Trapezoidal Channel Research Articles

Design of Thick Electrodes with Vertical Channels for Aqueous Batteries: Experimental and Numerical Analysis.

Developing thick electrodes with high-area loadings is a direct method for boosting the energy density. However, this approach also leads to a proportional increase in the resistance to charge transport. Optimizing the microstructure of the electrode can effectively enhance the charge transport kinetics in thick electrodes. Herein, a low-tortuosity nickel electrode with vertical channels (VC-Ni) is fabricated using a phase inversion method. A high-loading VC-Ni electrode (26.7 mg cm-2) delivers a superior specific capacity of 134.0 mAh g-1 at a 5 C rate, significantly outperforming the conventional nickel electrode (Con-Ni). Numerical simulations reveal the fast transport kinetics within the vertical channel electrodes. For the thick electrode, the VC-Ni electrode shows a substantially lower concentration gradient of OH- and H+ compared to the Con-Ni electrode. Notably, beyond a critical loading of 26.5 mg cm-2, the specific capacity initially increases with volume fraction, peaking at 50%, and then diminishes. The specific capacity increases as the channel size decreases, but the tendency to increase gradually decreases. The highest specific capacity is achieved with an inverted trapezoidal channel shape, characterized by larger pores near the separator and smaller pores near the current collector. This work is of guidance for the design of thick electrodes for high-performance aqueous batteries.

Phosphorus supply and floodplain design govern phosphorus reduction capacity in remediated agricultural streams

Abstract. Agricultural headwater streams are important pathways for diffuse sediment and nutrient losses, requiring mitigation strategies beyond in-field measures to intercept the transport of pollutants to downstream freshwater resources. As such, floodplains can be constructed along existing agricultural streams and ditches to improve fluvial stability and promote deposition of sediments and particulate phosphorus. In this study, we evaluated 10 remediated agricultural streams in Sweden for their capacity to reduce sediment and particulate phosphorus export and investigated the interplay between fluvial processes and phosphorus dynamics. Remediated streams with different floodplain designs (either on one side or both sides of the channel, with different width and elevation) were paired with upstream trapezoidal channels as controls. We used sedimentation plates to determine seasonal patterns in sediment deposition on channel beds and floodplains and monthly water quality monitoring. This was combined with continuous flow discharge measurements to examine suspended sediment and particulate phosphorus dynamics and reduction along reaches. Remediated streams with floodplains on both sides of the channel reduced particulate phosphorus concentrations and loads (−54 µg L−1, −0.21 kg ha−1 yr−1) along reaches, whereas increases occurred along streams with one-sided floodplains (27 µg L−1, 0.09 kg ha−1 yr−1) and control streams (46.6 µg L−1). Sediment deposition in remediated streams was five times higher on channel beds than on floodplains and there was no evident lateral distribution of sediments from channel to floodplains. There was no effect from sediment deposition on particulate phosphorus reduction, suggesting that bank stabilization was the key determinant for phosphorus mitigation in remediated streams, which can be realized with two-sided but not one-sided floodplains. Further, the overall narrow floodplain widths likely restricted reach-scale sediment deposition and its impact on P reductions. To fully understand remediated streams' potential for reductions in both nitrogen and different phosphorus species and to avoid pollution swapping effects, there is a need to further investigate how floodplain design can be optimized to achieve a holistic solution towards improved stream water quality.

Preissmann Four-Point Methods for Solution of Simplified Saint-Venant Equations Applied to Flood Routing in Prismatic Open Channels

This research goal to compare the flow properties in the rectangular and trapezoidal open channels by examining the influence of the channel side slope is depicted by simplified Saint Venant Equations. The solution of these equations has been completed numerically by using Preissmann four-point scheme. The model is simulated using the Matlab application to point out the flow properties. The proposed model is validated by the model without simplification which was selected from the literature. The validation outcomes indicate that in common, the simulation outcomes of the two models have a good agreement. The simulation results show that the greater the slope of the channel side, the greater the peak discharge and the greater the time shift. The analysis emphasizes how channel geometry influences flow behavior, indicating that trapezoidal channels, with inclined side slopes z, yield slightly higher peak discharges compared to rectangular ones. For z = 0, discharge of peak Q = 7.38 m3/s and t = 18 s. For z = 2, discharge of peak Q = 7.39 m3/s and t = 21 s. For z = 4, discharge of peak Q = 7.45 m3/s and t = 23 s. For z = 6, discharge of peak Q = 7.51 m3/s and t = 24 s.

