Keywords : Internal flow
Heat Transfer Enhancement for Rectangular Channels by Using Triangular-Shaped Ribs at High Reynold Numbers.
journal of kerbala university,
Volume 14, Issue 1, Pages 114-124
In this paper, an experimental system was built to study the effects of triangular ribs inside a rectangular duct on the heat transfer and flow behavior. Boundary conditions were: inlet air temperature,(300o K) and Reynolds numbers (Re=8082, 9698 and 11778). The surrounding constant temperature was (473 o K). The numerical simulations were done by solving the governing equations (Continuity, Reynolds Averaging Navier-stokes, and Energy equation) with (k-ε) model in three dimensions by using the SOLIDWORKS 3D CAD software. The effects of using triangular ribs fitted in rectangular passage channel on fluid flow and heat transfer characteristics were presented in this part. Ribs used with a pitch-rib height of 10, the rectangular channel of (30x60 mm) cross section, 1.5 mm duct thickness and 0.5 m long. The temperature, velocity distribution contours, cooling air temperature distribution at the duct centerline, the inner wall surface temperature of the duct, and thermal performance factor is found in this paper. The temperature distribution for the inner wall surface of the ribbed channel is lower than smooth one by (8.9 %) for case (1) and (Re=11778). The coolant air flow velocity seems to be accelerated and decelerated through the channel in the presence of ribs, so it was shown that the thermal performance factor along the duct is larger than 1, this is due to the fact that the ribs create turbulent conditions and increasing thermal surface area, and thus increasing heat transfer coefficient than the smooth channel. It concluded that, the triangular ribs with angle of 90o,case(1) is the best as compared to the other two cases in this study for cooling the rectangular duct. After modification and analysis have been done, Nusselt Number enhanced by (36%).