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THERMAL PERFORMANCE ASSESSMENT IN A CIRCULAR TUBE FITTED WITH VARIOUS SIZES OF MODIFIED V-BAFFLE: A NUMERICAL INVESTIGATION

Amnart Boonloi, Withada Jedsadaratanachai
Frontiers in Heat and Mass Transfer (FHMT) 16 - 17 (2021)


Abstract


This research reports numerical examinations on fluid flow, heat transfer behavior and thermal performance analysis in a circular tube interjected with the modified V-baffle (CTMVB). The modified V-baffle (MVB) is the combination vortex generator between the V-baffle that placed on the tube wall (or V-orifice) and the V-baffle which interjected at the core of the tested section. The MVB size is presented in terms of blockage ratio. The MVB height is separated into two parts; b1 represents the height of the baffle on the tube wall, while b2 represents the height of the baffle at the core of the tested round tube. The baffle height to the round tube diameter, 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 for the present research. 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 20o and 30o are opted for the current research. The finite volume method with SIMPLE algorithm (commercial code) is opted to analyze the present investigation. The computational domain of the CTMVB is validated (grid independence and validation of the smooth tube). It is found that the MVB generates many vortex cores in the tested section. The vortex flow near the tube wall disrupts the thermal boundary layer, while the vortex flow at the center of the tube helps to a superior fluid blending that the motive for heat transfer augmentation. In addition, the thermal enhancement factor of the CTMVB is found to be around 3.92. The thermal performance analysis and mechanisms both flow and heat transfer of the tested tube are also concluded.


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DOI: http://dx.doi.org/10.5098/hmt.16.17

ISSN: 2151-8629