Matric Flux Potential in Time Independent Infiltration Problems from a Single Triangular and a Trapezoidal Irrigation Channel

In this paper, steady infiltration problems into a homogeneous soil from a single triangular and trapezoidal irrigation channel are considered. The governing equation is Richard's equation that represents the movement of water in unsaturated soil. It is a non-linear equation and can be solved by linearizing to become a modified Helmholtz equation. Dual Reciprocity Boundary Element Methods (DRBEM) are used in this study to numerically solve the modified Helmholtz equation. Therefore, by using a provided solution, the numerical Matric Flux Potential (MFP) is calculated. This method was applied to the homogeneous soil problem of stationer infiltration from triangular and trapezoidal single irrigation. Both numerical solutions were compared. The result show that the MFP value from the triangular irrigation is higher than the trapezoidal irrigation. This indicates that content water from the triangular irrigation channel is higher than the trapezoidal irrigation channel.

Two-phase flow dynamics study in the trapezoidal gas channel of PEM fuel cell based on lattice Boltzmann model

ABSTRACT Water management is a critical challenge in ensuring the performance and durability of low-temperature proton exchange membrane fuel cells (PEMFCs). This study utilizes the phase-field lattice Boltzmann method to conduct three-dimensional numerical simulations, investigating the dynamics of two-phase flow in the cathode gas channel (GC) of PEMFC with a trapezoidal cross-section. The effects of the water inlet location, the surface wettability of GC, the open angle of GC, and the air velocity on liquid water distribution and discharge are analyzed. The results indicate that positioning the water inlet in the middle of the GC significantly enhances PEMFC performance while having minimal impact on average pressure drop. A wall contact angle of 70° or 110°Can optimize fuel cell performance from different directions. Setting a wall contact angle at 70° optimizes gas flow stability and maintains a low-pressure drop value for the GC. A wall contact angle of 110° focuses on optimizing gas reactant diffusion ability into porous electrodes and GC drainage rate. An opening angle of 55° for the trapezoidal gas channel improves overall fuel cell performance. Increasing air velocity facilitates the film flow formation of liquid water on top wall surfaces within the GC.

Perencanaan Saluran Terbuka Drainase Area Penambangan Komoditas Feldspar di Kecamatan Gandusari

PT MAS operates in the mining sector, extracting white rocks or feldspar from steep and rugged slopes. Inadequate drainage systems pose significant challenges, such as floods, erosion, and landslides, emphasizing the critical role of effective drainage in mining activities. The designed drainage system incorporates trapezoidal open channels at the mining steps' base. Before reaching natural water bodies, mining water is directed to sedimentation ponds to settle sediments. This research, an experimental study correlating theory with field data, begins with a literature review on open channel drainage theories in mining areas. Data collection includes location specifics, mining area dimensions, rainfall, and runoff coefficients. Manning equation calculations determine planned open channel dimensions, with a bottom width of 0.45 m, flow depth of 0.39 m, freeboard height of 0.097 m, water surface width of 0.9 m, and a slope angle of 60⁰. The research aims to contribute insights for the development and management of open channel drainage systems in mining areas.

