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Author: search.filters.author.Jedsadaratanachai, WithadaSubject: search.filters.subject.Pressure drop

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    HEAT TRANSFER AND FLOW PROFILES IN ROUND TUBE HEAT EXCHANGER EQUIPPED WITH VARIOUS V-RINGS
    (2022-01-01)
    Boonloi, Amnart
    ;
    Jedsadaratanachai, Withada
    This study numerically investigates pressure loss, heat transfer and thermal efficiency in round tube heat exchangers attached with various types of V-rings. A typical type A V-ring is compared with two types of modified V-rings (type B and C). The impacts of blockage ratios, b/D = 0.05, 0.10, 0.15 and 0.20 for all V-ring types in the turbulent region are discussed (Re = 3000 – 20,000). Flow directions in the round pipe attached with the V-rings are varied. The V-apex setting downstream is referred to as “V-Downstream, while the V-apex setting upstream is referred to as “V-Upstream”. The flow and heat transfer profiles in the tested section are analyzed using the finite volume method (a commercial code with the SIMPLE algorithm). The thermal performance of the tested tube is measured in terms of dimensionless variables: thermal enhancement factor (TEF), Nusselt number (Nu) and friction factor (f). Numerical results reveal that type B and C V-rings can reduce pressure drop compared with type A V-ring. Additionally, the V-Upstream of type C V-ring yields the maximum TEF of 3.10 at b/D = 0.05.
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    Numerical investigation on turbulent forced convection and heat transfer characteristic in spirally semicircle-grooved tube
    (2016-12-01)
    Promthaisong, Pitak
    ;
    Boonloi, Amnart
    ;
    Jedsadaratanachai, Withada
    Turbulent forced convection and heat transfer structure in the spirally semicircle-grooved tube heat exchanger are numerically examined. The computational problem is solved by finite volume method (FVM) with the SIMPLE algorithm. The influences of groove depth and helical pitch on heat transfer, pressure loss, and thermal performance are investigated for turbulent regime, Re = 5000–20,000. As a result, the swirling flow is found through the test section due to the groove on the tube wall. The flow structure in the spirally semicircle-grooved tube can separate into two types: main and secondary swirling flows. The main swirling flow is found in all cases, while the secondary swirling flow is detected when DR ≥ 0.06. The swirling flow disturbs the thermal boundary layer on the tube wall that is an important reason for heat transfer augmentation. In range studies, the enhancements on heat transfer and friction loss are around 1.16–1.96 and 1.2–10.8 time above the smooth tube, respectively. The optimum thermal performance is around 1.11, which detected at DR = 0.06, PR =1.4,andRe = 5000. The correlations of the Nusselt number and friction factor for the spirally semicircle-grooved tube with PR =1.4 are produced to help to design the tube heat exchanger.