Jedsadaratanachai, Withada

Preferred name

Alternative Name

Jedsadaratanachai, W.

Main Affiliation

School of Engineering

withada.je@kmitl.ac.th

Now showing 1 - 10 of 14

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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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3D numerical investigation on laminar forced convection and heat transfer in a circular tube inserted with right triangular wavy surfaces
(2017-01-01)
Jedsadaratanachai, Withada
;
Boonloi, Amnart
Numerical investigations on flow and heat transfer characteristics in a circular tube heat exchanger inserted with right triangular wavy surfaces are reported. The configurations of the wavy surfaces; incline and V-shape, are studied with flow attack angles of 30°, 45° and 60° for the Reynolds numbers, Re = 100-2000. The numerical results are compared with the smooth circular tube. The mechanisms on flow and heat transfer in the tube heat exchanger with the wavy surface are presented. As the results, the wavy surface can generate the vortex flow and impinging flow through the test section that helps to improve the heat transfer rate and thermal performance. The impingement of the flow on the tube wall disturbs the thermal boundary layer that is an important factor to enhance the heat transfer rate. The V-Downstream wavy surface can create the highest strength of the impinging flow that leads to the highest heat transfer rate. In the range investigate, the augmentations are around 1.2-7.6 and 4-43.6 times above the smooth tube for the heat transfer and friction loss, respectively. In addition, the optimum thermal enhancement factor, TEF, is around 2.42 for the V-Downstream wavy surface at α = 30° and Re = 2000.
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Effect of location in transverse plane for 45-degree V-baffle on flow and heat transfer mechanisms in a square channel
(2018-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
Numerical predictions on flow and heat transfer in a square channel heat exchanger placed with V-baffle are examined. The gap spacing between the V-baffle and channel wall is varied for all baffle heights. The laminar regime with Re = 100 - 1000 is considered. The numerical model for the square channel heat exchanger placed with V-baffle is validated. The preliminary result reveals that the computational domain has reliability to predict flow and heat transfer in the channel. The mechanisms on flow and heat transfer in the heat exchanger channel are illustrated at the numerical result section. The thermal performance analysis of the heating section when inserted with the V-baffle is also reported in forms of the Nusselt number ratio (Nu/Nu0 or NuR), friction factor ratio (f/f0 or fR) and thermal enhancement factor (TEF). As the results, it is found the gap spacing has extremely effect for flow structure and heat transfer behavior in the test section. The optimum gap spacing ratio may help to reduce the pressure loss or improves the heat transfer rate in the channel heat exchanger. The selection for the gap spacing ratio in the heating section at various baffle heights is also concluded. In addition, the gap spacing ratio around 5 - 10% is suggested for the range investigation.
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Effects of blockage ratio and pitch ratio on thermal performance in a square channel with 30° double V-baffles
(2014-11-01)
Jedsadaratanachai, Withada
;
Boonloi, Amnart
This article presents flow configurations and heat transfer characteristics in an isothermal square channel with 301 double V-baffles. The influences of blockage ratios (b/H, BR=0.05-0.25) and pitch ratios (L/H, PR=1-2) for Reynold numbers, Re=100-1200 are investigated numerically. The 30° double V-baffles are placed on both two opposite walls of the square channel with in-line arrangement and each V-tip pointing downstream. The numerical results are presented in four parts; accuracy validations, flow structures, heat transfer behaviors and performance evaluations. It is found that the use of the double V-baffles performs higher heat transfer rate and pressure loss than the smooth channel with no baffle. The rise of the blockage ratio and reducing the pitch ratio lead to the increase in heat transfer rate and pressure loss. The optimum thermal enhancement factor is found to be about 3.2 at PR=1, BR=0.10 and Re=1200.
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3D simulation on flow behavior and heat transfer in a circular tube with inclined different arrangement of thin rib
(2013-01-28)
Boonloi, Amnart
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Jedsadaratanachai, Withada
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Promvonge, Pongjet
This work deals with periodic flow, friction loss and heat transfer characteristics in a constant temperature-surfaced circular tube fitted with rib vortex generators (RVG). The computations are based on the finite volume method with the SIMPLE algorithm implemented. The fluid flow and heat transfer behaviors are presented for Reynolds numbers ranging from 100 to 1000. To generate two main vortex flows through the tested section, the 45<sup>o</sup> RVGs are mounted repeatedly in in-line arrangements on the top and bottom walls and in the central area of the tested section. Effects of different RVG heights, BR in a range from 0.1D to 0.3D with a single pitch of 1.5D on heat transfer and friction losses in the test section are examined. It is apparent that the vortex flows created by the RVG exist and help to induce periodically impinging flows on a sidewall leading to drastic increase in the heat transfer rate over the test section. The computational results reveal that the optimum thermal performance is about 2.38 for using the RVG height of 0.2D for the RVG placed on the tube walls at the highest Re value. © (2013) Trans Tech Publications, Switzerland.
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Numerical investigation on turbulent forced convection in heating channel inserted with discrete V-shaped baffles
(2016-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
The numerical examinations on flow visualization, heat transfer characteristic and performance improvement in a square duct inserted with discrete V-shaped baffles (DVB) are reported. The DVB is designed to reduce the pressure loss when compared with the V-shaped baffle. The influences of the flow blockage ratios (b/H, BR = 0.05-0.20), V-tip directions (V-Downstream and V-Upstream) are investigated for Reynolds number, Re = 3000-20,000, with a single pitch ratio and flow attack angle of 1 and 30°, respectively. As the results, the DVB can generate the vortex flow and impinging flow through the test section that assists to develop the thermal efficiency. The augmentations on the heat transfer coefficient and pressure drop are around 2.5-5.75 and 4-22.5 times above the smooth duct, respectively. The best thermal efficiency in forms of thermal enhancement factor, TEF, around 2.32 is detected at Re = 3000, BR = 0.10 and V-Upstream.