Study on heat transfer characteristics of supercritical co2 printed circuit heat exchangers with different shape channels

Printed circuit heat exchanger (PCHE) is a microchannel heat exchanger. Because of its high efficiency, high pressure and high temperature resistance, it has been widely used in photovoltaic power generation, nuclear energy and other fields. In particular, the research on the cross section shape of heat exchanger channel has been widely concerned by researchers. In this paper, the PCHE performance of semi-circular, square and trapezoidal channels with the same inlet and outlet area is compared under the pressure of 8MPa. The heat transfer performance of the mass flow rate in the range of 500-2000 kg /(m2) under three cross section shapes was investigated. The results show that the heat transfer effect of fluid in the trapezoidal channel is obviously better than the other two channels. This is mainly because the heat exchange contact area of cold and hot fluids in the trapezoidal channel is large, resulting in an increase in heat exchange between cold and hot fluids. When the inlet velocity is the same, the Reynolds number of the fluid in the trapezoidal channel is larger. The outlet temperature of the cold fluid in the trapezoidal channel is 7.9% higher than that in the semi-circular channel and 4.1% higher than that in the rectangular channel. The outlet temperature of the hot fluid in the trapezoidal channel is 6.28% lower than that in the semi-circular interface channel and 3.4% lower than that in the square channel. The trapezoidal channel has better PCHE heat transfer effect and better heat transfer performance.

Improving Hydraulic Performance of Drip Irrigation Emitters Through CFD Analysis

A drip irrigation system delicately nourishes plant roots by gently delivering water drop by drop, ensuring minimal water loss due to runoff or evaporation. This method allows soil particles ample time to absorb and retain the water, promoting optimal plant hydration. To enhance the efficiency of drip irrigation, a mesmerizingly detailed 3D solid model of a drip emitter was meticulously crafted using cutting-edge SolidWorks software, revolutionizing the irrigation system's performance. CFD simulation technique is used to understanding the internal flow behavior and optimum pressure inside the in -line drip irrigation emitters. Their labyrinth structures of channels are main cause of change in flow behavior and optimum pressure in the drip irrigation emitters. Standard k-ɛ model and Enhanced wall function are used to simulate the flow behavior in labyrinth channels. Key findings are the efficiency of triangular channel is greater than the other channels (rectangular, trapezoidal and circular) based on analysis of flow rate. The value of Discharge coefficient of these channels from CFD simulation present a relationship of kCircular>kTrapezoidal>kRectangular>kTriangular. When the channel shape is smooth (like a circular channel) than the higher value of k. The efficiency of triangular channel is greater than the other channels (rectangular, trapezoidal and circular) based on analysis of flow rate. Discharge is increased by 76%, 68.42%,66.67% and 39.39% for circular channel, Trapezoidal channel, rectangular channel and Triangular Channel respectively for pressure range of 1.02m of water head to 10.2m of water head.

Study of a Hydraulic Jump in an Asymmetric Trapezoidal Channel with Different Sluice Gates

Study of a Hydraulic Jump in an Asymmetric Trapezoidal Channel with Different Sluice Gates

Efficient separation of large particles and giant cancer cells using an isosceles trapezoidal spiral microchannel.

Polyploid giant cancer cells (PGCCs) contribute to the genetic heterogeneity and evolutionary dynamics of tumors. Their size, however, complicates their isolation from mainstream tumor cell populations. Standard techniques like fluorescence-activated cell sorting (FACS) rely on fluorescent labeling, introducing potential challenges in subsequent PGCC analyses. In response, we developed the Isosceles Trapezoidal Spiral Microchannel (ITSμC), a microfluidic device optimizing the Dean drag force (FD) and exploiting uniform vortices for enhanced separation. Numerical simulations highlighted ITSμC's advantage in producing robust FD compared to rectangular and standard trapezoidal channels. Empirical results confirmed its ability to segregate larger polystyrene (PS) particles (avg. diameter: 50 μm) toward the inner wall, while directing smaller ones (avg. diameter: 23 μm) outward. Utilizing ITSμC, we efficiently isolated PGCCs from doxorubicin-resistant triple-negative breast cancer (DOXR-TNBC) and patient-derived cancer (PDC) cells, achieving outstanding purity, yield, and viability rates (all greater than 90%). This precision was accomplished without fluorescent markers, and the versatility of ITSμC suggests its potential in differentiating a wide range of heterogeneous cell populations.

