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Author: search.filters.author.Jedsadaratanachai, WithadaSubject: search.filters.subject.Square duct

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    CFD analysis on heat transfer characteristics and fluid flow structure in a square duct with modified wavy baffles
    (2022-01-01)
    Boonloi, Amnart
    ;
    Jedsadaratanachai, Withada
    Performance assessments, and flow and heat transfer patterns of a square duct attached with different six types of modified wavy baffles are presented. The influences of fluid blockage ratios or baffle heights (b = 0.05H–0.30H), flow directions (+x and -x) and baffle shapes (A – F) on augmented Nusselt number and fluid flow mechanisms are numerically studied for the laminar flow of the Reynolds number in a range of 100–2000. The simulated problem is solved with the finite volume method (commercial program) using the Semi-Implicit Method for Pressure-Linked Equations (SIMPLE algorithm). The mechanisms (streamlines across the cross-sectional planes, temperature contours, Nusselt number contours) of the tested duct are focused. From the simulated results, the vortex flows are observed to be the main point for the heat transfer increment for all investigated cases. Over the investigated range, the greatest Nusselt number is found to be around 20.10 times higher than that of the plain duct. The maximum TEF of 3.70 is shown at b = 0.10H of the type D modified wavy baffle with the +x flow direction.
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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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    Heat transfer improvement in a square duct with diagonal inclined ribs
    (2014-01-01)
    Suwannapan, Supattarachai
    ;
    Poomsalood, Ratsak
    ;
    Promvonge, Pongjet
    ;
    Jedsadaratanachai, Withada
    ;
    Limkul, Thitipat
    This research presents a numerical study of turbulent periodic flow and heat transfer in three-dimensional isothermal-fluxed square duct with diagonal inclined rib inserted. The fluid flow and heat transfer characteristics are presented for Reynolds numbers in the range of 4000 to 20,000. The computations based on the finite volume method, and the SIMPLE algorithm has been implemented. Effects of rib pitch ratios (0.5 to 2) at a single blockage ratio of 0.2 and attack angle of 60° on heat transfer and friction factor in the duct are examined and their results of the inclined rib are also compared with those of the smooth duct. It is found that the inclined rib provides higher heat transfer rate and friction factor than the smooth duct for all cases. In addition, the decreasing of the pitch ratio leads to the rise in the Nusselt number and friction factor. © (2014) Trans Tech Publications, Switzerland.