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EFFECTS OF BLOCKAGE LOCATIONS FOR ENHANCED HEAT TRANSFER AND FLOW VISUALIZATION IN A TESTED DUCT WITH DUAL-INCLINED BAFFLES (DIB): A CFD ANALYSIS
(2022-01-01)
Boonloi, Amnart
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Jedsadaratanachai, Withada
Numerical analysis of fluid flow mechanism and heat transfer in a heat exchanger duct (HXD) with dual-inclined baffles (DIB) are reported. Three DIB types are examined: 1. “Type A” is located at the center of the HXD, 2. “Type B” is located on the upper-lower duct walls (as an orifice) and 3. “Type C” is a combination of the type A and B (as double orifices). The impacts of the ratio of DIB heights (b) to the square duct height (H; b/H) on increased heat transfer and friction loss are analyzed. Laminar flow (Re = 100 – 2000 based on the entry condition of the tested duct) is discussed. The simulated problems of the HXD equipped with various DIB types are analyzed by a commercial code (the finite volume method). To confirm accuracy results, the simulated domain of the HXD with the DIB is validated (optimum grid check and smooth duct validation). The simulated solutions are illustrated in terms of heat transfer and flow features. The performance assessments of the HXD with different DIB types are also presented in terms of thermal enhancement factor, Nusselt number and friction factor. It is interesting that the changed DIB position at an identical flow-blockage-ratio leads to the changed flow structure that impacts the variations of both the Nusselt number and pressure drop of the HXD. It is found that type C DIB provides the greatest thermal potentiality. The heat transfer rate of the HXD equipped with type A, B and C DIB is 1.38 – 13.93, 1.00 – 14.19 and 1.31– 14.45 times higher than that of the smooth duct, respectively, depending on the DIB height and Reynolds number. Additionally, the best thermal enhancement factor (TEF) of 4.04 is found for the HXD with the type C DIB at b<inf>1</inf>/H = 0.05 and b<inf>2</inf>/H = 0.15 at Re = 2000.
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Influence of ring size and location on flow topology, heat transfer structure and thermal efficiency in heat exchanger square channel placed with 30-degree inclined square ring
(2019-01-01)
Boonloi, Amnart
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Jedsadaratanachai, Withada
This paper presents the numerical investigations (finite volume method with SIMPLE algorithm) on flow structure, heat transfer behavior and performance assessment in heat exchanger square channel placed with 30<sup>o</sup> inclined square ring (ISR). The influences of ring size and placement on flow and heat transfer characteristics are considered for laminar flow region with the Reynolds number in the range around 100 – 2000. The purpose for the insertion of the ISR in the square channel is to induce the vortex flow and also increase the turbulent mixing. The numerical result reveals that the ring size and location have effects for the changes of the flow and heat transfer behaviors in the tested section. The present of the ISR in the tested section gives the maximum heat transfer rate around 8.13 times above the smooth square channel. In addition, the optimum thermal performance at similar pumping power or TEF is around 3.10.
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3D numerical study on laminar forced convection in V-baffled square channel
(2013-10-10)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
The article presents a mathematical study of fully developed periodic laminar flow visualization and heat transfer characteristics in an isothermal wall square-channel fitted with V-shaped baffles on one wall. The computations based on the finite volume method together with the SIMPLE algorithm have been performed. The investigation covers a range of Re based on the hydraulic diameter of the channel, Re = 100-1200. To create a pair of main streamwise vortex flows through the tested section, the V-baffles with the attack angle of 30° with the main flow direction are mounted in tandem and pointing downstream on the lower channel wall only. Effects of different baffle heights and pitches on heat transfer and pressure drop in the channel are examined and the results obtained are compared with smooth channel with no baffle. The numerical result shows that the presence of the V-baffle yields a significant heat transfer enhancement compared with the smooth channel. It is visible that the main vortex flows, a pair of streamwise twisted vortex (P-vortex) can induce impingement flows on the walls leading to a drastic increase in heat transfer rate over the channel. In addition, the increase in the baffle height leads to the rise in the heat transfer and pressure loss while that in the baffle pitch provides the opposite trend. The predicted results expose that the maximum thermal enhancement factors for the V-baffles with BR = 0.3, 0.3 and 0.4; and PR = 1, 1.5 and 2 are, respectively, about 2.44, 2.29 and 2.37 at higher Re. © 2013 Science Publication.
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Thermal performance improvement in a square channel heat exchanger with various parameters of V-wavy plates
(2019-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
Numerical examinations on flow and heat transfer behaviors in a square channel heat exchanger equipped with various configurations of V-wavy plate are performed. The pitch-to-channel height ratios, wavy height-to-channel height ratios and flow directions of the test section are investigated for the Reynolds number in the range of 100 – 1000 (laminar flow regime). The finite volume method is selected for the present investigation. The results are reported in terms of flow and heat transfer mechanisms in the channel. The thermal performance assessments of the square channel fitted with the V-wavy plate are also concluded. As the numerical results, the V-wavy plate can produce the swirling flow through the heating channel. The swirling flow disturbs the thermal boundary layer on the heat transfer surface that leads to enhance heat transfer rate and thermal efficiency.

Jedsadaratanachai, Withada

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