A Study of an Empirical Sequent Depths Equation of the Hydraulic Jump in a Horizontal Trapezoidal Channel

This study used existing studies and incorporated Pi theory to establish the connection between the sequent depth ratio (y2/y1) and the influencing factors (Fr1 and M1) on the hydraulic jump on a smooth horizontal trapezoidal channel, using a physical model with a side slope of 1:1. The study proposed four equations, from which the empirical equation (Y3) was used to calculate the y2/y1 ratio of the steady jump (4.0 ≤ Fr1 ≤ 9.0). An analysis of statistical indicators for (Y3) showed that the maximum error was 7.4%, R2 was 0.98, and other statistical indicators were close to the ideal point at zero (MSE = 0.027, RMSE = 0.163, MEA = 0.129, and MAPE ≈ 2.2%). Furthermore, statistical analysis for test data also provided good results (R2 = 0.94, MSE = 0.107, RMSE = 0.327, MEA = 0.25, and MAPE ≈ 3.7%), and the maximum error reached 8.8%. Therefore, the proposed equation ensures that the calculated values can be used in practice.

Flood Estimation and Control in a Micro-Watershed Using GIS-Based Integrated Approach

Flood analyses when using a GIS-based integrated approach have been successfully applied around the world in large-sized watersheds. This study employed hydrological-hydraulic modeling to analyze flash floods by integrating HEC-HMS, HEC-RAS, and ArcGIS software for flood evaluation and control in a micro-watershed in the Samaru River, Nigeria. The watershed boundaries, its characteristics (soil and land use), the topographical survey, and the intensity duration frequency curve (IDF) of the study area were produced using data-driven techniques. The HEC-HMS model was used to derive the peak discharges for 2-, 5-, 10-, 25-, 50-, 100-, and 200-year return periods with the frequency storm method. Afterward, the water surface profiles for the respective return periods were estimated using the HEC-RAS hydrodynamic model. The simulated design flood for the 2-, 5-, 10-, 25-, 50-, 100-, and 200-year return periods at the reference location (the NUGA gate culvert) were 3.5, 6.8, 9.1, 12.1, 14.3, 16.6, and 19.0 m3/s, respectively, while those at the watershed outlet for the respective return periods were 7.5, 14.9, 20.3, 27.3, 32.6, 38.0, and 43.5 m3/s, respectively (with a water height of 0.9 m, 1.1 m, 1.3 m, 1.33 m, 1.38 m, 1.5 3m, and 1.8 m, respectively), at the NUGA gate culvert cross-section. The maximum water depths of about 0.9 m and 1.0 m were recorded in the right and left overbanks, which were similar to the simulated water depth for the 2- and 5-year return periods. Hence, for the smart control of floods passing through the river and major hydraulic structures, a minimum design height of 1.50 m is recommended. For the most economic trapezoidal channel section, a normal depth of 1.50 m, a bottom width of 1.73 m, a top width of 3.50 m, and a free board of 0.30 m is proposed to curb the overtopping of floods along the channel sub-sections. The findings of this study could help hydraulic engineers minimize flooding in streams and rivers overbanks in a micro-watershed.

Effects of Different Channel Geometries of Metallic Bipolar Plates on Proton Exchange Membrane Fuel Cell Performance

