, while the best thermal enhancement factor (TEF) of 3.09 is observed at 15b5g, +x at Re = 2000.
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Investigations on thermal profiles and flow structures in a square channel equipped with staggered vortex turbulators
(2024-09-01)
Boonloi, Amnart
;
Lewpiriyawong, Nuttawut
;
Jedsadaratanachai, Withada
Given the escalating energy demands today, improving the efficiency of engineering equipment is crucial for optimizing energy use. This study focuses on enhancing heat exchanger performance through passive methods, particularly by installing vortex turbulators. Passive techniques can effectively manage energy costs while enhancing efficiency. The research examines thermal profiles and airflow structures within a square channel heat exchanger (SCHE) equipped with staggered vortex turbulators (SVTs). SVTs feature a unique design combining rectangular winglets and V-pattern baffles. The installation of SVTs aims to intensify vortex strength, thereby increasing SCHE efficiency, convective heat transfer coefficients, and overall heat transfer potential. The study investigates the effects of SVT dimensions (b<inf>1</inf>/H and b<inf>2</inf>/H), airflow directions (+x and -x), installation patterns (pattern no. 1 and 2), pitch to height ratios (P/H = 1, 1.5, and 2), and flow attack angles (α = 20°, 30°, and 45°). Computational simulations using the finite volume method with a commercial code (FLUENT) under laminar flow conditions (Reynolds number of 100–2000) provide insights into thermal profiles, fluid temperature distributions, and flow configurations within the SCHE. Staggered arrangement and gap spacing are employed to reduce pressure loss and enhance airflow strength. The results highlight flow structures and heat transfer characteristics in the heat exchanger channels, elucidating the underlying mechanisms of the heat exchange process. Understanding these behaviors is crucial for developing more efficient heat exchangers and vortex generators in the future. Simulation findings demonstrate that SVTs significantly enhance convective heat transfer over smooth channels due to increased vortex strength. Notably, pattern no. 2 SVTs (b<inf>1</inf>/H = b<inf>2</inf>/H = 0.20) achieve the highest Nu/Nu<inf>0</inf> of 19.21 in the +x flow direction at Re = 2000, α = 30°, and P/H = 1. In conclusion, the study identifies a maximum thermal enhancement factor of 4.38. It underscores the potential of pattern no. 2 SVTs for optimizing heat exchanger performance, offering valuable insights for future developments in thermal management technologies.
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Thermal performance assessment in a circular tube fitted with various sizes of modified v-baffles: A numerical investigation
(2021-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
This research reports numerical examinations on fluid flow, heat transfer behavior and thermal performance analysis in a circular tube equipped with modified V-baffles (CTMVB). The modified V-baffle (MVB) is a combination vortex generator between V-baffles/V-orifices which are placed on the tube wall and V-baffles which are inserted at the core of the tested tube. The MVB height is separated into two parts; b1 represents the MVB height on the tube wall, while b2 represents the MVB height at the core of the tested round tube. The MVB height to tube diameter ratios, b/D, are adjusted; b1/D = 0.05, 0.1, 0.15 and 0.2, and b2/D = 0.025, 0.05, 0.075 and 0.1. The Reynolds numbers of about 100 – 2000 (laminar regime) are considered. The flow directions in the tested section; V-tip directing downstream and V-tip directing upstream, are discussed. The flow attack angles for the MVB, α, of about 20<sup>o</sup> and 30<sup>o</sup> are compared. The finite volume method with SIMPLE algorithm (a commercial code) is opted to analyze the present investigation. The computational domain of the CTMVB is validated (grid independence and smooth tube validations). It is found that the MVB generates many vortex cores in the tested section. The vortex flows near the tube wall disrupt thermal boundary layer, while the vortex flows at the center of the tube help superior fluid blending. The disturbed thermal boundary layer and the better fluid blending are main two causes for heat transfer augmentation. In addition, the best thermal enhancement factor of the CTMVB is found to be around 3.92.
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Numerical predictions of flow topology and heat transfer in a square duct with staggered V-ribs
(2022-12-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
Performance augmentation of a square duct heat exchanger by a passive technique is numerically investigated. V-pattern ribs are used as vortex turbulators to enhance heat exchanger performance. The V-rib arrangement is designed with two important factors: 1. to increase the heat transfer coefficient by disturbing thermal boundary layers and to expedite fluid mixing and 2. to remain or decline the friction loss across the ribbed duct when compared with a typical in-line V-rib arrangement. The effects of rib heights (b/H = 0.05–0.20), rib pitch (P/H = 1–2) and flow paths (+x and -x) on fluid structure and thermal characteristics are studied within a laminar flow regime. Numerical analysis using the finite volume method (FVM) is chosen to predict the fluid structure and thermal mechanisms within the ribbed duct. Validating topics: smooth duct validation and grid independence, are firstly investigated. Simulation results are analyzed in forms of fluid structure and thermal behaviors. Performance assessment (thermal enhancement factor, friction factor ratio and Nusselt number ratio) within the tested section are also concluded. The simulation results show that the best TEF is found to be around 4.5, while the maximum Nusselt number ratio is around 19.39.

Jedsadaratanachai, Withada

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