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Ribs are known to enhance the heat transfer between the energy-carrying fluid and the heat transfer surfaces. One effect of surface roughness is to increase momentum transfer and flow resistance. An experimental investigation of forced convection heat transfer in a rectangular channel with perforated ribs is presented. Measurements are carried out...
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... experimental setup is shown in Fig. 1. The experimental system consisted of a honeycomb, an entrance section, a test section, a centrifugal blower, an infrared thermography system, perforated ribs, and devices for measuring flow velocity, temperature and pressure difference. Air was drawn in by a variable speed fan and passed through the test section of the channel. The ...
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Citations
... Bisht et al. (2014) analyze heat transfer in the circular and rectangular tube heat exchangers by the Ansys software and reported the circular pipe heat exchanger increased the heat transfer rate by 2.5% compared to rectangular tubes. Eren and Caliskan (2015) examined the rectangular channel with perforated ribs and enhanced the convective heat transfer when choosing the ranges of Reynolds number from 5375 to 36,362. The rectangular channel contains a square baffle with a triangular obstacle that increases the heat transfer rate in the heat exchange process. ...
An experimental investigation has been done for the performance enhancement of double-slope solar still (DSSS) by incorporating channels of different shapes. There are five solar stills including one conventional solar still, and four others modified with square (Sq), rectangular (Rect), triangular (Tri), and trapezoidal (Trap) channel are used. The temperature difference between the channel inlet and outlet, basin, and glass cover was measured at an optimum basin water depth of 2 cm. It is found that incorporating the channels inside the still enhances the basin water surface temperature. Results demonstrate that the best yield rate was achieved from the trapezoidal shape channel inserted in double-slope solar still (DSSS + Trap). DSSS + Sq, DSSS + Rect, DSSS + Tri, and DSSS + Trap channels increased the yield rate by 4.35%, 13.04%, 20.28%, and 30.43% compared to conventional double-slope solar still. Energy and exergy analysis was calculated for different days in the modified solar still. The cost per liter of distillate water was least ($0.034) for DSSS + Trap system with a payback period of 6.5 months. Moreover, it is observed that the modified double-slope solar still with trapezoidal channel attachment has reduced 5.33 tons CO2 for its life cycle. Furthermore, water samples collected during experimental have a drinking quality as per requirements of the World Health Organization standards.
Graphical Abstract
... The results verified that the usage of ribs showed considerable heat transfer augmentation where Nusselt number increased with the increase of Reynolds number value. Also, Eren et al. [12] performed experimental work about heat transfer improvement in a rectangular channel by using perforated ribs. Measurements were performed with a height ratio of 0.1 and by using affixed rib pitch ratio of p/e = 12. ...
A combined numerical and experimental study is conducted to test the heat transfer enhancement and friction factor characteristics for a rectangular duct fitted with three cases of ribs turbulators: continuous ribs, intermittent-continuous-intermittent ribs, and intermittent ribs. Experiments are conducted within a turbulent flow for Reynolds numbers values varied from 10000 to 35000, pitch ratio equal to 5 and height ratio of 0.33. The numerical study carried out using ANSYS FlU-ENT17.2. The turbulence is modeled by using k-ɛ model. The results showed that the case of intermittent ribs provide the highest over performance factor while the continuous ribs indicate less overall performance factor among the considered cases. In addition, the results show that the highest values of the friction factor are marked from the case of intermittent ribs and then the case of intermittent-continuous intermittent ribs followed by continuous rib case. The continuous rib case showed the lowest friction factor. The experimental results showed a good agreement with the computational results.
... Skullong et al. [11] studied heat transfer features in a square duct fitted with different rib heights for the turbulent flow, Reynolds number ranged from 4000-40,000.The results verified that the usage of ribs showed considerable heat transfer augmentation where Nusselt number increased with the increase of Reynolds number value. Also, Eren et al. [12] performed experimental work about heat transfer improvement in a rectangular channel by using perforated ribs. Measurements were performed with a height ratio of 0.1 and by using affixed rib pitch ratio of (p/e) =12. ...
A combined numerical and experimental study is conducted to test the heat transfer enhancement and friction factor characteristics for a rectangular duct fitted with three cases of ribs turbulators: continuous ribs (CR), intermittent-continuous-intermittent ribs (ICIR) and intermittent ribs (IR). Experiments are conducted within a turbulent flow for Reynolds numbers values varied from 10000 to 35000, pitch ratio (p/e) equal to 5 and height ratio (e/H) of 0.33. The numerical study carried out using ANSYS FlUENT17.2. The turbulence is modeled by using k-? model. The results showed that the case of intermittent ribs provide the highest over performance factor while the continuous ribs indicate less overall performance factor among the considered cases. In addition, the results show that the highest values of the friction factor are marked from the case of intermittent ribs (IR) and then the case of intermittent-continuous-intermittent ribs (ICIR) followed by continuous rib case (CR). The continuous rib case showed the lowest friction factor. The experimental results showed a good agreement with the computational results.
The aim of this study is to optimize the design parameters of a heat sink on which hollow trapezoidal baffles are mounted on the bottom surface by using Taguchi experimental-design method. The Nusselt number and the friction factor are considered as performance parameters. An orthogonal array is selected as experimental plan for the six parameters: the corner angle (α), the inclination angle (β), the baffle height (H), the baffle length (L), the baffle width (S) and Reynolds number. First of all, each goal has been optimized, separately. Then, all the goals have been optimized together, considering the priority of the goals. The length of the baffle is found to be the most influential parameter on the friction factor. This can be attributed the enhanced effect of longitudinal vortices with baffle length in flow direction. Likewise, it is demonstrated that the most effective parameter on the heat transfer is Reynolds number. The results show that the baffle width (S) and the corner angle (α) have insignificant effect on Nusselt number. The maximum heat transfer was obtained at Re = 17,000, H = 36 mm, L = 45 mm, S = 26 mm, α = 0°, β = 0°. The inclination angle (β) and the baffle height (H) have nearly no effect on the friction factor. The minimum friction factor was obtained at Re = 17,000, H = 20 mm, L = 25 mm, S = 26 mm, α = 16°, β = 0°. The inclination angle (β) and the baffle height (H) have nearly no effect on the friction factor. It can be concluded that the higher heat transfer rates can be achieved with lower pressure drop penalty with this type of vortex generator in particular configurations.