This paper investigates the effects of different channel geometries on the performance of Proton Exchange Membrane Fuel Cells (PEMFCs). The study employs computational fluid dynamics (CFD) coupled with thermal and electrochemical simulations to analyze five channel geometries (cases A to E) of bipolar plates. A thorough study on this topic is not found in the literature and aims to identify designs that optimize performance and align with cost-effective production methods. Among the various studied geometries, case D, featuring a trapezoidal cross-section, exhibited the most favorable performance compared to the others, with a current density value of 2.01 A/cm2 and a maximum temperature of 74.89 °C at 0.3 V, leading to an increase in generated power of 4.46%, compared to base case A. The trapezoidal shape enhanced the contact area with the reacting region, resulting in higher reaction rates and an improved overall performance. However, the study also highlights the relevance of velocity and turbulence, with case B demonstrating an enhanced performance due to its higher velocity, and case E benefiting from localized higher velocity regions and turbulence created by baffles. Case B can increase generated power at its peak by around 3.21%, and case E can improve it by 1.29%, with respect to case A. These findings underscore that contact area has a major impact on the PEMFC performance, but velocity and turbulence also play relevant roles. Additionally, trapezoidal channels can be easily manufactured through sheet metal-forming techniques, aligning well with new market trends of weight and cost reduction on bipolar plates. Fuel and oxygen utilization percentages, 38.14% and 62.96% at 0.3 V, respectively, further confirm the superiority of trapezoidal channels, providing insights into optimizing the PEMFC performance. This exhaustive study contributes valuable information for designing efficient metallic bipolar plates and advancing the development of practical fuel cell technologies.

Performance investigation of a hybrid PV/T collector with a novel trapezoidal fluid channel

The photovoltaic-thermal collector (PV/T) is an innovative technology that combines PV cells and solar thermal collectors into a co-generation unit, enabling full-spectrum solar utilization. This research proposes and examines a hybrid PV/T system with novel trapezoidal fluid channels embedded in graphite, arranged in a parallel S-shaped structure under outdoor conditions of Beijing. Parametric discussions and daily performance analysis are conducted to assess its effectiveness and stability. A daily average of 12.7 °C reduction in cell temperature compared to PV modules results in a relative 5.20 % improvement in electrical output under the intensity of solar radiation is 597 W/m2. Similarly, the peak temperature of the water tank reaches 56.9 °C, and thermal efficiency is enhanced by 7.86 % over conventional sheet-tube PV/T collectors. For further optimization, a constrained adaptive particle swarm optimization algorithm (EPF-APSO) is constructed based on the experimental data, implementing a variable water flow rate (VWV) strategy. Compared to a constant water flow rate (CWV), the overall energy collected varies from 2.755 to 2.828 kWh per day, potentially reducing pump energy consumption by 17.93 %. The contribution of this paper provides references on structural and operational parameters optimization of PV/T collectors applying machine learning algorithms for better comprehensive efficiency.

Numerical Analysis on the Flow Depth Behaviour in Dividing Open-Channel for Trapezoidal and Rectangular Cross-Sectional Channel

Open-channel with dividing flow refers to any side water withdrawals from streams, rivers or main channel. It has become an important issue, especially when measuring the flow rate and depth of water as part of environmental management schemes and many practical projects such as the system of irrigation and drainage, water and wastewater treatment plants and other water resources projects. Although the behaviour of water flow has been studied by the previous researchers, most studies have only been carried out in simulation and lab experiment for a straight prismatic main channel. The mathematical research has not yet been fully understood, particularly in relation to the behaviour of water flow. Therefore, in this study, the modified general equations of dividing open-channel flow for rectangular and trapezoidal in the form of non-linear polynomial equations are proposed to determine the upstream flow depth in rectangular and trapezoidal cross-sectional channel. The computations of water flow depth influenced by Froude number and discharge ratio are performed with Newton-Raphson procedure in Maple software. The numerical solution shows the good agreement with the experimental data as reported in the literature. When the discharge ratio is low, the flow depth in trapezoidal and rectangular channels exhibits similarity. However, as the discharge ratio increases, the flow depth in the rectangular channel surpasses that in the trapezoidal channel. Furthermore, as the Froude number increases, the rectangular channel experiences a greater flow depth in comparison to the trapezoidal channel.

