Numerical Investigation of Flow Friction and Heat Transfer in a Channel with Various Shaped Ribs Mounted on Two Opposite Ribbed Walls

Abstract

Heat transfer and fluid flow characteristics through a channel with two - dimensional transverse ribs are numerically investigated. The effects of different shaped ribs (rectangular rib, triangular rib, cylindrical rib, concave-concave rib, convex-concave rib, long convex-short concave rib and long concave-short concave rib) are examined. The investigation is performed for the ribs mounted on top and bottom walls with rib pitch to height ratio (P/e) of 6.67, in Reynolds number between 3000 and 7000, under constant wall temperature condition. For the present case, the data predicted by SST k-omega turbulence model show better agreement with the experimental data, than those predicted by RNG k-epsilon turbulence model. The mean heat transfer, flow friction, temperature fields and the local heat transfer coefficients as well as the flow structure behaviors are reported. For the ribs considered, the channel with triangular-ribs yields the highest Nusselt number, the one with concave-concave rib provides the highest friction and the one with cylindrical rib show the best thermal enhancement. At the similar condition, the triangular rib gives higher Nusselt number than that provided by the cylindrical one by around 29.3 percent, while the cylindrical rib offers the highest thermal enhancement factor of 1.4 which is higher than that of the cylindrical one by around 1.33 percent while the cylindrical rib offers the highest thermal enhancement factor of 1.33 which is higher than that of the triangular one by around 9.6 percent. In addition, in spite of their high heat transfer, the concave-concave rib and long concave-concave rib yield low thermal performance factors, due to the prominent effect of high friction factor.

Visualization of flow characteristics between the ribbed plates via particle image velocimetry

“…The staggered arrangement (Kilicaslan and Sarac [21]) and the symmetrical arrangement (Pehlivan et al [22], Aslan et al [23]) for the triangular cross-sectional ribs have been seen. Moreover, the specific geometrical shapes for the ribs have also been encountered such as convex-concave (Wongcharee et al [8], Yemenici and Umur, [24]), semi-circular cross-sectional (Kilicaslan and Sarac [21], Nine et al [25]), sinusoidal (Aslan et al [23]), diamond-shaped (Sripattanapipat and Promvonge [26]), trapezoidal (Ahmed et al [27]) in the previous studies. However, the ribs lead to the increment of the required pumping power in the meantime due to the increasing pressure loss in such systems.…”

“…The arrangement of the ribs affects the overall performance depending on the circumstances. For example, the effects of the rectangular cross-sectional ribs on heat transfer have been considered for the staggered arrangement (Mayle [5], Webb and Ramadhyani [6], Liu and Wang [7], Wongcharee et al [8], Desrues et al [9], Xie et al [10], Marocco and Franco [11]). On the other hand, the rectangular ribs have also been investigated in terms of the symmetrical arrangement (Hwang and Liou [12], Lopez et al [13], Tafti [14], Pourmahmoud et al [15], Tokgoz et al [16]).…”

Steering Hollow Multishelled Structures in Photocatalysis: Optimizing Surface and Mass Transport

“…Compared with traditional photocatalysts, the HoMSs process abundant closed concave-convex surfaces, which can effectively reduce the radiation angle coefficient of the material, thus decreasing the heat-dissipation, and further improving the utilization of photothermal conversion energy. [133] The 3D structure of HoMSs composed of nano-microcrystals is expected to solve the problems of large activator diffusion distance, thus effectively reduce the surface quenching effect. [134] It should be pointed out unlike the randomly stacked nanoparticles, the subunits of HoMSs have close contact between each other, which are formed in the sintering process of STA.…”

Numerical analysis of heat transfer and friction factor in two-pass channels with variable rib shapes

“…The highest heat transfer performance was shown by isosceles triangular rib. Wongcharee et al [19] numerically studied the heat transfer and friction loss aspects of rectangular channel with several rib designs viz. rectangular, cylindrical, triangular, concave-convex, concave-concave, short concave-long convex and short concave-long concave.…”