Analysis of exergy and heat transfer in a tube fitted with flapped V-baffles

Vortex generator is a device that shows promise in generating streamwise vortices that can be utilized for boosting the rate of heat transmission inside a cooling/heating system with a relatively smaller penalty in terms of friction loss. The primary goal of the current research is to maximize the comparative Nusselt number ratio ( Nu / Nu 0 ) to be as large as possible to lower the size of the system while keeping thermal performance as high as feasible to save more energy. Thus, in the current study, the impacts of inserting the flapped V -baffle vortex generator (FBVG) on the thermal effectiveness improvement of a round tube were experimentally investigated. At a fixed attack angle ( alpha = 60 degrees) and baffle blockage ratio (B-R = b/D = 0.3), the geometrical behaviors of FBVGs placed periodically along two edges of a straight tape were six different flap angles ( theta = 0 degrees, 25 degrees, 35 degrees, 45 degrees, 65 degrees and 90 degrees) and three ratios of baffle pitches ( P / D = P-R = 2.0, 1.5, and 1.0). The current V -baffles, which were positioned on both tape edges, were designed to reduce friction loss caused by interrupting the central core flow when placed on both tape sides. The measurement results focused on the friction loss and thermal behaviors, including exergy and entropy analyses for Reynolds number from 4750 to 29,270. In the findings, the Nusselt number and friction factor of FBVG at theta = 0 degrees and P-R = 1 are, respectively, up to 5.6 and 35.24 times larger than those of the smooth tube. The entropy generation ( S-gen ) seems to decline as theta and P-R increase, with the smallest S-gen found at theta = 0 degrees and P-R = 1 for lower Re. The FBVG has the greatest exergy efficiency ( eta (Ex) ) at theta = 0 degrees and P-R = 1. To find the true benefits of FBVG, its thermal performance is estimated and seen to reach a maximum at about 2.44 with Nu(R) = 4.65 at theta = 45 degrees and P-R = 1. The optimal scenario at theta = 25 degrees and P-R = 1 was preferred, however, since it yielded the largest Nu(R) = 5.42 at TEF = 2.39.