Experimental investigation of heat transfer in the trapezoidal channel with lateral outflow under rotation conditions

The heat transfer characteristics of wedge-shaped transverse outflow channels with different pin-fins under rotating conditions were measured experimentally. The Reynolds number varies from 10,000 to 70,000, and the rotation number varies from 0 to 0.6. For non-rotating state, the Nussel number decrease along the flow direction on the pin–fin rough surface as inner smooth area, albeit marginally. For rotating state, the enhancement of Nusselt number ratio in the outer pin-fins area is significantly weaker than inner smooth area. The heat transfer of the leading and trailing surfaces shows an increasing trend with the ascend of the rotation number. At the same time, due to the Coriolis force, the heat transfer of the trailing surface is stronger than that of the leading surface. Results show that the total heat transfer of the four experimental models intensify with the increase of the total cross-sectional area of the pin-fins. In particular, the total cross-sectional area of pin fin is increased by 3 times, and the heat transfer of channel can be strengthened by 46–77%. The effective method to increase the total cross-sectional areas of the pin fins is to increase their diameters.

A Study of Flow in Open Orthogonal and Trapezoidal Channels with Gabion Walls

The turbulent characteristics of the flow in open channels with gabion walls are studied numerically. Two trapezoidal and one orthogonal channel are used along with four different heights: 100mm, 150mm, 200mm, and 250mm of sand roughness in the gabion walls. Calculations of velocity, pressure, turbulence kinetic energy and eddy viscosity show clearly that the presence of the roughness affect considerably the fluid motion. As expected, the rough elements affect the mean velocity inside the channel and near the walls. Near the solid walls, the velocity profile is significantly affected and sharply lower velocities are observed very close to the walls.

Comments on “Delta-perturbation expansion for critical flow depth problem in trapezoidal channels”

This paper discusses the study presented by Amara and Achour (2023) [10] for directly determining the critical flow depth in trapezoidal open channels. Amara and Achour (2023) [10] have focused on an analytical method based on the Delta-perturbation expansion method. There are certain drawbacks associated with the use of the Delta-perturbation expansion method to find an analytical solution of the critical flow depth for the trapezoidal open channels. The proposed complex solution by Amara and Achour (2023) [10] with many terms clearly is inaccurate for large dimensionless critical flow depth. This discussion shows that the Delta-perturbation method is not as efficient as other analytical methods such as asymptotic matching technique to develop an accurate, simple, full-range, analytical solution of the critical depth for the trapezoidal open channel sections.

Effects of cathode gas channel design on air-cooled proton exchange membrane fuel cell performance

In the study, the impact of cathode gas channel (CGC) structure on the operation of air-cooled PEMFCs is investigated by a multiphase nonisothermal model. First, the influences of tapered channel configuration on the distribution of key variable distributions are studied. The distributions of these variables are found to be coupled with the reactive transport process within the catalyst layer (CL). The variation of local current density is found to be positively correlated with the dissolved water content. Although the tapered channel design can improve the current density, the weight of the bipolar plates (BPs) will be inevitably increased. Finally, the trapezoidal channel design is proposed aiming at improving the performance without increase of fuel cell weight. Several performance indexes are employed to comprehensively evaluate the different CGC designs, and the results demonstrate that the inverted trapezoidal CGC design, with which good thermal and water management are achieved, presents the best performance among the different CGC designs studied, leading to 18.9 % increase of the mass power density and 18.6 % increase of volume power density compared with the base case design.

Uniform flow depth in trapezoidal open channels

Uniform or normal flow depth is a key parameter for designing the open channels. The majority of irrigation channels are trapezoidal. Developing an explicit single-step solution based on Manning's formula to calculate the normal depth in trapezoidal open channels is not a simple task. This is due to special mathematical behavior of the governing uniform flow equation for some values of z < 1 (z = side slope of the channel). This work has focused on analytical-based solution. In this study, for the first time, explicit solutions for trapezoidal channels have been developed using asymptote matching technique (power mean concept). This technique enables to develop a solution for the entire flow depth range. The maximum error of proposed solution for z ≥ 1 is less than 0.7%. The efficiency of the asymptote matching technique can be improved by adding a power-law relation. According to this feature, a direct solution with a wider applicable range of z is developed. The maximum error of this solution for z ≥ 0.25 is less than 0.72%. A full range solution is also developed for rectangular channels with a maximum error less than 0.1%. The proposed explicit solutions have physical concept and high accuracy and are well-suited for practical applications.