Experimental and numerical study of the hydraulic performance of a trapezoidal Piano Key weir

2013 ◽  
pp. 265-272 ◽  
Author(s):  
G Cicero ◽  
J Delisle ◽  
V Lefebvre ◽  
J Vermeulen
Keyword(s):  
Numerical Study ◽  
Hydraulic Performance ◽  
Piano Key Weir

scholarly journals Numerical Study of Thermal-Hydraulic Performance of a New Spiral Z-Type PCHE for Supercritical CO2 Brayton Cycle

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4417
Author(s):  
Tingting Xu ◽  
Hongxia Zhao ◽  
Miao Wang ◽  
Jianhui Qi
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Pressure Loss ◽  
Numerical Study ◽  
Hydraulic Performance ◽  
Optimal Structure ◽  
Original Structure ◽  
Brayton Cycle ◽  
Compact Structure ◽  
Spiral Angle

Printed circuit heat exchangers (PCHEs) have the characteristics of high temperature and high pressure resistance, as well as compact structure, so they are widely used in the supercritical carbon dioxide (S-CO2) Brayton cycle. In order to fully study the heat transfer process of the Z-type PCHE, a numerical model of traditional Z-type PCHE was established and the accuracy of the model was verified. On this basis, a new type of spiral PCHE (S-ZPCHE) is proposed in this paper. The segmental design method was used to compare the pressure changes under 5 different spiral angles, and it was found that increasing the spiral angle θ of the spiral structure will reduce the pressure drop of the fluid. The effects of different spiral angles on the thermal-hydraulic performance of S-ZPCHE were compared. The results show that the pressure loss of fluid is greatly reduced, while the heat transfer performance is slightly reduced, and it was concluded that the spiral angle of 20° is optimal. The local fluid flow states of the original structure and the optimal structure were compared to analyze the reason for the pressure drop reduction effect of the optimal structure. Finally, the performance of the optimal structure was analyzed under variable working conditions. The results show that the effect of reducing pressure loss of the new S-ZPCHE is more obvious in the low Reynolds number region.

A large eddy simulation study to assess low-speed wind and baffle orientation effects in a water treatment sedimentation basin

2018 ◽  
Vol 2017 (2) ◽  
pp. 412-421 ◽  
Author(s):  
Danial Goodarzi ◽  
Kaveh Sookhak Lari ◽  
Abolghasem Alighardashi
Keyword(s):  
Large Eddy Simulation ◽  
Wastewater Treatment Plants ◽  
Numerical Study ◽  
Three Dimensional ◽  
Passive Scalar ◽  
Hydraulic Performance ◽  
Water And Wastewater Treatment ◽  
Particle Tracing ◽  
Eddy Simulation ◽  
Large Eddy

Abstract Hydraulic performance of clarifiers in water and wastewater treatment plants significantly affects the settling efficiency of suspended particles. Structural and ambient parameters can deteriorate this performance. Through a verified three dimensional numerical study, we evaluated hydraulic performance and settling efficiency in a rectangular clarifier with a nominal hydraulic retention time (HRT) of 1 h and options for structural baffles with angles of 20°, 30°, 45° and 70°. Large eddy simulation and Lagrangian particle tracing were used to trace particles 80 to 850 μm in diameter. A passive scalar tracer study was conducted to reveal discrepancies in nominal and real HRT. By posing a 5 m/s wind, ten different scenarios were simulated. The wind caused 17% and 6% reduction in HRT and settling efficiency, respectively. Baffles improved these indicators with the 45° baffle showing the best performance with an approximate settling efficiency of 93%. The study highlighted the importance of using baffles, in particular for small size particles for which influencing factors such as wind deteriorate their settling efficiency.

Vortex Heat Transfer Enhancement in Narrow Channel by Oval Dimples Arrangement

2013 ◽  
Author(s):  
Sergey Isaev ◽  
Yaroslav Chudnovsky ◽  
Alexander Leontiev ◽  
Nikolai Kornev ◽  
Egon Hassel
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Numerical Study ◽  
Heated Surface ◽  
Spherical Shape ◽  
Narrow Channel ◽  
Constant Heat Flux ◽  
Hydraulic Performance ◽  
Equivalent Diameter ◽  
Transfer Enhancement

There are many passive techniques of heat transfer enhancement ranging from surface (2D) to volumetric (3D) vortex generators, however only a few of them are capable to provide a reliable increase in a heat transfer rate overrunning the increase in pressure losses. One of such successful techniques is the profiling of a heat transfer surface with the regulated arrangement of 3D cavities (dimples). The authors explored that the deviation of the dimple geometry from the spherical shape affects the flow structure and thermal and hydraulic performance of the dimpled wall. Detailed numerical simulation of fluid flow and heat transfer has been performed in the narrow channel with the 2.5 × 0.33 cross section normalized by the equivalent diameter of the dimple footprint at the constant Reynolds number Re = 10,000 and the constant heat flux through the dimpled wall. The oval dimple geometry was varied by changing the aspect ratio of the dimple footprint from 1 to 4.5 keeping the same footprint area. In the course of the numerical study, the optimal geometry, the arrangement and the orientation of oval dimples on the heated surface to achieve the superior thermal and hydraulic performance over the spherical cavities are established. Numerical results of local and integral heat transfer characteristics enhanced with the visual representation of the generated vortices clearly illustrated the flow restructuring and an increase in the thermal and hydraulic performance.

scholarly journals Introducing the T-shaped weir: a new nonlinear weir

2021 ◽  
Author(s):  
Behzad Noroozi ◽  
Jalal Bazargan ◽  
Akbar Safarzadeh
Keyword(s):  
Discharge Coefficient ◽  
Vertical Wall ◽  
Hydraulic Performance ◽  
Height Ratio ◽  
Maximum Increase ◽  
Labyrinth Weir ◽  
Numerical Tests ◽  
Vertical Walls ◽  
Piano Key Weir ◽  
3D Software

Abstract In the present study, a new nonlinear weir called the T-Shaped Weir (TSW), which is a combination of the Labyrinth Weir (LW) and the Piano Key Weir (PKW), was introduced, and its hydraulic performance was compared with the PKW. Based on the presence of the vertical walls at the inlet key, outlet key, or both keys, the TSW weirs were classified as type A, B, and C weirs, respectively. The flow pattern of different TSW cases was analyzed, and the discharge coefficient curves were provided. Furthermore, to accurately study the hydrodynamics of the tested weirs, the 3D numerical simulations were performed using the FLOW-3D software. The results showed that inserting a vertical wall at the upstream of the outlet keys (C-TSW type) has a negligible effect on the hydraulic performance of the PKW. A maximum increase of 16% occurred in the discharge coefficient of the B-TSW in comparison to the PKW, and up to a head to height ratio (Ht/p) of 0.45, effect of the vertical wall on increasing the performance of the B-TSW was maintained. Based on the experimental and numerical tests, the optimal height ratio of the vertical wall (Pd/P) in B-TSW with highest discharge capacity was determined equal to 0.4.

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