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This article presents turbulent flow patterns and thermal behaviors in a circular tube mounted with 30° multiple V-baffles. The influences of V-baffle numbers (N) of 2, 3 and 4 with pitch ratios (PR) of 1.0, 1.5 and 2.0 for Reynolds number (Re) between 3000 and 20,000 were investigated numerically at a fixed blockage ratio, BR = 0.05. These simulated results were proposed in four sections: numerical validations, flow and thermal characteristics and thermal performance. It was visible that the multiple V-baffles can help induce the impinging jet leading to disrupting the boundary layer, increasing the fluid mixing, and then enhancing the heat transfer above the plain tube alone. The rises of the number of V-baffles and the lower baffle pitch length led to raising the heat transfer and friction loss. The maximum thermal performance was obtained around 2.06 at N = 4, PR = 1.0 and lower Re. [ABSTRACT FROM AUTHOR]

The article puts forward three-dimensional computational research on heat transmission augmentation within a square channel containing 45o V-type double-baffles positioned on the lower and top parts at regular intervals in the turbulence zone for Reynolds numbers (Re) that vary from 3000 to 20,000. The primary goal of this research is to increase the thermal effectiveness and relative Nusselt number (Nu/Nu 0), in order to conserve energy and reduce the size of the heating or cooling system. The simulations utilize a finite volume approach in common with the SIMPLE algorithm, whereas the turbulent model used is the realizable k–ε. The baffles are designed to be separated vertically for reducing pressure loss. Both single V-baffles and double V-baffles have four relative pitches (PR = 0.4, 0.5, 0.6, and 1.0) and height/blockage ratios (BR = 0.05, 0.1, 0.15, and 0.2), with a fixed attack angle (α) of 45o. The computational findings show that both V-baffles are capable of producing the primary vortices, but only the double V-baffles have the ability to provide the impinging streams onto the wall, cooling the region behind the baffles. This suggests that the double V-baffles not only boost heat transmission but also reduce frictional loss. When compared to a single V-baffle, the double ones enhance heat transfer by an average of 1.04–9.94% while decreasing frictional loss by an average of 9.88–31.73%. The thermal effectiveness factor (TEF) of the double V-baffles ranges from 1.03 to 3.21, and its peak value of around 3.21 is for PR = 0.4, BR = 0.05, at lower Re. • A novel V-type double-baffle is proposed for improving thermal effectiveness. • The double-V-baffle creates impinging jets on the wall apart from the main vortex flows. • The double-V-baffle gives a higher Nu but much lower f than the single-V-baffle. • The double-V-baffle's effectiveness is up to 21% greater than the single-V-baffle. • Optimal thermal effectiveness points are reported. [ABSTRACT FROM AUTHOR]