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TheyĪnalyzed the results from the view of field synergy principle Of the channel was presented by Wu and Tao. Pair of rectangular winglets VGs punched out from the wall Heat transfer performance of a rectangular channel with a Heat exchanger with dye-injection visualization was reportedīy Wang et al. The investigation on the effect ofĪnnular and delta winglet vortex generators in fin-and-tube Tube on heat transfer and flow structure for both in-line and Investigated punched winglets vortex generators in an oval numericallyĭownloaded from by guest on July 3, 2016 claimed that the main vortex,Ī corner vortex, and induced vortices appeared behind a On flow structure and heat transfer characteristics in aĬhannel. Transfer characteristics in a channel with vortex generators

numerical studied the flow structure and heat They concluded a 55–65% of heat transferĪugmentation with corresponding 20–45% increase in theĪpparent friction factor for in-line arrangement case. experimentally investigated three tube rows heat exchanger elements The uses of winglet vortex generators were reported by Have received considerable attention for the advantage of heat The longitudinal vortex generators applied in various heat exchangers Used heat transfer enhancement techniques is inserting turbulators or vortex generators in channel flow. Used in heat exchanger equipment, such as chemical process,Īir condition, heat recovery, and so forth. Heat transfer augmentation techniques have been widely Savings, more compact and less expensive equipment with The higher heat transfer rates with variousĮnhancement techniques can result in substantial energy Only increases heat transfer but also reaches higher thermal These researches focused on studying a technique that not Researches have been carried on heat transfer enhancement. Operation engineers for many systems because of the increase Both reducing energy lostįrom ineffective use and improvement of performance haveīecome an increasingly significant mission for design and Is of considerable interest to investigators as it leads to

The augmentation on heat transfer is the main aim, which The op timum TEF in the range studied is around 2.9 at BR = 0.15, PR = 1, and Re = 2000. Additionally, the rise in the BR and the reduction of PR result in the increase of both the Nusselt That the longitudinal vortex flows can induce impinging flows on a tube wall leading to an extreme increase in heat transfer rate (P/D, PR) on heat transfer, pressure loss, and the thermal enhancement factor (TEF) in the round tube are studied. Effects of different blockage ratios (b/D, BR) and pitch spacing ratios Produce longitudinal vortex flows through the tested section. In-line arrangement on both sides of a plate and the closed tip pointing upstream is inserted in the middle of the tested tube to The RWVGs with an attack angle of 45∘ are mounted with Reynolds numbers based on the diameter of the tube, Re = 100 to 2000. The fluid flow and heat transfer characteristics are proposed for Generators (RWVG) with closed end are investigated numerically. This is an open access article distributed under the CreativeĬommons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided theįully developed periodic laminar flow and heat transfer in an isothermal wall tube with 45∘ upstream rectangular winglet vortex Withada Jedsadaratanachai and Nuthvipa Jayranaiwachiraĭepartment of Mechanical Engineering, Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang,Ĭorrespondence should be addressed to Withada Jedsadaratanachai 19 September 2013 Accepted 30 December 2013 Published 1 April 2014Ĭopyright © 2014 W. Heat Transfer, and Thermal Performance in a Round Tube Effect of Pitch to Height Ratio on Flow Visualization,